1. 事前準備
假設有人問我有沒有辦法建立世界上最大的填字謎題。您回想自己在學校研究過的幾項 AI 技術，並想知道是否能使用 Flutter 來探索演算法選項，根據衍生出的運算密集問題找出解決方案。
在本程式碼研究室中，就是這麼簡單。最後，您將打造一項工具，在演算法的過程中發揮建造文字網格謎題的能力。有效的填字遊戲有許多不同的定義，這些技巧可協助您打造符合「您的」定義的謎題。
玩家可透過這款工具完成填字遊戲，運用填字產生器建立填字謎題，讓使用者解開謎題。這個謎題適用於 Android、iOS、Windows、macOS 和 Linux。在 Android 裝置上播放：
必要條件
- 完成您的第一個 Flutter 應用程式程式碼研究室
課程內容
- 如何使用隔離來執行會耗用大量運算資源的工作，同時又結合 Flutter 的
compute函式和 Riverpod 的select重建篩選器的價值快取功能。 - 如何利用
built_value和built_collection的不可變更資料結構，輕鬆導入深度優先搜尋和回溯追蹤等搜尋式的良好老時尚 AI (GOFAI) 技術。 - 如何使用
two_dimensional_scrollables套件的功能，以快速且直覺的方式顯示格線資料。
需求條件
- Flutter SDK。
- Visual Studio Code (VS Code)，需使用 Flutter 和 Dart 外掛程式。
- 適用於所選開發目標的編譯器軟體。本程式碼研究室適用於所有電腦平台、Android 和 iOS。您需要使用 VS Code 來指定 Windows，並透過 Xcode 指定 macOS 或 iOS，並且需要 Android Studio 指定 Android。
2. 建立專案
建立您的第一個 Flutter 專案
- 啟動 VS Code。
- 在指令列中輸入 flutter new，然後在選單中選取「Flutter: New Project」。
- 選取「Empty application」，然後選擇要建立專案的目錄。這應該是不需要進階權限，或在路徑中包含空格的目錄。例如主目錄或
C:\src\。
- 為專案「
generate_crossword」命名。本程式碼研究室的其餘部分會假設您將應用程式命名為generate_crossword。
Flutter 現在會建立專案資料夾，VS Code 會隨即開啟。現在，您可以使用應用程式的基本 Scaffold 覆寫兩個檔案的內容。
複製並貼上初始應用程式
- 在 VS Code 的左側窗格中，按一下「Explorer」Explorer，然後開啟
pubspec.yaml檔案。
- 將這個檔案的內容替換成以下內容：
pubspec.yaml
name: generate_crossword
description: "A new Flutter project."
publish_to: 'none'
version: 0.1.0
environment:
sdk: '>=3.3.3 <4.0.0'
dependencies:
built_collection: ^5.1.1
built_value: ^8.9.2
characters: ^1.3.0
flutter:
sdk: flutter
flutter_riverpod: ^2.5.1
intl: ^0.19.0
riverpod: ^2.5.1
riverpod_annotation: ^2.3.5
two_dimensional_scrollables: ^0.2.0
dev_dependencies:
flutter_test:
sdk: flutter
flutter_lints: ^3.0.0
build_runner: ^2.4.9
built_value_generator: ^8.9.2
custom_lint: ^0.6.4
riverpod_generator: ^2.4.0
riverpod_lint: ^2.3.10
flutter:
uses-material-design: true
pubspec.yaml 檔案會指定應用程式的基本資訊，例如目前版本及其依附元件。您會看到一系列不屬於一般空白 Flutter 應用程式的依附元件。在接下來的步驟中，所有這些套件都能受益。
- 在
lib/目錄中開啟main.dart檔案。
- 將這個檔案的內容替換成以下內容：
lib/main.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
void main() {
runApp(
ProviderScope(
child: MaterialApp(
title: 'Crossword Builder',
debugShowCheckedModeBanner: false,
theme: ThemeData(
useMaterial3: true,
colorSchemeSeed: Colors.blueGrey,
brightness: Brightness.light,
),
home: Scaffold(
body: Center(
child: Text(
'Hello, World!',
style: TextStyle(fontSize: 24),
),
),
),
),
),
);
}
- 執行這個程式碼，確認一切正常。畫面上應該會顯示新視窗，內含每個新專案規定的起始語句。有
ProviderScope，表示這個應用程式將使用riverpod管理狀態。
3. 新增字詞
填字遊戲的構成元素
填字遊戲的核心就是字詞清單。字詞會以格狀排列，有些則是跨越或向下排列，因此兩個字間會相互重疊。解開一個單字後，可從第一個字詞中得到線索做為線索。因此，第一個構成要素必須是字詞清單。
想知道這些字詞的好來源，請參閱 Peter Norvig 的「Natural Language Corpus Data」(自然語言語料庫資料) 頁面。SOWPODS 清單是實用的起點，其中有 267,750 個字。
在此步驟中，您將下載字詞清單，將其新增為 Flutter 資產，並安排 Riverpod 供應商，以便在啟動時將清單載入應用程式。
若要暫停或刪除廣告，請先按照下列步驟進行：
- 修改專案的
pubspec.yaml檔案，為所選字詞清單新增下列素材資源宣告。此資訊只會顯示應用程式設定的浮動式訊息，因為其他設定維持不變。
pubspec.yaml
flutter:
uses-material-design: true
assets: // Add this line
- assets/words.txt // And this one.
由於您尚未建立這個檔案，編輯器可能會醒目顯示最後一行出現警告。
- 使用瀏覽器和編輯器，在專案頂層建立
assets目錄，並在其中建立包含上述其中一個字詞清單的words.txt檔案。
這個程式碼是針對上述 SOWPODS 清單設計，但應該適用於所有僅由 A 到 Z 字元的字詞清單。擴充這個程式碼集以運用不同的字元集，還留待讀者一項練習。
載入字詞
如要編寫會在應用程式啟動時載入字詞清單的程式碼，請按照下列步驟操作：
- 在
lib目錄中建立providers.dart檔案。 - 請將以下內容新增到該檔案：
lib/providers.dart
import 'dart:convert';
import 'package:built_collection/built_collection.dart';
import 'package:flutter/services.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart';
part 'providers.g.dart';
/// A provider for the wordlist to use when generating the crossword.
@riverpod
Future<BuiltSet<String>> wordList(WordListRef ref) async {
// This codebase requires that all words consist of lowercase characters
// in the range 'a'-'z'. Words containing uppercase letters will be
// lowercased, and words containing runes outside this range will
// be removed.
final re = RegExp(r'^[a-z]+$');
final words = await rootBundle.loadString('assets/words.txt');
return const LineSplitter().convert(words).toBuiltSet().rebuild((b) => b
..map((word) => word.toLowerCase().trim())
..where((word) => word.length > 2)
..where((word) => re.hasMatch(word)));
}
這是您第一個適用於這個程式碼集的 Riverpod 供應商。您會發現編輯器在幾個區塊抱怨類別未定義或未產生的目標。這項專案針對多個依附元件 (包括 Riverpod) 使用程式碼產生功能，因此可能會出現未定義的類別錯誤。
- 如要開始產生程式碼，請執行下列指令：
$ dart run build_runner watch -d [INFO] Generating build script completed, took 174ms [INFO] Setting up file watchers completed, took 5ms [INFO] Waiting for all file watchers to be ready completed, took 202ms [INFO] Reading cached asset graph completed, took 65ms [INFO] Checking for updates since last build completed, took 680ms [INFO] Running build completed, took 2.3s [INFO] Caching finalized dependency graph completed, took 42ms [INFO] Succeeded after 2.3s with 122 outputs (243 actions)
變更專案時，系統會持續在背景執行這類檔案，並更新系統產生的檔案。當這個指令在 providers.g.dart 中產生程式碼後，您的編輯器應該會滿意您在上方新增至 providers.dart 的程式碼。
在 Riverpod 中，您上方定義的 wordList 函式等提供者通常會延遲例項化。不過，基於這個應用程式的用途，您需要積極載入字詞清單。Riverpod 說明文件建議您採用以下做法，與需要立即加載的供應商合作。您將立即實作此內容。
- 在
lib/widgets目錄中建立crossword_generator_app.dart檔案。 - 請將以下內容新增到該檔案：
lib/widgets/crossword_generator_app.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../providers.dart';
class CrosswordGeneratorApp extends StatelessWidget {
const CrosswordGeneratorApp({super.key});
@override
Widget build(BuildContext context) {
return _EagerInitialization(
child: Scaffold(
appBar: AppBar(
titleTextStyle: TextStyle(
color: Theme.of(context).colorScheme.primary,
fontSize: 16,
fontWeight: FontWeight.bold,
),
title: Text('Crossword Generator'),
),
body: SafeArea(
child: Consumer(
builder: (context, ref, _) {
final wordListAsync = ref.watch(wordListProvider);
return wordListAsync.when(
data: (wordList) => ListView.builder(
itemCount: wordList.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(wordList.elementAt(index)),
);
},
),
error: (error, stackTrace) => Center(
child: Text('$error'),
),
loading: () => Center(
child: CircularProgressIndicator(),
),
);
},
),
),
),
);
}
}
class _EagerInitialization extends ConsumerWidget {
const _EagerInitialization({required this.child});
final Widget child;
@override
Widget build(BuildContext context, WidgetRef ref) {
ref.watch(wordListProvider);
return child;
}
}
從兩個不同的方向來看，這個檔案很有趣。第一個是 _EagerInitialization 小工具，其唯一任務是要求您在上述步驟中建立的 wordList 提供者載入字詞清單。這個小工具是透過使用 ref.watch() 呼叫來監聽供應器，藉此達到這個目標。如要進一步瞭解這項技巧，請參閱 Riverpod 說明文件中的「立即初始化供應商」。
這個檔案中的第二個值得注意的是，Riverpod 如何處理非同步內容。如您所知，系統會將 wordList 提供者定義為非同步函式，因為從磁碟載入內容的速度很慢。在這個程式碼中查看字詞清單供應程式時，您會收到 AsyncValue<BuiltSet<String>>。該類型的 AsyncValue 部分是提供者非同步世界與小工具 build 方法同步世界之間的轉換器。
AsyncValue 的 when 方法會處理未來值可能處於的三種潛在狀態。未來可能已順利解析，此時叫用 data 回呼時可能處於錯誤狀態，此時會叫用 error 回呼，或最後可能仍在載入。when 方法會傳回已呼叫的回呼，因此這三個回呼的傳回類型都必須具有相容的傳回類型。在這個範例中，方法顯示為 Scaffold 小工具的 body 時的結果。
建立幾乎無限的清單應用程式
如要將 CrosswordGeneratorApp 小工具整合至應用程式中，請按照下列步驟操作：
- 加入下列程式碼以更新
lib/main.dart檔案：
lib/main.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'widgets/crossword_generator_app.dart'; // Add this import
void main() {
runApp(
ProviderScope(
child: MaterialApp(
title: 'Crossword Builder',
debugShowCheckedModeBanner: false,
theme: ThemeData(
useMaterial3: true,
colorSchemeSeed: Colors.blueGrey,
brightness: Brightness.light,
),
home: CrosswordGeneratorApp(), // Remove what was here and replace
),
),
);
}
- 重新啟動應用程式。畫面上應該會顯示會永久運作的捲動清單。
4. 以格線模式顯示字詞
在這個步驟中，您將使用 built_value 和 built_collection 套件建立資料結構，以建立填字遊戲。這兩個套件可將資料結構建構為不可變更的值，這有助於在 Isolates 之間輕鬆傳遞資料，以及實作深度首次搜尋和回溯追蹤作業也更加容易。
若要暫停或刪除廣告，請先按照下列步驟進行：
- 在
lib目錄中建立model.dart檔案，然後在檔案中加入下列內容：
lib/model.dart
import 'package:built_collection/built_collection.dart';
import 'package:built_value/built_value.dart';
import 'package:built_value/serializer.dart';
import 'package:characters/characters.dart';
part 'model.g.dart';
/// A location in a crossword.
abstract class Location implements Built<Location, LocationBuilder> {
static Serializer<Location> get serializer => _$locationSerializer;
/// The horizontal part of the location. The location is 0 based.
int get x;
/// The vertical part of the location. The location is 0 based.
int get y;
/// Returns a new location that is one step to the left of this location.
Location get left => rebuild((b) => b.x = x - 1);
/// Returns a new location that is one step to the right of this location.
Location get right => rebuild((b) => b.x = x + 1);
/// Returns a new location that is one step up from this location.
Location get up => rebuild((b) => b.y = y - 1);
/// Returns a new location that is one step down from this location.
Location get down => rebuild((b) => b.y = y + 1);
/// Returns a new location that is [offset] steps to the left of this location.
Location leftOffset(int offset) => rebuild((b) => b.x = x - offset);
/// Returns a new location that is [offset] steps to the right of this location.
Location rightOffset(int offset) => rebuild((b) => b.x = x + offset);
/// Returns a new location that is [offset] steps up from this location.
Location upOffset(int offset) => rebuild((b) => b.y = y - offset);
/// Returns a new location that is [offset] steps down from this location.
Location downOffset(int offset) => rebuild((b) => b.y = y + offset);
/// Pretty print a location as a (x,y) coordinate.
String prettyPrint() => '($x,$y)';
/// Returns a new location built from [updates]. Both [x] and [y] are
/// required to be non-null.
factory Location([void Function(LocationBuilder)? updates]) = _$Location;
Location._();
/// Returns a location at the given coordinates.
factory Location.at(int x, int y) {
return Location((b) {
b
..x = x
..y = y;
});
}
}
/// The direction of a word in a crossword.
enum Direction {
across,
down;
@override
String toString() => name;
}
/// A word in a crossword. This is a word at a location in a crossword, in either
/// the across or down direction.
abstract class CrosswordWord
implements Built<CrosswordWord, CrosswordWordBuilder> {
static Serializer<CrosswordWord> get serializer => _$crosswordWordSerializer;
/// The word itself.
