opt perf

Signed-off-by: dom <githubaccount56556@proton.me>

lib/common/widgets/flutter/layout_builder.dart

@@ -0,0 +1,526 @@
+// 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 'package:flutter/foundation.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter/widgets.dart';
+
+/// An abstract superclass for widgets that defer their building until layout.
+///
+/// Similar to the [Builder] widget except that the implementation calls the [builder]
+/// function at layout time and provides the [LayoutInfoType] that is required to
+/// configure the child widget subtree.
+///
+/// This is useful when the child widget tree relies on information that are only
+/// available during layout, and doesn't depend on the child's intrinsic size.
+///
+/// The [LayoutInfoType] should typically be immutable. The equality of the
+/// [LayoutInfoType] type is used by the implementation to avoid unnecessary
+/// rebuilds: if the new [LayoutInfoType] computed during layout is the same as
+/// (defined by `LayoutInfoType.==`) the previous [LayoutInfoType], the
+/// implementation will try to avoid calling the [builder] again unless
+/// [updateShouldRebuild] returns true. The corresponding [RenderObject] produced
+/// by this widget retains the most up-to-date [LayoutInfoType] for this purpose,
+/// which may keep a [LayoutInfoType] object in memory until the widget is removed
+/// from the tree.
+///
+/// Subclasses must return a [RenderObject] that mixes in [RenderAbstractLayoutBuilderMixin].
+abstract class AbstractLayoutBuilder<LayoutInfoType>
+    extends RenderObjectWidget {
+  /// Creates a widget that defers its building until layout.
+  const AbstractLayoutBuilder({super.key});
+
+  /// Called at layout time to construct the widget tree.
+  ///
+  /// The builder must not return null.
+  Widget Function(BuildContext context, LayoutInfoType layoutInfo) get builder;
+
+  @override
+  RenderObjectElement createElement() =>
+      _LayoutBuilderElement<LayoutInfoType>(this);
+
+  /// Whether [builder] needs to be called again even if the layout constraints
+  /// are the same.
+  ///
+  /// When this widget's configuration is updated, the [builder] callback most
+  /// likely needs to be called to build this widget's child. However,
+  /// subclasses may provide ways in which the widget can be updated without
+  /// needing to rebuild the child. Such subclasses can use this method to tell
+  /// the framework when the child widget should be rebuilt.
+  ///
+  /// When this method is called by the framework, the newly configured widget
+  /// is asked if it requires a rebuild, and it is passed the old widget as a
+  /// parameter.
+  ///
+  /// See also:
+  ///
+  ///  * [State.setState] and [State.didUpdateWidget], which talk about widget
+  ///    configuration changes and how they're triggered.
+  ///  * [Element.update], the method that actually updates the widget's
+  ///    configuration.
+  @protected
+  bool updateShouldRebuild(
+    covariant AbstractLayoutBuilder<LayoutInfoType> oldWidget,
+  ) => true;
+
+  @override
+  RenderAbstractLayoutBuilderMixin<LayoutInfoType, RenderObject>
+  createRenderObject(
+    BuildContext context,
+  );
+
+  // updateRenderObject is redundant with the logic in the LayoutBuilderElement below.
+}
+
+/// A specialized [AbstractLayoutBuilder] whose widget subtree depends on the
+/// incoming [ConstraintType] that will be imposed on the widget.
+///
+/// {@template flutter.widgets.ConstrainedLayoutBuilder}
+/// The [builder] function is called in the following situations:
+///
+/// * The first time the widget is laid out.
+/// * When the parent widget passes different layout constraints.
+/// * When the parent widget updates this widget and [updateShouldRebuild] returns `true`.
+/// * When the dependencies that the [builder] function subscribes to change.
+///
+/// The [builder] function is _not_ called during layout if the parent passes
+/// the same constraints repeatedly.
+///
+/// In the event that an ancestor skips the layout of this subtree so the
+/// constraints become outdated, the `builder` rebuilds with the last known
+/// constraints.
