在Flutter中实现多个widget的矩阵手势检测器,可以使用Transform
和GestureDetector
来实现。以下是一个示例代码:
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text('Matrix Gesture Detector'),
),
body: MatrixGestureDetector(),
),
);
}
}
class MatrixGestureDetector extends StatefulWidget {
@override
_MatrixGestureDetectorState createState() => _MatrixGestureDetectorState();
}
class _MatrixGestureDetectorState extends State<MatrixGestureDetector> {
Matrix4 matrix = Matrix4.identity();
Offset translation = Offset.zero;
double scale = 1.0;
double rotation = 0.0;
@override
Widget build(BuildContext context) {
return GestureDetector(
onScaleStart: (details) {
setState(() {
translation = details.focalPoint;
});
},
onScaleUpdate: (details) {
setState(() {
scale = details.scale;
rotation = details.rotation;
});
},
onScaleEnd: (details) {
setState(() {
translation = Offset.zero;
scale = 1.0;
rotation = 0.0;
});
},
child: Transform(
transform: Matrix4.translationValues(translation.dx, translation.dy, 0)
..scale(scale)
..rotateZ(rotation),
child: Stack(
children: [
Positioned(
left: 50,
top: 50,
child: DraggableTextWidget(),
),
Positioned(
left: 150,
top: 150,
child: DraggableTextWidget(),
),
],
),
),
);
}
}
class DraggableTextWidget extends StatefulWidget {
@override
_DraggableTextWidgetState createState() => _DraggableTextWidgetState();
}
class _DraggableTextWidgetState extends State<DraggableTextWidget> {
Offset position = Offset.zero;
@override
Widget build(BuildContext context) {
return GestureDetector(
onPanStart: (details) {
setState(() {
position = details.localPosition;
});
},
onPanUpdate: (details) {
setState(() {
position += details.delta;
});
},
child: Container(
color: Colors.blue,
child: Text(
'Drag me',
style: TextStyle(color: Colors.white),
),
padding: EdgeInsets.all(8),
transformAlignment: Alignment.center,
transform: Matrix4.translationValues(position.dx, position.dy, 0),
),
);
}
}
在上述代码中,我们创建了一个MatrixGestureDetector
组件,它包含了一个GestureDetector
和一个Transform
组件。GestureDetector
用于检测手势操作,Transform
用于对子组件进行矩阵变换。
在MatrixGestureDetector
的build
方法中,我们将两个DraggableTextWidget
放置在Stack
中,并使用Positioned
来指定它们的位置。DraggableTextWidget
是一个可拖动的文本组件,通过GestureDetector
来检测手势操作,并通过Transform
来实现拖动效果。
通过onScaleStart
、onScaleUpdate
和onScaleEnd
回调,我们可以获取手势的缩放、旋转和平移信息,并更新matrix
、translation
、scale
和rotation
的值。然后,我们将这些值应用到Transform
的变换矩阵中,实现多个widget的矩阵手势检测器效果。
这样,当你在屏幕上进行手势操作时,两个文本widget将会跟随手势进行拖动、缩放和旋转。
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