PDF Viewer: Unset page fitting on pinch zoom

When the user manually zooms, any page fitting (e.g. fit-to-width) is
unset and subsequent window resizes do not change zoom. This was not
being done for the PDF viewer's internal pinch zoom mechanism.

Bug: 1123976
Change-Id: Ifcc2b14fb05b7a339a7463d89f9a00c00739a43a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2392700Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Kevin McNee <mcnee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804447}

chrome/browser/resources/pdf/viewport.js

@@ -1428,6 +1428,8 @@ export class Viewport {
           this.keepContentCentered_ = false;
         }
 
+        this.fittingType_ = FittingType.NONE;
+
         this.setPinchZoomInternal_(
             scaleDelta, this.frameToPluginCoordinate_(center));
         this.updateViewport_();
@@ -1484,6 +1486,11 @@ export class Viewport {
       this.firstPinchCenterInFrame_ = e.detail.center;
     });
   }
+
+  /** @return {!GestureDetector} */
+  getGestureDetectorForTesting() {
+    return this.gestureDetector_;
+  }
 }
 
 /**

chrome/test/data/pdf/test_util.js

@@ -311,6 +311,10 @@ export function getZoomableViewport(
   const dummyContent =
       /** @type {!HTMLDivElement} */ (document.createElement('div'));
   document.body.appendChild(dummyContent);
+  const dummyPlugin =
+      /** @type {!HTMLEmbedElement} */ (document.createElement('embed'));
+  dummyPlugin.id = 'plugin';
+  dummyContent.appendChild(dummyPlugin);
   const viewport = new Viewport(
       /** @type {!HTMLElement} */ (scrollParent),
       /** @type {!HTMLDivElement} */ (sizer), dummyContent, scrollbarWidth,

chrome/test/data/pdf/viewport_test.js

@@ -620,6 +620,56 @@ const tests = [
     chrome.test.succeed();
   },
 
+  // Regression test for https://crbug.com/1123976
+  function testPinchZoomingUnsetsPageFitting() {
+    const mockWindow = new MockElement(100, 100, null);
+    const viewport = getZoomableViewport(mockWindow, new MockSizer(), 0, 1, 0);
+    const documentDimensions = new MockDocumentDimensions();
+    documentDimensions.addPage(50, 100);
+    viewport.setDocumentDimensions(documentDimensions);
+
+    viewport.fitToWidth();
+    chrome.test.assertEq(FittingType.FIT_TO_WIDTH, viewport.fittingType);
+    chrome.test.assertEq(2, viewport.getZoom());
+
+    // Change the zoom using the viewer's pinch zooming mechanism.
+    const gestureEventTarget =
+        viewport.getGestureDetectorForTesting().getEventTarget();
+    const pinchCenter = {x: 25, y: 25};
+    const scaleChange = 0.5;
+    gestureEventTarget.dispatchEvent(
+        new CustomEvent('pinchstart', {detail: {center: pinchCenter}}));
+    gestureEventTarget.dispatchEvent(new CustomEvent('pinchupdate', {
+      detail: {
+        scaleRatio: scaleChange,
+        direction: 'out',
+        startScaleRatio: scaleChange,
+        center: pinchCenter,
+      }
+    }));
+    gestureEventTarget.dispatchEvent(new CustomEvent('pinchend', {
+      detail: {
+        startScaleRatio: scaleChange,
+        center: pinchCenter,
+      }
+    }));
+
+    // Pinch updates are throttled by rAF, so we schedule the rest of the test
+    // after the pinch takes effect.
+    window.requestAnimationFrame(() => {
+      chrome.test.assertEq(1, viewport.getZoom());
+
+      // Changing the zoom using a pinch should unset the page fitting as it
+      // would with other zooming mechanisms.
+      chrome.test.assertEq(FittingType.NONE, viewport.fittingType);
+      // A subsequent window resize should not cause a zoom change.
+      mockWindow.setSize(101, 100);
+      chrome.test.assertEq(1, viewport.getZoom());
+
+      chrome.test.succeed();
+    });
+  },
+
   function testGoToNextPage() {
     const mockWindow = new MockElement(100, 100, null);
     const mockSizer = new MockSizer();