String get word;
/// The location of this word in the crossword.
Location get location;
/// The direction of this word in the crossword.
Direction get direction;
/// Compare two CrosswordWord by coordinates, x then y.
static int locationComparator(CrosswordWord a, CrosswordWord b) {
final compareRows = a.location.y.compareTo(b.location.y);
final compareColumns = a.location.x.compareTo(b.location.x);
return switch (compareColumns) { 0 => compareRows, _ => compareColumns };
}
/// Constructor for [CrosswordWord].
factory CrosswordWord.word({
required String word,
required Location location,
required Direction direction,
}) {
return CrosswordWord((b) => b
..word = word
..direction = direction
..location.replace(location));
}
/// Constructor for [CrosswordWord].
/// Use [CrosswordWord.word] instead.
factory CrosswordWord([void Function(CrosswordWordBuilder)? updates]) =
_$CrosswordWord;
CrosswordWord._();
}
/// A character in a crossword. This is a single character at a location in a
/// crossword. It may be part of an across word, a down word, both, but not
/// neither. The neither constraint is enforced elsewhere.
abstract class CrosswordCharacter
implements Built<CrosswordCharacter, CrosswordCharacterBuilder> {
static Serializer<CrosswordCharacter> get serializer =>
_$crosswordCharacterSerializer;
/// The character at this location.
String get character;
/// The across word that this character is a part of.
CrosswordWord? get acrossWord;
/// The down word that this character is a part of.
CrosswordWord? get downWord;
/// Constructor for [CrosswordCharacter].
/// [acrossWord] and [downWord] are optional.
factory CrosswordCharacter.character({
required String character,
CrosswordWord? acrossWord,
CrosswordWord? downWord,
}) {
return CrosswordCharacter((b) {
b.character = character;
if (acrossWord != null) {
b.acrossWord.replace(acrossWord);
}
if (downWord != null) {
b.downWord.replace(downWord);
}
});
}
/// Constructor for [CrosswordCharacter].
/// Use [CrosswordCharacter.character] instead.
factory CrosswordCharacter(
[void Function(CrosswordCharacterBuilder)? updates]) =
_$CrosswordCharacter;
CrosswordCharacter._();
}
/// A crossword puzzle. This is a grid of characters with words placed in it.
/// The puzzle constraint is in the English crossword puzzle tradition.
abstract class Crossword implements Built<Crossword, CrosswordBuilder> {
/// Serializes and deserializes the [Crossword] class.
static Serializer<Crossword> get serializer => _$crosswordSerializer;
/// Width across the [Crossword] puzzle.
int get width;
/// Height down the [Crossword] puzzle.
int get height;
/// The words in the crossword.
BuiltList<CrosswordWord> get words;
/// The characters by location. Useful for displaying the crossword.
BuiltMap<Location, CrosswordCharacter> get characters;
/// Add a word to the crossword at the given location and direction.
Crossword addWord({
required Location location,
required String word,
required Direction direction,
}) {
return rebuild(
(b) => b
..words.add(
CrosswordWord.word(
word: word,
direction: direction,
location: location,
),
),
);
}
/// As a finalize step, fill in the characters map.
@BuiltValueHook(finalizeBuilder: true)
static void _fillCharacters(CrosswordBuilder b) {
b.characters.clear();
for (final word in b.words.build()) {
for (final (idx, character) in word.word.characters.indexed) {
switch (word.direction) {
case Direction.across:
b.characters.updateValue(
word.location.rightOffset(idx),
(b) => b.rebuild((bInner) => bInner.acrossWord.replace(word)),
ifAbsent: () => CrosswordCharacter.character(
acrossWord: word,
character: character,
),
);
case Direction.down:
b.characters.updateValue(
word.location.downOffset(idx),
(b) => b.rebuild((bInner) => bInner.downWord.replace(word)),
ifAbsent: () => CrosswordCharacter.character(
downWord: word,
character: character,
),
);
}
}
}
}
/// Pretty print a crossword. Generates the character grid, and lists
/// the down words and across words sorted by location.
String prettyPrintCrossword() {
final buffer = StringBuffer();
final grid = List.generate(
height,
(_) => List.generate(
width, (_) => '░', // https://www.compart.com/en/unicode/U+2591
),
);
for (final MapEntry(key: Location(:x, :y), value: character)
in characters.entries) {
grid[y][x] = character.character;
}
for (final row in grid) {
buffer.writeln(row.join());
}
buffer.writeln();
buffer.writeln('Across:');
for (final word
in words.where((word) => word.direction == Direction.across).toList()
..sort(CrosswordWord.locationComparator)) {
buffer.writeln('${word.location.prettyPrint()}: ${word.word}');
}
buffer.writeln();
buffer.writeln('Down:');
for (final word
in words.where((word) => word.direction == Direction.down).toList()
..sort(CrosswordWord.locationComparator)) {
buffer.writeln('${word.location.prettyPrint()}: ${word.word}');
}
return buffer.toString();
}
/// Constructor for [Crossword].
factory Crossword.crossword({
required int width,
required int height,
Iterable<CrosswordWord>? words,
}) {
return Crossword((b) {
b
..width = width
..height = height;
if (words != null) {
b.words.addAll(words);
}
});
}
/// Constructor for [Crossword].
/// Use [Crossword.crossword] instead.
factory Crossword([void Function(CrosswordBuilder)? updates]) = _$Crossword;
Crossword._();
}
/// Construct the serialization/deserialization code for the data model.
@SerializersFor([
Location,
Crossword,
CrosswordWord,
CrosswordCharacter,
])
final Serializers serializers = _$serializers;
這個檔案會說明資料結構的開頭，您將用來建立跨字詞。以填字遊戲為中心，填字遊戲中的水平與垂直字詞在格狀檢視畫面中有交錯組合。如要使用這個資料結構，您可以使用 Crossword.crossword 具名建構函式建構適當大小的 Crossword，然後使用 addWord 方法新增字詞。在建構最終值的過程中，_fillCharacters 方法會建立 CrosswordCharacter 的格線。
如要使用這個資料結構，請按照下列步驟操作：
- 在
lib目錄中建立utils檔案，然後在檔案中加入下列內容：
lib/utils.dart
import 'dart:math';
import 'package:built_collection/built_collection.dart';
/// A [Random] instance for generating random numbers.
final _random = Random();
/// An extension on [BuiltSet] that adds a method to get a random element.
extension RandomElements<E> on BuiltSet<E> {
E randomElement() {
return elementAt(_random.nextInt(length));
}
}
這是 BuiltSet 的擴充功能，可以輕鬆擷取組合的隨機元素。擴充功能方法可讓您輕鬆擴充類別及使用其他功能。您必須為擴充功能命名，才能在 utils.dart 檔案之外使用擴充功能。
- 在您的
lib/providers.dart檔案中，新增以下匯入項目：
lib/providers.dart
import 'dart:convert';
import 'dart:math'; // Add this import
import 'package:built_collection/built_collection.dart';
import 'package:flutter/foundation.dart'; // Add this import
import 'package:flutter/services.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'model.dart' as model; // And this import
import 'utils.dart'; // And this one
part 'providers.g.dart';
/// A provider for the wordlist to use when generating the crossword.
@riverpod
Future<BuiltSet<String>> wordList(WordListRef ref) async {
這些匯入作業會向即將建立的提供者揭露上方定義的模型。Random 已納入 dart:math 匯入作業，debugPrint 和 flutter/foundation.dart 匯入作業包含於 debugPrint、模型的 model.dart，以及 utils.dart 的 BuiltSet 擴充功能。
- 在同一個檔案的結尾新增下列提供者：
lib/providers.dart
/// An enumeration for different sizes of [model.Crossword]s.
enum CrosswordSize {
small(width: 20, height: 11),
medium(width: 40, height: 22),
large(width: 80, height: 44),
xlarge(width: 160, height: 88),
xxlarge(width: 500, height: 500);
const CrosswordSize({
required this.width,
required this.height,
});
final int width;
final int height;
String get label => '$width x $height';
}
/// A provider that holds the current size of the crossword to generate.
@Riverpod(keepAlive: true)
class Size extends _$Size {
var _size = CrosswordSize.medium;
@override
CrosswordSize build() => _size;
void setSize(CrosswordSize size) {
_size = size;
ref.invalidateSelf();
}
}
final _random = Random();
@riverpod
Stream<model.Crossword> crossword(CrosswordRef ref) async* {
final size = ref.watch(sizeProvider);
final wordListAsync = ref.watch(wordListProvider);
var crossword =
model.Crossword.crossword(width: size.width, height: size.height);
yield* wordListAsync.when(
data: (wordList) async* {
while (crossword.characters.length < size.width * size.height * 0.8) {
final word = wordList.randomElement();
final direction =
_random.nextBool() ? model.Direction.across : model.Direction.down;
final location = model.Location.at(
_random.nextInt(size.width), _random.nextInt(size.height));
crossword = crossword.addWord(
word: word, direction: direction, location: location);
yield crossword;
await Future.delayed(Duration(milliseconds: 100));
}
yield crossword;
},
error: (error, stackTrace) async* {
debugPrint('Error loading word list: $error');
yield crossword;
},
loading: () async* {
yield crossword;
},
);
}
這些變更會在應用程式中加入兩個提供者。第一個是 Size，實際上是全域變數，內含目前 CrosswordSize 列舉目前選取的值。這樣一來，UI 就能顯示畫面，同時設定建構中的填字字的大小。第二個提供者 crossword 是更有趣的建立方式。此函式會傳回一系列 Crossword。是以 Dart 提供的產生器支援建構而成，如函式中的 async* 標示。這表示，它不會結束傳回，而是會產生一系列的 Crossword，這是撰寫傳回中間結果的運算更簡單的方法。
由於 crossword 提供者函式開始時出現一對 ref.watch 呼叫，因此每當您選擇的填字大小變更及字詞清單載入完成時，Riverpod 系統將會重新啟動 Crossword 串流。
雖然您已擁有可產生填字的程式碼，但還是要向工具的使用者顯示這些字詞，將是好消息。
- 在含有以下內容的
lib/widgets目錄中建立crossword_widget.dart檔案：
lib/widgets/crossword_widget.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:two_dimensional_scrollables/two_dimensional_scrollables.dart';
import '../model.dart';
import '../providers.dart';
class CrosswordWidget extends ConsumerWidget {
const CrosswordWidget({super.key});
@override
Widget build(BuildContext context, WidgetRef ref) {
final size = ref.watch(sizeProvider);
return TableView.builder(
diagonalDragBehavior: DiagonalDragBehavior.free,
cellBuilder: _buildCell,
columnCount: size.width,
columnBuilder: (index) => _buildSpan(context, index),
rowCount: size.height,
rowBuilder: (index) => _buildSpan(context, index),
);
}
TableViewCell _buildCell(BuildContext context, TableVicinity vicinity) {
final location = Location.at(vicinity.column, vicinity.row);
return TableViewCell(
child: Consumer(
builder: (context, ref, _) {
final character = ref.watch(
crosswordProvider.select(
(crosswordAsync) => crosswordAsync.when(
data: (crossword) => crossword.characters[location],
error: (error, stackTrace) => null,
loading: () => null,
),
),
);
if (character != null) {
return Container(
color: Theme.of(context).colorScheme.onPrimary,
child: Center(
child: Text(
character.character,
style: TextStyle(
fontSize: 24,
color: Theme.of(context).colorScheme.primary,
),
),
),
);
}
return ColoredBox(
color: Theme.of(context).colorScheme.primaryContainer,
);
},
),
);
}
TableSpan _buildSpan(BuildContext context, int index) {
return TableSpan(
extent: FixedTableSpanExtent(32),
foregroundDecoration: TableSpanDecoration(
border: TableSpanBorder(
leading: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
trailing: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
),
),
);
}
}
這個小工具為 ConsumerWidget，可以直接依賴 Size 提供者，決定用於顯示 Crossword 字元的格線大小。此格狀檢視畫面會透過 two_dimensional_scrollables 套件中的 TableView 小工具完成。
值得注意的是，_buildCell 輔助函式轉譯的個別儲存格，每個儲存格都會在傳回的 Widget 樹狀結構中納入 Consumer 小工具。這可做為重新整理邊界。當 ref.watch 的傳回值有所變更時，系統會重新建立 Consumer 小工具中的所有內容。系統試圖在每次 Crossword 變更時重新建立整個樹狀結構，但這會導致使用這項設定略過許多運算。
如果查看 ref.watch 的參數，您會發現使用 crosswordProvider.select 卻能避免重新計算版面配置。這表示只有在儲存格負責轉譯變更的字元時，ref.watch 才會觸發 TableViewCell 內容的重新建構程序。這項減少重新轉譯作業，是讓 UI 持續回應的關鍵要素。
如要向使用者公開 CrosswordWidget 和 Size 供應器，請按照下列方式變更 crossword_generator_app.dart 檔案：
lib/widgets/crossword_generator_app.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../providers.dart';
import 'crossword_widget.dart'; // Add this import
class CrosswordGeneratorApp extends StatelessWidget {
const CrosswordGeneratorApp({super.key});
@override
Widget build(BuildContext context) {
return _EagerInitialization(
child: Scaffold(
appBar: AppBar(
actions: [_CrosswordGeneratorMenu()], // Add this line
titleTextStyle: TextStyle(
color: Theme.of(context).colorScheme.primary,
fontSize: 16,
fontWeight: FontWeight.bold,
),
title: Text('Crossword Generator'),
),
body: SafeArea(
child: CrosswordWidget(), // Replaces everything that was here before
),
),
);
}
}
class _EagerInitialization extends ConsumerWidget {
const _EagerInitialization({required this.child});
final Widget child;
@override
Widget build(BuildContext context, WidgetRef ref) {
ref.watch(wordListProvider);
return child;
}
}
class _CrosswordGeneratorMenu extends ConsumerWidget { // Add from here
@override
Widget build(BuildContext context, WidgetRef ref) => MenuAnchor(
menuChildren: [
for (final entry in CrosswordSize.values)
MenuItemButton(
onPressed: () => ref.read(sizeProvider.notifier).setSize(entry),
leadingIcon: entry == ref.watch(sizeProvider)
? Icon(Icons.radio_button_checked_outlined)
: Icon(Icons.radio_button_unchecked_outlined),
child: Text(entry.label),
),
],
builder: (context, controller, child) => IconButton(
onPressed: () => controller.open(),
icon: Icon(Icons.settings),
),
); // To here.
