opt ui

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

lib/common/widgets/scaffold/simple_scaffold.dart

@@ -0,0 +1,152 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart'
+    show BoxParentData, BoxHitTestResult, ChildLayoutHelper;
+
+class SimpleScaffold extends StatelessWidget {
+  const SimpleScaffold({
+    super.key,
+    this.backgroundColor,
+    this.fab,
+    this.appBar,
+    required this.body,
+  });
+
+  final Color? backgroundColor;
+  final Widget? fab;
+  final Widget? appBar;
+  final Widget body;
+
+  @override
+  Widget build(BuildContext context) {
+    return Material(
+      color: backgroundColor,
+      child: ScaffoldLayout(
+        fab: fab,
+        appBar: appBar,
+        body: body,
+      ),
+    );
+  }
+}
+
+enum ScaffoldType { fab, appBar, body }
+
+class ScaffoldLayout
+    extends SlottedMultiChildRenderObjectWidget<ScaffoldType, RenderBox> {
+  const ScaffoldLayout({
+    super.key,
+    this.fab,
+    this.appBar,
+    required this.body,
+  });
+
+  final Widget? fab;
+  final Widget? appBar;
+  final Widget body;
+
+  @override
+  Iterable<ScaffoldType> get slots => ScaffoldType.values;
+
+  @override
+  Widget? childForSlot(slot) => switch (slot) {
+    .fab => fab,
+    .appBar => appBar,
+    .body => body,
+  };
+
+  @override
+  SlottedContainerRenderObjectMixin<ScaffoldType, RenderBox> createRenderObject(
+    BuildContext context,
+  ) {
+    return _RenderScaffoldLayout();
+  }
+}
+
+class _RenderScaffoldLayout extends RenderBox
+    with SlottedContainerRenderObjectMixin<ScaffoldType, RenderBox> {
+  RenderBox? get fab => childForSlot(.fab);
+  RenderBox? get appBar => childForSlot(.appBar);
+  RenderBox get body => childForSlot(.body)!;
+
+  Offset _getOffset(RenderBox child) {
+    return (child.parentData as BoxParentData).offset;
+  }
+
+  void _setOffset(RenderBox child, Offset offset) {
+    (child.parentData as BoxParentData).offset = offset;
+  }
+
+  @override
+  void performLayout() {
+    final constraints = this.constraints;
+    size = constraints.biggest;
+
+    final Offset bodyOffset;
+    final BoxConstraints bodyConstraints;
+
+    final appBar = this.appBar;
+    if (appBar != null) {
+      final appBarHeight = ChildLayoutHelper.layoutChild(
+        appBar,
+        BoxConstraints.tightFor(width: constraints.maxWidth),
+      ).height;
+      _setOffset(appBar, .zero);
+
+      bodyOffset = Offset(0, appBarHeight);
+      bodyConstraints = BoxConstraints.tightFor(
+        width: constraints.maxWidth,
+        height: constraints.maxHeight - appBarHeight,
+      );
+    } else {
+      bodyOffset = .zero;
+      bodyConstraints = constraints;
+    }
+
+    final body = this.body..layout(bodyConstraints);
+    _setOffset(body, bodyOffset);
+
+    final fab = this.fab;
+    if (fab != null) {
+      final fabSize = ChildLayoutHelper.layoutChild(fab, constraints.loosen());
+      _setOffset(
+        fab,
+        Offset(
+          constraints.maxWidth - fabSize.width,
+          constraints.maxHeight - fabSize.height,
+        ),
+      );
+    }
+  }
+
+  @override
+  void paint(PaintingContext context, Offset offset) {
+    void doPaint(RenderBox? child) {
+      if (child != null) {
+        context.paintChild(child, _getOffset(child) + offset);
+      }
+    }
+
+    doPaint(appBar);
+    doPaint(body);
+    doPaint(fab);
+  }
+
+  @override
+  bool hitTestChildren(BoxHitTestResult result, {required Offset position}) {
+    for (final type in ScaffoldType.values) {
+      final child = childForSlot(type);
+      if (child == null) continue;
+      final bool isHit = result.addWithPaintOffset(
+        offset: _getOffset(child),
+        position: position,
+        hitTest: (BoxHitTestResult result, Offset transformed) {
+          return child.hitTest(result, position: transformed);
+        },
+      );
+      if (isHit) {
+        return true;
+      }
+    }
+    return false;
+  }
+}