packages/flutter/lib/src/rendering/debug_overflow_indicator.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'dart:math' as math;
 import 'dart:ui' as ui;

 import 'package:flutter/foundation.dart';

 import 'object.dart';
 import 'stack.dart';

 // Describes which side the region data overflows on.
 enum _OverflowSide {
   left,
   top,
   bottom,
   right,
 }

 // Data used by the DebugOverflowIndicator to manage the regions and labels for
 // the indicators.
 class _OverflowRegionData {
   const _OverflowRegionData({
     required this.rect,
     this.label = '',
     this.labelOffset = Offset.zero,
     this.rotation = 0.0,
     required this.side,
   });

   final Rect rect;
   final String label;
   final Offset labelOffset;
   final double rotation;
   final _OverflowSide side;
 }

 /// An mixin indicator that is drawn when a [RenderObject] overflows its
 /// container.
 ///
 /// This is used by some RenderObjects that are containers to show where, and by
 /// how much, their children overflow their containers. These indicators are
 /// typically only shown in a debug build (where the call to
 /// [paintOverflowIndicator] is surrounded by an assert).
 ///
 /// This class will also print a debug message to the console when the container
 /// overflows. It will print on the first occurrence, and once after each time that
 /// [reassemble] is called.
 ///
 /// {@tool snippet}
 ///
 /// ```dart
 /// class MyRenderObject extends RenderAligningShiftedBox with DebugOverflowIndicatorMixin {
 ///   MyRenderObject({
 ///     AlignmentGeometry alignment = Alignment.center,
 ///     TextDirection? textDirection,
 ///     RenderBox? child,
 ///   }) : super.mixin(alignment, textDirection, child);
 ///
 ///   late Rect _containerRect;
 ///   late Rect _childRect;
 ///
 ///   @override
 ///   void performLayout() {
 ///     // ...
 ///     final BoxParentData childParentData = child!.parentData! as BoxParentData;
 ///     _containerRect = Offset.zero & size;
 ///     _childRect = childParentData.offset & child!.size;
 ///   }
 ///
 ///   @override
 ///   void paint(PaintingContext context, Offset offset) {
 ///     // Do normal painting here...
 ///     // ...
 ///
 ///     assert(() {
 ///       paintOverflowIndicator(context, offset, _containerRect, _childRect);
 ///       return true;
 ///     }());
 ///   }
 /// }
 /// ```
 /// {@end-tool}
 ///
 /// See also:
 ///
 ///  * [RenderConstraintsTransformBox], [RenderUnconstrainedBox] and
 ///    [RenderFlex], for examples of classes that use this indicator mixin.
 mixin DebugOverflowIndicatorMixin on RenderObject {
   static const Color _black = Color(0xBF000000);
   static const Color _yellow = Color(0xBFFFFF00);
   // The fraction of the container that the indicator covers.
   static const double _indicatorFraction = 0.1;
   static const double _indicatorFontSizePixels = 7.5;
   static const double _indicatorLabelPaddingPixels = 1.0;
   static const TextStyle _indicatorTextStyle = TextStyle(
     color: Color(0xFF900000),
     fontSize: _indicatorFontSizePixels,
     fontWeight: FontWeight.w800,
   );
   static final Paint _indicatorPaint = Paint()
     ..shader = ui.Gradient.linear(
       Offset.zero,
       const Offset(10.0, 10.0),
       <Color>[_black, _yellow, _yellow, _black],
       <double>[0.25, 0.25, 0.75, 0.75],
       TileMode.repeated,
     );
   static final Paint _labelBackgroundPaint = Paint()..color = const Color(0xFFFFFFFF);

   final List<TextPainter> _indicatorLabel = List<TextPainter>.filled(
     _OverflowSide.values.length,
     TextPainter(textDirection: TextDirection.ltr), // This label is in English.
   );

   // Set to true to trigger a debug message in the console upon
   // the next paint call. Will be reset after each paint.
   bool _overflowReportNeeded = true;

