原生epub阅读

lib/utils/epub/web/reader_api.dart

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+import 'dart:convert';
+
+import 'webview_bridge.dart';
+
+/// Typed Dart mirror of the TypeScript `ReaderApi` interface
+/// (`web_assets/controller.js/api.ts`).
+///
+/// Every public method corresponds 1-to-1 with its TypeScript counterpart.
+/// The token parameter is managed internally by [WebViewBridge] — callers
+/// never touch raw token integers through this class.
+///
+/// Methods that return `Future<int>` fire the JS call and return a token the
+/// caller can later pass to [WebViewBridge.waitForEvent] / [waitForEvents]
+/// when it wants to batch-await multiple operations together.
+///
+/// Methods that return `Future<void>` fire the JS call and await its
+/// completion before returning.
+class ReaderApi {
+  final WebViewBridge _bridge;
+
+  ReaderApi(this._bridge);
+
+  // ─── Token-based (deferred await) ──────────────────────────────────
+
+  /// Loads [url] into the iframe identified by [slot].
+  /// [anchors] should be a JSON-encoded list: `'["id1","id2"]'`.
+  Future<int> loadFrame(
+    String slot,
+    String url,
+    String anchors,
+    String properties,
+  ) => _bridge.call(
+    (t) => "window.api.loadFrame($t, '$slot', '$url', $anchors, $properties)",
+  );
+
+  /// Scrolls [slot]'s iframe to [pageIndex] without immediately awaiting.
+  Future<int> jumpToPageFor(String slot, int pageIndex) =>
+      _bridge.call((t) => "window.api.jumpToPageFor($t, '$slot', $pageIndex)");
+
+  /// Scrolls [slot]'s iframe to its last page without immediately awaiting.
+  Future<int> jumpToLastPageOfFrame(String slot) =>
+      _bridge.call((t) => "window.api.jumpToLastPageOfFrame($t, '$slot')");
+
+  /// Rotates the iframe triple in [direction] (`'next'` or `'prev'`).
+  Future<int> cycleFrames(String direction) =>
+      _bridge.call((t) => "window.api.cycleFrames($t, '$direction')");
+
+  // ─── Fire-and-await ────────────────────────────────────────────────
+
+  /// Scrolls the current iframe to [pageIndex] and awaits completion.
+  Future<void> jumpToPage(int pageIndex) =>
+      _bridge.callAndWait((t) => 'window.api.jumpToPage($t, $pageIndex)', 1000);
+
+  /// Restores the scroll position using a fractional [ratio] in [0,1].
+  Future<void> restoreScrollPosition(double ratio) => _bridge.callAndWait(
+    (t) => 'window.api.restoreScrollPosition($t, $ratio)',
+    1000,
+  );
+
+  /// Waits for the current frame to finish rendering.
+  Future<void> waitForRender() =>
+      _bridge.callAndWait((t) => 'window.api.waitForRender($t)', 1000);
+
+  /// Updates the reader theme/layout and awaits completion.
+  ///
+  /// [theme] must be a JSON-serialisable map produced by `EpubTheme.toMap()`.
+  Future<void> updateTheme(
+    double viewWidth,
+    double viewHeight,
+    Map<String, dynamic> theme,
+  ) {
+    final themeJson = jsonEncode(theme);
+    return _bridge.callAndWait(
+      (t) => 'window.api.updateTheme($t, $viewWidth, $viewHeight, $themeJson)',
+    );
+  }
+
+  // ─── Fire-and-forget ───────────────────────────────────────────────
+
+  /// Checks whether there is an interactive element (image, etc.) at (x, y).
+  Future<void> checkLongPressElementAt(double x, double y) =>
+      _bridge.evaluate('window.api.checkLongPressElementAt($x, $y)');
+
+  /// Checks whether the tap at (x, y) hits a link, footnote, or other element.
+  Future<void> checkTapElementAt(double x, double y) =>
+      _bridge.evaluate('window.api.checkTapElementAt($x, $y)');
+}

