Issue 1:

Issue 2:
If you put a widget inside of a stack, and you offset it in such a way that parts of it would exist outside of that stack, and then you wrap it in some sort of animation that animates the opacity, it will animate oddly. This is 100% reproducible.

This is pretty severe in some cases, for example an image that is faded in but is made to aspect fit. it animates in what looks like progressive chunks, but it's actually this bug.

Here's a video of the bug in action: https://www.youtube.com/watch?v=teHlNhBuTzs

Here's a main.dart file I used in the video above:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}

class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);

final String title;

@override
_MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
AnimationController _controller;
double _leftOffset = 0.0;
@override
void initState() {
_controller = AnimationController(
vsync: this, duration: Duration(milliseconds: 1000));
super.initState();
}

@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Container(
color: Colors.white,
child: Stack(
children: <Widget>[
GestureDetector(
onTapDown: (details) {
setState(() {
_leftOffset = details.globalPosition.dx;
});
},
),
Positioned(
left: _leftOffset,
top: 0.0,
width: 300.0,
height: 200.0,
child: AnimatedBuilder(
animation: _controller,
builder: (context, child) {
return Opacity(
opacity: _controller.value,
child: child,
);
},
child: Container(
color: Colors.blueAccent,
),
),
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
_controller.forward(from: 0.0);
},
child: Icon(Icons.add),
),
);
}
}

Logs

[ +2 ms] 🔥 To hot reload changes while running, press "r". To hot restart (and rebuild state), press "R".
[ +1 ms] An Observatory debugger and profiler on iPhone XS is available at: http://127.0.0.1:53526/
[ ] For a more detailed help message, press "h". To detach, press "d"; to quit, press "q".
[+115689 ms] [DEVICE LOG] 2018-11-09 11:13:51.200335-0500 localhost Runner[5498]: (AggregateDictionary)
AggregateDictionary is not supported on this platform

$ flutter analyze
Analyzing animatedopacitytest...
No issues found! (ran in 1.9s)

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• Flutter version 0.11.1-pre.127 at /Users/KG/Developer/Flutter/flutter
• Framework revision ae2b215efe (7 hours ago), 2018-11-09 00:40:29 -0800
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