}
這裡有幾項改變。首先，用於將 wordList 算繪為 ListView 的程式碼，已替換為在先前檔案中定義的 CrosswordWidget 呼叫。另一項重大變更則是變更應用程式行為的選單開頭，開始變更填字的大小。日後的步驟中還會新增更多 MenuItemButton。執行應用程式，畫面會如下所示：
格狀檢視畫面會顯示字元，以及可讓使用者變更格狀檢視的選單。但這些文字並非拼湊起來，看起來不像填字謎題。這是因為在填字遊戲中加入字詞的方式沒有任何限制。簡單來說，真是一團亂。下一步就是掌控一切！
5. 強制執行限制
在模型中新增程式碼以強制執行跨字詞限制，是這個步驟的目標。填字遊戲有許多不同類型的填字，本程式碼研究室將以英文填字遊戲的傳統來說，展現出本程式碼研究室的風格。修改這個程式碼可以產生其他風格的填字謎題，這是供讀者練習的。
若要暫停或刪除廣告，請先按照下列步驟進行：
- 開啟
model.dart檔案，並將Crossword模型替換為下列內容：
lib/model.dart
/// A crossword puzzle. This is a grid of characters with words placed in it.
/// The puzzle constraint is in the English crossword puzzle tradition.
abstract class Crossword implements Built<Crossword, CrosswordBuilder> {
/// Serializes and deserializes the [Crossword] class.
static Serializer<Crossword> get serializer => _$crosswordSerializer;
/// Width across the [Crossword] puzzle.
int get width;
/// Height down the [Crossword] puzzle.
int get height;
/// The words in the crossword.
BuiltList<CrosswordWord> get words;
/// The characters by location. Useful for displaying the crossword,
/// or checking the proposed solution.
BuiltMap<Location, CrosswordCharacter> get characters;
/// Checks if this crossword is valid.
bool get valid {
// Check that there are no duplicate words.
final wordSet = words.map((word) => word.word).toBuiltSet();
if (wordSet.length != words.length) {
return false;
}
for (final MapEntry(key: location, value: character)
in characters.entries) {
// All characters must be a part of an across or down word.
if (character.acrossWord == null && character.downWord == null) {
return false;
}
// All characters must be within the crossword puzzle.
// No drawing outside the lines.
if (location.x < 0 ||
location.y < 0 ||
location.x >= width ||
location.y >= height) {
return false;
}
// Characters above and below this character must be related
// by a vertical word
if (characters[location.up] case final up?) {
if (character.downWord == null) {
return false;
}
if (up.downWord != character.downWord) {
return false;
}
}
if (characters[location.down] case final down?) {
if (character.downWord == null) {
return false;
}
if (down.downWord != character.downWord) {
return false;
}
}
// Characters to the left and right of this character must be
// related by a horizontal word
final left = characters[location.left];
if (left != null) {
if (character.acrossWord == null) {
return false;
}
if (left.acrossWord != character.acrossWord) {
return false;
}
}
final right = characters[location.right];
if (right != null) {
if (character.acrossWord == null) {
return false;
}
if (right.acrossWord != character.acrossWord) {
return false;
}
}
}
return true;
}
/// Add a word to the crossword at the given location and direction.
Crossword? addWord({
required Location location,
required String word,
required Direction direction,
}) {
// Require that the word is not already in the crossword.
if (words.map((crosswordWord) => crosswordWord.word).contains(word)) {
return null;
}
final wordCharacters = word.characters;
bool overlap = false;
// Check that the word fits in the crossword.
for (final (index, character) in wordCharacters.indexed) {
final characterLocation = switch (direction) {
Direction.across => location.rightOffset(index),
Direction.down => location.downOffset(index),
};
final target = characters[characterLocation];
if (target != null) {
overlap = true;
if (target.character != character) {
return null;
}
if (direction == Direction.across && target.acrossWord != null ||
direction == Direction.down && target.downWord != null) {
return null;
}
}
}
if (words.isNotEmpty && !overlap) {
return null;
}
final candidate = rebuild(
(b) => b
..words.add(
CrosswordWord.word(
word: word,
direction: direction,
location: location,
),
),
);
if (candidate.valid) {
return candidate;
} else {
return null;
}
}
/// As a finalize step, fill in the characters map.
@BuiltValueHook(finalizeBuilder: true)
static void _fillCharacters(CrosswordBuilder b) {
b.characters.clear();
for (final word in b.words.build()) {
for (final (idx, character) in word.word.characters.indexed) {
switch (word.direction) {
case Direction.across:
b.characters.updateValue(
word.location.rightOffset(idx),
(b) => b.rebuild((bInner) => bInner.acrossWord.replace(word)),
ifAbsent: () => CrosswordCharacter.character(
acrossWord: word,
character: character,
),
);
case Direction.down:
b.characters.updateValue(
word.location.downOffset(idx),
(b) => b.rebuild((bInner) => bInner.downWord.replace(word)),
ifAbsent: () => CrosswordCharacter.character(
downWord: word,
character: character,
),
);
}
}
}
}
/// Pretty print a crossword. Generates the character grid, and lists
/// the down words and across words sorted by location.
String prettyPrintCrossword() {
final buffer = StringBuffer();
final grid = List.generate(
height,
(_) => List.generate(
width, (_) => '░', // https://www.compart.com/en/unicode/U+2591
),
);
for (final MapEntry(key: Location(:x, :y), value: character)
in characters.entries) {
grid[y][x] = character.character;
}
for (final row in grid) {
buffer.writeln(row.join());
}
buffer.writeln();
buffer.writeln('Across:');
for (final word
in words.where((word) => word.direction == Direction.across).toList()
..sort(CrosswordWord.locationComparator)) {
buffer.writeln('${word.location.prettyPrint()}: ${word.word}');
}
buffer.writeln();
buffer.writeln('Down:');
for (final word
in words.where((word) => word.direction == Direction.down).toList()
..sort(CrosswordWord.locationComparator)) {
buffer.writeln('${word.location.prettyPrint()}: ${word.word}');
}
return buffer.toString();
}
/// Constructor for [Crossword].
factory Crossword.crossword({
required int width,
required int height,
Iterable<CrosswordWord>? words,
}) {
return Crossword((b) {
b
..width = width
..height = height;
if (words != null) {
b.words.addAll(words);
}
});
}
/// Constructor for [Crossword].
/// Use [Crossword.crossword] instead.
factory Crossword([void Function(CrosswordBuilder)? updates]) = _$Crossword;
Crossword._();
}
謹此提醒，您對 model.dart 和 providers.dart 檔案所做的變更需要 build_runner 才能更新各自的 model.g.dart 和 providers.g.dart 檔案。如果這些檔案尚未自動更新，您現在可以使用 dart run build_runner watch -d 重新啟動 build_runner。
如要在模型層中使用這項新功能，您必須更新提供者圖層。
- 按照下列方式編輯
providers.dart檔案：
lib/providers.dart
import 'dart:convert';
import 'dart:math';
import 'package:built_collection/built_collection.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'model.dart' as model;
import 'utils.dart';
part 'providers.g.dart';
/// A provider for the wordlist to use when generating the crossword.
@riverpod
Future<BuiltSet<String>> wordList(WordListRef ref) async {
// This codebase requires that all words consist of lowercase characters
// in the range 'a'-'z'. Words containing uppercase letters will be
// lowercased, and words containing runes outside this range will
// be removed.
final re = RegExp(r'^[a-z]+$');
final words = await rootBundle.loadString('assets/words.txt');
return const LineSplitter().convert(words).toBuiltSet().rebuild((b) => b
..map((word) => word.toLowerCase().trim())
..where((word) => word.length > 2)
..where((word) => re.hasMatch(word)));
}
/// An enumeration for different sizes of [model.Crossword]s.
enum CrosswordSize {
small(width: 20, height: 11),
medium(width: 40, height: 22),
large(width: 80, height: 44),
xlarge(width: 160, height: 88),
xxlarge(width: 500, height: 500);
const CrosswordSize({
required this.width,
required this.height,
});
final int width;
final int height;
String get label => '$width x $height';
}
/// A provider that holds the current size of the crossword to generate.
@Riverpod(keepAlive: true)
class Size extends _$Size {
var _size = CrosswordSize.medium;
@override
CrosswordSize build() => _size;
void setSize(CrosswordSize size) {
_size = size;
ref.invalidateSelf();
}
}
final _random = Random();
@riverpod
Stream<model.Crossword> crossword(CrosswordRef ref) async* {
final size = ref.watch(sizeProvider);
final wordListAsync = ref.watch(wordListProvider);
var crossword =
model.Crossword.crossword(width: size.width, height: size.height);
yield* wordListAsync.when(
data: (wordList) async* {
while (crossword.characters.length < size.width * size.height * 0.8) {
final word = wordList.randomElement();
final direction =
_random.nextBool() ? model.Direction.across : model.Direction.down;
final location = model.Location.at(
_random.nextInt(size.width), _random.nextInt(size.height));
var candidate = crossword.addWord( // Edit from here
word: word, direction: direction, location: location);
await Future.delayed(Duration(milliseconds: 10));
if (candidate != null) {
debugPrint('Added word: $word');
crossword = candidate;
yield crossword;
} else {
debugPrint('Failed to add word: $word');
} // To here.
}
yield crossword;
},
error: (error, stackTrace) async* {
debugPrint('Error loading word list: $error');
yield crossword;
},
loading: () async* {
yield crossword;
},
);
}
- 執行應用程式。UI 中幾乎不會有點麻煩，但查看記錄檔會發生這種情況。
說到發生這種事，我們難免會隨機出現一個填字。Crossword 模型中的 addWord 方法會拒絕任何不符合目前跨字詞的建議，因此，我們意外看到任何結果。
為了更加瞭解挑選要嘗試的字詞，建議您將這項運算作業從 UI 執行緒移至背景隔離。Flutter 提供非常實用的包裝函式，可用來處理工作區塊並在背景隔離中執行，也就是 compute 函式。
- 在
providers.dart檔案中，按照下列方式修改跨字詞提供者：
lib/providers.dart
@riverpod
Stream<model.Crossword> crossword(CrosswordRef ref) async* {
final size = ref.watch(sizeProvider);
final wordListAsync = ref.watch(wordListProvider);
var crossword =
model.Crossword.crossword(width: size.width, height: size.height);
yield* wordListAsync.when(
data: (wordList) async* {
while (crossword.characters.length < size.width * size.height * 0.8) {
final word = wordList.randomElement();
final direction =
_random.nextBool() ? model.Direction.across : model.Direction.down;
final location = model.Location.at(
_random.nextInt(size.width), _random.nextInt(size.height));
try {
var candidate = await compute( // Edit from here.
((String, model.Direction, model.Location) wordToAdd) {
final (word, direction, location) = wordToAdd;
return crossword.addWord(
word: word, direction: direction, location: location);
}, (word, direction, location));
if (candidate != null) {
crossword = candidate;
yield crossword;
}
} catch (e) {
debugPrint('Error running isolate: $e');
} // To here.
}
yield crossword;
},
error: (error, stackTrace) async* {
debugPrint('Error loading word list: $error');
yield crossword;
},
loading: () async* {
yield crossword;
},
);
}
這個程式碼可以正常運作。但裡面有個陷阱。如果您繼續採用這個路徑，最終將贏得並記錄錯誤，如下所示：
flutter: Error running isolate: Invalid argument(s): Illegal argument in isolate message: object is unsendable - Library:'dart:async' Class: _Future@4048458 (see restrictions listed at `SendPort.send()` documentation for more information)
flutter: <- Instance of 'AutoDisposeStreamProviderElement<Crossword>' (from package:riverpod/src/stream_provider.dart)
flutter: <- Context num_variables: 2 <- Context num_variables: 1 parent:{ Context num_variables: 2 }
flutter: <- Context num_variables: 1 parent:{ Context num_variables: 1 parent:{ Context num_variables: 2 } }
flutter: <- Closure: () => Crossword? (from package:generate_crossword/providers.dart)
這是關閉 compute 後，從供應器的背景隔離到背景隔離，無法透過 SendPort.send() 傳送。這個問題的解決方式是，確認沒有任何東西可關閉關閉且無法傳送。
第一步是將供應商與隔離程式碼分開。
- 在
lib目錄中建立isolates.dart檔案，然後加入下列內容：
lib/isolates.dart
import 'dart:math';
import 'package:built_collection/built_collection.dart';
import 'package:flutter/foundation.dart';
import 'model.dart';
import 'utils.dart';
final _random = Random();
Stream<Crossword> exploreCrosswordSolutions({
required Crossword crossword,
required BuiltSet<String> wordList,
}) async* {
while (
crossword.characters.length < crossword.width * crossword.height * 0.8) {
final word = wordList.randomElement();
final direction = _random.nextBool() ? Direction.across : Direction.down;
final location = Location.at(
_random.nextInt(crossword.width), _random.nextInt(crossword.height));
try {
var candidate = await compute(((String, Direction, Location) wordToAdd) {
final (word, direction, location) = wordToAdd;
return crossword.addWord(
word: word, direction: direction, location: location);
}, (word, direction, location));
if (candidate != null) {
crossword = candidate;
yield crossword;
}
} catch (e) {
debugPrint('Error running isolate: $e');
}
}
}
這個程式碼應相當熟悉。也是 crossword 提供者的核心功能，但現在已做為獨立產生器的功能。您現在可以更新 providers.dart 檔案，以使用這個新函式將背景隔離例項化。
lib/providers.dart
// Drop the dart:math import, the _random instance moved to isolates.dart
import 'dart:convert';
import 'package:built_collection/built_collection.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'isolates.dart'; // Add this import
import 'model.dart' as model;
// Drop the utils.dart import
part 'providers.g.dart';
/// A provider for the wordlist to use when generating the crossword.
