Drawing all shapes in one place without additional widgets.

Author: ilopX

patterns/abstract_factory/tool_panel_factory/widgets/drawing_board.dart

@@ -1,7 +1,6 @@
 import 'package:flutter/material.dart';
 import '../app/shapes.dart';
 import 'independent/event_listenable_builder.dart';
-import 'shape_widget.dart';
 
 class DrawingBoard extends StatelessWidget {
   final Shapes shapes;
@@ -15,19 +14,25 @@ class DrawingBoard extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return GestureDetector(
-      onTapDown: (e) => addShape(e.localPosition),
-      child: Container(
-        color: Color(0xff1f1f1f),
-        child: EventListenableBuilder(
-          event: shapes.onAddShapeEvent,
-          builder: (_) {
-            return Stack(
-              children: [
-                for (final shape in shapes) ShapeWidget(shape: shape),
-              ],
-            );
-          },
+    return Listener(
+      onPointerMove: (e) => addShape(e.localPosition),
+      child: GestureDetector(
+        onTapDown: (e) => addShape(e.localPosition),
+        child: Container(
+          color: Color(0xff1f1f1f),
+          child: EventListenableBuilder(
+            event: shapes.onAddShapeEvent,
+            builder: (_) {
+              return LayoutBuilder(
+                builder: (_, constraints) {
+                  return CustomPaint(
+                    size: Size(constraints.maxWidth, constraints.maxHeight),
+                    painter: ShapesPainter(shapes),
+                  );
+                },
+              );
+            },
+          ),
         ),
       ),
     );
@@ -37,3 +42,24 @@ class DrawingBoard extends StatelessWidget {
     onClick(position.dx, position.dy);
   }
 }
+
+class ShapesPainter extends CustomPainter {
+  final Shapes shapes;
+
+  ShapesPainter(this.shapes);
+
+  @override
+  void paint(Canvas canvas, Size _) {
+    for (final shape in shapes) {
+      canvas.save();
+      canvas.translate(shape.x, shape.y);
+      shape.paint(canvas);
+      canvas.restore();
+    }
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter _) {
+    return false;
+  }
+}