[Impeller] : Opacity widget not working on a CustomPaint with a shader on iOS #158500
Description
Steps to reproduce
Put a CustomPaint widget, that paint a shader, into an Opacity widget
Expected results
The Opacity should be applied on the painted shader
Actual results
The Opacity is not applied
Code sample
Code sample
import 'dart:ui' as ui;
import 'package:flutter/services.dart';
import 'package:flutter/material.dart';
class MyApp extends StatelessWidget {
const MyApp({
super.key,
});
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: FutureBuilder(
future: () async {
final imageBytes = await rootBundle.load('lib/assets/img.jpeg');
final image = await decodeImageFromList(imageBytes.buffer.asUint8List());
final program = await ui.FragmentProgram.fromAsset('lib/assets/simple.frag');
return (image, program);
}(),
builder: (context, snapshot) {
if (snapshot.hasData == false) {
return const Center(child: CircularProgressIndicator());
}
final image = snapshot.data!.$1;
final program = snapshot.data!.$2;
return Opacity(
opacity: 0.5,
child: Center(
child: FittedBox(
child: SizedBox(
width: image.width.toDouble(),
height: image.height.toDouble(),
child: CustomPaint(
painter: MyCustomPainter(
image: image,
program: program,
),
),
),
),
),
);
},
),
),
);
}
}
class MyCustomPainter extends CustomPainter {
const MyCustomPainter({
required this.image,
required this.program,
});
final ui.Image image;
final ui.FragmentProgram program;
@override
void paint(Canvas canvas, Size size) {
final shader = program.fragmentShader();
shader.setFloat(0, image.width.toDouble());
shader.setFloat(1, image.height.toDouble());
shader.setImageSampler(0, image);
final paint = Paint()..shader = shader;
canvas.drawRect(Offset.zero & size, paint);
}
@override
bool shouldRepaint(covariant CustomPainter oldDelegate) => true;
}Shader
#include <flutter/runtime_effect.glsl>
uniform vec2 uSize;
uniform sampler2D uTexture;
out vec4 fragColor;
void main() {
vec2 uv = FlutterFragCoord() / uSize;
fragColor = texture(uTexture, uv);
}Screenshots or Video
Screenshots
Expected
Actual
Logs
No response
Flutter Doctor output
Doctor output
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.24.3, on macOS 14.5 23F79 darwin-arm64, locale en-IT)
[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 16.0)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2023.3)
[✓] IntelliJ IDEA Community Edition (version 2024.2.1)
[✓] VS Code (version 1.95.2)
[✓] Connected device (5 available)
! Error: Browsing on the local area network for Giacomo’s iPhone. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)
[✓] Network resources
• No issues found!