@riverpod
Future<BuiltSet<String>> wordList(WordListRef ref) async {
// This codebase requires that all words consist of lowercase characters
// in the range 'a'-'z'. Words containing uppercase letters will be
// lowercased, and words containing runes outside this range will
// be removed.
final re = RegExp(r'^[a-z]+$');
final words = await rootBundle.loadString('assets/words.txt');
return const LineSplitter().convert(words).toBuiltSet().rebuild((b) => b
..map((word) => word.toLowerCase().trim())
..where((word) => word.length > 2)
..where((word) => re.hasMatch(word)));
}
/// An enumeration for different sizes of [model.Crossword]s.
enum CrosswordSize {
small(width: 20, height: 11),
medium(width: 40, height: 22),
large(width: 80, height: 44),
xlarge(width: 160, height: 88),
xxlarge(width: 500, height: 500);
const CrosswordSize({
required this.width,
required this.height,
});
final int width;
final int height;
String get label => '$width x $height';
}
/// A provider that holds the current size of the crossword to generate.
@Riverpod(keepAlive: true)
class Size extends _$Size {
var _size = CrosswordSize.medium;
@override
CrosswordSize build() => _size;
void setSize(CrosswordSize size) {
_size = size;
ref.invalidateSelf();
}
}
// Drop the _random instance
@riverpod
Stream<model.Crossword> crossword(CrosswordRef ref) async* {
final size = ref.watch(sizeProvider);
final wordListAsync = ref.watch(wordListProvider);
final emptyCrossword = // Edit from here
model.Crossword.crossword(width: size.width, height: size.height);
yield* wordListAsync.when(
data: (wordList) => exploreCrosswordSolutions(
crossword: emptyCrossword,
wordList: wordList,
),
error: (error, stackTrace) async* {
debugPrint('Error loading word list: $error');
yield emptyCrossword;
},
loading: () async* {
yield emptyCrossword; // To here.
},
);
}
現在您已有一個工具，可製作不同大小的填字遊戲，compute 則可在背景隔離開謎題。現在，在決定要嘗試為填字遊戲加入哪些字詞時，如果只有程式碼才能更有效率。
6. 管理工作佇列
程式碼的部分問題，就是要解決的問題實際上就是搜尋問題，而目前的解決方案則是盲目搜尋。如果程式碼的重點在於尋找附加至目前字詞的字詞，而不是隨機嘗試將字詞放在網格上的任何位置，則系統會更快找到解決方案。其中一種方法是引入一個位置的工作佇列，以嘗試尋找字詞。
程式碼目前正在建構候選解決方案，檢查候選解決方案是否有效，並且根據有效性，會納入或捨棄候選解決方案。以上是來自回溯追蹤演算法的實作範例。此實作由 built_value 和 built_collection 緩解，其有助於建立可衍生的新不可變值，因此會將共同狀態與衍生自不可變動值共用。這樣就能以低廉的價格利用潛在候選項目，不必為了深度複製而產生記憶體費用。
若要暫停或刪除廣告，請先按照下列步驟進行：
- 開啟
model.dart檔案，並為其加入下列WorkQueue定義：
lib/model.dart
/// Constructor for [Crossword].
/// Use [Crossword.crossword] instead.
factory Crossword([void Function(CrosswordBuilder)? updates]) = _$Crossword;
Crossword._();
}
// Add from here
/// A work queue for a worker to process. The work queue contains a crossword
/// and a list of locations to try, along with candidate words to add to the
/// crossword.
abstract class WorkQueue implements Built<WorkQueue, WorkQueueBuilder> {
static Serializer<WorkQueue> get serializer => _$workQueueSerializer;
/// The crossword the worker is working on.
Crossword get crossword;
/// The outstanding queue of locations to try.
BuiltMap<Location, Direction> get locationsToTry;
/// Known bad locations.
BuiltSet<Location> get badLocations;
/// The list of unused candidate words that can be added to this crossword.
BuiltSet<String> get candidateWords;
/// Returns true if the work queue is complete.
bool get isCompleted => locationsToTry.isEmpty || candidateWords.isEmpty;
/// Create a work queue from a crossword.
static WorkQueue from({
required Crossword crossword,
required Iterable<String> candidateWords,
required Location startLocation,
}) =>
WorkQueue((b) {
if (crossword.words.isEmpty) {
// Strip candidate words too long to fit in the crossword
b.candidateWords.addAll(candidateWords
.where((word) => word.characters.length <= crossword.width));
b.crossword.replace(crossword);
b.locationsToTry.addAll({startLocation: Direction.across});
} else {
// Assuming words have already been stripped to length
b.candidateWords.addAll(
candidateWords.toBuiltSet().rebuild(
(b) => b.removeAll(crossword.words.map((word) => word.word))),
);
b.crossword.replace(crossword);
crossword.characters
.rebuild((b) => b.removeWhere((location, character) {
if (character.acrossWord != null &&
character.downWord != null) {
return true;
}
final left = crossword.characters[location.left];
if (left != null && left.downWord != null) return true;
final right = crossword.characters[location.right];
if (right != null && right.downWord != null) return true;
final up = crossword.characters[location.up];
if (up != null && up.acrossWord != null) return true;
final down = crossword.characters[location.down];
if (down != null && down.acrossWord != null) return true;
return false;
}))
.forEach((location, character) {
b.locationsToTry.addAll({
location: switch ((character.acrossWord, character.downWord)) {
(null, null) =>
throw StateError('Character is not part of a word'),
(null, _) => Direction.across,
(_, null) => Direction.down,
(_, _) => throw StateError('Character is part of two words'),
}
});
});
}
});
WorkQueue remove(Location location) => rebuild((b) => b
..locationsToTry.remove(location)
..badLocations.add(location));
/// Update the work queue from a crossword derived from the current crossword
/// that this work queue is built from.
WorkQueue updateFrom(final Crossword crossword) => WorkQueue.from(
crossword: crossword,
candidateWords: candidateWords,
startLocation: locationsToTry.isNotEmpty
? locationsToTry.keys.first
: Location.at(0, 0),
).rebuild((b) => b
..badLocations.addAll(badLocations)
..locationsToTry
.removeWhere((location, _) => badLocations.contains(location)));
/// Factory constructor for [WorkQueue]
factory WorkQueue([void Function(WorkQueueBuilder)? updates]) = _$WorkQueue;
WorkQueue._();
} // To here.
/// Construct the serialization/deserialization code for the data model.
@SerializersFor([
Location,
Crossword,
CrosswordWord,
CrosswordCharacter,
WorkQueue, // Add this line
])
final Serializers serializers = _$serializers;
- 如果在新增此內容幾秒鐘後，這個檔案還存在紅色邊緣，請確認
build_runner仍在執行中。如果沒有，請執行dart run build_runner watch -d指令。
在您將引進記錄功能的程式碼中，顯示建立不同大小的填字所需時間。如果 Durations 曾採用格式良好的顯示內容，那就很理想。幸好，有了擴充方法，我們就可以根據需求新增確切方法。
- 按照下列方式編輯
utils.dart檔案：
lib/utils.dart
import 'dart:math';
import 'package:built_collection/built_collection.dart';
/// A [Random] instance for generating random numbers.
final _random = Random();
/// An extension on [BuiltSet] that adds a method to get a random element.
extension RandomElements<E> on BuiltSet<E> {
E randomElement() {
return elementAt(_random.nextInt(length));
}
}
// Add from here
/// An extension on [Duration] that adds a method to format the duration.
extension DurationFormat on Duration {
/// A human-readable string representation of the duration.
/// This format is tuned for durations in the seconds to days range.
String get formatted {
final hours = inHours.remainder(24).toString().padLeft(2, '0');
final minutes = inMinutes.remainder(60).toString().padLeft(2, '0');
final seconds = inSeconds.remainder(60).toString().padLeft(2, '0');
return switch ((inDays, inHours, inMinutes, inSeconds)) {
(0, 0, 0, _) => '${inSeconds}s',
(0, 0, _, _) => '$inMinutes:$seconds',
(0, _, _, _) => '$inHours:$minutes:$seconds',
_ => '$inDays days, $hours:$minutes:$seconds',
};
}
} // To here.
這個擴充方法利用切換運算式和模式比對記錄，選取適當方式顯示不同的時間長度 (時間介於幾秒到數天)。如要進一步瞭解這個程式碼樣式，請參閱「深入瞭解 Dart 的模式和記錄」程式碼研究室。
- 如要整合這項新功能，請替換
isolates.dart檔案來重新定義exploreCrosswordSolutions函式的定義，如下所示：
lib/isolates.dart
import 'package:built_collection/built_collection.dart';
import 'package:characters/characters.dart';
import 'package:flutter/foundation.dart';
import 'model.dart';
import 'utils.dart';
Stream<Crossword> exploreCrosswordSolutions({
required Crossword crossword,
required BuiltSet<String> wordList,
}) async* {
final start = DateTime.now();
var workQueue = WorkQueue.from(
crossword: crossword,
candidateWords: wordList,
startLocation: Location.at(0, 0),
);
while (!workQueue.isCompleted) {
final location = workQueue.locationsToTry.keys.toBuiltSet().randomElement();
try {
final crossword = await compute(((WorkQueue, Location) workMessage) {
final (workQueue, location) = workMessage;
final direction = workQueue.locationsToTry[location]!;
final target = workQueue.crossword.characters[location];
if (target == null) {
return workQueue.crossword.addWord(
direction: direction,
location: location,
word: workQueue.candidateWords.randomElement(),
);
}
var words = workQueue.candidateWords.toBuiltList().rebuild((b) => b
..where((b) => b.characters.contains(target.character))
..shuffle());
int tryCount = 0;
for (final word in words) {
tryCount++;
for (final (index, character) in word.characters.indexed) {
if (character != target.character) continue;
final candidate = workQueue.crossword.addWord(
location: switch (direction) {
Direction.across => location.leftOffset(index),
Direction.down => location.upOffset(index),
},
word: word,
direction: direction,
);
if (candidate != null) {
return candidate;
}
}
if (tryCount > 1000) {
break;
}
}
}, (workQueue, location));
if (crossword != null) {
workQueue = workQueue.updateFrom(crossword);
yield crossword;
} else {
workQueue = workQueue.remove(location);
}
} catch (e) {
debugPrint('Error running isolate: $e');
}
}
debugPrint('${crossword.width} x ${crossword.height} Crossword generated in '
'${DateTime.now().difference(start).formatted}');
}
執行這段程式碼會導致應用程式在表面上看起來完全相同，但差別在於找到完成的填字遊戲需要多久的時間。這是 1 分 29 秒內生成的 80 x 44 填字謎題。
顯而易見的問題是，我們能否加快腳步？當然可以。
7. 途徑統計資料
想要快速製作內容，瞭解實際情況會很有幫助。為達成這個目標，其中一個的好處是即時提供程序相關資訊，現在我們要新增檢測設備，並將該資訊顯示為懸浮資訊面板。
您必須從 WorkQueue 擷取要顯示的資訊，並顯示在使用者介面中。
實用的第一步是定義新的模型類別，其中包含您要顯示的資訊。
若要暫停或刪除廣告，請先按照下列步驟進行：
- 請按照下列步驟編輯
model.dart檔案，新增DisplayInfo類別：
lib/model.dart
import 'package:built_collection/built_collection.dart';
import 'package:built_value/built_value.dart';
import 'package:built_value/serializer.dart';
import 'package:characters/characters.dart';
import 'package:intl/intl.dart'; // Add this import
part 'model.g.dart';
/// A location in a crossword.
abstract class Location implements Built<Location, LocationBuilder> {
- 在檔案結尾進行下列變更，以新增
DisplayInfo類別：
lib/model.dart
/// Factory constructor for [WorkQueue]
factory WorkQueue([void Function(WorkQueueBuilder)? updates]) = _$WorkQueue;
WorkQueue._();
}
// Add from here.
/// Display information for the current state of the crossword solve.
abstract class DisplayInfo implements Built<DisplayInfo, DisplayInfoBuilder> {
static Serializer<DisplayInfo> get serializer => _$displayInfoSerializer;
/// The number of words in the grid.
String get wordsInGridCount;
/// The number of candidate words.
String get candidateWordsCount;
/// The number of locations to explore.
String get locationsToExploreCount;
/// The number of known bad locations.
String get knownBadLocationsCount;
/// The percentage of the grid filled.
String get gridFilledPercentage;
/// Construct a [DisplayInfo] instance from a [WorkQueue].
factory DisplayInfo.from({required WorkQueue workQueue}) {
final gridFilled = (workQueue.crossword.characters.length /
(workQueue.crossword.width * workQueue.crossword.height));
final fmt = NumberFormat.decimalPattern();
return DisplayInfo((b) => b
..wordsInGridCount = fmt.format(workQueue.crossword.words.length)
..candidateWordsCount = fmt.format(workQueue.candidateWords.length)
..locationsToExploreCount = fmt.format(workQueue.locationsToTry.length)
..knownBadLocationsCount = fmt.format(workQueue.badLocations.length)
..gridFilledPercentage = '${(gridFilled * 100).toStringAsFixed(2)}%');
}
/// An empty [DisplayInfo] instance.
static DisplayInfo get empty => DisplayInfo((b) => b
..wordsInGridCount = '0'
..candidateWordsCount = '0'
..locationsToExploreCount = '0'
..knownBadLocationsCount = '0'
..gridFilledPercentage = '0%');
factory DisplayInfo([void Function(DisplayInfoBuilder)? updates]) =
_$DisplayInfo;
DisplayInfo._();
} // To here.
