Improved Pinch-Zoom for PDF.

chrome/test/data/pdf/gesture_detector_test.js

Index: chrome/test/data/pdf/gesture_detector_test.js
diff --git a/chrome/test/data/pdf/gesture_detector_test.js b/chrome/test/data/pdf/gesture_detector_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..e990bc473f1405406f9d4d6f2331dda084ca57c4
--- /dev/null
+++ b/chrome/test/data/pdf/gesture_detector_test.js
@@ -0,0 +1,187 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+chrome.test.runTests(function() {
+  'use strict';
+
+  class StubElement {
+    constructor() {
+      this.listeners_ = new Map([
+        ['touchstart', []],
+        ['touchmove', []],
+        ['touchend', []],
+        ['touchcancel', []]
+      ]);
+    }
+
+    addEventListener(type, listener) {
+      if (this.listeners_.has(type)) {

[dpapad, 2016/11/08 18:32:35]

Let's be consistent within this file regarding when to use or omit curly braces.

[Kevin McNee - google account, 2016/11/08 23:08:21]

Done.

+        this.listeners_.get(type).push(listener);
+      }
+    }
+
+    sendEvent(event) {
+      let listeners = this.listeners_.get(event.type);
+
+      for (let l of listeners)

[dpapad, 2016/11/08 18:32:35]

for (let l of this.listeners_.get(event.type))
  l(event);

[Kevin McNee - google account, 2016/11/08 23:08:21]

Done.

+        l(event);
+    }
+  }
+
+  class MockTouchEvent {
+    constructor(type, touches) {
+      this.type = type;
+      this.touches = touches;
+      this.defaultPrevented = false;
+    }
+
+    preventDefault() {
+      this.defaultPrevented = true;
+    }
+  }
+
+  class PinchListener {
+    constructor(gestureDetector) {
+      this.lastEvent = null;
+      gestureDetector.addEventListener('pinchstart', this.onPinch_.bind(this));
+      gestureDetector.addEventListener('pinchupdate', this.onPinch_.bind(this));
+      gestureDetector.addEventListener('pinchend', this.onPinch_.bind(this));
+    }
+
+    onPinch_(pinchEvent) {
+      this.lastEvent = pinchEvent;
+    }
+  }
+
+  return [
+    function testPinchZoomIn() {
+      let stubElement = new StubElement();
+      let gestureDetector = new GestureDetector(stubElement);
+      let pinchListener = new PinchListener(gestureDetector);
+
+      stubElement.sendEvent(new MockTouchEvent('touchstart', [
+        {clientX: 0, clientY: 0},
+        {clientX: 0, clientY: 2}
+      ]));
+      chrome.test.assertEq('pinchstart', pinchListener.lastEvent.type);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(1, pinchListener.lastEvent.center.y);
+
+      stubElement.sendEvent(new MockTouchEvent('touchmove', [
+        {clientX: 0, clientY: 0},
+        {clientX: 0, clientY: 4}
+      ]));
+      chrome.test.assertEq('pinchupdate', pinchListener.lastEvent.type);
+      chrome.test.assertEq(2, pinchListener.lastEvent.scaleRatio);
+      chrome.test.assertEq('in', pinchListener.lastEvent.direction);
+      chrome.test.assertEq(2, pinchListener.lastEvent.startScaleRatio);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(2, pinchListener.lastEvent.center.y);
+
+      stubElement.sendEvent(new MockTouchEvent('touchmove', [
+        {clientX: 0, clientY: 0},
+        {clientX: 0, clientY: 8}
+      ]));
+      chrome.test.assertEq('pinchupdate', pinchListener.lastEvent.type);

[dpapad, 2016/11/08 18:32:35]

There are multiple blocks of code that assert lastEvent type, scaleRatio,
direction, startScaleRation, center.x, center.y.

Can you avoid the code duplication by creating a helper
assertEventEquals(expected, actual) {...}

and use it as follows

var expected = {type: '...', scaleRatio: ...', .... };
assertEventEquals(expected, pinchListener.lastEvent);

[Kevin McNee - google account, 2016/11/08 23:08:21]

It looks like chrome.test.assertEq compares objects by value, so I just used
that.

Done.

+      chrome.test.assertEq(2, pinchListener.lastEvent.scaleRatio);
+      chrome.test.assertEq('in', pinchListener.lastEvent.direction);
+      chrome.test.assertEq(4, pinchListener.lastEvent.startScaleRatio);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(4, pinchListener.lastEvent.center.y);
+
+      stubElement.sendEvent(new MockTouchEvent('touchend', []));
+      chrome.test.assertEq('pinchend', pinchListener.lastEvent.type);
+      chrome.test.assertEq(4, pinchListener.lastEvent.startScaleRatio);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(4, pinchListener.lastEvent.center.y);
+
+      chrome.test.succeed();
+    },
+
+    function testPinchZoomInAndBackOut() {
+      let stubElement = new StubElement();
+      let gestureDetector = new GestureDetector(stubElement);
+      let pinchListener = new PinchListener(gestureDetector);
+
+      stubElement.sendEvent(new MockTouchEvent('touchstart', [
+        {clientX: 0, clientY: 0},
+        {clientX: 0, clientY: 2}
+      ]));
+      chrome.test.assertEq('pinchstart', pinchListener.lastEvent.type);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(1, pinchListener.lastEvent.center.y);
+
+      stubElement.sendEvent(new MockTouchEvent('touchmove', [
+        {clientX: 0, clientY: 0},
+        {clientX: 0, clientY: 4}
+      ]));
+      chrome.test.assertEq('pinchupdate', pinchListener.lastEvent.type);
+      chrome.test.assertEq(2, pinchListener.lastEvent.scaleRatio);
+      chrome.test.assertEq('in', pinchListener.lastEvent.direction);
+      chrome.test.assertEq(2, pinchListener.lastEvent.startScaleRatio);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(2, pinchListener.lastEvent.center.y);
+
+      stubElement.sendEvent(new MockTouchEvent('touchmove', [
+        {clientX: 0, clientY: 0},
+        {clientX: 0, clientY: 2}
+      ]));
+      // This should be part of the same gesture as an update.
+      // A change in direction should not end the gesture and start a new one.
+      chrome.test.assertEq('pinchupdate', pinchListener.lastEvent.type);
+      chrome.test.assertEq(0.5, pinchListener.lastEvent.scaleRatio);
+      chrome.test.assertEq('out', pinchListener.lastEvent.direction);
+      chrome.test.assertEq(1, pinchListener.lastEvent.startScaleRatio);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(1, pinchListener.lastEvent.center.y);
+
+      stubElement.sendEvent(new MockTouchEvent('touchend', []));
+      chrome.test.assertEq('pinchend', pinchListener.lastEvent.type);
+      chrome.test.assertEq(1, pinchListener.lastEvent.startScaleRatio);
+      chrome.test.assertEq(0, pinchListener.lastEvent.center.x);
+      chrome.test.assertEq(1, pinchListener.lastEvent.center.y);
+
+      chrome.test.succeed();
+    },
+
+    function testIgnoreTouchScrolling() {
+      let stubElement = new StubElement();
+      let gestureDetector = new GestureDetector(stubElement);
+      let pinchListener = new PinchListener(gestureDetector);
+
+      let touchScrollStartEvent = new MockTouchEvent('touchstart', [
+        {clientX: 0, clientY: 0},
+      ]);
+      stubElement.sendEvent(touchScrollStartEvent);
+      chrome.test.assertEq(null, pinchListener.lastEvent);
+      chrome.test.assertFalse(touchScrollStartEvent.defaultPrevented);
+
+      stubElement.sendEvent(new MockTouchEvent('touchmove', [
+        {clientX: 0, clientY: 1},
+      ]));
+      chrome.test.assertEq(null, pinchListener.lastEvent);
+
+      stubElement.sendEvent(new MockTouchEvent('touchend', []));
+      chrome.test.assertEq(null, pinchListener.lastEvent);
+
+      chrome.test.succeed();
+    },
+
+    function testPreventNativePinchZoom() {
+      let stubElement = new StubElement();
+      let gestureDetector = new GestureDetector(stubElement);
+      let pinchListener = new PinchListener(gestureDetector);
+
+      let pinchStartEvent = new MockTouchEvent('touchstart', [
+        {clientX: 0, clientY: 0},
+        {clientX: 0, clientY: 2}
+      ]);
+      stubElement.sendEvent(pinchStartEvent);
+      chrome.test.assertEq('pinchstart', pinchListener.lastEvent.type);
+      chrome.test.assertTrue(pinchStartEvent.defaultPrevented);
+
+      chrome.test.succeed();
+    }
+  ];
+}());