   String _formatPixels(double value) {
     assert(value > 0.0);
     final String pixels;
     if (value > 10.0) {
       pixels = value.toStringAsFixed(0);
     } else if (value > 1.0) {
       pixels = value.toStringAsFixed(1);
     } else {
       pixels = value.toStringAsPrecision(3);
     }
     return pixels;
   }

   List<_OverflowRegionData> _calculateOverflowRegions(RelativeRect overflow, Rect containerRect) {
     final List<_OverflowRegionData> regions = <_OverflowRegionData>[];
     if (overflow.left > 0.0) {
       final Rect markerRect = Rect.fromLTWH(
         0.0,
         0.0,
         containerRect.width * _indicatorFraction,
         containerRect.height,
       );
       regions.add(_OverflowRegionData(
         rect: markerRect,
         label: 'LEFT OVERFLOWED BY ${_formatPixels(overflow.left)} PIXELS',
         labelOffset: markerRect.centerLeft +
             const Offset(_indicatorFontSizePixels + _indicatorLabelPaddingPixels, 0.0),
         rotation: math.pi / 2.0,
         side: _OverflowSide.left,
       ));
     }
     if (overflow.right > 0.0) {
       final Rect markerRect = Rect.fromLTWH(
         containerRect.width * (1.0 - _indicatorFraction),
         0.0,
         containerRect.width * _indicatorFraction,
         containerRect.height,
       );
       regions.add(_OverflowRegionData(
         rect: markerRect,
         label: 'RIGHT OVERFLOWED BY ${_formatPixels(overflow.right)} PIXELS',
         labelOffset: markerRect.centerRight -
             const Offset(_indicatorFontSizePixels + _indicatorLabelPaddingPixels, 0.0),
         rotation: -math.pi / 2.0,
         side: _OverflowSide.right,
       ));
     }
     if (overflow.top > 0.0) {
       final Rect markerRect = Rect.fromLTWH(
         0.0,
         0.0,
         containerRect.width,
         containerRect.height * _indicatorFraction,
       );
       regions.add(_OverflowRegionData(
         rect: markerRect,
         label: 'TOP OVERFLOWED BY ${_formatPixels(overflow.top)} PIXELS',
         labelOffset: markerRect.topCenter + const Offset(0.0, _indicatorLabelPaddingPixels),
         side: _OverflowSide.top,
       ));
     }
     if (overflow.bottom > 0.0) {
       final Rect markerRect = Rect.fromLTWH(
         0.0,
         containerRect.height * (1.0 - _indicatorFraction),
         containerRect.width,
         containerRect.height * _indicatorFraction,
       );
       regions.add(_OverflowRegionData(
         rect: markerRect,
         label: 'BOTTOM OVERFLOWED BY ${_formatPixels(overflow.bottom)} PIXELS',
         labelOffset: markerRect.bottomCenter -
             const Offset(0.0, _indicatorFontSizePixels + _indicatorLabelPaddingPixels),
         side: _OverflowSide.bottom,
       ));
     }
     return regions;
   }

   void _reportOverflow(RelativeRect overflow, List<DiagnosticsNode>? overflowHints) {
     overflowHints ??= <DiagnosticsNode>[];
     if (overflowHints.isEmpty) {
       overflowHints.add(ErrorDescription(
         'The edge of the $runtimeType that is '
         'overflowing has been marked in the rendering with a yellow and black '
         'striped pattern. This is usually caused by the contents being too big '
         'for the $runtimeType.',
       ));
       overflowHints.add(ErrorHint(
         'This is considered an error condition because it indicates that there '
         'is content that cannot be seen. If the content is legitimately bigger '
         'than the available space, consider clipping it with a ClipRect widget '
         'before putting it in the $runtimeType, or using a scrollable '
         'container, like a ListView.',
       ));
     }

