feat(web): OCR overlay interactivity during zoom (#27039)

Change-Id: Id62e1a0264df2de0f3177a59b24bc5176a6a6964

web/src/lib/actions/zoom-image.ts

@@ -1,11 +1,18 @@
 import { assetViewerManager } from '$lib/managers/asset-viewer-manager.svelte';
 import { createZoomImageWheel } from '@zoom-image/core';
 
-export const zoomImageAction = (node: HTMLElement, options?: { disabled?: boolean }) => {
+// Minimal touch shape — avoids importing DOM TouchEvent which isn't available in all TS targets.
+type TouchEventLike = {
+  touches: Iterable<{ clientX: number; clientY: number }> & { length: number };
+  targetTouches: ArrayLike<unknown>;
+};
+const asTouchEvent = (event: Event) => event as unknown as TouchEventLike;
+
+export const zoomImageAction = (node: HTMLElement, options?: { zoomTarget?: HTMLElement }) => {
   const zoomInstance = createZoomImageWheel(node, {
     maxZoom: 10,
     initialState: assetViewerManager.zoomState,
-    zoomTarget: null,
+    zoomTarget: options?.zoomTarget,
   });
 
   const unsubscribes = [
@@ -13,47 +20,130 @@ export const zoomImageAction = (node: HTMLElement, options?: { disabled?: boolea
     zoomInstance.subscribe(({ state }) => assetViewerManager.onZoomChange(state)),
   ];
 
-  const onInteractionStart = (event: Event) => {
-    if (options?.disabled) {
-      event.stopImmediatePropagation();
+  const controller = new AbortController();
+  const { signal } = controller;
+
+  node.addEventListener('pointerdown', () => assetViewerManager.cancelZoomAnimation(), { capture: true, signal });
+
+  // Intercept events in capture phase to prevent zoom-image from seeing interactions on
+  // overlay elements (e.g. OCR text boxes), preserving browser defaults like text selection.
+  const isOverlayEvent = (event: Event) => !!(event.target as HTMLElement).closest('[data-overlay-interactive]');
+  const isOverlayAtPoint = (x: number, y: number) =>
+    !!document.elementFromPoint(x, y)?.closest('[data-overlay-interactive]');
+
+  // Pointer event interception: track pointers that start on overlays and intercept the entire gesture.
+  const overlayPointers = new Set<number>();
+  const interceptedPointers = new Set<number>();
+  const interceptOverlayPointerDown = (event: PointerEvent) => {
+    if (isOverlayEvent(event) || isOverlayAtPoint(event.clientX, event.clientY)) {
+      overlayPointers.add(event.pointerId);
+      interceptedPointers.add(event.pointerId);
+      event.stopPropagation();
+    } else if (overlayPointers.size > 0) {
+      // Split gesture (e.g. pinch with one finger on overlay) — intercept entirely.
+      interceptedPointers.add(event.pointerId);
+      event.stopPropagation();
     }
-    assetViewerManager.cancelZoomAnimation();
   };
+  const interceptOverlayPointerEvent = (event: PointerEvent) => {
+    if (interceptedPointers.has(event.pointerId)) {
+      event.stopPropagation();
+    }
+  };
+  const interceptOverlayPointerEnd = (event: PointerEvent) => {
+    overlayPointers.delete(event.pointerId);
+    if (interceptedPointers.delete(event.pointerId)) {
+      event.stopPropagation();
+    }
+  };
+  node.addEventListener('pointerdown', interceptOverlayPointerDown, { capture: true, signal });
+  node.addEventListener('pointermove', interceptOverlayPointerEvent, { capture: true, signal });
+  node.addEventListener('pointerup', interceptOverlayPointerEnd, { capture: true, signal });
+  node.addEventListener('pointerleave', interceptOverlayPointerEnd, { capture: true, signal });
 
