fix(flutter): size unzoomed remote cursors to the local system

flutter/lib/desktop/pages/remote_page.dart

@@ -19,6 +19,7 @@ import '../../models/input_model.dart';
 import '../../models/platform_model.dart';
 import '../../common/shared_state.dart';
 import '../../utils/image.dart';
+import '../../utils/cursor_size.dart';
 import '../widgets/remote_toolbar.dart';
 import '../widgets/kb_layout_type_chooser.dart';
 import '../widgets/tabbar_widget.dart';
@@ -1088,6 +1089,21 @@ class ImagePaint extends StatefulWidget {
 
 class _ImagePaintState extends State<ImagePaint> {
   bool _lastRemoteCursorMoved = false;
+  final _localCursorSize = LocalCursorSize();
+
+  @override
+  void initState() {
+    super.initState();
+    _localCursorSize.addListener(_cursorSizeChanged);
+  }
+
+  void _cursorSizeChanged() => setState(() {});
+
+  @override
+  void dispose() {
+    _localCursorSize.dispose();
+    super.dispose();
+  }
 
   String get id => widget.id;
   RxBool get zoomCursor => widget.zoomCursor;
@@ -1109,6 +1125,11 @@ class _ImagePaintState extends State<ImagePaint> {
     bool isViewOriginal() => c.viewStyle.style == kRemoteViewStyleOriginal;
 
     mouseRegion({child}) => Obx(() {
+          final useLocalSize = !isWeb &&
+              (isLinux || isMacOS || isWindows) &&
+              !zoomCursor.value &&
+              isViewAdaptive();
+          if (useLocalSize) _localCursorSize.ensureLoaded(dpr);
           double getCursorScale() {
             var c = Provider.of<CanvasModel>(context);
             var cursorScale = 1.0;
@@ -1149,11 +1170,16 @@ class _ImagePaintState extends State<ImagePaint> {
                                       _firstEnterImage.value = true;
                                     }
                                     return _buildCustomCursor(
-                                        context, getCursorScale());
+                                        context, getCursorScale(),
+                                        useLocalSize: useLocalSize);
                                   }
                                 }())
-                              : _buildDisabledCursor(context, getCursorScale())
+                              : _buildDisabledCursor(context, getCursorScale(),
+                                  useLocalSize: useLocalSize)
                   : MouseCursor.defer,
+              onEnter: (_) {
+                if (useLocalSize) _localCursorSize.refresh();
+              },
               onHover: (evt) {},
               child: child);
         });
@@ -1266,15 +1292,21 @@ class _ImagePaintState extends State<ImagePaint> {
     );
   }
 
-  MouseCursor _buildCustomCursor(BuildContext context, double scale) {
+  MouseCursor _buildCustomCursor(BuildContext context, double scale,
+      {bool useLocalSize = false}) {
     final cursor = Provider.of<CursorModel>(context);
     final cache = cursor.cache ?? preDefaultCursor.cache;
+    if (useLocalSize && _localCursorSize.value == null) return MouseCursor.defer;
+    cache?.localSize = useLocalSize ? _localCursorSize.value : null;
     return buildCursorOfCache(cursor, scale, cache);
   }
 
-  MouseCursor _buildDisabledCursor(BuildContext context, double scale) {
+  MouseCursor _buildDisabledCursor(BuildContext context, double scale,
+      {bool useLocalSize = false}) {
     final cursor = Provider.of<CursorModel>(context);
     final cache = preForbiddenCursor.cache;
+    if (useLocalSize && _localCursorSize.value == null) return MouseCursor.defer;
+    cache?.localSize = useLocalSize ? _localCursorSize.value : null;
     return buildCursorOfCache(cursor, scale, cache);
   }
 

flutter/lib/models/model.dart

@@ -39,6 +39,7 @@ import 'package:vector_math/vector_math.dart' show Vector2;
 
 import '../common.dart';
 import '../utils/image.dart' as img;
+import '../utils/cursor_size.dart';
 import '../common/widgets/dialog.dart';
 import 'input_model.dart';
 import 'platform_model.dart';
@@ -2863,6 +2864,8 @@ class CursorData {
   double hoty;
   final int width;
   final int height;
+  double? localSize;
+  late final int _visibleSize = cursorVisibleSize(image);
 