     final List<String> overflows = <String>[
       if (overflow.left > 0.0) '${_formatPixels(overflow.left)} pixels on the left',
       if (overflow.top > 0.0) '${_formatPixels(overflow.top)} pixels on the top',
       if (overflow.bottom > 0.0) '${_formatPixels(overflow.bottom)} pixels on the bottom',
       if (overflow.right > 0.0) '${_formatPixels(overflow.right)} pixels on the right',
     ];
     String overflowText = '';
     assert(overflows.isNotEmpty, "Somehow $runtimeType didn't actually overflow like it thought it did.");
     switch (overflows.length) {
       case 1:
         overflowText = overflows.first;
         break;
       case 2:
         overflowText = '${overflows.first} and ${overflows.last}';
         break;
       default:
         overflows[overflows.length - 1] = 'and ${overflows[overflows.length - 1]}';
         overflowText = overflows.join(', ');
     }
     // TODO(jacobr): add the overflows in pixels as structured data so they can
     // be visualized in debugging tools.
     FlutterError.reportError(
       FlutterErrorDetails(
         exception: FlutterError('A $runtimeType overflowed by $overflowText.'),
         library: 'rendering library',
         context: ErrorDescription('during layout'),
         informationCollector: () => <DiagnosticsNode>[
           // debugCreator should only be set in DebugMode, but we want the
           // treeshaker to know that.
           if (kDebugMode && debugCreator != null)
             DiagnosticsDebugCreator(debugCreator!),
           ...overflowHints!,
           describeForError('The specific $runtimeType in question is'),
           // TODO(jacobr): this line is ascii art that it would be nice to
           // handle a little more generically in GUI debugging clients in the
           // future.
           DiagnosticsNode.message('◢◤' * (FlutterError.wrapWidth ~/ 2), allowWrap: false),
         ],
       ),
     );
   }

   /// To be called when the overflow indicators should be painted.
   ///
   /// Typically only called if there is an overflow, and only from within a
   /// debug build.
   ///
   /// See example code in [DebugOverflowIndicatorMixin] documentation.
   void paintOverflowIndicator(
     PaintingContext context,
     Offset offset,
     Rect containerRect,
     Rect childRect, {
     List<DiagnosticsNode>? overflowHints,
   }) {
     final RelativeRect overflow = RelativeRect.fromRect(containerRect, childRect);

     if (overflow.left <= 0.0 &&
         overflow.right <= 0.0 &&
         overflow.top <= 0.0 &&
         overflow.bottom <= 0.0) {
       return;
     }

     final List<_OverflowRegionData> overflowRegions = _calculateOverflowRegions(overflow, containerRect);
     for (final _OverflowRegionData region in overflowRegions) {
       context.canvas.drawRect(region.rect.shift(offset), _indicatorPaint);
       final TextSpan? textSpan = _indicatorLabel[region.side.index].text as TextSpan?;
       if (textSpan?.text != region.label) {
         _indicatorLabel[region.side.index].text = TextSpan(
           text: region.label,
           style: _indicatorTextStyle,
         );
         _indicatorLabel[region.side.index].layout();
       }

       final Offset labelOffset = region.labelOffset + offset;
       final Offset centerOffset = Offset(-_indicatorLabel[region.side.index].width / 2.0, 0.0);
       final Rect textBackgroundRect = centerOffset & _indicatorLabel[region.side.index].size;
       context.canvas.save();
       context.canvas.translate(labelOffset.dx, labelOffset.dy);
       context.canvas.rotate(region.rotation);
       context.canvas.drawRect(textBackgroundRect, _labelBackgroundPaint);
       _indicatorLabel[region.side.index].paint(context.canvas, centerOffset);
       context.canvas.restore();
     }

     if (_overflowReportNeeded) {
       _overflowReportNeeded = false;
       _reportOverflow(overflow, overflowHints);
     }
   }

