Apng(Animated Png) with alpha channel won't get blended to background properly #128102
Description
Is there an existing issue for this?
- I have searched the existing issues
- I have read the guide to filing a bug
Steps to reproduce
- create apng with alpha channel which has slightly transparent(not perfectly intransparent, nor perfectly transparent. consider like shadows that darken the background color).
- show it with
Imagewidget, e.g.Image.asset("assets/animated.apng") - On Android, this will cause buggy behavior. The more transparent the pixel is, the brighter it will be.
Expected results
Image will be mixed with the background, corresponding to the value of the alpha channel.
Actual results
On Android, 100% transparent pixel will be fine, but other pixel will gets whiter and not transparent.
On web (dartpad), the behavior is totally fine.
Code sample
Code sample
Screenshots or Video
Screenshots / Video demonstration
tested apng is this below.
Expected result (dartpad behavior)
2023-06-02.145019.mp4
Actual result (Android Pixel 7 Pro)
screen-20230602-144922.2.mp4
Logs
Logs
log is too long to write here, so uploaded to gist
https://gist.github.com/nagataaaas/fa74ad7bcf7c3565f0a8d0e1087d35b6#file-flutter_verbose-log
Flutter Doctor output
Doctor output
[√] Flutter (Channel stable, 3.10.2, on Microsoft Windows [Version 10.0.22621.1755], locale ja-JP)
• Flutter version 3.10.2 on channel stable at C:\Users\nagata\Desktop\tools\flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 9cd3d0d9ff (9 days ago), 2023-05-23 20:57:28 -0700
• Engine revision 90fa3ae28f
• Dart version 3.0.2
• DevTools version 2.23.1
[√] Windows Version (Installed version of Windows is version 10 or higher)
[√] Android toolchain - develop for Android devices (Android SDK version 33.0.2)
• Android SDK at C:\Users\nagata\AppData\Local\Android\sdk
• Platform android-33-ext5, build-tools 33.0.2
• Java binary at: C:\Program Files\Android\Android Studio\jbr\bin\java
• Java version openjdk version "11.0.15" 2022-04-19
• All Android licenses accepted.
[√] Chrome - develop for the web
• Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe
[√] Visual Studio - develop for Windows (Visual Studio Enterprise 2019 16.8.2)
• Visual Studio at C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise
• Visual Studio Enterprise 2019 version 16.8.30717.126
• Windows 10 SDK version 10.0.18362.0
[√] Android Studio (version 2022.1)
• Android Studio at C:\Program Files\Android\Android Studio
• Flutter plugin can be installed from:
https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
https://plugins.jetbrains.com/plugin/6351-dart
• Java version openjdk version "11.0.15" 2022-04-19
[√] IntelliJ IDEA Ultimate Edition (version 2020.2)
• IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA 2020.2.2
• Flutter plugin can be installed from:
https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
https://plugins.jetbrains.com/plugin/6351-dart
[√] VS Code (version 1.78.2)
• VS Code at C:\Users\nagata\AppData\Local\Programs\Microsoft VS Code
• Flutter extension version 3.64.0
[√] Connected device (4 available)
• Pixel 7 Pro (mobile) • 2B071FDH300330 • android-arm64 • Android 13 (API 33)
• Windows (desktop) • windows • windows-x64 • Microsoft Windows [Version 10.0.22621.1755]
• Chrome (web) • chrome • web-javascript • Google Chrome 113.0.5672.127
• Edge (web) • edge • web-javascript • Microsoft Edge 113.0.1774.50
[√] Network resources
• All expected network resources are available.
• No issues found!