/// Construct the serialization/deserialization code for the data model.
@SerializersFor([
Location,
Crossword,
CrosswordWord,
CrosswordCharacter,
WorkQueue,
DisplayInfo, // Add this line.
])
final Serializers serializers = _$serializers;
- 修改
isolates.dart檔案以公開WorkQueue模型，如下所示：
lib/isolates.dart
import 'package:built_collection/built_collection.dart';
import 'package:characters/characters.dart';
import 'package:flutter/foundation.dart';
import 'model.dart';
import 'utils.dart';
Stream<WorkQueue> exploreCrosswordSolutions({ // Modify this line
required Crossword crossword,
required BuiltSet<String> wordList,
}) async* {
final start = DateTime.now();
var workQueue = WorkQueue.from(
crossword: crossword,
candidateWords: wordList,
startLocation: Location.at(0, 0),
);
while (!workQueue.isCompleted) {
final location = workQueue.locationsToTry.keys.toBuiltSet().randomElement();
try {
final crossword = await compute(((WorkQueue, Location) workMessage) {
final (workQueue, location) = workMessage;
final direction = workQueue.locationsToTry[location]!;
final target = workQueue.crossword.characters[location];
if (target == null) {
return workQueue.crossword.addWord(
direction: direction,
location: location,
word: workQueue.candidateWords.randomElement(),
);
}
var words = workQueue.candidateWords.toBuiltList().rebuild((b) => b
..where((b) => b.characters.contains(target.character))
..shuffle());
int tryCount = 0;
for (final word in words) {
tryCount++;
for (final (index, character) in word.characters.indexed) {
if (character != target.character) continue;
final candidate = workQueue.crossword.addWord(
location: switch (direction) {
Direction.across => location.leftOffset(index),
Direction.down => location.upOffset(index),
},
word: word,
direction: direction,
);
if (candidate != null) {
return candidate;
}
}
if (tryCount > 1000) {
break;
}
}
}, (workQueue, location));
if (crossword != null) {
workQueue = workQueue.updateFrom(crossword); // Drop the yield crossword;
} else {
workQueue = workQueue.remove(location);
}
yield workQueue; // Add this line.
} catch (e) {
debugPrint('Error running isolate: $e');
}
}
debugPrint('${crossword.width} x ${crossword.height} Crossword generated in '
'${DateTime.now().difference(start).formatted}');
}
背景隔離正在公開工作佇列，現在則是從這個資料來源取得統計資料的方式與位置。
- 將舊的跨字詞供應器替換為工作佇列提供者，然後新增更多從工作佇列供應商串流衍生資訊的供應商：
lib/providers.dart
import 'dart:convert';
import 'dart:math'; // Add this import
import 'package:built_collection/built_collection.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'isolates.dart';
import 'model.dart' as model;
part 'providers.g.dart';
/// A provider for the wordlist to use when generating the crossword.
@riverpod
Future<BuiltSet<String>> wordList(WordListRef ref) async {
// This codebase requires that all words consist of lowercase characters
// in the range 'a'-'z'. Words containing uppercase letters will be
// lowercased, and words containing runes outside this range will
// be removed.
final re = RegExp(r'^[a-z]+$');
final words = await rootBundle.loadString('assets/words.txt');
return const LineSplitter().convert(words).toBuiltSet().rebuild((b) => b
..map((word) => word.toLowerCase().trim())
..where((word) => word.length > 2)
..where((word) => re.hasMatch(word)));
}
/// An enumeration for different sizes of [model.Crossword]s.
enum CrosswordSize {
small(width: 20, height: 11),
medium(width: 40, height: 22),
large(width: 80, height: 44),
xlarge(width: 160, height: 88),
xxlarge(width: 500, height: 500);
const CrosswordSize({
required this.width,
required this.height,
});
final int width;
final int height;
String get label => '$width x $height';
}
/// A provider that holds the current size of the crossword to generate.
@Riverpod(keepAlive: true)
class Size extends _$Size {
var _size = CrosswordSize.medium;
@override
CrosswordSize build() => _size;
void setSize(CrosswordSize size) {
_size = size;
ref.invalidateSelf();
}
}
@riverpod
Stream<model.WorkQueue> workQueue(WorkQueueRef ref) async* { // Modify this provider
final size = ref.watch(sizeProvider);
final wordListAsync = ref.watch(wordListProvider);
final emptyCrossword =
model.Crossword.crossword(width: size.width, height: size.height);
final emptyWorkQueue = model.WorkQueue.from(
crossword: emptyCrossword,
candidateWords: BuiltSet<String>(),
startLocation: model.Location.at(0, 0),
);
ref.read(startTimeProvider.notifier).start();
ref.read(endTimeProvider.notifier).clear();
yield* wordListAsync.when(
data: (wordList) => exploreCrosswordSolutions(
crossword: emptyCrossword,
wordList: wordList,
),
error: (error, stackTrace) async* {
debugPrint('Error loading word list: $error');
yield emptyWorkQueue;
},
loading: () async* {
yield emptyWorkQueue;
},
);
ref.read(endTimeProvider.notifier).end();
} // To here.
@Riverpod(keepAlive: true) // Add from here to end of file
class StartTime extends _$StartTime {
@override
DateTime? build() => _start;
DateTime? _start;
void start() {
_start = DateTime.now();
ref.invalidateSelf();
}
}
@Riverpod(keepAlive: true)
class EndTime extends _$EndTime {
@override
DateTime? build() => _end;
DateTime? _end;
void clear() {
_end = null;
ref.invalidateSelf();
}
void end() {
_end = DateTime.now();
ref.invalidateSelf();
}
}
const _estimatedTotalCoverage = 0.54;
@riverpod
Duration expectedRemainingTime(ExpectedRemainingTimeRef ref) {
final startTime = ref.watch(startTimeProvider);
final endTime = ref.watch(endTimeProvider);
final workQueueAsync = ref.watch(workQueueProvider);
return workQueueAsync.when(
data: (workQueue) {
if (startTime == null || endTime != null || workQueue.isCompleted) {
return Duration.zero;
}
try {
final soFar = DateTime.now().difference(startTime);
final completedPercentage = min(
0.99,
(workQueue.crossword.characters.length /
(workQueue.crossword.width * workQueue.crossword.height) /
_estimatedTotalCoverage));
final expectedTotal = soFar.inSeconds / completedPercentage;
final expectedRemaining = expectedTotal - soFar.inSeconds;
return Duration(seconds: expectedRemaining.toInt());
} catch (e) {
return Duration.zero;
}
},
error: (error, stackTrace) => Duration.zero,
loading: () => Duration.zero,
);
}
/// A provider that holds whether to display info.
@Riverpod(keepAlive: true)
class ShowDisplayInfo extends _$ShowDisplayInfo {
var _display = true;
@override
bool build() => _display;
void toggle() {
_display = !_display;
ref.invalidateSelf();
}
}
/// A provider that summarise the DisplayInfo from a [model.WorkQueue].
@riverpod
class DisplayInfo extends _$DisplayInfo {
@override
model.DisplayInfo build() => ref.watch(workQueueProvider).when(
data: (workQueue) => model.DisplayInfo.from(workQueue: workQueue),
error: (error, stackTrace) => model.DisplayInfo.empty,
loading: () => model.DisplayInfo.empty,
);
}
這類新供應商涵蓋全球狀態，意味著顯示資訊是否應重疊在跨字詞網格上方，以及取得的等衍生資料，例如跨字詞產生作業的執行時間。這一切的複雜之處在於，監聽器中某些狀態的監聽器具有轉換性。如果資訊顯示畫面隱藏，系統就不會監聽填字內容的開始和結束時間。如果資訊顯示時間準確無誤，則需要保留在記憶體中。在此情況下，Riverpod 屬性的 keepAlive 參數非常實用。
顯示資訊顯示畫面時，會有些許皺紋。我們希望能夠顯示目前經過的執行時間，但這裡沒有一個能輕易強制更新目前經過時間的常數。回到「在 Flutter 建構新一代 UI」程式碼研究室中，這個實用小工具可以滿足這項要求。
- 在
lib/widgets目錄中建立ticker_builder.dart檔案，然後加入下列內容：
lib/widgets/ticker_builder.dart
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
/// A Builder widget that invokes its [builder] function on every animation frame.
class TickerBuilder extends StatefulWidget {
const TickerBuilder({super.key, required this.builder});
final Widget Function(BuildContext context) builder;
@override
State<TickerBuilder> createState() => _TickerBuilderState();
}
class _TickerBuilderState extends State<TickerBuilder>
with SingleTickerProviderStateMixin {
late final Ticker _ticker;
@override
void initState() {
super.initState();
_ticker = createTicker(_handleTick)..start();
}
@override
void dispose() {
_ticker.dispose();
super.dispose();
}
void _handleTick(Duration elapsed) {
setState(() {
// Force a rebuild without changing the widget tree.
});
}
@override
Widget build(BuildContext context) => widget.builder.call(context);
}
這項小工具是雪橇床。它會在每個影格上重建內容。這通常令人擔憂，但相較於搜尋填字謎題的運算負荷，重新繪製每幅影格經過時間的計算負荷，可能會消失。如要運用這些新產生的資訊，應建立新的小工具。
- 在
lib/widgets目錄中建立crossword_info_widget.dart檔案，然後加入下列內容：
lib/widgets/crossword_info_widget.dart
class CrosswordInfoWidget extends ConsumerWidget {
const CrosswordInfoWidget({
super.key,
});
@override
Widget build(BuildContext context, WidgetRef ref) {
final size = ref.watch(sizeProvider);
final displayInfo = ref.watch(displayInfoProvider);
final startTime = ref.watch(startTimeProvider);
final endTime = ref.watch(endTimeProvider);
final remaining = ref.watch(expectedRemainingTimeProvider);
return Align(
alignment: Alignment.bottomRight,
child: Padding(
padding: const EdgeInsets.only(
right: 32.0,
bottom: 32.0,
),
child: ClipRRect(
borderRadius: BorderRadius.circular(8),
child: ColoredBox(
color: Theme.of(context).colorScheme.onPrimary.withAlpha(230),
child: Padding(
padding: const EdgeInsets.symmetric(
horizontal: 12,
vertical: 8,
),
child: DefaultTextStyle(
style: TextStyle(
fontSize: 16, color: Theme.of(context).colorScheme.primary),
child: Column(
mainAxisSize: MainAxisSize.min,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
_CrosswordInfoRichText(
label: 'Grid Size',
value: '${size.width} x ${size.height}'),
_CrosswordInfoRichText(
label: 'Words in grid',
value: displayInfo.wordsInGridCount),
_CrosswordInfoRichText(
label: 'Candidate words',
value: displayInfo.candidateWordsCount),
_CrosswordInfoRichText(
label: 'Locations to explore',
value: displayInfo.locationsToExploreCount),
_CrosswordInfoRichText(
label: 'Known bad locations',
value: displayInfo.knownBadLocationsCount),
_CrosswordInfoRichText(
label: 'Grid filled',
value: displayInfo.gridFilledPercentage),
switch ((startTime, endTime)) {
(null, _) => _CrosswordInfoRichText(
label: 'Time elapsed',
value: 'Not started yet',
),
(DateTime start, null) => TickerBuilder(
builder: (context) => _CrosswordInfoRichText(
label: 'Time elapsed',
value: DateTime.now().difference(start).formatted,
),
),
(DateTime start, DateTime end) => _CrosswordInfoRichText(
label: 'Completed in',
value: end.difference(start).formatted),
},
if (startTime != null && endTime == null)
_CrosswordInfoRichText(
label: 'Est. remaining', value: remaining.formatted),
],
),
),
),
),
),
),
);
}
}
class _CrosswordInfoRichText extends StatelessWidget {
final String label;
final String value;
const _CrosswordInfoRichText({required this.label, required this.value});
@override
Widget build(BuildContext context) => RichText(
text: TextSpan(
children: [
TextSpan(
text: '$label ',
style: DefaultTextStyle.of(context).style,
),
TextSpan(
text: value,
style: DefaultTextStyle.of(context)
.style
.copyWith(fontWeight: FontWeight.bold),
),
],
),
);
}
這個小工具就是 Riverpod 供應商之強大力量的典範。如果這五家供應商的其中任一項更新，這個小工具就會標示為重新建構。這個步驟的最後一項變更是將這個新小工具整合到使用者介面。
- 按照下列方式編輯
crossword_generator_app.dart檔案：
lib/widgets/crossword_generator_app.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../providers.dart';
import 'crossword_info_widget.dart'; // Add this import
import 'crossword_widget.dart';
class CrosswordGeneratorApp extends StatelessWidget {
const CrosswordGeneratorApp({super.key});
@override
Widget build(BuildContext context) {
return _EagerInitialization(
child: Scaffold(
appBar: AppBar(
actions: [_CrosswordGeneratorMenu()],
titleTextStyle: TextStyle(
color: Theme.of(context).colorScheme.primary,
fontSize: 16,
fontWeight: FontWeight.bold,
),
title: Text('Crossword Generator'),
),
body: SafeArea(
child: Consumer( // Modify from here
builder: (context, ref, child) {
return Stack(
children: [
Positioned.fill(
child: CrosswordWidget(),
),
if (ref.watch(showDisplayInfoProvider)) CrosswordInfoWidget(),
],
);
},
), // To here.