   @override
   void reassemble() {
     super.reassemble();
     // Users expect error messages to be shown again after hot reload.
     assert(() {
       _overflowReportNeeded = true;
       return true;
     }());
   }
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'dart:math' as math;
	import 'dart:ui' as ui;

	import 'package:flutter/foundation.dart';

	import 'object.dart';
	import 'stack.dart';

	// Describes which side the region data overflows on.
	enum _OverflowSide {
	left,
	top,
	bottom,
	right,
	}

	// Data used by the DebugOverflowIndicator to manage the regions and labels for
	// the indicators.
	class _OverflowRegionData {
	const _OverflowRegionData({
	required this.rect,
	this.label = '',
	this.labelOffset = Offset.zero,
	this.rotation = 0.0,
	required this.side,
	});

	final Rect rect;
	final String label;
	final Offset labelOffset;
	final double rotation;
	final _OverflowSide side;
	}

	/// An mixin indicator that is drawn when a [RenderObject] overflows its
	/// container.
	///
	/// This is used by some RenderObjects that are containers to show where, and by
	/// how much, their children overflow their containers. These indicators are
	/// typically only shown in a debug build (where the call to
	/// [paintOverflowIndicator] is surrounded by an assert).
	///
	/// This class will also print a debug message to the console when the container
	/// overflows. It will print on the first occurrence, and once after each time that
	/// [reassemble] is called.
	///
	/// {@tool snippet}
	///
	/// ```dart
	/// class MyRenderObject extends RenderAligningShiftedBox with DebugOverflowIndicatorMixin {
	/// MyRenderObject({
	/// AlignmentGeometry alignment = Alignment.center,
	/// TextDirection? textDirection,
	/// RenderBox? child,
	/// }) : super.mixin(alignment, textDirection, child);
	///
	/// late Rect _containerRect;
	/// late Rect _childRect;
	///
	/// @override
	/// void performLayout() {
	/// // ...
	/// final BoxParentData childParentData = child!.parentData! as BoxParentData;
	/// _containerRect = Offset.zero & size;
	/// _childRect = childParentData.offset & child!.size;
	/// }
	///
	/// @override
	/// void paint(PaintingContext context, Offset offset) {
	/// // Do normal painting here...
	/// // ...
	///
	/// assert(() {
	/// paintOverflowIndicator(context, offset, _containerRect, _childRect);
	/// return true;
	/// }());
	/// }
	/// }
	/// ```
	/// {@end-tool}
	///
	/// See also:
	///
	/// * [RenderConstraintsTransformBox], [RenderUnconstrainedBox] and
	/// [RenderFlex], for examples of classes that use this indicator mixin.
	mixin DebugOverflowIndicatorMixin on RenderObject {
	static const Color _black = Color(0xBF000000);
	static const Color _yellow = Color(0xBFFFFF00);
	// The fraction of the container that the indicator covers.
	static const double _indicatorFraction = 0.1;
	static const double _indicatorFontSizePixels = 7.5;
	static const double _indicatorLabelPaddingPixels = 1.0;
	static const TextStyle _indicatorTextStyle = TextStyle(
	color: Color(0xFF900000),
	fontSize: _indicatorFontSizePixels,
	fontWeight: FontWeight.w800,
	);
	static final Paint _indicatorPaint = Paint()
	..shader = ui.Gradient.linear(
	Offset.zero,
	const Offset(10.0, 10.0),
	<Color>[_black, _yellow, _yellow, _black],
	<double>[0.25, 0.25, 0.75, 0.75],
	TileMode.repeated,
	);
	static final Paint _labelBackgroundPaint = Paint()..color = const Color(0xFFFFFFFF);

	final List<TextPainter> _indicatorLabel = List<TextPainter>.filled(
	_OverflowSide.values.length,
	TextPainter(textDirection: TextDirection.ltr), // This label is in English.
	);

	// Set to true to trigger a debug message in the console upon
	// the next paint call. Will be reset after each paint.
	bool _overflowReportNeeded = true;

