PDF Viewer: Presentation mode initial approach.

Upon entering Presentation mode:
 - Disable scrolling and hide scrollbars.
 - Disable zooming with ctrl+wheel and pinch gestures.
 - Force fit-to-height.
 - Next/previous page can be shown using the left/right keyboard
  arrows.

The following known issues
 - Zooming is still possible with ctrl+/-
 - Rotating is still possible via ctrl]/[
 - Using the scroll wheel does not update to the next/previous page

will be addressed in a follow up CL.

Bug: 1148478
Change-Id: I8b0e3b9ea6c3ed6738bc07f313935c7ea4d770a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2539741
Commit-Queue: dpapad <dpapad@chromium.org>
Reviewed-by: Daniel Hosseinian <dhoss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832284}

chrome/browser/resources/pdf/gesture_detector.js

@@ -164,6 +164,11 @@ export class GestureDetector {
 
     event.preventDefault();
 
+    // Disable wheel gestures in Presentation mode.
+    if (document.fullscreenElement !== null) {
+      return;
+    }
+
     const wheelScale = Math.exp(-event.deltaY / 100);
     // Clamp scale changes from the wheel event as they can be
     // quite dramatic for non-synthetic ctrl-wheels.

chrome/browser/resources/pdf/pdf_viewer.html

@@ -121,6 +121,11 @@
     overflow: auto;
     position: relative;
   }
+
+  /* Hide scrollbars when in Presentation mode. */
+  #scroller:fullscreen {
+    overflow: hidden;
+  }
 </style>
 
 <template is="dom-if" if="[[!pdfViewerUpdateEnabled_]]">

chrome/browser/resources/pdf/pdf_viewer.js

@@ -683,7 +683,11 @@ export class PDFViewerElement extends PDFViewerBaseElement {
   /** @private */
   onFullscreenClick_() {
     assert(this.presentationModeEnabled_);
-    this.shadowRoot.querySelector('#main').requestFullscreen();
+    this.shadowRoot.querySelector('#scroller').requestFullscreen().then(() => {
+      this.forceFit(FittingType.FIT_TO_HEIGHT);
+      // Nothing else to do here. The viewport will be updated as a result of a
+      // 'resize' event callback.
+    });
   }
 
   /**

chrome/browser/resources/pdf/viewport.js

@@ -454,12 +454,20 @@ export class Viewport {
    * @private
    */
   resize_() {
+    // Force fit-to-height when resizing happens as a result of entering full
+    // screen mode.
+    if (document.fullscreenElement !== null) {
+      this.fittingType_ = FittingType.FIT_TO_HEIGHT;
+      this.window_.dispatchEvent(
+          new CustomEvent('fitting-type-changed-for-testing'));
+    }
+
     if (this.fittingType_ === FittingType.FIT_TO_PAGE) {
       this.fitToPageInternal_(false);
     } else if (this.fittingType_ === FittingType.FIT_TO_WIDTH) {
       this.fitToWidth();
     } else if (this.fittingType_ === FittingType.FIT_TO_HEIGHT) {
-      this.fitToHeightInternal_(false);
+      this.fitToHeightInternal_(document.fullscreenElement !== null);
     } else if (this.internalZoom_ === 0) {
       this.fitToNone();
     } else {
@@ -1502,6 +1510,11 @@ export class Viewport {
    * @private
    */
   onPinchStart_(e) {
+    // Disable pinch gestures in Presentation  mode.
+    if (document.fullscreenElement !== null) {
+      return;
+    }
+
     // We also use rAF for pinch start, so that if there is a pinch end event
     // scheduled by rAF, this pinch start will be sent after.
     window.requestAnimationFrame(() => {

chrome/test/data/pdf/BUILD.gn

@@ -130,6 +130,7 @@ js_library("download_controls_test") {
 js_library("fullscreen_test") {
   deps = [
     "../webui:test_util.m",
+    "//chrome/browser/resources/pdf:constants",
     "//chrome/browser/resources/pdf:pdf_viewer",
   ]
   externs_list = [ "$externs_path/test.js" ]

chrome/test/data/pdf/fullscreen_test.js

@@ -3,19 +3,35 @@
 // found in the LICENSE file.
 
 import {eventToPromise} from 'chrome-extension://mhjfbmdgcfjbbpaeojofohoefgiehjai/_test_resources/webui/test_util.m.js';
+import {FittingType} from 'chrome-extension://mhjfbmdgcfjbbpaeojofohoefgiehjai/constants.js';
 import {PDFViewerElement} from 'chrome-extension://mhjfbmdgcfjbbpaeojofohoefgiehjai/pdf_viewer.js';
 
 const tests = [
-  function testFullscreen() {
+  async function testFullscreen() {
     const viewer = /** @type {!PDFViewerElement} */ (
         document.body.querySelector('pdf-viewer'));
+    const scroller = /** @type {!HTMLElement} */ (
+        viewer.shadowRoot.querySelector('#scroller'));
+    chrome.test.assertTrue(scroller !== null);
+
+    chrome.test.assertEq(FittingType.NONE, viewer.viewport.fittingType);
+
+    const whenFitToTypeChanged =
+        eventToPromise('fitting-type-changed-for-testing', scroller);
+    const whenFullscreenChange = eventToPromise('fullscreenchange', scroller);
+
     const toolbar = viewer.shadowRoot.querySelector('viewer-pdf-toolbar-new');
     toolbar.dispatchEvent(new CustomEvent('fullscreen-click'));
-    eventToPromise('fullscreenchange', viewer).then(e => {
-      chrome.test.assertEq(
-          viewer.shadowRoot.querySelector('#main'), e.composedPath()[0]);
-      chrome.test.succeed();
-    });
+    await whenFitToTypeChanged;
+    await whenFullscreenChange;
+
+    // Check that the scrollbars are hidden.
+    chrome.test.assertEq('hidden', window.getComputedStyle(scroller).overflow);
+    // Check that the `fittingType` has changed.
+    chrome.test.assertEq(
+        FittingType.FIT_TO_HEIGHT, viewer.viewport.fittingType);
+
+    chrome.test.succeed();
   },
 ];