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

   1 // Copyright 2012 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 ScrollAction object, which scrolls a page
   6 // to the bottom or for a specified distance:
   7 //   1. var action = new __ScrollAction(callback, opt_distance_func)
   8 //   2. action.start(scroll_options)
   9 'use strict';
  10
  11 (function() {
  12   var MAX_SCROLL_LENGTH_TIME_MS = 6250;
  13
  14   function ScrollGestureOptions(opt_options) {
  15     if (opt_options) {
  16       this.element_ = opt_options.element;
  17       this.left_start_ratio_ = opt_options.left_start_ratio;
  18       this.top_start_ratio_ = opt_options.top_start_ratio;
  19       this.direction_ = opt_options.direction;
  20       this.speed_ = opt_options.speed;
  21       this.gesture_source_type_ = opt_options.gesture_source_type;
  22     } else {
  23       this.element_ = document.scrollingElement || document.body;
  24       this.left_start_ratio_ = 0.5;
  25       this.top_start_ratio_ = 0.5;
  26       this.direction_ = 'down';
  27       this.speed_ = 800;
  28       this.gesture_source_type_ = chrome.gpuBenchmarking.DEFAULT_INPUT;
  29     }
  30   }
  31
  32   function supportedByBrowser() {
  33     return !!(window.chrome &&
  34               chrome.gpuBenchmarking &&
  35               chrome.gpuBenchmarking.smoothScrollBy &&
  36               chrome.gpuBenchmarking.visualViewportHeight &&
  37               chrome.gpuBenchmarking.visualViewportWidth);
  38   }
  39
  40   // This class scrolls a page from the top to the bottom once.
  41   //
  42   // The page is scrolled down by a single scroll gesture.
  43   function ScrollAction(opt_callback, opt_distance_func) {
  44     var self = this;
  45
  46     this.beginMeasuringHook = function() {};
  47     this.endMeasuringHook = function() {};
  48
  49     this.callback_ = opt_callback;
  50     this.distance_func_ = opt_distance_func;
  51   }
  52
  53   ScrollAction.prototype.getScrollDistanceDown_ = function() {
  54     var clientHeight;
  55     // clientHeight is "special" for the body element.
  56     if (this.element_ == document.body)
  57       clientHeight = __GestureCommon_GetWindowHeight();
  58     else
  59       clientHeight = this.element_.clientHeight;
  60
  61     return this.element_.scrollHeight -
  62            this.element_.scrollTop -
  63            clientHeight;
  64   };
  65
  66   ScrollAction.prototype.getScrollDistanceUp_ = function() {
  67     return this.element_.scrollTop;
  68   };
  69
  70   ScrollAction.prototype.getScrollDistanceRight_ = function() {
  71     var clientWidth;
  72     // clientWidth is "special" for the body element.
  73     if (this.element_ == document.body)
  74       clientWidth = __GestureCommon_GetWindowWidth();
  75     else
  76       clientWidth = this.element_.clientWidth;
  77
  78     return this.element_.scrollWidth - this.element_.scrollLeft - clientWidth;
  79   };
  80
  81   ScrollAction.prototype.getScrollDistanceLeft_ = function() {
  82     return this.element_.scrollLeft;
  83   };
  84
  85   ScrollAction.prototype.getScrollDistance_ = function() {
  86     if (this.distance_func_)
  87       return this.distance_func_();
  88
  89     if (this.options_.direction_ == 'down') {
  90       return this.getScrollDistanceDown_();
  91     } else if (this.options_.direction_ == 'up') {
  92       return this.getScrollDistanceUp_();
  93     } else if (this.options_.direction_ == 'right') {
  94       return this.getScrollDistanceRight_();
  95     } else if (this.options_.direction_ == 'left') {
  96       return this.getScrollDistanceLeft_();
  97     } else if (this.options_.direction_ == 'upleft') {
  98       return Math.min(this.getScrollDistanceUp_(),
  99                       this.getScrollDistanceLeft_());
 100     } else if (this.options_.direction_ == 'upright') {
 101       return Math.min(this.getScrollDistanceUp_(),
 102                       this.getScrollDistanceRight_());
 103     } else if (this.options_.direction_ == 'downleft') {
 104       return Math.min(this.getScrollDistanceDown_(),
 105                       this.getScrollDistanceLeft_());
 106     } else if (this.options_.direction_ == 'downright') {
 107       return Math.min(this.getScrollDistanceDown_(),
 108                       this.getScrollDistanceRight_());
 109     }
 110   };
 111
 112   ScrollAction.prototype.start = function(opt_options) {
 113     this.options_ = new ScrollGestureOptions(opt_options);
 114     // Assign this.element_ here instead of constructor, because the constructor
 115     // ensures this method will be called after the document is loaded.
 116     this.element_ = this.options_.element_;
 117     requestAnimationFrame(this.startGesture_.bind(this));
 118   };
 119
 120   ScrollAction.prototype.startGesture_ = function() {
 121     this.beginMeasuringHook();
 122
 123     var max_scroll_length_pixels = (MAX_SCROLL_LENGTH_TIME_MS / 1000) *
 124         this.options_.speed_;
 125     var distance = Math.min(max_scroll_length_pixels,
 126                             this.getScrollDistance_());
 127
 128     var rect = __GestureCommon_GetBoundingVisibleRect(this.options_.element_);
 129     var start_left =
 130         rect.left + rect.width * this.options_.left_start_ratio_;
 131     var start_top =
 132         rect.top + rect.height * this.options_.top_start_ratio_;
 133     chrome.gpuBenchmarking.smoothScrollBy(
 134         distance, this.onGestureComplete_.bind(this), start_left, start_top,
 135         this.options_.gesture_source_type_, this.options_.direction_,
 136         this.options_.speed_);
 137   };
 138
 139   ScrollAction.prototype.onGestureComplete_ = function() {
 140     this.endMeasuringHook();
 141
 142     // We're done.
 143     if (this.callback_)
 144       this.callback_();
 145   };
 146
 147   window.__ScrollAction = ScrollAction;
 148   window.__ScrollAction_SupportedByBrowser = supportedByBrowser;
 149 })();