feat: 优化填充组图层背景命令，重构填充对象创建逻辑

src/component/Canvas/CanvasEditor/commands/FillGroupLayerBackgroundCommand.js

@@ -123,29 +123,42 @@ export class FillGroupLayerBackgroundCommand extends Command {
           scaleX: clippingMaskFabricObject.scaleX || 1,
           scaleY: clippingMaskFabricObject.scaleY || 1,
         });
-        this.newFill.clipPath = clippingMaskFabricObject; // 设置填充的遮罩
-        this.newFill.dirty = true; // 标记为脏，以便重新
-        this.canvas.add(this.newFill);
-        this.firstObj = this.newFill;
-        layer.fabricObjects = [
-          this.newFill.toObject(["id", "layerId"]) || this.newFill,
-        ];
-        layer.fill = null; // this.newFill.toObject(["id", "layerId"]);
-        layer.fillColor = this.fillColor;
-        // 取消激活对象
-
-        this.canvas.discardActiveObject(); // 取消当前活动对象
-        // 重新排序
-        await this.layerManager?.sortLayersWithTool?.();
-        // 更新画布上对象的可选择状态
-        await this.layerManager?.updateLayersObjectsInteractivity?.();
-        this.canvas.renderAll();
-
-        this.canvasManager.thumbnailManager?.generateLayerThumbnail(
-          this.layer.id
-        );
+      } else {
+        this.newFill = new fabric.Rect({
+          width: this.canvasManager?.canvasWidth?.value || this.canvas.width,
+          height: this.canvasManager?.canvasHeight?.value || this.canvas.height,
+          left: this.canvas.width / 2 || 0,
+          top: this.canvas.height / 2 || 0,
+          fill: this.fillColor,
+          layerId: this.layerId,
+          id: this.oldFill?.id || generateId("fill-"),
+          selectable: false,
+          evented: false,
+          originX: "center",
+          originY: "center",
+        });
       }
+      this.newFill.clipPath = clippingMaskFabricObject; // 设置填充的遮罩
+      this.newFill.dirty = true; // 标记为脏，以便重新
+      this.canvas.add(this.newFill);
+      this.firstObj = this.newFill;
+      layer.fabricObjects = [
+        this.newFill.toObject(["id", "layerId"]) || this.newFill,
+      ];
+      layer.fill = null; // this.newFill.toObject(["id", "layerId"]);
+      layer.fillColor = this.fillColor;
+      // 取消激活对象
 
+      this.canvas.discardActiveObject(); // 取消当前活动对象
+      // 重新排序
+      await this.layerManager?.sortLayersWithTool?.();
+      // 更新画布上对象的可选择状态
+      await this.layerManager?.updateLayersObjectsInteractivity?.();
+      this.canvas.renderAll();
+
+      this.canvasManager.thumbnailManager?.generateLayerThumbnail(
+        this.layer.id
+      );
       return false;
     }
     const canvasObj = findObjectById(this.canvas, firstObj?.id)?.object;