opt dyn

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

lib/utils/waterfall.dart

@@ -0,0 +1,68 @@
+import 'package:flutter/material.dart' show ValueChanged;
+import 'package:flutter/rendering.dart' show SliverConstraints;
+import 'package:waterfall_flow/waterfall_flow.dart'
+    show SliverWaterfallFlowDelegate;
+
+class SliverWaterfallFlowDelegateWithMaxCrossAxisExtent
+    extends SliverWaterfallFlowDelegate {
+  /// Creates a delegate that makes masonry layouts with tiles that have a maximum
+  /// cross-axis extent.
+  ///
+  /// All of the arguments must not be null. The [maxCrossAxisExtent],
+  /// [mainAxisSpacing], and [crossAxisSpacing] arguments must not be negative.
+  SliverWaterfallFlowDelegateWithMaxCrossAxisExtent({
+    required this.maxCrossAxisExtent,
+    super.mainAxisSpacing,
+    super.crossAxisSpacing,
+    super.lastChildLayoutTypeBuilder,
+    super.collectGarbage,
+    super.viewportBuilder,
+    super.closeToTrailing,
+    this.callback,
+  }) : assert(maxCrossAxisExtent >= 0);
+
+  /// The maximum extent of tiles in the cross axis.
+  ///
+  /// This delegate will select a cross-axis extent for the tiles that is as
+  /// large as possible subject to the following conditions:
+  ///
+  ///  - The extent evenly divides the cross-axis extent of the grid.
+  ///  - The extent is at most [maxCrossAxisExtent].
+  ///
+  /// For example, if the grid is vertical, the grid is 500.0 pixels wide, and
+  /// [maxCrossAxisExtent] is 150.0, this delegate will create a grid with 4
+  /// columns that are 125.0 pixels wide.
+  final double maxCrossAxisExtent;
+
+  int? crossAxisCount;
+  double? crossAxisExtent;
+
+  final ValueChanged<double>? callback;
+
+  @override
+  int getCrossAxisCount(SliverConstraints constraints) {
+    if (crossAxisCount != null &&
+        constraints.crossAxisExtent == crossAxisExtent) {
+      return crossAxisCount!;
+    }
+    crossAxisExtent = constraints.crossAxisExtent;
+    crossAxisCount =
+        (constraints.crossAxisExtent / (maxCrossAxisExtent + crossAxisSpacing))
+            .ceil();
+    callback?.call(constraints.crossAxisExtent / crossAxisCount!);
+    return crossAxisCount!;
+  }
+
+  @override
+  bool shouldRelayout(SliverWaterfallFlowDelegate oldDelegate) {
+    final flag =
+        (oldDelegate.runtimeType != runtimeType) ||
+        (oldDelegate is SliverWaterfallFlowDelegateWithMaxCrossAxisExtent &&
+            (oldDelegate.maxCrossAxisExtent != maxCrossAxisExtent ||
+                super.shouldRelayout(oldDelegate)));
+    if (flag) {
+      crossAxisCount = null;
+    }
+    return flag;
+  }
+}