41 lines
1.0 KiB
Dart
41 lines
1.0 KiB
Dart
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import 'package:flutter/rendering.dart';
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import 'package:flutter/widgets.dart';
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typedef OnWidgetSizeChange = void Function(Size size);
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class MeasureSize extends SingleChildRenderObjectWidget {
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final OnWidgetSizeChange onChange;
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const MeasureSize({super.key, required this.onChange, required Widget child})
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: super(child: child);
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@override
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RenderObject createRenderObject(BuildContext context) {
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return _MeasureSizeRenderObject(onChange);
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}
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@override
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void updateRenderObject(
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BuildContext context, covariant _MeasureSizeRenderObject renderObject) {
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renderObject.onChange = onChange;
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}
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}
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class _MeasureSizeRenderObject extends RenderProxyBox {
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_MeasureSizeRenderObject(this.onChange);
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OnWidgetSizeChange onChange;
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Size? _oldSize;
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@override
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void performLayout() {
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super.performLayout();
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Size? newSize = child?.size;
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if (_oldSize == newSize || newSize == null) return;
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_oldSize = newSize;
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WidgetsBinding.instance.addPostFrameCallback((_) {
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onChange(newSize);
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});
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}
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}
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