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Forked from Sunbreak/Example.md
Created April 21, 2024 15:35
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RenderProxyBox

RenderProxyBox

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: Center(
child: Shimmer(
gradient: gradient,
child: Container(
width: 500,
height: 500,
color: Colors.red,
),
),
),
),
);
}
}
final gradient = LinearGradient(
begin: Alignment.topLeft,
end: Alignment.centerRight,
colors: <Color>[
Colors.grey[300],
Colors.grey[300],
Colors.grey[100],
Colors.grey[300],
Colors.grey[300]
],
stops: const <double>[0.0, 0.35, 0.5, 0.65, 1.0],
);
class Shimmer extends SingleChildRenderObjectWidget {
final Gradient gradient;
const Shimmer({
Key key,
@required this.gradient,
Widget child,
}) : super(key: key, child: child);
@override
RenderObject createRenderObject(BuildContext context) {
return RenderShimmer(this.gradient);
}
}
class RenderShimmer extends RenderProxyBox {
final Gradient gradient;
RenderShimmer(this.gradient);
@override
bool get alwaysNeedsCompositing => child != null;
@override
void paint(PaintingContext context, Offset offset) {
if (child != null) {
assert(needsCompositing);
var rect = offset & child.size;
context.canvas.saveLayer(rect, Paint());
context.paintChild(child, offset);
final gradientPaint = Paint()
..blendMode = BlendMode.srcIn
..shader = gradient.createShader(rect);
print('paint');
context.canvas.drawRect(rect, gradientPaint);
context.canvas.restore();
}
}
}
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