+/// {@endtemplate}
+abstract class ConstrainedLayoutBuilder<ConstraintType extends Constraints>
+    extends AbstractLayoutBuilder<ConstraintType> {
+  /// Creates a widget that defers its building until layout.
+  const ConstrainedLayoutBuilder({super.key, required this.builder});
+
+  @override
+  final Widget Function(BuildContext context, ConstraintType constraints)
+  builder;
+}
+
+class _LayoutBuilderElement<LayoutInfoType> extends RenderObjectElement {
+  _LayoutBuilderElement(AbstractLayoutBuilder<LayoutInfoType> super.widget);
+
+  @override
+  RenderAbstractLayoutBuilderMixin<LayoutInfoType, RenderObject>
+  get renderObject =>
+      super.renderObject
+          as RenderAbstractLayoutBuilderMixin<LayoutInfoType, RenderObject>;
+
+  Element? _child;
+
+  // @override
+  // BuildScope get buildScope => _buildScope;
+
+  // late final BuildScope _buildScope = BuildScope(
+  //   scheduleRebuild: _scheduleRebuild,
+  // );
+
+  // To schedule a rebuild, markNeedsLayout needs to be called on this Element's
+  // render object (as the rebuilding is done in its performLayout call). However,
+  // the render tree should typically be kept clean during the postFrameCallbacks
+  // and the idle phase, so the layout data can be safely read.
+  // bool _deferredCallbackScheduled = false;
+  // void _scheduleRebuild() {
+  //   if (_deferredCallbackScheduled) {
+  //     return;
+  //   }
+
+  //   final bool deferMarkNeedsLayout =
+  //       switch (SchedulerBinding.instance.schedulerPhase) {
+  //         SchedulerPhase.idle || SchedulerPhase.postFrameCallbacks => true,
+  //         SchedulerPhase.transientCallbacks ||
+  //         SchedulerPhase.midFrameMicrotasks ||
+  //         SchedulerPhase.persistentCallbacks => false,
+  //       };
+  //   if (!deferMarkNeedsLayout) {
+  //     renderObject.scheduleLayoutCallback();
+  //     return;
+  //   }
+  //   _deferredCallbackScheduled = true;
+  //   SchedulerBinding.instance.scheduleFrameCallback(_frameCallback);
+  // }
+
+  // void _frameCallback(Duration timestamp) {
+  //   _deferredCallbackScheduled = false;
+  //   // This method is only called when the render tree is stable, if the Element
+  //   // is deactivated it will never be reincorporated back to the tree.
+  //   if (mounted) {
+  //     renderObject.scheduleLayoutCallback();
+  //   }
+  // }
+
+  @override
+  void visitChildren(ElementVisitor visitor) {
+    if (_child != null) {
+      visitor(_child!);
+    }
+  }
+
+  @override
+  void forgetChild(Element child) {
+    assert(child == _child);
+    _child = null;
+    super.forgetChild(child);
+  }
+
+  @override
+  void mount(Element? parent, Object? newSlot) {
+    super.mount(parent, newSlot); // Creates the renderObject.
+    renderObject._updateCallback(_rebuildWithConstraints);
+  }
+
+  @override
+  void update(AbstractLayoutBuilder<LayoutInfoType> newWidget) {
+    assert(widget != newWidget);
+    final oldWidget = widget as AbstractLayoutBuilder<LayoutInfoType>;
+    super.update(newWidget);
+    assert(widget == newWidget);
+
+    renderObject._updateCallback(_rebuildWithConstraints);
+    if (newWidget.updateShouldRebuild(oldWidget)) {
+      _needsBuild = true;
+      renderObject.scheduleLayoutCallback();
+    }
+  }
+
+  @override
+  void markNeedsBuild() {
+    // Calling super.markNeedsBuild is not needed. This Element does not need
+    // to performRebuild since this call already does what performRebuild does,
+    // So the element is clean as soon as this method returns and does not have
+    // to be added to the dirty list or marked as dirty.
