| // Copyright 2008 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| /** |
| * @fileoverview Class for making an element detach and float to remain visible |
| * even when the viewport has been scrolled. |
| * <p> |
| * The element remains at its normal position in the layout until scrolling |
| * would cause its top edge to scroll off the top of the viewport; at that |
| * point, the element is replaced with an invisible placeholder (to keep the |
| * layout stable), reattached in the dom tree to a new parent (the body element |
| * by default), and set to "fixed" positioning (emulated for IE < 7) so that it |
| * remains at its original X position while staying fixed to the top of the |
| * viewport in the Y dimension. |
| * <p> |
| * When the window is scrolled up past the point where the original element |
| * would be fully visible again, the element snaps back into place, replacing |
| * the placeholder. |
| * |
| * @see ../demos/scrollfloater.html |
| * |
| * Adapted from http://go/elementfloater.js |
| */ |
| |
| |
| goog.provide('goog.ui.ScrollFloater'); |
| goog.provide('goog.ui.ScrollFloater.EventType'); |
| |
| goog.require('goog.array'); |
| goog.require('goog.asserts'); |
| goog.require('goog.dom'); |
| goog.require('goog.dom.classlist'); |
| goog.require('goog.events.EventType'); |
| goog.require('goog.style'); |
| goog.require('goog.ui.Component'); |
| goog.require('goog.userAgent'); |
| |
| |
| |
| /** |
| * Creates a ScrollFloater; see file overview for details. |
| * |
| * @param {Element=} opt_parentElement Where to attach the element when it's |
| * floating. Default is the document body. If the floating element |
| * contains form inputs, it will be necessary to attach it to the |
| * corresponding form element, or to an element in the DOM subtree under |
| * the form element. |
| * @param {goog.dom.DomHelper=} opt_domHelper Optional DOM helper. |
| * @constructor |
| * @extends {goog.ui.Component} |
| */ |
| goog.ui.ScrollFloater = function(opt_parentElement, opt_domHelper) { |
| // If a parentElement is supplied, we want to use its domHelper, |
| // ignoring the caller-supplied one. |
| var domHelper = opt_parentElement ? |
| goog.dom.getDomHelper(opt_parentElement) : opt_domHelper; |
| |
| goog.ui.ScrollFloater.base(this, 'constructor', domHelper); |
| |
| /** |
| * The element to which the scroll-floated element will be attached |
| * when it is floating. |
| * @type {Element} |
| * @private |
| */ |
| this.parentElement_ = |
| opt_parentElement || this.getDomHelper().getDocument().body; |
| |
| /** |
| * The original styles applied to the element before it began floating; |
| * used to restore those styles when the element stops floating. |
| * @type {Object} |
| * @private |
| */ |
| this.originalStyles_ = {}; |
| |
| /** |
| * A vertical offset from which to start floating the element. This is |
| * useful in cases when there are 'position:fixed' elements covering up |
| * part of the viewport. |
| * @type {number} |
| * @private |
| */ |
| this.viewportTopOffset_ = 0; |
| |
| /** |
| * An element used to define the boundaries within which the floater can |
| * be positioned. |
| * @type {Element} |
| * @private |
| */ |
| this.containerElement_ = null; |
| |
| /** |
| * Container element's bounding rectangle. |
| * @type {goog.math.Rect} |
| * @private |
| */ |
| this.containerBounds_ = null; |
| |
| /** |
| * Element's original bounding rectangle. |
| * @type {goog.math.Rect} |
| * @private |
| */ |
| this.originalBounds_ = null; |
| |
| /** |
| * Element's top offset when it's not floated or pinned. |
| * @type {number} |
| * @private |
| */ |
| this.originalTopOffset_ = 0; |
| |
| /** |
| * The placeholder element dropped in to hold the layout for |
| * the floated element. |
| * @type {Element} |
| * @private |
| */ |
| this.placeholder_ = null; |
| |
| /** |
| * Whether scrolling is enabled for this element; true by default. |
| * The {@link #setScrollingEnabled} method can be used to change this value. |
| * @type {boolean} |
| * @private |
| */ |
| this.scrollingEnabled_ = true; |
| |
| /** |
| * A flag indicating whether this instance is currently pinned to the bottom |
| * of the container element. |
| * @type {boolean} |
| * @private |
| */ |
| this.pinned_ = false; |
| |
| /** |
| * A flag indicating whether this instance is currently floating. |
| * @type {boolean} |
| * @private |
| */ |
| this.floating_ = false; |
| }; |
| goog.inherits(goog.ui.ScrollFloater, goog.ui.Component); |
| |
| |
| /** |
| * Events dispatched by this component. |
| * @enum {string} |
| */ |
| goog.ui.ScrollFloater.EventType = { |
| /** |
| * Dispatched when the component starts floating. The event is |
| * cancellable. |
| */ |
| FLOAT: 'float', |
| |
| /** |
| * Dispatched when the component returns to its original state. |
| * The event is cancellable. |
| */ |
| DOCK: 'dock', |
| |
| /** |
| * Dispatched when the component gets pinned to the bottom of the |
| * container element. This event is cancellable. |
| */ |
| PIN: 'pin' |
| }; |
| |
| |
| /** |
| * The element can float at different positions on the page. |
| * @enum {number} |
| * @private |
| */ |
| goog.ui.ScrollFloater.FloatMode_ = { |
| TOP: 0, |