	String _formatPixels(double value) {
	assert(value > 0.0);
	final String pixels;
	if (value > 10.0) {
	pixels = value.toStringAsFixed(0);
	} else if (value > 1.0) {
	pixels = value.toStringAsFixed(1);
	} else {
	pixels = value.toStringAsPrecision(3);
	}
	return pixels;
	}

	List<_OverflowRegionData> _calculateOverflowRegions(RelativeRect overflow, Rect containerRect) {
	final List<_OverflowRegionData> regions = <_OverflowRegionData>[];
	if (overflow.left > 0.0) {
	final Rect markerRect = Rect.fromLTWH(
	0.0,
	0.0,
	containerRect.width * _indicatorFraction,
	containerRect.height,
	);
	regions.add(_OverflowRegionData(
	rect: markerRect,
	label: 'LEFT OVERFLOWED BY ${_formatPixels(overflow.left)} PIXELS',
	labelOffset: markerRect.centerLeft +
	const Offset(_indicatorFontSizePixels + _indicatorLabelPaddingPixels, 0.0),
	rotation: math.pi / 2.0,
	side: _OverflowSide.left,
	));
	}
	if (overflow.right > 0.0) {
	final Rect markerRect = Rect.fromLTWH(
	containerRect.width * (1.0 - _indicatorFraction),
	0.0,
	containerRect.width * _indicatorFraction,
	containerRect.height,
	);
	regions.add(_OverflowRegionData(
	rect: markerRect,
	label: 'RIGHT OVERFLOWED BY ${_formatPixels(overflow.right)} PIXELS',
	labelOffset: markerRect.centerRight -
	const Offset(_indicatorFontSizePixels + _indicatorLabelPaddingPixels, 0.0),
	rotation: -math.pi / 2.0,
	side: _OverflowSide.right,
	));
	}
	if (overflow.top > 0.0) {
	final Rect markerRect = Rect.fromLTWH(
	0.0,
	0.0,
	containerRect.width,
	containerRect.height * _indicatorFraction,
	);
	regions.add(_OverflowRegionData(
	rect: markerRect,
	label: 'TOP OVERFLOWED BY ${_formatPixels(overflow.top)} PIXELS',
	labelOffset: markerRect.topCenter + const Offset(0.0, _indicatorLabelPaddingPixels),
	side: _OverflowSide.top,
	));
	}
	if (overflow.bottom > 0.0) {
	final Rect markerRect = Rect.fromLTWH(
	0.0,
	containerRect.height * (1.0 - _indicatorFraction),
	containerRect.width,
	containerRect.height * _indicatorFraction,
	);
	regions.add(_OverflowRegionData(
	rect: markerRect,
	label: 'BOTTOM OVERFLOWED BY ${_formatPixels(overflow.bottom)} PIXELS',
	labelOffset: markerRect.bottomCenter -
	const Offset(0.0, _indicatorFontSizePixels + _indicatorLabelPaddingPixels),
	side: _OverflowSide.bottom,
	));
	}
	return regions;
	}

	void _reportOverflow(RelativeRect overflow, List<DiagnosticsNode>? overflowHints) {
	overflowHints ??= <DiagnosticsNode>[];
	if (overflowHints.isEmpty) {
	overflowHints.add(ErrorDescription(
	'The edge of the $runtimeType that is '
	'overflowing has been marked in the rendering with a yellow and black '
	'striped pattern. This is usually caused by the contents being too big '
	'for the $runtimeType.',
	));
	overflowHints.add(ErrorHint(
	'This is considered an error condition because it indicates that there '
	'is content that cannot be seen. If the content is legitimately bigger '
	'than the available space, consider clipping it with a ClipRect widget '
	'before putting it in the $runtimeType, or using a scrollable '
	'container, like a ListView.',
	));
	}