+    renderObject.scheduleLayoutCallback();
+    _needsBuild = true;
+  }
+
+  @override
+  void performRebuild() {
+    // This gets called if markNeedsBuild() is called on us.
+    // That might happen if, e.g., our builder uses Inherited widgets.
+
+    // Force the callback to be called, even if the layout constraints are the
+    // same. This is because that callback may depend on the updated widget
+    // configuration, or an inherited widget.
+    renderObject.scheduleLayoutCallback();
+    _needsBuild = true;
+    super
+        .performRebuild(); // Calls widget.updateRenderObject (a no-op in this case).
+  }
+
+  @override
+  void unmount() {
+    renderObject._callback = null;
+    super.unmount();
+  }
+
+  // The LayoutInfoType that was used to invoke the layout callback with last time,
+  // during layout. The `_previousLayoutInfo` value is compared to the new one
+  // to determine whether [LayoutBuilderBase.builder] needs to be called.
+  LayoutInfoType? _previousLayoutInfo;
+  bool _needsBuild = true;
+
+  void _rebuildWithConstraints(Constraints _) {
+    final LayoutInfoType layoutInfo = renderObject.layoutInfo;
+    @pragma('vm:notify-debugger-on-exception')
+    void updateChildCallback() {
+      Widget built;
+      try {
+        assert(layoutInfo == renderObject.layoutInfo);
+        built = (widget as AbstractLayoutBuilder<LayoutInfoType>).builder(
+          this,
+          layoutInfo,
+        );
+        debugWidgetBuilderValue(widget, built);
+      } catch (e, stack) {
+        built = ErrorWidget.builder(
+          _reportException(
+            ErrorDescription('building $widget'),
+            e,
+            stack,
+            informationCollector: () => <DiagnosticsNode>[
+              if (kDebugMode) DiagnosticsDebugCreator(DebugCreator(this)),
+            ],
+          ),
+        );
+      }
+      try {
+        _child = updateChild(_child, built, null);
+        assert(_child != null);
+      } catch (e, stack) {
+        built = ErrorWidget.builder(
+          _reportException(
+            ErrorDescription('building $widget'),
+            e,
+            stack,
+            informationCollector: () => <DiagnosticsNode>[
+              if (kDebugMode) DiagnosticsDebugCreator(DebugCreator(this)),
+            ],
+          ),
+        );
+        _child = updateChild(null, built, slot);
+      } finally {
+        _needsBuild = false;
+        _previousLayoutInfo = layoutInfo;
+      }
+    }
+
+    final VoidCallback? callback =
+        _needsBuild || (layoutInfo != _previousLayoutInfo)
+        ? updateChildCallback
+        : null;
+    owner!.buildScope(this, callback);
+  }
+
+  @override
+  void insertRenderObjectChild(RenderObject child, Object? slot) {
+    final RenderObjectWithChildMixin<RenderObject> renderObject =
+        this.renderObject;
+    assert(slot == null);
+    assert(renderObject.debugValidateChild(child));
+    renderObject.child = child;
+    assert(renderObject == this.renderObject);
+  }
+
+  @override
+  void moveRenderObjectChild(
+    RenderObject child,
+    Object? oldSlot,
+    Object? newSlot,
+  ) {
+    assert(false);
+  }
+
+  @override
+  void removeRenderObjectChild(RenderObject child, Object? slot) {
+    final RenderAbstractLayoutBuilderMixin<LayoutInfoType, RenderObject>
+    renderObject = this.renderObject;
+    assert(renderObject.child == child);
+    renderObject.child = null;
+    assert(renderObject == this.renderObject);
+  }
+}
+
+/// Generic mixin for [RenderObject]s created by an [AbstractLayoutBuilder] with
+/// the the same `LayoutInfoType`.
