PageView seems to ignore PageController's page after state changes #106708
Description
Steps to Reproduce
- Pull down the
pagecontroller_problem_demobranch from https://github.com/thesmythgroup/easy_image_viewer/tree/pagecontroller_problem_demo - Run the example app (
example/lib/main.dart) in an iOS simulator - Tap on
Show Multiple Images (Simple). - Swipe to the second image
- Use pinch & zoom to zoom in.
Expected results:
The PageView stays on the 2nd image
Actual results:
The PageView jumps back to the first image.
Background
I'm having the following problem: My library easy_image_viewer has a request to add swipe-to-dismiss. I implemented it using the Dismissible widget. However, when the user zooms in on an image, I noticed I had to find a way to "deactivate" the Dismissible widget because otherwise the user can't pan around on the zoomed-in image. I solved that by using setState and a dismissDirection variable on the state that can be either none or down. Now for the weird part: Whenever I call setState and the dismissDirection changes, the PageView jumps back to the first item. I've tried using AutomaticKeepAliveClientMixin, but to no avail. I'm probably doing something wrong, but I can't figure out what it is.
Logs
[✓] Flutter (Channel stable, 3.0.2, on macOS 12.4 21F79 darwin-arm, locale en-US)
• Flutter version 3.0.2 at /Users/johannes/Code/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision cd41fdd495 (3 weeks ago), 2022-06-08 09:52:13 -0700
• Engine revision f15f824b57
• Dart version 2.17.3
• DevTools version 2.12.2
[✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
• Android SDK at /Users/johannes/Library/Android/sdk
• Platform android-31, build-tools 31.0.0
• Java binary at: /Applications/Android Studio.app/Contents/jre/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 11.0.11+0-b60-7772763)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 13.4)
• Xcode at /Applications/Xcode.app/Contents/Developer
• CocoaPods version 1.11.3
[✓] Chrome - develop for the web
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
[✓] Android Studio (version 2021.1)
• Android Studio at /Applications/Android Studio.app/Contents
• 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 Runtime Environment (build 11.0.11+0-b60-7772763)
[✓] VS Code (version 1.68.1)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.42.0
[✓] Connected device (4 available)
• sdk gphone64 arm64 (mobile) • emulator-5554 • android-arm64 • Android 12 (API 32) (emulator)
• iPad (9th generation) (mobile) • 6EEE8A28-98D4-45D9-BB99-2E7AE15EADC2 • ios • com.apple.CoreSimulator.SimRuntime.iOS-15-5 (simulator)
• macOS (desktop) • macos • darwin-arm64 • macOS 12.4 21F79 darwin-arm
• Chrome (web) • chrome • web-javascript • Google Chrome 103.0.5060.53
! Error: Johannes' iPad Air is not connected. Xcode will continue when Johannes' iPad Air is connected. (code -13)
[✓] HTTP Host Availability
• All required HTTP hosts are available
• No issues found!
Movie: