Preserve batch generation area during canvas changes

Introduces a 'generationArea' context for batch image generation, ensuring that batch preview outlines and image placement remain accurate when the canvas is moved or resized. Updates related logic in Canvas, CanvasInteractions, CanvasLayers, and CanvasRenderer to track and render the correct area, and synchronizes context updates across user interactions.

js/CanvasRenderer.js

@@ -82,6 +82,7 @@ export class CanvasRenderer {
         });
 
         this.drawCanvasOutline(ctx);
+        this.drawPendingGenerationAreas(ctx); // Draw snapshot outlines
         const maskImage = this.canvas.maskTool.getMask();
         if (maskImage && this.canvas.maskTool.isOverlayVisible) {
 
@@ -328,4 +329,36 @@ export class CanvasRenderer {
             ctx.stroke();
         }
     }
+
+    drawPendingGenerationAreas(ctx) {
+        const areasToDraw = [];
+
+        // 1. Get areas from active managers
+        if (this.canvas.batchPreviewManagers && this.canvas.batchPreviewManagers.length > 0) {
+            this.canvas.batchPreviewManagers.forEach(manager => {
+                if (manager.generationArea) {
+                    areasToDraw.push(manager.generationArea);
+                }
+            });
+        }
+
+        // 2. Get the area from the pending context (if it exists)
+        if (this.canvas.pendingBatchContext && this.canvas.pendingBatchContext.outputArea) {
+            areasToDraw.push(this.canvas.pendingBatchContext.outputArea);
+        }
+
+        if (areasToDraw.length === 0) {
+            return;
+        }
+
+        // 3. Draw all collected areas
+        areasToDraw.forEach(area => {
+            ctx.save();
+            ctx.strokeStyle = 'rgba(0, 150, 255, 0.9)'; // Blue color
+            ctx.lineWidth = 3 / this.canvas.viewport.zoom;
+            ctx.setLineDash([12 / this.canvas.viewport.zoom, 6 / this.canvas.viewport.zoom]);
+            ctx.strokeRect(area.x, area.y, area.width, area.height);
+            ctx.restore();
+        });
+    }
 }