opt perf

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

lib/common/widgets/flutter/sliver_layout_builder.dart

@@ -0,0 +1,83 @@
+// 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:PiliPlus/common/widgets/flutter/layout_builder.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter/widgets.dart'
+    hide
+        ConstrainedLayoutBuilder,
+        LayoutBuilder,
+        RenderConstrainedLayoutBuilder;
+
+/// Builds a sliver widget tree that can depend on its own [SliverConstraints].
+///
+/// Similar to the [LayoutBuilder] widget except its builder should return a sliver
+/// widget, and [SliverLayoutBuilder] is itself a sliver. The framework calls the
+/// [builder] function at layout time and provides the current [SliverConstraints].
+/// The [SliverLayoutBuilder]'s final [SliverGeometry] will match the [SliverGeometry]
+/// of its child.
+///
+/// {@macro flutter.widgets.ConstrainedLayoutBuilder}
+///
+/// See also:
+///
+///  * [LayoutBuilder], the non-sliver version of this widget.
+class SliverLayoutBuilder extends ConstrainedLayoutBuilder<SliverConstraints> {
+  /// Creates a sliver widget that defers its building until layout.
+  const SliverLayoutBuilder({super.key, required super.builder});
+
+  @override
+  RenderConstrainedLayoutBuilder<SliverConstraints, RenderSliver>
+  createRenderObject(
+    BuildContext context,
+  ) => _RenderSliverLayoutBuilder();
+}
+
+class _RenderSliverLayoutBuilder extends RenderSliver
+    with
+        RenderObjectWithChildMixin<RenderSliver>,
+        RenderObjectWithLayoutCallbackMixin,
+        RenderConstrainedLayoutBuilder<SliverConstraints, RenderSliver> {
+  @override
+  double childMainAxisPosition(RenderObject child) {
+    assert(child == this.child);
+    return 0;
+  }
+
+  @override
+  void performLayout() {
+    runLayoutCallback();
+    child?.layout(constraints, parentUsesSize: true);
+    geometry = child?.geometry ?? SliverGeometry.zero;
+  }
+
+  @override
+  void applyPaintTransform(RenderObject child, Matrix4 transform) {
+    assert(child == this.child);
+    // child's offset is always (0, 0), transform.translate(0, 0) does not mutate the transform.
+  }
+
+  @override
+  void paint(PaintingContext context, Offset offset) {
+    // This renderObject does not introduce additional offset to child's position.
+    if (child?.geometry?.visible ?? false) {
+      context.paintChild(child!, offset);
+    }
+  }
+
+  @override
+  bool hitTestChildren(
+    SliverHitTestResult result, {
+    required double mainAxisPosition,
+    required double crossAxisPosition,
+  }) {
+    return child != null &&
+        child!.geometry!.hitTestExtent > 0 &&
+        child!.hitTest(
+          result,
+          mainAxisPosition: mainAxisPosition,
+          crossAxisPosition: crossAxisPosition,
+        );
+  }
+}