Initial commit: imajViewer Flutter Linux image viewer

lib/widgets/window_resize_zones.dart

@@ -0,0 +1,118 @@
+import 'package:flutter/material.dart';
+import 'package:window_manager/window_manager.dart';
+
+/// Resize edge zones for frameless windows.
+class WindowResizeZones extends StatelessWidget {
+  final Widget child;
+
+  const WindowResizeZones({super.key, required this.child});
+
+  static const _edgeSize = 4.0;
+  static const _cornerSize = 10.0;
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      children: [
+        child,
+
+        // Top edge
+        _ResizeEdge(
+          edge: ResizeEdge.top,
+          top: 0, left: _cornerSize, right: _cornerSize, height: _edgeSize,
+        ),
+        // Bottom edge
+        _ResizeEdge(
+          edge: ResizeEdge.bottom,
+          bottom: 0, left: _cornerSize, right: _cornerSize, height: _edgeSize,
+        ),
+        // Left edge
+        _ResizeEdge(
+          edge: ResizeEdge.left,
+          left: 0, top: _cornerSize, bottom: _cornerSize, width: _edgeSize,
+        ),
+        // Right edge
+        _ResizeEdge(
+          edge: ResizeEdge.right,
+          right: 0, top: _cornerSize, bottom: _cornerSize, width: _edgeSize,
+        ),
+
+        // Corners
+        _ResizeCorner(edge: ResizeEdge.topLeft, top: 0, left: 0),
+        _ResizeCorner(edge: ResizeEdge.topRight, top: 0, right: 0),
+        _ResizeCorner(edge: ResizeEdge.bottomLeft, bottom: 0, left: 0),
+        _ResizeCorner(edge: ResizeEdge.bottomRight, bottom: 0, right: 0),
+      ],
+    );
+  }
+}
+
+class _ResizeEdge extends StatelessWidget {
+  final ResizeEdge edge;
+  final double? top, bottom, left, right, width, height;
+
+  const _ResizeEdge({
+    required this.edge,
+    this.top, this.bottom, this.left, this.right,
+    this.width, this.height,
+  });
+
+  MouseCursor _cursor(ResizeEdge e) {
+    return switch (e) {
+      ResizeEdge.top || ResizeEdge.bottom => SystemMouseCursors.resizeRow,
+      ResizeEdge.left || ResizeEdge.right => SystemMouseCursors.resizeColumn,
+      _ => SystemMouseCursors.basic,
+    };
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Positioned(
+      top: top, bottom: bottom, left: left, right: right,
+      width: width, height: height,
+      child: MouseRegion(
+        cursor: _cursor(edge),
+        child: GestureDetector(
+          behavior: HitTestBehavior.opaque,
+          onPanStart: (_) => windowManager.startResizing(edge),
+        ),
+      ),
+    );
+  }
+}
+
+class _ResizeCorner extends StatelessWidget {
+  final ResizeEdge edge;
+  final double? top, bottom, left, right;
+
+  const _ResizeCorner({
+    required this.edge,
+    this.top, this.bottom, this.left, this.right,
+  });
+
+  MouseCursor _cursor(ResizeEdge e) {
+    return switch (e) {
+      ResizeEdge.topLeft || ResizeEdge.bottomRight =>
+        SystemMouseCursors.resizeDownLeft,
+      ResizeEdge.topRight || ResizeEdge.bottomLeft =>
+        SystemMouseCursors.resizeDownRight,
+      _ => SystemMouseCursors.basic,
+    };
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Positioned(
+      top: top, bottom: bottom, left: left, right: right,
+      width: WindowResizeZones._cornerSize,
+      height: WindowResizeZones._cornerSize,
+      child: MouseRegion(
+        cursor: _cursor(edge),
+        child: GestureDetector(
+          behavior: HitTestBehavior.opaque,
+          onPanStart: (_) => windowManager.startResizing(edge),
+        ),
+      ),
+    );
+  }
+}