Add image copy functionality.

Currently only supports Windows.
Close #260

assets/translation.json

@@ -376,7 +376,8 @@
     "Show Page Number": "显示页码",
     "Jump to page": "跳转到页面",
     "Page": "页面",
-    "Jump": "跳转"
+    "Jump": "跳转",
+    "Copy Image": "复制图片"
   },
   "zh_TW": {
     "Home": "首頁",
@@ -755,6 +756,7 @@
     "Show Page Number": "顯示頁碼",
     "Jump to page": "跳轉到頁面",
     "Page": "頁面",
-    "Jump": "跳轉"
+    "Jump": "跳轉",
+    "Copy Image": "複製圖片"
   }
 }

lib/pages/reader/comic_image.dart

@@ -24,6 +24,8 @@ class ComicImage extends StatefulWidget {
     Map<String, String>? headers,
     int? cacheWidth,
     int? cacheHeight,
+    this.onInit,
+    this.onDispose,
   })  : image = ResizeImage.resizeIfNeeded(cacheWidth, cacheHeight, image),
         assert(cacheWidth == null || cacheWidth > 0),
         assert(cacheHeight == null || cacheHeight > 0);
@@ -60,6 +62,10 @@ class ComicImage extends StatefulWidget {
 
   final bool isAntiAlias;
 
+  final void Function(State<ComicImage> state)? onInit;
+
+  final void Function(State<ComicImage> state)? onDispose;
+
   static void clear() => _ComicImageState.clear();
 
   @override
@@ -87,6 +93,7 @@ class _ComicImageState extends State<ComicImage> with WidgetsBindingObserver {
     super.initState();
     WidgetsBinding.instance.addObserver(this);
     _scrollAwareContext = DisposableBuildContext<State<ComicImage>>(this);
+    widget.onInit?.call(this);
   }
 
   @override
@@ -97,6 +104,7 @@ class _ComicImageState extends State<ComicImage> with WidgetsBindingObserver {
     _completerHandle?.dispose();
     _scrollAwareContext.dispose();
     _replaceImage(info: null);
+    widget.onDispose?.call(this);
     super.dispose();
   }
 
@@ -136,6 +144,15 @@ class _ComicImageState extends State<ComicImage> with WidgetsBindingObserver {
     super.reassemble();
   }
 
+  bool containsPoint(Offset point) {
+    if (!mounted) {
+      return false;
+    }
+    var renderBox = context.findRenderObject() as RenderBox;
+    var localPoint = renderBox.globalToLocal(point);
+    return renderBox.paintBounds.contains(localPoint);
+  }
+
   void _updateInvertColors() {
     _invertColors = MediaQuery.maybeInvertColorsOf(context) ??
         SemanticsBinding.instance.accessibilityFeatures.invertColors;

lib/pages/reader/gesture.dart

@@ -281,6 +281,12 @@ class _ReaderGestureDetectorState extends AutomaticGlobalState<_ReaderGestureDet
             context.pop();
           },
         ),
+        if (App.isDesktop && !reader.isLoading)
+          MenuEntry(
+            icon: Icons.copy,
+            text: "Copy Image".tl,
+            onClick: () => copyImage(location),
+          ),
       ],
     );
   }
@@ -303,6 +309,16 @@ class _ReaderGestureDetectorState extends AutomaticGlobalState<_ReaderGestureDet
 
   @override
   Object? get key => "reader_gesture";
+
+  void copyImage(Offset location) async {
+    var controller = reader._imageViewController;
+    var image = await controller!.getImageByOffset(location);
+    if (image != null) {
+      writeImageToClipboard(image);
+    } else {
+      context.showMessage(message: "No Image");
+    }
+  }
 }
 
 class _DragListener {

lib/pages/reader/images.dart

@@ -113,6 +113,8 @@ class _GalleryModeState extends State<_GalleryMode>
 
   int get totalPages => (reader.images!.length / reader.imagesPerPage).ceil();
 
+  var imageStates = <State<ComicImage>>{};
+
   @override
   void initState() {
     reader = context.reader;
@@ -234,6 +236,8 @@ class _GalleryModeState extends State<_GalleryMode>
         child: ComicImage(
           image: imageProvider,
           fit: BoxFit.contain,
+          onInit: (state) => imageStates.add(state),
+          onDispose: (state) => imageStates.remove(state),
         ),
       );
     }).toList();
@@ -370,6 +374,28 @@ class _GalleryModeState extends State<_GalleryMode>
   bool handleOnTap(Offset location) {
     return false;
   }
+
+  @override
+  Future<Uint8List?> getImageByOffset(Offset offset) async {
+    String? imageKey;
+    if (reader.imagesPerPage == 1) {
+      imageKey = reader.images![reader.page - 1];
+    } else {
+      for (var imageState in imageStates) {
+        if ((imageState as _ComicImageState).containsPoint(offset)) {
+          imageKey = (imageState.widget.image as ReaderImageProvider).imageKey;
+        }
+      }
+    }
+    if (imageKey == null) return null;
+    if (imageKey.startsWith("file://")) {
+      return await File(imageKey.substring(7)).readAsBytes();
+    } else {
+      return (await CacheManager().findCache(
+              "$imageKey@${context.reader.type.sourceKey}@${context.reader.cid}@${context.reader.eid}"))!
+          .readAsBytes();
+    }
+  }
 }
 
 const Set<PointerDeviceKind> _kTouchLikeDeviceTypes = <PointerDeviceKind>{
@@ -414,6 +440,8 @@ class _ContinuousModeState extends State<_ContinuousMode>
   /// To handle the tap event, we need to know if the user was scrolling before the delay.
   bool delayedIsScrolling = false;
 
