src/tools/telemetry/telemetry/page/actions/scroll.js

   1 // Copyright (c) 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.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   }
  37
  38   // This class scrolls a page from the top to the bottom once.
  39   //
  40   // The page is scrolled down by a single scroll gesture.
  41   function ScrollAction(opt_callback, opt_distance_func) {
  42     var self = this;
  43
  44     this.beginMeasuringHook = function() {}
  45     this.endMeasuringHook = function() {}
  46
  47     this.callback_ = opt_callback;
  48     this.distance_func_ = opt_distance_func;
  49   }
  50
  51   ScrollAction.prototype.getScrollDistance_ = function() {
  52     if (this.distance_func_)
  53       return this.distance_func_();
  54
  55     if (this.options_.direction_ == 'down') {
  56       var clientHeight;
  57       // clientHeight is "special" for the body element.
  58       if (this.element_ == document.body)
  59         clientHeight = window.innerHeight;
  60       else
  61         clientHeight = this.element_.clientHeight;
  62
  63       return this.element_.scrollHeight -
  64              this.element_.scrollTop -
  65              clientHeight;
  66     } else if (this.options_.direction_ == 'up') {
  67       return this.element_.scrollTop;
  68     } else if (this.options_.direction_ == 'right') {
  69       var clientWidth;
  70       // clientWidth is "special" for the body element.
  71       if (this.element_ == document.body)
  72         clientWidth = window.innerWidth;
  73       else
  74         clientWidth = this.element_.clientWidth;
  75
  76       return this.element_.scrollWidth - this.element_.scrollLeft - clientWidth;
  77     } else if (this.options_.direction_ == 'left') {
  78       return this.element_.scrollLeft;
  79     }
  80   }
  81
  82   ScrollAction.prototype.start = function(opt_options) {
  83     this.options_ = new ScrollGestureOptions(opt_options);
  84     // Assign this.element_ here instead of constructor, because the constructor
  85     // ensures this method will be called after the document is loaded.
  86     this.element_ = this.options_.element_;
  87     requestAnimationFrame(this.startGesture_.bind(this));
  88   };
  89
  90   ScrollAction.prototype.startGesture_ = function() {
  91     this.beginMeasuringHook();
  92
  93     var max_scroll_length_pixels = (MAX_SCROLL_LENGTH_TIME_MS / 1000) *
  94         this.options_.speed_;
  95     var distance = Math.min(max_scroll_length_pixels,
  96                             this.getScrollDistance_());
  97
  98     var rect = __GestureCommon_GetBoundingVisibleRect(this.options_.element_);
  99     var start_left =
 100         rect.left + rect.width * this.options_.left_start_ratio_;
 101     var start_top =
 102         rect.top + rect.height * this.options_.top_start_ratio_;
 103     chrome.gpuBenchmarking.smoothScrollBy(
 104         distance, this.onGestureComplete_.bind(this), start_left, start_top,
 105         this.options_.gesture_source_type_, this.options_.direction_,
 106         this.options_.speed_);
 107   };
 108
 109   ScrollAction.prototype.onGestureComplete_ = function() {
 110     this.endMeasuringHook();
 111
 112     // We're done.
 113     if (this.callback_)
 114       this.callback_();
 115   };
 116
 117   window.__ScrollAction = ScrollAction;
 118   window.__ScrollAction_SupportedByBrowser = supportedByBrowser;
 119 })();