InteractiveViewer with contrained = false, results in scale immediately jumping to maxScale and staying at that value. #88467
Description
Flutter 2.2.3 • channel stable • https://github.com/flutter/flutter.git
Framework • revision f4abaa0 (7 weeks ago) • 2021-07-01 12:46:11 -0700
Engine • revision 241c87ad80
Tools • Dart 2.13.4
I am using an InteractiveWidget for the use of is transform matrix. Ultimately I will be using the matrix to scale a path without scaling the stroke thickness by settings path.transform property.
In the following minimal example I have a CustomPainter that draws and updates based on the TransformController passed from a InteractiveViewer. I have set the constrained property to false.
As as I begin a a two finger zoom in gesture, the scale immediately jumps to maxScale value. In this case I get the following matrix...
[0] 8.0,0.0,0.0,-1474.117674624082
[1] 0.0,8.0,0.0,-2227.0196568174856
[2] 0.0,0.0,8.0,0.0
[3] 0.0,0.0,0.0,1.0
From that point forward, the scale always remains at maxScale, regardless if I try to zoom out. In other words, as soon as a scale in gesture occurs, the scale jumps to and permanently stays at maxScale.
Here is a minimal example:
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key? key}) : super(key: key);
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
TransformationController _transformController = TransformationController();
@override
void initState() {
super.initState();
// _transformController.addListener(() {
// setState(() {
//
// });
// });
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Transform Test"),
),
body: Center(
child: Stack(
children: [
CustomPaint(
painter: CustomLayer(
context,
_transformController,
),
child: Container(),
),
InteractiveViewer(
transformationController: _transformController,
constrained: false,
maxScale: 8.0,
minScale: 0.5,
child: Container(),
),
],
),
),
);
}
}
class CustomLayer extends CustomPainter {
TransformationController _transformationController;
CustomLayer(
BuildContext context,
this._transformationController
) : super(repaint: _transformationController);
@override
void paint(Canvas canvas, Size size) {
var circleRadius = 6.0;
var x = size.width / 2 - circleRadius / 2;
var y = size.height / 2 - circleRadius / 2;
canvas.transform(_transformationController.value.storage);
canvas.drawCircle(Offset(x,y), circleRadius, Paint()..color = Colors.red);
print(_transformationController.value.toString());
}
@override
bool shouldRepaint(CustomLayer oldDelegate) => true;
}