	final List<String> overflows = <String>[
	if (overflow.left > 0.0) '${_formatPixels(overflow.left)} pixels on the left',
	if (overflow.top > 0.0) '${_formatPixels(overflow.top)} pixels on the top',
	if (overflow.bottom > 0.0) '${_formatPixels(overflow.bottom)} pixels on the bottom',
	if (overflow.right > 0.0) '${_formatPixels(overflow.right)} pixels on the right',
	];
	String overflowText = '';
	assert(overflows.isNotEmpty, "Somehow $runtimeType didn't actually overflow like it thought it did.");
	switch (overflows.length) {
	case 1:
	overflowText = overflows.first;
	break;
	case 2:
	overflowText = '${overflows.first} and ${overflows.last}';
	break;
	default:
	overflows[overflows.length - 1] = 'and ${overflows[overflows.length - 1]}';
	overflowText = overflows.join(', ');
	}
	// TODO(jacobr): add the overflows in pixels as structured data so they can
	// be visualized in debugging tools.
	FlutterError.reportError(
	FlutterErrorDetails(
	exception: FlutterError('A $runtimeType overflowed by $overflowText.'),
	library: 'rendering library',
	context: ErrorDescription('during layout'),
	informationCollector: () => <DiagnosticsNode>[
	// debugCreator should only be set in DebugMode, but we want the
	// treeshaker to know that.
	if (kDebugMode && debugCreator != null)
	DiagnosticsDebugCreator(debugCreator!),
	...overflowHints!,
	describeForError('The specific $runtimeType in question is'),
	// TODO(jacobr): this line is ascii art that it would be nice to
	// handle a little more generically in GUI debugging clients in the
	// future.
	DiagnosticsNode.message('◢◤' * (FlutterError.wrapWidth ~/ 2), allowWrap: false),
	],
	),
	);
	}

	/// To be called when the overflow indicators should be painted.
	///
	/// Typically only called if there is an overflow, and only from within a
	/// debug build.
	///
	/// See example code in [DebugOverflowIndicatorMixin] documentation.
	void paintOverflowIndicator(
	PaintingContext context,
	Offset offset,
	Rect containerRect,
	Rect childRect, {
	List<DiagnosticsNode>? overflowHints,
	}) {
	final RelativeRect overflow = RelativeRect.fromRect(containerRect, childRect);

	if (overflow.left <= 0.0 &&
	overflow.right <= 0.0 &&
	overflow.top <= 0.0 &&
	overflow.bottom <= 0.0) {
	return;
	}

	final List<_OverflowRegionData> overflowRegions = _calculateOverflowRegions(overflow, containerRect);
	for (final _OverflowRegionData region in overflowRegions) {
	context.canvas.drawRect(region.rect.shift(offset), _indicatorPaint);
	final TextSpan? textSpan = _indicatorLabel[region.side.index].text as TextSpan?;
	if (textSpan?.text != region.label) {
	_indicatorLabel[region.side.index].text = TextSpan(
	text: region.label,
	style: _indicatorTextStyle,
	);
	_indicatorLabel[region.side.index].layout();
	}

	final Offset labelOffset = region.labelOffset + offset;
	final Offset centerOffset = Offset(-_indicatorLabel[region.side.index].width / 2.0, 0.0);
	final Rect textBackgroundRect = centerOffset & _indicatorLabel[region.side.index].size;
	context.canvas.save();
	context.canvas.translate(labelOffset.dx, labelOffset.dy);
	context.canvas.rotate(region.rotation);
	context.canvas.drawRect(textBackgroundRect, _labelBackgroundPaint);
	_indicatorLabel[region.side.index].paint(context.canvas, centerOffset);
	context.canvas.restore();
	}

	if (_overflowReportNeeded) {
	_overflowReportNeeded = false;
	_reportOverflow(overflow, overflowHints);
	}
	}

	@override
	void reassemble() {
	super.reassemble();
	// Users expect error messages to be shown again after hot reload.
	assert(() {
	_overflowReportNeeded = true;
	return true;
	}());
	}
	}