+///
+/// Provides a [layoutCallback] implementation which, if needed, invokes
+/// [AbstractLayoutBuilder]'s builder callback.
+///
+/// Implementers can override the [layoutInfo] implementation with a value
+/// that is safe to access in [layoutCallback], which is called in
+/// [performLayout]. The default [layoutInfo] returns the incoming
+/// [Constraints].
+///
+/// This mixin replaces [RenderConstrainedLayoutBuilder].
+mixin RenderAbstractLayoutBuilderMixin<
+  LayoutInfoType,
+  ChildType extends RenderObject
+>
+    on
+        RenderObjectWithChildMixin<ChildType>,
+        RenderObjectWithLayoutCallbackMixin {
+  LayoutCallback<Constraints>? _callback;
+
+  /// Change the layout callback.
+  void _updateCallback(LayoutCallback<Constraints> value) {
+    if (value == _callback) {
+      return;
+    }
+    _callback = value;
+    scheduleLayoutCallback();
+  }
+
+  /// Invokes the builder callback supplied via [AbstractLayoutBuilder] and
+  /// rebuilds the [AbstractLayoutBuilder]'s widget tree, if needed.
+  ///
+  /// No further work will be done if [layoutInfo] has not changed since the last
+  /// time this method was called, and [AbstractLayoutBuilder.updateShouldRebuild]
+  /// returned `false` when the widget was rebuilt.
+  ///
+  /// This method should typically be called as soon as possible in the class's
+  /// [performLayout] implementation, before any layout work is done.
+  @visibleForOverriding
+  @override
+  void layoutCallback() => _callback!(constraints);
+
+  /// The information to invoke the [AbstractLayoutBuilder.builder] callback with.
+  ///
+  /// This is typically the information that are only made available in
+  /// [performLayout], which is inaccessible for regular [Builder] widget,
+  /// such as the incoming [Constraints], which are the default value.
+  @protected
+  LayoutInfoType get layoutInfo => constraints as LayoutInfoType;
+}
+
+/// Generic mixin for [RenderObject]s created by an [AbstractLayoutBuilder] with
+/// the the same `LayoutInfoType`.
+///
+/// Use [RenderAbstractLayoutBuilderMixin] instead, which replaces this mixin.
+typedef RenderConstrainedLayoutBuilder<
+  LayoutInfoType,
+  ChildType extends RenderObject
+> = RenderAbstractLayoutBuilderMixin<LayoutInfoType, ChildType>;
+
+/// Builds a widget tree that can depend on the parent widget's size.
+///
+/// Similar to the [Builder] widget except that the framework calls the [builder]
+/// function at layout time and provides the parent widget's constraints. This
+/// is useful when the parent constrains the child's size and doesn't depend on
+/// the child's intrinsic size. The [LayoutBuilder]'s final size will match its
+/// child's size.
+///
+/// {@macro flutter.widgets.ConstrainedLayoutBuilder}
+///
+/// {@youtube 560 315 https://www.youtube.com/watch?v=IYDVcriKjsw}
+///
+/// If the child should be smaller than the parent, consider wrapping the child
+/// in an [Align] widget. If the child might want to be bigger, consider
+/// wrapping it in a [SingleChildScrollView] or [OverflowBox].
+///
+/// {@tool dartpad}
+/// This example uses a [LayoutBuilder] to build a different widget depending on the available width. Resize the
+/// DartPad window to see [LayoutBuilder] in action!
+///
+/// ** See code in examples/api/lib/widgets/layout_builder/layout_builder.0.dart **
+/// {@end-tool}
+///
+/// See also:
+///
+///  * [SliverLayoutBuilder], the sliver counterpart of this widget.
+///  * [Builder], which calls a `builder` function at build time.
+///  * [StatefulBuilder], which passes its `builder` function a `setState` callback.
+///  * [CustomSingleChildLayout], which positions its child during layout.
+///  * The [catalog of layout widgets](https://flutter.dev/widgets/layout/).