+  var imageStates = <State<ComicImage>>{};
+
   void delayedSetIsScrolling(bool value) {
     Future.delayed(
       const Duration(milliseconds: 300),
@@ -574,6 +602,8 @@ class _ContinuousModeState extends State<_ContinuousMode>
             width: width,
             height: height,
             fit: BoxFit.contain,
+            onInit: (state) => imageStates.add(state),
+            onDispose: (state) => imageStates.remove(state),
           ),
         );
       },
@@ -857,6 +887,24 @@ class _ContinuousModeState extends State<_ContinuousMode>
     }
     return false;
   }
+
+  @override
+  Future<Uint8List?> getImageByOffset(Offset offset) async {
+    String? imageKey;
+    for (var imageState in imageStates) {
+      if ((imageState as _ComicImageState).containsPoint(offset)) {
+        imageKey = (imageState.widget.image as ReaderImageProvider).imageKey;
+      }
+    }
+    if (imageKey == null) return null;
+    if (imageKey.startsWith("file://")) {
+      return await File(imageKey.substring(7)).readAsBytes();
+    } else {
+      return (await CacheManager().findCache(
+              "$imageKey@${context.reader.type.sourceKey}@${context.reader.cid}@${context.reader.eid}"))!
+          .readAsBytes();
+    }
+  }
 }
 
 ImageProvider _createImageProviderFromKey(

lib/pages/reader/reader.dart

@@ -30,6 +30,7 @@ import 'package:venera/foundation/local.dart';
 import 'package:venera/foundation/log.dart';
 import 'package:venera/foundation/res.dart';
 import 'package:venera/pages/settings/settings_page.dart';
+import 'package:venera/utils/clipboard_image.dart';
 import 'package:venera/utils/data_sync.dart';
 import 'package:venera/utils/ext.dart';
 import 'package:venera/utils/file_type.dart';
@@ -577,4 +578,6 @@ abstract interface class _ImageViewController {
 
   /// Returns true if the event is handled.
   bool handleOnTap(Offset location);
+
+  Future<Uint8List?> getImageByOffset(Offset offset);
 }

lib/utils/clipboard_image.dart

@@ -0,0 +1,22 @@
+import 'dart:io';
+import 'dart:ui';
+
+import 'package:flutter/services.dart';
+
+Future<void> writeImageToClipboard(Uint8List imageBytes) async {
+  const channel = MethodChannel("venera/clipboard");
+  if (Platform.isWindows) {
+    var image = await instantiateImageCodec(imageBytes);
+    var frame = await image.getNextFrame();
+    var data = await frame.image.toByteData(format: ImageByteFormat.rawRgba);
+    await channel.invokeMethod("writeImageToClipboard", {
+      "width": frame.image.width,
+      "height": frame.image.height,
+      "data": Uint8List.view(data!.buffer)
+    });
+    image.dispose();
+  } else {
+    // TODO: Implement for other platforms
+    throw UnsupportedError("Clipboard image is not supported on this platform");
+  }
+}

windows/runner/flutter_window.cpp

@@ -102,6 +102,47 @@ bool FlutterWindow::OnCreate() {
 
   channel2.SetStreamHandler(std::move(eventHandler));
 
+  const flutter::MethodChannel<> channel3(
+    flutter_controller_->engine()->messenger(), "venera/clipboard",
+    &flutter::StandardMethodCodec::GetInstance()
+  );
+  channel3.SetMethodCallHandler(
+    [](const flutter::MethodCall<>& call,const std::unique_ptr<flutter::MethodResult<>>& result) {
+      if(call.method_name() == "writeImageToClipboard"){
+          flutter::EncodableMap arguments = std::get<flutter::EncodableMap>(*call.arguments());
+          std::vector<uint8_t> data = std::get<std::vector<uint8_t>>(arguments["data"]);
+          std::int32_t width = std::get<std::int32_t>(arguments["width"]);
+          std::int32_t height = std::get<std::int32_t>(arguments["height"]);
+
+          // convert rgba to bgra
+          for (int i = 0; i < data.size()/4; i++) {
+              uint8_t temp = data[i * 4];
+              data[i * 4] = data[i * 4 + 2];
+              data[i * 4 + 2] = temp;
+          }
+          
+          auto bitmap = CreateBitmap((int)width, (int)height, 1, 32, data.data());
+
+          if (!bitmap) {
+              result->Error("0", "Invalid Image Data");
+              return;
+          }
+
+          if (OpenClipboard(NULL))
+          {
+              EmptyClipboard();
+              SetClipboardData(CF_BITMAP, bitmap);
+              CloseClipboard();
+              result->Success();
+          }
+          else {
+              result->Error("Failed to open clipboard");
+          }
+
+          DeleteObject(bitmap);
+      }
+  });
+
   SetChildContent(flutter_controller_->view()->GetNativeWindow());
 
   flutter_controller_->engine()->SetNextFrameCallback([&]() {