42 lines
880 B
Dart
42 lines
880 B
Dart
import 'package:flutter/material.dart';
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import 'package:flutter/rendering.dart';
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typedef SizeCallback = void Function(Size size);
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class _RenderSizeObserver extends RenderProxyBox {
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_RenderSizeObserver({
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RenderBox? child,
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required this.onLayoutChangedCallback,
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}) : super(child);
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final SizeCallback onLayoutChangedCallback;
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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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if (size != _oldSize) {
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onLayoutChangedCallback(size);
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}
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_oldSize = size;
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}
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}
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class SizeObserver extends SingleChildRenderObjectWidget {
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const SizeObserver({
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super.key,
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required Widget super.child,
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required this.onSized,
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});
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final SizeCallback onSized;
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@override
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_RenderSizeObserver createRenderObject(BuildContext context) {
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return _RenderSizeObserver(
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onLayoutChangedCallback: onSized,
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);
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}
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}
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