fix(): dirty flag bubbling for group (#9540)

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [next]
 
+- fix(): bubble dirty flag for group only when true [#9540](https://github.com/fabricjs/fabric.js/pull/9540)
 - test() Backport a test to capture a failing text style situation [#9531](https://github.com/fabricjs/fabric.js/pull/9531)
 
 ## [6.0.0-beta16]

src/shapes/Object/Object.spec.ts

@@ -1,6 +1,7 @@
 import { Shadow } from '../../Shadow';
 import { Rect } from '../Rect';
 import { FabricObject } from './Object';
+import { Group } from '../Group';
 
 describe('Object', () => {
   it('rotate with centered rotation', () => {
@@ -100,4 +101,22 @@ describe('Object', () => {
       expect(rect.needsItsOwnCache()).toBe(false);
     });
   });
+  describe('set method and dirty flag bubbling', () => {
+    it('when dirty is true it bubbles', () => {
+      const rect = new Rect({ width: 100, height: 100 });
+      const group = new Group([rect]);
+      group.dirty = false;
+      expect(group.dirty).toBe(false);
+      rect.set('dirty', true);
+      expect(group.dirty).toBe(true);
+    });
+    it('when dirty is false it does not bubble', () => {
+      const rect = new Rect({ width: 100, height: 100 });
+      const group = new Group([rect]);
+      group.dirty = true;
+      expect(group.dirty).toBe(true);
+      rect.set('dirty', false);
+      expect(group.dirty).toBe(true);
+    });
+  });
 });

src/shapes/Object/Object.ts

@@ -706,7 +706,10 @@ export class FabricObject<
       // i don't like this automatic initialization here
     } else if (key === 'shadow' && value && !(value instanceof Shadow)) {
       value = new Shadow(value);
-    } else if (key === 'dirty' && this.group) {
+    } else if (key === 'dirty' && this.group && value) {
+      // a dirty child makes the parent dirty
+      // but a non dirty child will not make the parent non dirty.
+      // the parent could be dirty for some other reason
       this.group.set('dirty', value);
     }