OpenContacts/lib/widgets/blend_mask.dart

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import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
// Applies a BlendMode to its child.
class BlendMask extends SingleChildRenderObjectWidget {
final BlendMode blendMode;
final double opacity;
const BlendMask({
required this.blendMode,
this.opacity = 1.0,
super.key,
super.child,
});
@override
RenderObject createRenderObject(context) {
return RenderBlendMask(blendMode, opacity);
}
@override
void updateRenderObject(BuildContext context, RenderBlendMask renderObject) {
renderObject.blendMode = blendMode;
renderObject.opacity = opacity;
}
}
class RenderBlendMask extends RenderProxyBox {
BlendMode blendMode;
double opacity;
RenderBlendMask(this.blendMode, this.opacity);
@override
void paint(context, offset) {
// Create a new layer and specify the blend mode and opacity to composite it with:
context.canvas.saveLayer(
offset & size,
Paint()
..blendMode = blendMode
..color = Color.fromARGB((opacity * 255).round(), 255, 255, 255),
);
super.paint(context, offset);
// Composite the layer back into the canvas using the blendmode:
context.canvas.restore();
}
}