lib/utils/epub/web/webview_bridge.dart

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+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter_inappwebview/flutter_inappwebview.dart';
+
+/// Manages JS↔Dart communication over an [InAppWebViewController].
+///
+/// Provides token-based async call tracking so that callers can fire a JS
+/// method that will eventually invoke `FlutterBridge.onEventFinished(token)`,
+/// and await the result on the Dart side via [waitForEvent].
+///
+/// Typical usage:
+/// ```dart
+/// // Fire and forget the token; caller awaits separately.
+/// final token = await _bridge.call((t) => "window.api.loadFrame($t, ...)");
+/// await _bridge.waitForEvent(token);
+///
+/// // Fire and immediately await.
+/// await _bridge.callAndWait((t) => "window.api.jumpToPage($t, $idx)");
+/// ```
+class WebViewBridge {
+  InAppWebViewController? _controller;
+
+  int _currentToken = 0;
+  final Map<int, Completer<void>> _completers = {};
+
+  // ─── Controller lifecycle ──────────────────────────────────────────
+
+  /// Attaches a live [InAppWebViewController]. Call this in `onWebViewCreated`.
+  void attach(InAppWebViewController controller) {
+    _controller = controller;
+  }
+
+  /// Detaches the controller and cancels all pending completers.
+  void detach() {
+    _controller = null;
+    for (final completer in _completers.values) {
+      if (!completer.isCompleted) {
+        completer.completeError(StateError('WebViewBridge detached'));
+      }
+    }
+    _completers.clear();
+  }
+
+  // ─── JS evaluation ─────────────────────────────────────────────────
+
+  /// Evaluates [source] in the WebView. No-ops if no controller is attached.
+  Future<void> evaluate(String source) async {
+    await _controller?.evaluateJavascript(source: source);
+  }
+
+  // ─── Token management ──────────────────────────────────────────────
+
+  /// Allocates a new token and registers a [Completer] for it.
+  ///
+  /// Embed the returned token in the JS call so JS can resolve it via
+  /// `FlutterBridge.onEventFinished(token)`.
+  int issueToken() {
+    _currentToken++;
+    _completers[_currentToken] = Completer<void>();
+    return _currentToken;
+  }
+
+  /// Called by the `onEventFinished` JS handler to resolve a pending token.
+  ///
+  /// A [token] of `-1` is a sentinel for fire-and-forget notifications that
+  /// do not need to be tracked.
+  void resolveToken(int token) {
+    if (token == -1) return;
+    final completer = _completers.remove(token);
+    if (completer != null && !completer.isCompleted) {
+      completer.complete();
+    }
+  }
+
+  // ─── Awaiting ──────────────────────────────────────────────────────
+
+  /// Waits for [token] to be resolved, or times out after [timeoutMs] ms.
+  Future<void> waitForEvent(int token, [int timeoutMs = 10000]) async {
+    final completer = _completers[token];
+    if (completer == null) {
+      debugPrint('WebViewBridge: no completer for token $token');
+      return;
+    }
+    return completer.future.timeout(
+      Duration(milliseconds: timeoutMs),
+      onTimeout: () {
+        _completers.remove(token);
+        debugPrint('WebViewBridge: timeout for token $token');
+      },
+    );
+  }
+
+  /// Waits for all [tokens] to be resolved concurrently.
+  Future<void> waitForEvents(List<int> tokens, [int timeoutMs = 10000]) async {
+    await Future.wait(tokens.map((t) => waitForEvent(t, timeoutMs)));
+  }
+
+  // ─── Convenience helpers ───────────────────────────────────────────
+
+  /// Issues a token, evaluates the JS returned by [source], and returns the
+  /// token so the caller can [waitForEvent] later.
+  Future<int> call(String Function(int token) source) async {
+    final token = issueToken();
+    await evaluate(source(token));
+    return token;
+  }
+
+  /// Issues a token, evaluates the JS returned by [source], and immediately
+  /// awaits [waitForEvent] before returning.
+  Future<void> callAndWait(
+    String Function(int token) source, [
+    int timeoutMs = 10000,
+  ]) async {
+    final token = issueToken();
+    await evaluate(source(token));
+    await waitForEvent(token, timeoutMs);
+  }
+}