| // Copyright (c) 2012 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. |
| |
| // This file provides the ScrollAction object, which scrolls a page |
| // to the bottom or for a specified distance: |
| // 1. var action = new __ScrollAction(callback, opt_distance_func) |
| // 2. action.start(scroll_options) |
| 'use strict'; |
| |
| (function() { |
| var MAX_SCROLL_LENGTH_TIME_MS = 6250; |
| |
| function ScrollGestureOptions(opt_options) { |
| if (opt_options) { |
| this.element_ = opt_options.element; |
| this.left_start_ratio_ = opt_options.left_start_ratio; |
| this.top_start_ratio_ = opt_options.top_start_ratio; |
| this.direction_ = opt_options.direction; |
| this.speed_ = opt_options.speed; |
| this.gesture_source_type_ = opt_options.gesture_source_type; |
| } else { |
| this.element_ = document.scrollingElement; |
| this.left_start_ratio_ = 0.5; |
| this.top_start_ratio_ = 0.5; |
| this.direction_ = 'down'; |
| this.speed_ = 800; |
| this.gesture_source_type_ = chrome.gpuBenchmarking.DEFAULT_INPUT; |
| } |
| } |
| |
| function supportedByBrowser() { |
| return !!(window.chrome && |
| chrome.gpuBenchmarking && |
| chrome.gpuBenchmarking.smoothScrollBy); |
| } |
| |
| // This class scrolls a page from the top to the bottom once. |
| // |
| // The page is scrolled down by a single scroll gesture. |
| function ScrollAction(opt_callback, opt_distance_func) { |
| var self = this; |
| |
| this.beginMeasuringHook = function() {}; |
| this.endMeasuringHook = function() {}; |
| |
| this.callback_ = opt_callback; |
| this.distance_func_ = opt_distance_func; |
| } |
| |
| ScrollAction.prototype.getScrollDistanceDown_ = function() { |
| var clientHeight; |
| // clientHeight is "special" for the body element. |
| if (this.element_ == document.body) |
| clientHeight = window.innerHeight; |
| else |
| clientHeight = this.element_.clientHeight; |
| |
| return this.element_.scrollHeight - |
| this.element_.scrollTop - |
| clientHeight; |
| }; |
| |
| ScrollAction.prototype.getScrollDistanceUp_ = function() { |
| return this.element_.scrollTop; |
| }; |
| |
| ScrollAction.prototype.getScrollDistanceRight_ = function() { |
| var clientWidth; |
| // clientWidth is "special" for the body element. |
| if (this.element_ == document.body) |
| clientWidth = window.innerWidth; |
| else |
| clientWidth = this.element_.clientWidth; |
| |
| return this.element_.scrollWidth - this.element_.scrollLeft - clientWidth; |
| }; |
| |
| ScrollAction.prototype.getScrollDistanceLeft_ = function() { |
| return this.element_.scrollLeft; |
| }; |
| |
| ScrollAction.prototype.getScrollDistance_ = function() { |
| if (this.distance_func_) |
| return this.distance_func_(); |
| |
| if (this.options_.direction_ == 'down') { |
| return this.getScrollDistanceDown_(); |
| } else if (this.options_.direction_ == 'up') { |
| return this.getScrollDistanceUp_(); |
| } else if (this.options_.direction_ == 'right') { |
| return this.getScrollDistanceRight_(); |
| } else if (this.options_.direction_ == 'left') { |
| return this.getScrollDistanceLeft_(); |
| } else if (this.options_.direction_ == 'upleft') { |
| return Math.min(this.getScrollDistanceUp_(), |
| this.getScrollDistanceLeft_()); |
| } else if (this.options_.direction_ == 'upright') { |
| return Math.min(this.getScrollDistanceUp_(), |
| this.getScrollDistanceRight_()); |
| } else if (this.options_.direction_ == 'downleft') { |
| return Math.min(this.getScrollDistanceDown_(), |
| this.getScrollDistanceLeft_()); |
| } else if (this.options_.direction_ == 'downright') { |
| return Math.min(this.getScrollDistanceDown_(), |
| this.getScrollDistanceRight_()); |
| } |
| }; |
| |
| ScrollAction.prototype.start = function(opt_options) { |
| this.options_ = new ScrollGestureOptions(opt_options); |
| // Assign this.element_ here instead of constructor, because the constructor |
| // ensures this method will be called after the document is loaded. |
| this.element_ = this.options_.element_; |
| requestAnimationFrame(this.startGesture_.bind(this)); |
| }; |
| |
| ScrollAction.prototype.startGesture_ = function() { |
| this.beginMeasuringHook(); |
| |
| var max_scroll_length_pixels = (MAX_SCROLL_LENGTH_TIME_MS / 1000) * |
| this.options_.speed_; |
| var distance = Math.min(max_scroll_length_pixels, |
| this.getScrollDistance_()); |
| |
| var rect = __GestureCommon_GetBoundingVisibleRect(this.options_.element_); |
| var start_left = |
| rect.left + rect.width * this.options_.left_start_ratio_; |
| var start_top = |
| rect.top + rect.height * this.options_.top_start_ratio_; |
| chrome.gpuBenchmarking.smoothScrollBy( |
| distance, this.onGestureComplete_.bind(this), start_left, start_top, |
| this.options_.gesture_source_type_, this.options_.direction_, |
| this.options_.speed_); |
| }; |
| |
| ScrollAction.prototype.onGestureComplete_ = function() { |
| this.endMeasuringHook(); |
| |
| // We're done. |
| if (this.callback_) |
| this.callback_(); |
| }; |
| |
| window.__ScrollAction = ScrollAction; |
| window.__ScrollAction_SupportedByBrowser = supportedByBrowser; |
| })(); |