sdk/platform-tools/systrace/catapult/telemetry/telemetry/internal/actions/pinch.js

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This file provides the PinchAction object, which zooms into or out of a
   6 // page by a given scale factor:
   7 //   1. var action = new __PinchAction(callback)
   8 //   2. action.start(pinch_options)
   9 'use strict';
  10
  11 (function() {
  12
  13   function PinchGestureOptions(opt_options) {
  14     if (opt_options) {
  15       this.element_ = opt_options.element;
  16       this.left_anchor_ratio_ = opt_options.left_anchor_ratio;
  17       this.top_anchor_ratio_ = opt_options.top_anchor_ratio;
  18       this.scale_factor_ = opt_options.scale_factor;
  19       this.speed_ = opt_options.speed;
  20     } else {
  21       this.element_ = document.body;
  22       this.left_anchor_ratio_ = 0.5;
  23       this.top_anchor_ratio_ = 0.5;
  24       this.scale_factor_ = 2.0;
  25       this.speed_ = 800;
  26     }
  27   }
  28
  29   function supportedByBrowser() {
  30     return !!(window.chrome &&
  31               chrome.gpuBenchmarking &&
  32               chrome.gpuBenchmarking.pinchBy &&
  33               chrome.gpuBenchmarking.visualViewportHeight &&
  34               chrome.gpuBenchmarking.visualViewportWidth);
  35   }
  36
  37   // This class zooms into or out of a page, given a number of pixels for
  38   // the synthetic pinch gesture to cover.
  39   function PinchAction(opt_callback) {
  40     var self = this;
  41
  42     this.beginMeasuringHook = function() {};
  43     this.endMeasuringHook = function() {};
  44
  45     this.callback_ = opt_callback;
  46   };
  47
  48   PinchAction.prototype.start = function(opt_options) {
  49     this.options_ = new PinchGestureOptions(opt_options);
  50
  51     requestAnimationFrame(this.startPass_.bind(this));
  52   };
  53
  54   PinchAction.prototype.startPass_ = function() {
  55     this.beginMeasuringHook();
  56
  57     var rect = __GestureCommon_GetBoundingVisibleRect(this.options_.element_);
  58     var anchor_left =
  59         rect.left + rect.width * this.options_.left_anchor_ratio_;
  60     var anchor_top =
  61         rect.top + rect.height * this.options_.top_anchor_ratio_;
  62     chrome.gpuBenchmarking.pinchBy(this.options_.scale_factor_,
  63                                    anchor_left, anchor_top,
  64                                    this.onGestureComplete_.bind(this),
  65                                    this.options_.speed_);
  66   };
  67
  68   PinchAction.prototype.onGestureComplete_ = function() {
  69     this.endMeasuringHook();
  70
  71     if (this.callback_)
  72       this.callback_();
  73   };
  74
  75   window.__PinchAction = PinchAction;
  76   window.__PinchAction_SupportedByBrowser = supportedByBrowser;
  77 })();