+class LayoutBuilder extends ConstrainedLayoutBuilder<BoxConstraints> {
+  /// Creates a widget that defers its building until layout.
+  const LayoutBuilder({super.key, required super.builder});
+
+  @override
+  RenderAbstractLayoutBuilderMixin<BoxConstraints, RenderBox>
+  createRenderObject(
+    BuildContext context,
+  ) => _RenderLayoutBuilder();
+}
+
+class _RenderLayoutBuilder extends RenderBox
+    with
+        RenderObjectWithChildMixin<RenderBox>,
+        RenderObjectWithLayoutCallbackMixin,
+        RenderAbstractLayoutBuilderMixin<BoxConstraints, RenderBox> {
+  @override
+  double computeMinIntrinsicWidth(double height) {
+    assert(_debugThrowIfNotCheckingIntrinsics());
+    return 0.0;
+  }
+
+  @override
+  double computeMaxIntrinsicWidth(double height) {
+    assert(_debugThrowIfNotCheckingIntrinsics());
+    return 0.0;
+  }
+
+  @override
+  double computeMinIntrinsicHeight(double width) {
+    assert(_debugThrowIfNotCheckingIntrinsics());
+    return 0.0;
+  }
+
+  @override
+  double computeMaxIntrinsicHeight(double width) {
+    assert(_debugThrowIfNotCheckingIntrinsics());
+    return 0.0;
+  }
+
+  @override
+  Size computeDryLayout(BoxConstraints constraints) {
+    assert(
+      debugCannotComputeDryLayout(
+        reason:
+            'Calculating the dry layout would require running the layout callback '
+            'speculatively, which might mutate the live render object tree.',
+      ),
+    );
+    return Size.zero;
+  }
+
+  @override
+  double? computeDryBaseline(
+    BoxConstraints constraints,
+    TextBaseline baseline,
+  ) {
+    assert(
+      debugCannotComputeDryLayout(
+        reason:
+            'Calculating the dry baseline would require running the layout callback '
+            'speculatively, which might mutate the live render object tree.',
+      ),
+    );
+    return null;
+  }
+
+  @override
+  void performLayout() {
+    final BoxConstraints constraints = this.constraints;
+    runLayoutCallback();
+    if (child != null) {
+      child!.layout(constraints, parentUsesSize: true);
+      size = constraints.constrain(child!.size);
+    } else {
+      size = constraints.biggest;
+    }
+  }
+
+  @override
+  double? computeDistanceToActualBaseline(TextBaseline baseline) {
+    return child?.getDistanceToActualBaseline(baseline) ??
+        super.computeDistanceToActualBaseline(baseline);
+  }
+
+  @override
+  bool hitTestChildren(BoxHitTestResult result, {required Offset position}) {
+    return child?.hitTest(result, position: position) ?? false;
+  }
+
+  @override
+  void paint(PaintingContext context, Offset offset) {
+    if (child != null) {
+      context.paintChild(child!, offset);
+    }
+  }
+
+  bool _debugThrowIfNotCheckingIntrinsics() {
+    assert(() {
+      if (!RenderObject.debugCheckingIntrinsics) {
+        throw FlutterError(
+          'LayoutBuilder does not support returning intrinsic dimensions.\n'
+          'Calculating the intrinsic dimensions would require running the layout '
+          'callback speculatively, which might mutate the live render object tree.',
+        );
+      }
+      return true;
+    }());
+
+    return true;
+  }
+}
+
+FlutterErrorDetails _reportException(
+  DiagnosticsNode context,
+  Object exception,
+  StackTrace stack, {
+  InformationCollector? informationCollector,
+}) {
+  final details = FlutterErrorDetails(
+    exception: exception,
+    stack: stack,
+    library: 'widgets library',
+    context: context,
+    informationCollector: informationCollector,
+  );
+  FlutterError.reportError(details);
+  return details;
+}