),
),
);
}
}
class _EagerInitialization extends ConsumerWidget {
const _EagerInitialization({required this.child});
final Widget child;
@override
Widget build(BuildContext context, WidgetRef ref) {
ref.watch(wordListProvider);
return child;
}
}
class _CrosswordGeneratorMenu extends ConsumerWidget {
@override
Widget build(BuildContext context, WidgetRef ref) => MenuAnchor(
menu Children: [
for (final entry in CrosswordSize.values)
MenuItemButton(
onPressed: () => ref.read(sizeProvider.notifier).setSize(entry),
leadingIcon: entry == ref.watch(sizeProvider)
? Icon(Icons.radio_button_checked_outlined)
: Icon(Icons.radio_button_unchecked_outlined),
child: Text(entry.label),
),
MenuItemButton( // Add from here
leadingIcon: ref.watch(showDisplayInfoProvider)
? Icon(Icons.check_box_outlined)
: Icon(Icons.check_box_outline_blank_outlined),
onPressed: () =>
ref.read(showDisplayInfoProvider.notifier).toggle(),
child: Text('Display Info'),
), // To here.
],
builder: (context, controller, child) => IconButton(
onPressed: () => controller.open(),
icon: Icon(Icons.settings),
),
);
}
這裡的兩項變更示範了不同的供應商整合方法。在 CrosswordGeneratorApp 的 build 方法中，您已導入新的 Consumer 建構工具，以納入顯示或隱藏資訊顯示時強制重建的區域。另一方面，整個下拉式選單都是一個 ConsumerWidget，無論輸入的是填字遊戲的大小，還是顯示/隱藏資訊顯示方式，系統都會重新建構該選單。要採取何種方法，通常在工程方面做出取捨，需要的是簡化作業，而不需要重新計算重新建構的小工具樹狀結構。
現在可以執行應用程式，讓使用者進一步瞭解產生跨字詞的進度。不過在填字遊戲接近尾聲時，我們發現數字的部分有所變化，但字元的網格數不多。
進一步瞭解發生的情況和原因，會有幫助。
8. 與執行緒平行處理
想要瞭解結尾慢速的原因，可以將演算法的執行過程視覺化。其中一個關鍵部分是 WorkQueue 中尚未解決的 locationsToTry。TableView 可協助我們調查這個問題。我們可以根據是否為 locationsToTry 變更儲存格顏色。
若要暫停或刪除廣告，請先按照下列步驟進行：
- 按照下列方式修改
crossword_widget.dart檔案：
lib/widgets/crossword_widget.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:two_dimensional_scrollables/two_dimensional_scrollables.dart';
import '../model.dart';
import '../providers.dart';
class CrosswordWidget extends ConsumerWidget {
const CrosswordWidget({super.key});
@override
Widget build(BuildContext context, WidgetRef ref) {
final size = ref.watch(sizeProvider);
return TableView.builder(
diagonalDragBehavior: DiagonalDragBehavior.free,
cellBuilder: _buildCell,
columnCount: size.width,
columnBuilder: (index) => _buildSpan(context, index),
rowCount: size.height,
rowBuilder: (index) => _buildSpan(context, index),
);
}
TableViewCell _buildCell(BuildContext context, TableVicinity vicinity) {
final location = Location.at(vicinity.column, vicinity.row);
return TableViewCell(
child: Consumer(
builder: (context, ref, _) {
final character = ref.watch(
workQueueProvider.select(
(workQueueAsync) => workQueueAsync.when(
data: (workQueue) => workQueue.crossword.characters[location],
error: (error, stackTrace) => null,
loading: () => null,
),
),
);
final explorationCell = ref.watch( // Add from here
workQueueProvider.select(
(workQueueAsync) => workQueueAsync.when(
data: (workQueue) =>
workQueue.locationsToTry.keys.contains(location),
error: (error, stackTrace) => false,
loading: () => false,
),
),
); // To here.
if (character != null) { // Modify from here
return AnimatedContainer(
duration: Durations.extralong1,
curve: Curves.easeInOut,
color: explorationCell
? Theme.of(context).colorScheme.primary
: Theme.of(context).colorScheme.onPrimary,
child: Center(
child: AnimatedDefaultTextStyle(
duration: Durations.extralong1,
curve: Curves.easeInOut,
style: TextStyle(
fontSize: 24,
color: explorationCell
? Theme.of(context).colorScheme.onPrimary
: Theme.of(context).colorScheme.primary,
),
child: Text(character.character),
), // To here.
),
);
}
return ColoredBox(
color: Theme.of(context).colorScheme.primaryContainer,
);
},
),
);
}
TableSpan _buildSpan(BuildContext context, int index) {
return TableSpan(
extent: FixedTableSpanExtent(32),
foregroundDecoration: TableSpanDecoration(
border: TableSpanBorder(
leading: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
trailing: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
),
),
);
}
}
執行這個程式碼時，您會看到視覺化呈現的卓越位置，指出演算法尚未進行調查。
隨著填字遊戲進度逐漸完成，值得一提的是，還有一系列待調查的要點，無法帶來任何有用的內容。這裡有幾個選項另一個做法是在填入跨字詞儲存格的特定百分比時限制調查，第二項則是一次調查多個搜尋點。第二個路徑聽起來更有樂趣，開始吧。
- 編輯
isolates.dart檔案。這幾乎是完整的程式碼重寫作業，將某一背景運算作業分割為多個 N 背景的隔離集區。
lib/isolates.dart
import 'package:built_collection/built_collection.dart';
import 'package:characters/characters.dart';
import 'package:flutter/foundation.dart';
import 'model.dart';
import 'utils.dart';
Stream<WorkQueue> exploreCrosswordSolutions({
required Crossword crossword,
required BuiltSet<String> wordList,
required int maxWorkerCount,
}) async* {
final start = DateTime.now();
var workQueue = WorkQueue.from(
crossword: crossword,
candidateWords: wordList,
startLocation: Location.at(0, 0),
);
while (!workQueue.isCompleted) {
try {
workQueue = await compute(_generate, (workQueue, maxWorkerCount));
yield workQueue;
} catch (e) {
debugPrint('Error running isolate: $e');
}
}
debugPrint('Generated ${workQueue.crossword.width} x '
'${workQueue.crossword.height} crossword in '
'${DateTime.now().difference(start).formatted} '
'with $maxWorkerCount workers.');
}
Future<WorkQueue> _generate((WorkQueue, int) workMessage) async {
var (workQueue, maxWorkerCount) = workMessage;
final candidateGeneratorFutures = <Future<(Location, Direction, String?)>>[];
final locations = workQueue.locationsToTry.keys.toBuiltList().rebuild((b) => b
..shuffle()
..take(maxWorkerCount));
for (final location in locations) {
final direction = workQueue.locationsToTry[location]!;
candidateGeneratorFutures.add(compute(_generateCandidate,
(workQueue.crossword, workQueue.candidateWords, location, direction)));
}
try {
final results = await candidateGeneratorFutures.wait;
var crossword = workQueue.crossword;
for (final (location, direction, word) in results) {
if (word != null) {
final candidate = crossword.addWord(
location: location, word: word, direction: direction);
if (candidate != null) {
crossword = candidate;
}
} else {
workQueue = workQueue.remove(location);
}
}
workQueue = workQueue.updateFrom(crossword);
} catch (e) {
debugPrint('$e');
}
return workQueue;
}
(Location, Direction, String?) _generateCandidate(
(Crossword, BuiltSet<String>, Location, Direction) searchDetailMessage) {
final (crossword, candidateWords, location, direction) = searchDetailMessage;
final target = crossword.characters[location];
if (target == null) {
return (location, direction, candidateWords.randomElement());
}
// Filter down the candidate word list to those that contain the letter
// at the current location
final words = candidateWords.toBuiltList().rebuild((b) => b
..where((b) => b.characters.contains(target.character))
..shuffle());
int tryCount = 0;
final start = DateTime.now();
for (final word in words) {
tryCount++;
for (final (index, character) in word.characters.indexed) {
if (character != target.character) continue;
final candidate = crossword.addWord(
location: switch (direction) {
Direction.across => location.leftOffset(index),
Direction.down => location.upOffset(index),
},
word: word,
direction: direction,
);
if (candidate != null) {
return switch (direction) {
Direction.across => (location.leftOffset(index), direction, word),
Direction.down => (location.upOffset(index), direction, word),
};
}
final deltaTime = DateTime.now().difference(start);
if (tryCount >= 1000 || deltaTime > Duration(seconds: 10)) {
return (location, direction, null);
}
}
}
return (location, direction, null);
}
由於核心商業邏輯並未變更，此程式碼大部分應該都熟悉。已變更的是 compute 呼叫現在有兩層。第一層負責將個別位置移出，以搜尋 N 個工作站隔離，然後在所有 N 個工作站隔離完成後重新合併結果。第二層是由 N 個工作站隔離而成。如要取得最佳效能，需同時調整電腦和相關資料。電網規模越大，工作人員就越能共同合作，不會互相干擾。
其中一個有趣的問題是，編寫程式碼，指出程式碼現在如何處理閉鎖無法擷取的事物問題。目前沒有關閉的道路。_generate 和 _generateWorker 函式會定義為頂層函式，沒有可擷取的周圍環境。傳入及上述兩項函式的結果都是 Dart 記錄的形式。透過這種方式，您可以輕鬆地處理 compute 呼叫的語意中的單一值。
現在您已經能夠建立背景工作人員集區，能夠搜尋在網格中組合而成的字詞，進而形成填字遊戲。接下來，就是向填字產生器的其餘功能介紹這項功能。
- 請按照下列方式編輯 WorkQueue 供應器，來編輯
providers.dart檔案：
lib/providers.dart
@riverpod
Stream<model.WorkQueue> workQueue(WorkQueueRef ref) async* {
final workers = ref.watch(workerCountProvider); // Add this line
final size = ref.watch(sizeProvider);
final wordListAsync = ref.watch(wordListProvider);
final emptyCrossword =
model.Crossword.crossword(width: size.width, height: size.height);
final emptyWorkQueue = model.WorkQueue.from(
crossword: emptyCrossword,
candidateWords: BuiltSet<String>(),
startLocation: model.Location.at(0, 0),
);
ref.read(startTimeProvider.notifier).start();
ref.read(endTimeProvider.notifier).clear();
yield* wordListAsync.when(
data: (wordList) => exploreCrosswordSolutions(
crossword: emptyCrossword,
wordList: wordList,
maxWorkerCount: workers.count, // Add this line
),
error: (error, stackTrace) async* {
debugPrint('Error loading word list: $error');
yield emptyWorkQueue;
},
loading: () async* {
yield emptyWorkQueue;
},
);
ref.read(endTimeProvider.notifier).end();
}
- 將
WorkerCount供應器新增至檔案結尾，如下所示：
lib/providers.dart
/// A provider that summarise the DisplayInfo from a [model.WorkQueue].
@riverpod
class DisplayInfo extends _$DisplayInfo {
@override
model.DisplayInfo build() => ref.watch(workQueueProvider).when(
data: (workQueue) => model.DisplayInfo.from(workQueue: workQueue),
error: (error, stackTrace) => model.DisplayInfo.empty,
loading: () => model.DisplayInfo.empty,
);
}
enum BackgroundWorkers { // Add from here
one(1),
two(2),
four(4),
eight(8),
sixteen(16),
thirtyTwo(32),
sixtyFour(64),
oneTwentyEight(128);
const BackgroundWorkers(this.count);
final int count;
String get label => count.toString();
}
/// A provider that holds the current number of background workers to use.
@Riverpod(keepAlive: true)
class WorkerCount extends _$WorkerCount {
var _count = BackgroundWorkers.four;
@override
BackgroundWorkers build() => _count;
void setCount(BackgroundWorkers count) {
_count = count;
ref.invalidateSelf();
}
} // To here.
進行這兩項變更後，提供者層現在能夠公開設定背景隔離集區的工作站數量上限，以正確設定區隔函式。
- 請修改
CrosswordInfoWidget以更新crossword_info_widget.dart檔案，如下所示：
lib/widgets/crossword_info_widget.dart
class CrosswordInfoWidget extends ConsumerWidget {
const CrosswordInfoWidget({
super.key,
});
@override
Widget build(BuildContext context, WidgetRef ref) {
final size = ref.watch(sizeProvider);
final displayInfo = ref.watch(displayInfoProvider);
final workerCount = ref.watch(workerCountProvider).label; // Add this line
final startTime = ref.watch(startTimeProvider);
final endTime = ref.watch(endTimeProvider);
final remaining = ref.watch(expectedRemainingTimeProvider);
return Align(
alignment: Alignment.bottomRight,
child: Padding(
padding: const EdgeInsets.only(
right: 32.0,
bottom: 32.0,
),
child: ClipRRect(
borderRadius: BorderRadius.circular(8),
child: ColoredBox(
color: Theme.of(context).colorScheme.onPrimary.withAlpha(230),
child: Padding(
padding: const EdgeInsets.symmetric(
horizontal: 12,
vertical: 8,
),
child: DefaultTextStyle(
style: TextStyle(
fontSize: 16, color: Theme.of(context).colorScheme.primary),
child: Column(
mainAxisSize: MainAxisSize.min,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
_CrosswordInfoRichText(
label: 'Grid Size',
value: '${size.width} x ${size.height}'),
_CrosswordInfoRichText(
label: 'Words in grid',
value: displayInfo.wordsInGridCount),
_CrosswordInfoRichText(
label: 'Candidate words',
value: displayInfo.candidateWordsCount),
_CrosswordInfoRichText(
label: 'Locations to explore',
value: displayInfo.locationsToExploreCount),
_CrosswordInfoRichText(
label: 'Known bad locations',
value: displayInfo.knownBadLocationsCount),
_CrosswordInfoRichText(
label: 'Grid filled',
value: displayInfo.gridFilledPercentage),
_CrosswordInfoRichText( // Add these two lines
label: 'Max worker count', value: workerCount),
switch ((startTime, endTime)) {
(null, _) => _CrosswordInfoRichText(
label: 'Time elapsed',
value: 'Not started yet',
),
(DateTime start, null) => TickerBuilder(
builder: (context) => _CrosswordInfoRichText(
label: 'Time elapsed',
value: DateTime.now().difference(start).formatted,
),
),
(DateTime start, DateTime end) => _CrosswordInfoRichText(
label: 'Completed in',
value: end.difference(start).formatted),
},
if (startTime != null && endTime == null)
_CrosswordInfoRichText(
label: 'Est. remaining', value: remaining.formatted),
],
),
),
),
),
),
),
);
}
}
- 在
_CrosswordGeneratorMenu小工具中新增下列區段，即可修改crossword_generator_app.dart檔案：
lib/widgets/crossword_generator_app.dart
class _CrosswordGeneratorMenu extends ConsumerWidget {
@override
Widget build(BuildContext context, WidgetRef ref) => MenuAnchor(
menuChildren: [
for (final entry in CrosswordSize.values)
MenuItemButton(
onPressed: () => ref.read(sizeProvider.notifier).setSize(entry),
leadingIcon: entry == ref.watch(sizeProvider)
? Icon(Icons.radio_button_checked_outlined)
: Icon(Icons.radio_button_unchecked_outlined),
child: Text(entry.label),
),
MenuItemButton(
leadingIcon: ref.watch(showDisplayInfoProvider)
? Icon(Icons.check_box_outlined)
: Icon(Icons.check_box_outline_blank_outlined),
onPressed: () =>
ref.read(showDisplayInfoProvider.notifier).toggle(),
child: Text('Display Info'),
),
for (final count in BackgroundWorkers.values) // Add from here
MenuItemButton(
leadingIcon: count == ref.watch(workerCountProvider)
? Icon(Icons.radio_button_checked_outlined)
: Icon(Icons.radio_button_unchecked_outlined),
onPressed: () =>
ref.read(workerCountProvider.notifier).setCount(count),
child: Text(count.label), // To here.
