fix: delete area animation (#8149)

* fix: delete area animation

* chore: format

* Update core/dragging/dragger.ts

Co-authored-by: Christopher Allen <cpcallen+github@gmail.com>

---------

Co-authored-by: Christopher Allen <cpcallen+github@gmail.com>

core/block_animations.ts

@@ -42,15 +42,11 @@ export function disposeUiEffect(block: BlockSvg) {
   // Deeply clone the current block.
   const clone: SVGGElement = svgGroup.cloneNode(true) as SVGGElement;
   clone.setAttribute('transform', 'translate(' + xy.x + ',' + xy.y + ')');
-  if (workspace.isDragging()) {
-    workspace.getLayerManager()?.moveToDragLayer({
-      getSvgRoot: () => {
-        return clone;
-      },
-    });
-  } else {
-    workspace.getLayerManager()?.getBlockLayer().appendChild(clone);
-  }
+  workspace.getLayerManager()?.appendToAnimationLayer({
+    getSvgRoot: () => {
+      return clone;
+    },
+  });
   const cloneRect = {
     'x': xy.x,
     'y': xy.y,

core/css.ts

@@ -500,7 +500,7 @@ input[type=number] {
   margin-right: -24px;
 }
 
-.blocklyBlockDragSurface {
+.blocklyBlockDragSurface, .blocklyAnimationLayer {
   position: absolute;
   top: 0;
   left: 0;

core/dragging/dragger.ts

@@ -14,6 +14,8 @@ import {ComponentManager} from '../component_manager.js';
 import {IDeleteArea} from '../interfaces/i_delete_area.js';
 import * as registry from '../registry.js';
 import * as eventUtils from '../events/utils.js';
+import * as blockAnimations from '../block_animations.js';
+import {BlockSvg} from '../block_svg.js';
 
 export class Dragger implements IDragger {
   protected startLoc: Coordinate;
@@ -105,12 +107,18 @@ export class Dragger implements IDragger {
       this.draggable.revertDrag();
     }
 
+    const wouldDelete =
+      isDeletable(this.draggable) &&
+      this.wouldDeleteDraggable(e, this.draggable);
+
+    // TODO(#8148): use a generalized API instead of an instanceof check.
+    if (wouldDelete && this.draggable instanceof BlockSvg) {
+      blockAnimations.disposeUiEffect(this.draggable);
+    }
+
     this.draggable.endDrag(e);
 
-    if (
-      isDeletable(this.draggable) &&
-      this.wouldDeleteDraggable(e, this.draggable)
-    ) {
+    if (wouldDelete && isDeletable(this.draggable)) {
       // We want to make sure the delete gets grouped with any possible
       // move event.
       const newGroup = eventUtils.getGroup();

core/layer_manager.ts

@@ -15,6 +15,8 @@ import {Coordinate} from './utils/coordinate.js';
 export class LayerManager {
   /** The layer elements being dragged are appended to. */
   private dragLayer: SVGGElement | undefined;
+  /** The layer elements being animated are appended to. */
+  private animationLayer: SVGGElement | undefined;
   /** The layers elements not being dragged are appended to.  */
   private layers = new Map<number, SVGGElement>();
 
@@ -26,6 +28,7 @@ export class LayerManager {
     // been appended yet.
     if (injectionDiv) {
       this.dragLayer = this.createDragLayer(injectionDiv);
+      this.animationLayer = this.createAnimationLayer(injectionDiv);
     }
 
     // We construct these manually so we can add the css class for backwards
@@ -48,6 +51,35 @@ export class LayerManager {
     return dom.createSvgElement(Svg.G, {}, svg);
   }
 
+  private createAnimationLayer(injectionDiv: Element) {
+    const svg = dom.createSvgElement(Svg.SVG, {
+      'class': 'blocklyAnimationLayer',
+      'xmlns': dom.SVG_NS,
+      'xmlns:html': dom.HTML_NS,
+      'xmlns:xlink': dom.XLINK_NS,
+      'version': '1.1',
+    });
+    injectionDiv.append(svg);
+    return dom.createSvgElement(Svg.G, {}, svg);
+  }
+
+  /**
+   * Appends the element to the animation layer. The animation layer doesn't
+   * move when the workspace moves, so e.g. delete animations don't move
+   * when a block delete triggers a workspace resize.
+   *
+   * @internal
+   */
+  appendToAnimationLayer(elem: IRenderedElement) {
+    const currentTransform = this.dragLayer?.getAttribute('transform');
+    // Only update the current transform when appending, so animations don't
+    // move if the workspace moves.
+    if (currentTransform) {
+      this.animationLayer?.setAttribute('transform', currentTransform);
+    }
+    this.animationLayer?.appendChild(elem.getSvgRoot());
+  }
+
   /**
    * Translates layers when the workspace is dragged or zoomed.
    *