fix paste location for blocks (microsoft#10442)

Author: riknoll

webapp/src/blocks.tsx

@@ -1957,29 +1957,23 @@ export class Editor extends toolboxeditor.ToolboxEditor {
         }
     }
 
-    protected pasteCallback = () => {
+    protected pasteCallback = (workspace: Blockly.Workspace, ev: Event) => {
         const data = getCopyData();
         if (!data?.data || !this.editor || !this.canPasteData(data)) return false;
 
-        this.pasteAsync(data);
+        this.pasteAsync(data, ev.type === "pointerdown" ? ev as PointerEvent : undefined);
         return true;
     }
 
-    protected async pasteAsync(data: CopyDataEntry) {
+    protected async pasteAsync(data: CopyDataEntry, ev?: PointerEvent) {
         const copyData = data.data;
         const copyWorkspace = this.editor;
         const copyCoords = copyWorkspace.id === data.workspaceId ? data.coord : undefined;
 
         // this pasting code is adapted from Blockly/core/shortcut_items.ts
         const doPaste = () => {
-            if (!copyCoords) {
-                // If we don't have location data about the original copyable, let the
-                // paster determine position.
-                return !!Blockly.clipboard.paste(copyData, copyWorkspace);
-            }
-
-            const { left, top, width, height } = copyWorkspace
-                .getMetricsManager()
+            const metricsManager = copyWorkspace.getMetricsManager();
+            const { left, top, width, height } = metricsManager
                 .getViewMetrics(true);
             const viewportRect = new Blockly.utils.Rect(
                 top,
@@ -1988,7 +1982,21 @@ export class Editor extends toolboxeditor.ToolboxEditor {
                 left + width
             );
 
-            if (viewportRect.contains(copyCoords.x, copyCoords.y)) {
+            if (ev) {
+                // if we have a pointer event, then paste at that location
+                const injectionDivBBox = copyWorkspace.getInjectionDiv().getBoundingClientRect();
+                const pixelViewport = metricsManager.getViewMetrics();
+                const workspaceSvgOffset = metricsManager.getAbsoluteMetrics();
+
+                const offsetX = ((ev.clientX - injectionDivBBox.left - workspaceSvgOffset.left) / pixelViewport.width);
+                const offsetY = ((ev.clientY - injectionDivBBox.top - workspaceSvgOffset.top) / pixelViewport.height);
+
+                const contextMenuCoords = new Blockly.utils.Coordinate(left + offsetX * width, top + offsetY * height);
+
+                return !!Blockly.clipboard.paste(copyData, copyWorkspace, contextMenuCoords);
+            }
+
+            if (copyCoords && viewportRect.contains(copyCoords.x, copyCoords.y)) {
                 // If the original copyable is inside the viewport, let the paster
                 // determine position.
                 return !!Blockly.clipboard.paste(copyData, copyWorkspace);