),
],
builder: (context, controller, child) => IconButton(
onPressed: () => controller.open(),
icon: Icon(Icons.settings),
),
);
}
如果您現在執行應用程式，將可以修改要例項化的背景隔離數量，以便在跨字詞中搜尋字詞。
- 按一下齒輪圖示即可開啟內容相關選單，其中包含填字內容的大小選單、是否要針對目前產生的填字顯示統計資料，以及現在要使用的隔離數量。
執行跨字詞產生器會同時使用多個核心，大幅縮短 80x44 填字的運算時間。
9. 化身遊戲
最後一部分是追加回合。您將建構出填字產生器，並運用這些技巧打造遊戲，完全可以運用在遊戲過程中學到的所有技巧。您將使用填字產生器建立填字遊戲。您將重複使用內容選單的慣用語，讓使用者選取和取消選取字詞，將其放入格線中的各個字詞形狀孔。您的目標是完成填字遊戲。
而且這個遊戲要經過精心設計，還是玩得過頭，其實還差不多。除了平衡性和難度的問題，還能改善替代字詞的選擇方式。沒有引導使用者進程的教學，而且思考動畫非常值得期待。我根本不會提到「你贏了！」。
但這樣做的取捨是適當地將這項 proto 遊戲微調成完整的遊戲，所需要的程式碼會大幅增加。單個程式碼研究室應提供的程式碼多。因此，這個速度測試步驟會變更使用方式和使用方式，以強化本程式碼研究室目前為止學到的技術。希望以上說明能強化先前在本程式碼研究室中學到的教訓。或者，您也可以依據這個程式碼，自行打造專屬體驗。我們很期待看到您打造的內容！
若要暫停或刪除廣告，請先按照下列步驟進行：
- 刪除
lib/widgets目錄中的所有內容。您將為遊戲打造閃亮的新小工具。這剛好是透過舊小工具借用許多東西。 - 請編輯
model.dart檔案，以更新Crossword的addWord方法，如下所示：
lib/model.dart
/// Add a word to the crossword at the given location and direction.
Crossword? addWord({
required Location location,
required String word,
required Direction direction,
bool requireOverlap = true, // Add this parameter
}) {
// Require that the word is not already in the crossword.
if (words.map((crosswordWord) => crosswordWord.word).contains(word)) {
return null;
}
final wordCharacters = word.characters;
bool overlap = false;
// Check that the word fits in the crossword.
for (final (index, character) in wordCharacters.indexed) {
final characterLocation = switch (direction) {
Direction.across => location.rightOffset(index),
Direction.down => location.downOffset(index),
};
final target = characters[characterLocation];
if (target != null) {
overlap = true;
if (target.character != character) {
return null;
}
if (direction == Direction.across && target.acrossWord != null ||
direction == Direction.down && target.downWord != null) {
return null;
}
}
}
// Edit from here
// If overlap is required, make sure that the word overlaps with an existing
// word. Skip this test if the crossword is empty.
if (words.isNotEmpty && !overlap && requireOverlap) { // To here.
return null;
}
final candidate = rebuild(
(b) => b
..words.add(
CrosswordWord.word(
word: word,
direction: direction,
location: location,
),
),
);
if (candidate.valid) {
return candidate;
} else {
return null;
}
}
只要對填字模型進行小幅修改，就能加入不重疊的字詞。讓玩家在 Jamboard 上隨處玩遊戲，同時仍能使用 Crossword 做為儲存玩家動作的基礎模型，十分實用。只是列出放置在特定方向的特定位置字詞清單。
- 將
CrosswordPuzzleGame模型類別新增至model.dart檔案的結尾。
lib/model.dart
/// Creates a puzzle from a crossword and a set of candidate words.
abstract class CrosswordPuzzleGame
implements Built<CrosswordPuzzleGame, CrosswordPuzzleGameBuilder> {
static Serializer<CrosswordPuzzleGame> get serializer =>
_$crosswordPuzzleGameSerializer;
/// The [Crossword] that this puzzle is based on.
Crossword get crossword;
/// The alternate words for each [CrosswordWord] in the crossword.
BuiltMap<Location, BuiltMap<Direction, BuiltList<String>>> get alternateWords;
/// The player's selected words.
BuiltList<CrosswordWord> get selectedWords;
bool canSelectWord({
required Location location,
required String word,
required Direction direction,
}) {
final crosswordWord = CrosswordWord.word(
word: word,
location: location,
direction: direction,
);
if (selectedWords.contains(crosswordWord)) {
return true;
}
var puzzle = this;
if (puzzle.selectedWords
.where((b) => b.direction == direction && b.location == location)
.isNotEmpty) {
puzzle = puzzle.rebuild((b) => b
..selectedWords.removeWhere(
(selectedWord) =>
selectedWord.location == location &&
selectedWord.direction == direction,
));
}
return null !=
puzzle.crosswordFromSelectedWords.addWord(
location: location,
word: word,
direction: direction,
requireOverlap: false);
}
CrosswordPuzzleGame? selectWord({
required Location location,
required String word,
required Direction direction,
}) {
final crosswordWord = CrosswordWord.word(
word: word,
location: location,
direction: direction,
);
if (selectedWords.contains(crosswordWord)) {
return rebuild((b) => b.selectedWords.remove(crosswordWord));
}
var puzzle = this;
if (puzzle.selectedWords
.where((b) => b.direction == direction && b.location == location)
.isNotEmpty) {
puzzle = puzzle.rebuild((b) => b
..selectedWords.removeWhere(
(selectedWord) =>
selectedWord.location == location &&
selectedWord.direction == direction,
));
}
// Check if the selected word meshes with the already selected words.
// Note this version of the crossword does not enforce overlap to
// allow the player to select words anywhere on the grid. Enforcing words
// to be solved in order is a possible alternative.
final updatedSelectedWordsCrossword =
puzzle.crosswordFromSelectedWords.addWord(
location: location,
word: word,
direction: direction,
requireOverlap: false,
);
// Make sure the selected word is in the crossword or is an alternate word.
if (updatedSelectedWordsCrossword != null) {
if (puzzle.crossword.words.contains(crosswordWord) ||
puzzle.alternateWords[location]?[direction]?.contains(word) == true) {
return puzzle.rebuild((b) => b
..selectedWords.add(CrosswordWord.word(
word: word, location: location, direction: direction)));
}
}
return null;
}
/// The crossword from the selected words.
Crossword get crosswordFromSelectedWords => Crossword.crossword(
width: crossword.width, height: crossword.height, words: selectedWords);
/// Test if the puzzle is solved. Note, this allows for the possibility of
/// multiple solutions.
bool get solved =>
crosswordFromSelectedWords.valid &&
crosswordFromSelectedWords.words.length == crossword.words.length &&
crossword.words.isNotEmpty;
/// Create a crossword puzzle game from a crossword and a set of candidate
/// words.
factory CrosswordPuzzleGame.from({
required Crossword crossword,
required BuiltSet<String> candidateWords,
}) {
// Remove all of the currently used words from the list of candidates
candidateWords = candidateWords
.rebuild((p0) => p0.removeAll(crossword.words.map((p1) => p1.word)));
// This is the list of alternate words for each word in the crossword
var alternates =
BuiltMap<Location, BuiltMap<Direction, BuiltList<String>>>();
// Build the alternate words for each word in the crossword
for (final crosswordWord in crossword.words) {
final alternateWords = candidateWords.toBuiltList().rebuild((b) => b
..where((b) => b.length == crosswordWord.word.length)
..shuffle()
..take(4)
..sort());
candidateWords =
candidateWords.rebuild((b) => b.removeAll(alternateWords));
alternates = alternates.rebuild(
(b) => b.updateValue(
crosswordWord.location,
(b) => b.rebuild(
(b) => b.updateValue(
crosswordWord.direction,
(b) => b.rebuild((b) => b.replace(alternateWords)),
ifAbsent: () => alternateWords,
),
),
ifAbsent: () => {crosswordWord.direction: alternateWords}.build(),
),
);
}
return CrosswordPuzzleGame((b) {
b
..crossword.replace(crossword)
..alternateWords.replace(alternates);
});
}
factory CrosswordPuzzleGame(
[void Function(CrosswordPuzzleGameBuilder)? updates]) =
_$CrosswordPuzzleGame;
CrosswordPuzzleGame._();
}
/// Construct the serialization/deserialization code for the data model.
@SerializersFor([
Location,
Crossword,
CrosswordWord,
CrosswordCharacter,
WorkQueue,
DisplayInfo,
CrosswordPuzzleGame, // Add this line
])
final Serializers serializers = _$serializers;
對 providers.dart 檔案的更新來說，是很有趣的變更擷取工具。目前，我們原本是為了支援收集統計資料的供應商已經移除。變更背景隔離數量的功能已經移除，並以常數取代。此外，也有新的供應商可讓您存取剛才新增的新 CrosswordPuzzleGame 模型。
lib/providers.dart
import 'dart:convert';
// Drop the dart:math import
import 'package:built_collection/built_collection.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'isolates.dart';
import 'model.dart' as model;
part 'providers.g.dart';
const backgroundWorkerCount = 4; // Add this line
/// A provider for the wordlist to use when generating the crossword.
@riverpod
Future<BuiltSet<String>> wordList(WordListRef ref) async {
// This codebase requires that all words consist of lowercase characters
// in the range 'a'-'z'. Words containing uppercase letters will be
// lowercased, and words containing runes outside this range will
// be removed.
final re = RegExp(r'^[a-z]+$');
final words = await rootBundle.loadString('assets/words.txt');
return const LineSplitter().convert(words).toBuiltSet().rebuild((b) => b
..map((word) => word.toLowerCase().trim())
..where((word) => word.length > 2)
..where((word) => re.hasMatch(word)));
}
/// An enumeration for different sizes of [model.Crossword]s.
enum CrosswordSize {
small(width: 20, height: 11),
medium(width: 40, height: 22),
large(width: 80, height: 44),
xlarge(width: 160, height: 88),
xxlarge(width: 500, height: 500);
const CrosswordSize({
required this.width,
required this.height,
});
final int width;
final int height;
String get label => '$width x $height';
}
/// A provider that holds the current size of the crossword to generate.
@Riverpod(keepAlive: true)
class Size extends _$Size {
var _size = CrosswordSize.medium;
@override
CrosswordSize build() => _size;
void setSize(CrosswordSize size) {
_size = size;
ref.invalidateSelf();
}
}
@riverpod
Stream<model.WorkQueue> workQueue(WorkQueueRef ref) async* {
final size = ref.watch(sizeProvider); // Drop the ref.watch(workerCountProvider)
final wordListAsync = ref.watch(wordListProvider);
final emptyCrossword =
model.Crossword.crossword(width: size.width, height: size.height);
final emptyWorkQueue = model.WorkQueue.from(
crossword: emptyCrossword,
candidateWords: BuiltSet<String>(),
startLocation: model.Location.at(0, 0),
);
// Drop the startTimeProvider and endTimeProvider refs
yield* wordListAsync.when(
data: (wordList) => exploreCrosswordSolutions(
crossword: emptyCrossword,
wordList: wordList,
maxWorkerCount: backgroundWorkerCount, // Edit this line
),
error: (error, stackTrace) async* {
debugPrint('Error loading word list: $error');
yield emptyWorkQueue;
},
loading: () async* {
yield emptyWorkQueue;
},
);
} // Drop the endTimeProvider ref
@riverpod // Add from here to end of file
class Puzzle extends _$Puzzle {
model.CrosswordPuzzleGame _puzzle = model.CrosswordPuzzleGame.from(
crossword: model.Crossword.crossword(width: 0, height: 0),
candidateWords: BuiltSet<String>(),
);
@override
model.CrosswordPuzzleGame build() {
final size = ref.watch(sizeProvider);
final wordList = ref.watch(wordListProvider).value;
final workQueue = ref.watch(workQueueProvider).value;
if (wordList != null &&
workQueue != null &&
workQueue.isCompleted &&
(_puzzle.crossword.height != size.height ||
_puzzle.crossword.width != size.width ||
_puzzle.crossword != workQueue.crossword)) {
compute(_puzzleFromCrosswordTrampoline, (workQueue.crossword, wordList))
.then((puzzle) {
_puzzle = puzzle;
ref.invalidateSelf();
});
}
return _puzzle;
}
Future<void> selectWord({
required model.Location location,
required String word,
required model.Direction direction,
}) async {
final candidate = await compute(
_puzzleSelectWordTrampoline, (_puzzle, location, word, direction));
if (candidate != null) {
_puzzle = candidate;
ref.invalidateSelf();
} else {
debugPrint('Invalid word selection: $word');
}
}
bool canSelectWord({
required model.Location location,
required String word,
required model.Direction direction,
}) {
return _puzzle.canSelectWord(
location: location,
word: word,
direction: direction,
);
}
}
// Trampoline functions to disentangle these Isolate target calls from the
// unsendable reference to the [Puzzle] provider.