-  node.addEventListener('wheel', onInteractionStart, { capture: true });
-  node.addEventListener('pointerdown', onInteractionStart, { capture: true });
+  // Touch event interception for overlay touches or split gestures (pinch across container boundary).
+  // Once intercepted, stays intercepted until all fingers are lifted.
+  let touchGestureIntercepted = false;
+  const interceptOverlayTouchEvent = (event: Event) => {
+    if (touchGestureIntercepted) {
+      event.stopPropagation();
+      return;
+    }
+    const { touches, targetTouches } = asTouchEvent(event);
+    if (touches && targetTouches) {
+      if (touches.length > targetTouches.length) {
+        touchGestureIntercepted = true;
+        event.stopPropagation();
+        return;
+      }
+      for (const touch of touches) {
+        if (isOverlayAtPoint(touch.clientX, touch.clientY)) {
+          touchGestureIntercepted = true;
+          event.stopPropagation();
+          return;
+        }
+      }
+    } else if (isOverlayEvent(event)) {
+      event.stopPropagation();
+    }
+  };
+  const resetTouchGesture = (event: Event) => {
+    const { touches } = asTouchEvent(event);
+    if (touches.length === 0) {
+      touchGestureIntercepted = false;
+    }
+  };
+  node.addEventListener('touchstart', interceptOverlayTouchEvent, { capture: true, signal });
+  node.addEventListener('touchmove', interceptOverlayTouchEvent, { capture: true, signal });
+  node.addEventListener('touchend', resetTouchGesture, { capture: true, signal });
 
-  // Suppress Safari's synthetic dblclick on double-tap. Without this, zoom-image's touchstart
-  // handler zooms to maxZoom (10x), then Safari's synthetic dblclick triggers photo-viewer's
-  // handler which conflicts. Chrome does not fire synthetic dblclick on touch.
+  // Wheel and dblclick interception on overlay elements.
+  // Dblclick also intercepted for all touch double-taps (Safari fires synthetic dblclick
+  // on double-tap, which conflicts with zoom-image's touch zoom handler).
   let lastPointerWasTouch = false;
-  const trackPointerType = (event: PointerEvent) => {
-    lastPointerWasTouch = event.pointerType === 'touch';
-  };
-  const suppressTouchDblClick = (event: MouseEvent) => {
-    if (lastPointerWasTouch) {
-      event.stopImmediatePropagation();
-    }
-  };
-  node.addEventListener('pointerdown', trackPointerType, { capture: true });
-  node.addEventListener('dblclick', suppressTouchDblClick, { capture: true });
+  node.addEventListener('pointerdown', (event) => (lastPointerWasTouch = event.pointerType === 'touch'), {
+    capture: true,
+    signal,
+  });
+  node.addEventListener(
+    'wheel',
+    (event) => {
+      if (isOverlayEvent(event)) {
+        event.stopPropagation();
+      }
+    },
+    { capture: true, signal },
+  );
+  node.addEventListener(
+    'dblclick',
+    (event) => {
+      if (lastPointerWasTouch || isOverlayEvent(event)) {
+        event.stopImmediatePropagation();
+      }
+    },
+    { capture: true, signal },
+  );
 
-  // Allow zoomed content to render outside the container bounds
+  if (options?.zoomTarget) {
+    options.zoomTarget.style.willChange = 'transform';
+  }
   node.style.overflow = 'visible';
-  // Prevent browser handling of touch gestures so zoom-image can manage them
   node.style.touchAction = 'none';
   return {
-    update(newOptions?: { disabled?: boolean }) {
+    update(newOptions?: { zoomTarget?: HTMLElement }) {
       options = newOptions;
+      if (newOptions?.zoomTarget !== undefined) {
+        zoomInstance.setState({ zoomTarget: newOptions.zoomTarget });
+      }
     },
     destroy() {
+      controller.abort();
+      if (options?.zoomTarget) {
+        options.zoomTarget.style.willChange = '';
+      }
       for (const unsubscribe of unsubscribes) {
         unsubscribe();
       }
-      node.removeEventListener('wheel', onInteractionStart, { capture: true });
-      node.removeEventListener('pointerdown', onInteractionStart, { capture: true });
-      node.removeEventListener('pointerdown', trackPointerType, { capture: true });
-      node.removeEventListener('dblclick', suppressTouchDblClick, { capture: true });
       zoomInstance.cleanup();
     },
   };