init

lib/features/core/widgets/gap.dart

@@ -0,0 +1,202 @@
+import 'package:flutter/rendering.dart';
+import 'package:flutter/widgets.dart';
+
+class Gap extends LeafRenderObjectWidget {
+  const Gap(this.size, {Key? key}) : super(key: key);
+
+  final double size;
+
+  @override
+  RenderGap createRenderObject(BuildContext context) => RenderGap(size);
+
+  @override
+  void updateRenderObject(BuildContext context, covariant RenderGap renderObject) {
+    renderObject.gap = size;
+    super.updateRenderObject(context, renderObject);
+  }
+
+  static const size4 = Gap(4);
+  static const size8 = Gap(8);
+  static const size16 = Gap(16);
+  static const size24 = Gap(24);
+  static const size32 = Gap(32);
+  static const size64 = Gap(64);
+}
+
+class RenderGap extends RenderBox {
+  RenderGap(this._gap) : super() {
+    markNeedsLayout();
+  }
+
+  double _gap;
+  double get gap => _gap;
+
+  set gap(double value) {
+    if (_gap != value) {
+      _gap = value;
+      markNeedsLayout();
+    }
+  }
+
+  @override
+  void performLayout() {
+    final parent = this.parent;
+    Size newSize;
+    if (parent is RenderFlex) {
+      switch (parent.direction) {
+        case Axis.vertical:
+          newSize = Size(0, gap);
+          break;
+        case Axis.horizontal:
+          newSize = Size(gap, 0);
+          break;
+      }
+    } else {
+      newSize = Size.square(gap);
+    }
+    size = constraints.constrain(newSize);
+  }
+}
+
+class AnimatedGap extends StatefulWidget {
+  const AnimatedGap(
+    this.gap, {
+    Key? key,
+    this.duration = const Duration(milliseconds: 200),
+    this.curve = Curves.easeInOut,
+  }) : super(key: key);
+
+  final Duration duration;
+  final double gap;
+  final Curve curve;
+
+  @override
+  State<AnimatedGap> createState() => _AnimatedGapState();
+}
+
+class _AnimatedGapState extends State<AnimatedGap> with SingleTickerProviderStateMixin {
+  late final _controller = AnimationController(
+    vsync: this,
+    value: widget.gap,
+    upperBound: double.infinity,
+  );
+
+  @override
+  void didUpdateWidget(covariant AnimatedGap oldWidget) {
+    if (oldWidget.gap != widget.gap) {
+      _controller.animateTo(
+        widget.gap,
+        curve: widget.curve,
+        duration: widget.duration,
+      );
+    }
+    super.didUpdateWidget(oldWidget);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ValueListenableBuilder<double>(
+      valueListenable: _controller,
+      builder: (context, gap, _) {
+        return Gap(gap);
+      },
+    );
+  }
+}
+
+class AnimatedSliverGap extends StatefulWidget {
+  const AnimatedSliverGap(
+    this.gap, {
+    Key? key,
+    this.duration = const Duration(milliseconds: 200),
+    this.curve = Curves.easeInOut,
+  }) : super(key: key);
+
+  final Duration duration;
+  final double gap;
+  final Curve curve;
+
+  @override
+  State<AnimatedSliverGap> createState() => _AnimatedSliverGapState();
+}
+
+class _AnimatedSliverGapState extends State<AnimatedSliverGap> with SingleTickerProviderStateMixin {
+  late final _controller = AnimationController(
+    vsync: this,
+    value: widget.gap,
+    upperBound: double.infinity,
+  );
+
+  @override
+  void didUpdateWidget(covariant AnimatedSliverGap oldWidget) {
+    if (oldWidget.gap != widget.gap) {
+      _controller.animateTo(
+        widget.gap,
+        curve: widget.curve,
+        duration: widget.duration,
+      );
+    }
+    super.didUpdateWidget(oldWidget);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ValueListenableBuilder<double>(
+      valueListenable: _controller,
+      builder: (context, gap, _) {
+        return SliverGap(gap);
+      },
+    );
+  }
+}
+
+class SliverGap extends LeafRenderObjectWidget {
+  const SliverGap(this.gap, {Key? key}) : super(key: key);
+
+  final double gap;
+
+  static const size4 = SliverGap(4);
+  static const size8 = SliverGap(8);
+  static const size16 = SliverGap(16);
+  static const size24 = SliverGap(24);
+  static const size32 = SliverGap(32);
+  static const size64 = SliverGap(64);
+
+  @override
+  RenderSliverGap createRenderObject(BuildContext context) => RenderSliverGap(gap);
+
+  @override
+  void updateRenderObject(BuildContext context, covariant RenderSliverGap renderObject) {
+    renderObject.gap = gap;
+    super.updateRenderObject(context, renderObject);
+  }
+}
+
+class RenderSliverGap extends RenderSliver {
+  RenderSliverGap(this._gap) : super() {
+    markNeedsLayout();
+  }
+
+  double _gap;
+  double get gap => _gap;
+
+  set gap(double value) {
+    if (_gap != value) {
+      _gap = value;
+      markNeedsLayout();
+    }
+  }
+
+  @override
+  void performLayout() {
+    final cacheExtent = calculateCacheOffset(constraints, from: 0, to: gap);
+    final paintExtent = calculatePaintOffset(constraints, from: 0, to: gap);
+    geometry = SliverGeometry(
+      paintExtent: paintExtent,
+      scrollExtent: gap,
+      visible: false,
+      cacheExtent: cacheExtent,
+      maxPaintExtent: gap,
+    );
+  }
+}