fix(cursor): decode legacy macOS alpha for native cursors

This commit is contained in:
fufesou
2026-09-12 18:40:27 +08:00
parent be1f4e0a33
commit 8f3beba2d1
2 changed files with 175 additions and 1 deletions

View File

@@ -3463,8 +3463,12 @@ class CursorModel with ChangeNotifier {
pixelRatio > 0 &&
parent.target?.ffiModel.pi.platform == kPeerPlatformMacOS) {
// macOS cursors with density metadata use premultiplied alpha; older
// hosts send straight alpha. Keep native decoding and old hosts unchanged.
// hosts send straight alpha. Web needs a straight-alpha resize source.
(rgba, image) = await _decodeWebMacCursor(rgba, width, height);
} else if (!isWeb &&
pixelRatio == 0 &&
parent.target?.ffiModel.pi.platform == kPeerPlatformMacOS) {
image = await _decodeLegacyMacCursor(rgba, width, height);
} else {
image = await img.decodeImageFromPixels(
rgba, width, height, ui.PixelFormat.rgba8888);
@@ -3485,6 +3489,22 @@ class CursorModel with ChangeNotifier {
_updateCurData();
}
Future<ui.Image?> _decodeLegacyMacCursor(
Uint8List rgba, int width, int height) async {
// Old macOS packets are straight alpha. Premultiply a copy for native
// ui.Image, retaining the original colors for the separate byte cache.
final source = img2.Image.fromBytes(
width: width, height: height, bytes: rgba.buffer, order: img2.ChannelOrder.rgba);
for (final pixel in source) {
final opacity = pixel.a / pixel.maxChannelValue;
pixel.r = (pixel.r * opacity).round();
pixel.g = (pixel.g * opacity).round();
pixel.b = (pixel.b * opacity).round();
}
return img.decodeImageFromPixels(
source.getBytes(), width, height, ui.PixelFormat.rgba8888);
}
Future<(Uint8List, ui.Image)> _decodeWebMacCursor(
Uint8List rgba, int width, int height) async {
final source = img2.Image.fromBytes(