Future<model.CrosswordPuzzleGame> _puzzleFromCrosswordTrampoline(
(model.Crossword, BuiltSet<String>) args) async =>
model.CrosswordPuzzleGame.from(crossword: args.$1, candidateWords: args.$2);
model.CrosswordPuzzleGame? _puzzleSelectWordTrampoline(
(
model.CrosswordPuzzleGame,
model.Location,
String,
model.Direction
) args) =>
args.$1.selectWord(location: args.$2, word: args.$3, direction: args.$4);
Puzzle 提供者中最有趣的部分是在 Crossword 和 wordList 中建立 CrosswordPuzzleGame 所需的成本，以及選取字詞的費用。在沒有背景隔離的情況下執行，這兩個動作都會導致 UI 互動過慢。藉由運用幾隻手功能推出中間的結果，同時在背景計算最終結果，您可以贏得回應式 UI，同時在背景中進行所需的運算。
- 在現在空白的
lib/widgets目錄中，建立含有以下內容的crossword_puzzle_app.dart檔案：
lib/widgets/crossword_puzzle_app.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../providers.dart';
import 'crossword_generator_widget.dart';
import 'crossword_puzzle_widget.dart';
import 'puzzle_completed_widget.dart';
class CrosswordPuzzleApp extends StatelessWidget {
const CrosswordPuzzleApp({super.key});
@override
Widget build(BuildContext context) {
return _EagerInitialization(
child: Scaffold(
appBar: AppBar(
actions: [_CrosswordPuzzleAppMenu()],
titleTextStyle: TextStyle(
color: Theme.of(context).colorScheme.primary,
fontSize: 16,
fontWeight: FontWeight.bold,
),
title: Text('Crossword Puzzle'),
),
body: SafeArea(
child: Consumer(builder: (context, ref, _) {
final workQueueAsync = ref.watch(workQueueProvider);
final puzzleSolved =
ref.watch(puzzleProvider.select((puzzle) => puzzle.solved));
return workQueueAsync.when(
data: (workQueue) {
if (puzzleSolved) {
return PuzzleCompletedWidget();
}
if (workQueue.isCompleted &&
workQueue.crossword.characters.isNotEmpty) {
return CrosswordPuzzleWidget();
}
return CrosswordGeneratorWidget();
},
loading: () => Center(child: CircularProgressIndicator()),
error: (error, stackTrace) => Center(child: Text('$error')),
);
}),
),
),
);
}
}
class _EagerInitialization extends ConsumerWidget {
const _EagerInitialization({required this.child});
final Widget child;
@override
Widget build(BuildContext context, WidgetRef ref) {
ref.watch(wordListProvider);
return child;
}
}
class _CrosswordPuzzleAppMenu extends ConsumerWidget {
@override
Widget build(BuildContext context, WidgetRef ref) => MenuAnchor(
menuChildren: [
for (final entry in CrosswordSize.values)
MenuItemButton(
onPressed: () => ref.read(sizeProvider.notifier).setSize(entry),
leadingIcon: entry == ref.watch(sizeProvider)
? Icon(Icons.radio_button_checked_outlined)
: Icon(Icons.radio_button_unchecked_outlined),
child: Text(entry.label),
),
],
builder: (context, controller, child) => IconButton(
onPressed: () => controller.open(),
icon: Icon(Icons.settings),
),
);
}
現在應該已經相當熟悉這個檔案的大部分內容。是的，這個小工具會出現未定義的小工具，讓您開始修正這類錯誤。
- 建立
crossword_generator_widget.dart檔案，並在當中加入下列內容：
lib/widgets/crossword_generator_widget.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:two_dimensional_scrollables/two_dimensional_scrollables.dart';
import '../model.dart';
import '../providers.dart';
class CrosswordGeneratorWidget extends ConsumerWidget {
const CrosswordGeneratorWidget({super.key});
@override
Widget build(BuildContext context, WidgetRef ref) {
final size = ref.watch(sizeProvider);
return TableView.builder(
diagonalDragBehavior: DiagonalDragBehavior.free,
cellBuilder: _buildCell,
columnCount: size.width,
columnBuilder: (index) => _buildSpan(context, index),
rowCount: size.height,
rowBuilder: (index) => _buildSpan(context, index),
);
}
TableViewCell _buildCell(BuildContext context, TableVicinity vicinity) {
final location = Location.at(vicinity.column, vicinity.row);
return TableViewCell(
child: Consumer(
builder: (context, ref, _) {
final character = ref.watch(
workQueueProvider.select(
(workQueueAsync) => workQueueAsync.when(
data: (workQueue) => workQueue.crossword.characters[location],
error: (error, stackTrace) => null,
loading: () => null,
),
),
);
final explorationCell = ref.watch(
workQueueProvider.select(
(workQueueAsync) => workQueueAsync.when(
data: (workQueue) =>
workQueue.locationsToTry.keys.contains(location),
error: (error, stackTrace) => false,
loading: () => false,
),
),
);
if (character != null) {
return AnimatedContainer(
duration: Durations.extralong1,
curve: Curves.easeInOut,
color: explorationCell
? Theme.of(context).colorScheme.primary
: Theme.of(context).colorScheme.onPrimary,
child: Center(
child: AnimatedDefaultTextStyle(
duration: Durations.extralong1,
curve: Curves.easeInOut,
style: TextStyle(
fontSize: 24,
color: explorationCell
? Theme.of(context).colorScheme.onPrimary
: Theme.of(context).colorScheme.primary,
),
child: Text('•'), // https://www.compart.com/en/unicode/U+2022
),
),
);
}
return ColoredBox(
color: Theme.of(context).colorScheme.primaryContainer,
);
},
),
);
}
TableSpan _buildSpan(BuildContext context, int index) {
return TableSpan(
extent: FixedTableSpanExtent(32),
foregroundDecoration: TableSpanDecoration(
border: TableSpanBorder(
leading: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
trailing: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
),
),
);
}
}
您應該在合理範圍內瞭解這一點。主要差異在於，現在不會顯示產生的字詞字元，而是顯示萬國碼 (Unicode) 字元來表示存在未知字元。確實應該花一些心力來改善外型。
- 建立
crossword_puzzle_widget.dart檔案並加入下列內容：
lib/widgets/crossword_puzzle_widget.dart
import 'package:built_collection/built_collection.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:two_dimensional_scrollables/two_dimensional_scrollables.dart';
import '../model.dart';
import '../providers.dart';
class CrosswordPuzzleWidget extends ConsumerWidget {
const CrosswordPuzzleWidget({super.key});
@override
Widget build(BuildContext context, WidgetRef ref) {
final size = ref.watch(sizeProvider);
return TableView.builder(
diagonalDragBehavior: DiagonalDragBehavior.free,
cellBuilder: _buildCell,
columnCount: size.width,
columnBuilder: (index) => _buildSpan(context, index),
rowCount: size.height,
rowBuilder: (index) => _buildSpan(context, index),
);
}
TableViewCell _buildCell(BuildContext context, TableVicinity vicinity) {
final location = Location.at(vicinity.column, vicinity.row);
return TableViewCell(
child: Consumer(
builder: (context, ref, _) {
final character = ref.watch(puzzleProvider
.select((puzzle) => puzzle.crossword.characters[location]));
final selectedCharacter = ref.watch(puzzleProvider.select((puzzle) =>
puzzle.crosswordFromSelectedWords.characters[location]));
final alternateWords = ref
.watch(puzzleProvider.select((puzzle) => puzzle.alternateWords));
if (character != null) {
final acrossWord = character.acrossWord;
var acrossWords = BuiltList<String>();
if (acrossWord != null) {
acrossWords = acrossWords.rebuild((b) => b
..add(acrossWord.word)
..addAll(alternateWords[acrossWord.location]
?[acrossWord.direction] ??
[])
..sort());
}
final downWord = character.downWord;
var downWords = BuiltList<String>();
if (downWord != null) {
downWords = downWords.rebuild((b) => b
..add(downWord.word)
..addAll(alternateWords[downWord.location]
?[downWord.direction] ??
[])
..sort());
}
return MenuAnchor(
builder: (context, controller, _) {
return GestureDetector(
onTapDown: (details) =>
controller.open(position: details.localPosition),
child: AnimatedContainer(
duration: Durations.extralong1,
curve: Curves.easeInOut,
color: Theme.of(context).colorScheme.onPrimary,
child: Center(
child: AnimatedDefaultTextStyle(
duration: Durations.extralong1,
curve: Curves.easeInOut,
style: TextStyle(
fontSize: 24,
color: Theme.of(context).colorScheme.primary,
),
child: Text(selectedCharacter?.character ?? ''),
),
),
),
);
},
menuChildren: [
if (acrossWords.isNotEmpty && downWords.isNotEmpty)
Padding(
padding: const EdgeInsets.all(4),
child: Text('Across'),
),
for (final word in acrossWords)
_WordSelectMenuItem(
location: acrossWord!.location,
word: word,
selectedCharacter: selectedCharacter,
direction: Direction.across,
),
if (acrossWords.isNotEmpty && downWords.isNotEmpty)
Padding(
padding: const EdgeInsets.all(4),
child: Text('Down'),
),
for (final word in downWords)
_WordSelectMenuItem(
location: downWord!.location,
word: word,
selectedCharacter: selectedCharacter,
direction: Direction.down,
),
],
);
}
return ColoredBox(
color: Theme.of(context).colorScheme.primaryContainer,
);
},
),
);
}
TableSpan _buildSpan(BuildContext context, int index) {
return TableSpan(
extent: FixedTableSpanExtent(32),
foregroundDecoration: TableSpanDecoration(
border: TableSpanBorder(
leading: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
trailing: BorderSide(
color: Theme.of(context).colorScheme.onPrimaryContainer),
),
),
);
}
}
class _WordSelectMenuItem extends ConsumerWidget {
const _WordSelectMenuItem({
required this.location,
required this.word,
required this.selectedCharacter,
required this.direction,
});
final Location location;
final String word;
final CrosswordCharacter? selectedCharacter;
final Direction direction;
@override
Widget build(BuildContext context, WidgetRef ref) {
final notifier = ref.read(puzzleProvider.notifier);
return MenuItemButton(
onPressed: ref.watch(puzzleProvider.select((puzzle) =>
puzzle.canSelectWord(
location: location, word: word, direction: direction)))
? () => notifier.selectWord(
location: location, word: word, direction: direction)
: null,
leadingIcon: switch (direction) {
Direction.across => selectedCharacter?.acrossWord?.word == word,
Direction.down => selectedCharacter?.downWord?.word == word,
}
? Icon(Icons.radio_button_checked_outlined)
: Icon(Icons.radio_button_unchecked_outlined),
child: Text(word),
);
}
}
雖然這個小工具的強度比上一個部分來得高，但這個小工具是根據您過去在其他地方用過的零件製作而成。現在，使用者點選每個填入的儲存格都會產生內容選單，其中列出使用者可選取的字詞。若已選取字詞，無法選取衝突的字詞。如要取消選取字詞，使用者可以輕觸該字詞的選單項目。
假設玩家只要選取多個字詞，即可填滿整個填字遊戲，「你就是贏了！」。
- 建立
puzzle_completed_widget.dart檔案，然後在該檔案中加入下列內容：
lib/widgets/puzzle_completed_widget.dart
import 'package:flutter/material.dart';
class PuzzleCompletedWidget extends StatelessWidget {
const PuzzleCompletedWidget({super.key});
@override
Widget build(BuildContext context) {
return Center(
child: Text(
'Puzzle Completed!',
style: TextStyle(
fontSize: 36,
fontWeight: FontWeight.bold,
),
),
);
}
}
我相信你還是可以從中學到一些，更有趣。如要進一步瞭解動畫工具，請參閱「在 Flutter 中建構新一代 UI」程式碼研究室。
- 按照下列方式編輯
lib/main.dart檔案：
lib/main.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'widgets/crossword_puzzle_app.dart'; // Update this line
void main() {
runApp(
ProviderScope(
child: MaterialApp(
title: 'Crossword Puzzle', // Update this line
debugShowCheckedModeBanner: false,
theme: ThemeData(
useMaterial3: true,
colorSchemeSeed: Colors.blueGrey,
brightness: Brightness.light,
),
home: CrosswordPuzzleApp(), // Update this line
),
),
);
}
執行這個應用程式後，就會在填字機產生謎題時看到動畫。系統會顯示一個空白謎題。假設您回答了問題，畫面上應該會顯示類似下方的畫面：
10. 恭喜
恭喜！您已使用 Flutter 打造益智遊戲！
你打造的填字產生器已經成為益智遊戲。您成功在一組隔離池中執行背景運算。您使用了不可變動的資料結構來簡化回溯追蹤演算法的實作。並花了一些時間使用 TableView，這在下次需要顯示表格資料時非常實用。