   CursorData({
     required this.peerId,
@@ -2886,14 +2889,18 @@ class CursorData {
   int _scaledDimension(int dimension, double scale) {
     const minBitmapSize = 1;
     final pixels = dimension * scale;
-    return _usesLogicalCursorPixels
+    return _usesLogicalCursorPixels || localSize != null
         ? max(minBitmapSize, pixels.round())
         : pixels.toInt();
   }
 
   double _checkUpdateScale(double scale) {
     double oldScale = this.scale;
-    if (scale != 1.0) {
+    if (localSize != null) {
+      scale = _visibleSize == 0
+          ? 1.0
+          : max(localSize!, kMinCursorSize) / _visibleSize;
+    } else if (scale != 1.0) {
       // Update data if scale changed.
       final tgtWidth = (width * scale).toInt();
       final tgtHeight = (height * scale).toInt();
@@ -2904,13 +2911,17 @@ class CursorData {
       }
     }
 
-    if (_doubleToInt(oldScale) != _doubleToInt(scale)) {
+    const bytesPerPixel = 4;
+    final byteLength = _scaledDimension(width, scale) *
+        _scaledDimension(height, scale) * bytesPerPixel;
+    if (_doubleToInt(oldScale) != _doubleToInt(scale) ||
+        (isWindows && data != null && data!.length != byteLength)) {
       if (isWindows) {
         data = img2
             .copyResize(
               image,
-              width: (width * scale).toInt(),
-              height: (height * scale).toInt(),
+              width: _scaledDimension(width, scale),
+              height: _scaledDimension(height, scale),
               interpolation: img2.Interpolation.average,
             )
             .getBytes(order: img2.ChannelOrder.bgra);
@@ -2936,7 +2947,7 @@ class CursorData {
 
   String updateGetKey(double scale) {
     scale = _checkUpdateScale(scale);
-    return '${peerId}_${id}_${_doubleToInt(width * scale)}_${_doubleToInt(height * scale)}';
+    return '${peerId}_${id}_${_doubleToInt(width * scale)}_${_doubleToInt(height * scale)}${localSize == null ? '' : '_local'}';
   }
 }
 

flutter/lib/utils/cursor_size.dart

@@ -0,0 +1,55 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+import 'package:image/image.dart' as img;
+
+int cursorVisibleSize(img.Image image) {
+  var left = image.width;
+  var top = image.height;
+  var right = -1;
+  var bottom = -1;
+  for (final pixel in image) {
+    if (pixel.a == 0) continue;
+    if (pixel.x < left) left = pixel.x;
+    if (pixel.x > right) right = pixel.x;
+    if (pixel.y < top) top = pixel.y;
+    if (pixel.y > bottom) bottom = pixel.y;
+  }
+  if (right < left) return 0;
+  final width = right - left + 1;
+  final height = bottom - top + 1;
+  return width > height ? width : height;
+}
+
+class LocalCursorSize extends ValueNotifier<double?> {
+  LocalCursorSize() : super(null);
+
+  static const _channel = MethodChannel('org.rustdesk.rustdesk/cursor');
+  double? _devicePixelRatio;
+  int _generation = 0;
+
+  void ensureLoaded(double devicePixelRatio) {
+    if (_devicePixelRatio == devicePixelRatio) return;
+    _devicePixelRatio = devicePixelRatio;
+    refresh();
+  }
+
+  Future<void> refresh() async {
+    final generation = ++_generation;
+    try {
+      final size = await _channel.invokeMethod<double>('getSystemCursorSize');
+      if (size == null || !size.isFinite || size <= 0) {
+        throw const FormatException('Invalid local system cursor size');
+      }
+      if (generation == _generation) value = size;
+    } catch (error, stack) {
+      FlutterError.reportError(FlutterErrorDetails(
+          exception: error, stack: stack, library: 'local cursor size'));
+    }
+  }
+
+  @override
+  void dispose() {
+    ++_generation;
+    super.dispose();
+  }
+}