| BOTTOM: 1 |
| }; |
| |
| |
| /** |
| * The style properties which are stored when we float an element, so they |
| * can be restored when it 'docks' again. |
| * @type {Array<string>} |
| * @private |
| */ |
| goog.ui.ScrollFloater.STORED_STYLE_PROPS_ = [ |
| 'position', 'top', 'left', 'width', 'cssFloat']; |
| |
| |
| /** |
| * The style elements managed for the placeholder object. |
| * @type {Array<string>} |
| * @private |
| */ |
| goog.ui.ScrollFloater.PLACEHOLDER_STYLE_PROPS_ = [ |
| 'position', 'top', 'left', 'display', 'cssFloat', |
| 'marginTop', 'marginLeft', 'marginRight', 'marginBottom']; |
| |
| |
| /** |
| * The class name applied to the floating element. |
| * @type {string} |
| * @private |
| */ |
| goog.ui.ScrollFloater.CSS_CLASS_ = goog.getCssName('goog-scrollfloater'); |
| |
| |
| /** |
| * Delegates dom creation to superclass, then constructs and |
| * decorates required DOM elements. |
| * @override |
| */ |
| goog.ui.ScrollFloater.prototype.createDom = function() { |
| goog.ui.ScrollFloater.base(this, 'createDom'); |
| |
| this.decorateInternal(this.getElement()); |
| }; |
| |
| |
| /** |
| * Decorates the floated element with the standard ScrollFloater CSS class. |
| * @param {Element} element The element to decorate. |
| * @override |
| */ |
| goog.ui.ScrollFloater.prototype.decorateInternal = function(element) { |
| goog.ui.ScrollFloater.base(this, 'decorateInternal', element); |
| goog.asserts.assert(element); |
| goog.dom.classlist.add(element, goog.ui.ScrollFloater.CSS_CLASS_); |
| }; |
| |
| |
| /** @override */ |
| goog.ui.ScrollFloater.prototype.enterDocument = function() { |
| goog.ui.ScrollFloater.base(this, 'enterDocument'); |
| |
| if (!this.placeholder_) { |
| this.placeholder_ = |
| this.getDomHelper().createDom('div', {'style': 'visibility:hidden'}); |
| } |
| |
| this.update(); |
| |
| this.setScrollingEnabled(this.scrollingEnabled_); |
| var win = this.getDomHelper().getWindow(); |
| this.getHandler(). |
| listen(win, goog.events.EventType.SCROLL, this.handleScroll_). |
| listen(win, goog.events.EventType.RESIZE, this.update); |
| }; |
| |
| |
| /** |
| * Forces the component to update the cached element positions and sizes and |
| * to re-evaluate whether the the component should be docked, floated or |
| * pinned. |
| */ |
| goog.ui.ScrollFloater.prototype.update = function() { |
| if (!this.isInDocument()) { |
| return; |
| } |
| |
| // These values can only be calculated when the element is in its original |
| // state, so we dock first, and then re-evaluate. |
| this.dock_(); |
| if (this.containerElement_) { |
| this.containerBounds_ = goog.style.getBounds(this.containerElement_); |
| } |
| this.originalBounds_ = goog.style.getBounds(this.getElement()); |
| this.originalTopOffset_ = goog.style.getPageOffset(this.getElement()).y; |
| this.handleScroll_(); |
| }; |
| |
| |
| /** @override */ |
| goog.ui.ScrollFloater.prototype.disposeInternal = function() { |
| goog.ui.ScrollFloater.base(this, 'disposeInternal'); |
| |
| this.placeholder_ = null; |
| }; |
| |
| |
| /** |
| * Sets whether the element should be floated if it scrolls out of view. |
| * @param {boolean} enable Whether floating is enabled for this element. |
| */ |
| goog.ui.ScrollFloater.prototype.setScrollingEnabled = function(enable) { |
| this.scrollingEnabled_ = enable; |
| |
| if (enable) { |
| this.applyIeBgHack_(); |
| this.handleScroll_(); |
| } else { |
| this.dock_(); |
| } |
| }; |
| |
| |
| /** |
| * @return {boolean} Whether the component is enabled for scroll-floating. |
| */ |
| goog.ui.ScrollFloater.prototype.isScrollingEnabled = function() { |
| return this.scrollingEnabled_; |
| }; |
| |
| |
| /** |
| * @return {boolean} Whether the component is currently scroll-floating. |
| */ |
| goog.ui.ScrollFloater.prototype.isFloating = function() { |
| return this.floating_; |
| }; |
| |
| |
| /** |
| * @return {boolean} Whether the component is currently pinned to the bottom |
| * of the container. |
| */ |
| goog.ui.ScrollFloater.prototype.isPinned = function() { |
| return this.pinned_; |
| }; |
| |
| |
| /** |
| * @param {number} offset A vertical offset from the top of the viewport, from |
| * which to start floating the element. Default is 0. This is useful in cases |
| * when there are 'position:fixed' elements covering up part of the viewport. |
| */ |
| goog.ui.ScrollFloater.prototype.setViewportTopOffset = function(offset) { |
| this.viewportTopOffset_ = offset; |
| this.update(); |
| }; |
| |
| |
| /** |
| * @param {Element} container An element used to define the boundaries within |
| * which the floater can be positioned. If not specified, scrolling the page |
| * down far enough may result in the floated element extending past the |
| * containing element as it is being scrolled out of the viewport. In some |
| * cases, such as a list with a sticky header, this may be undesirable. If |
| * the container element is specified and the floated element extends past |
| * the bottom of the container, the element will be pinned to the bottom of |
| * the container. |
| */ |
| goog.ui.ScrollFloater.prototype.setContainerElement = function(container) { |
| this.containerElement_ = container; |
| this.update(); |
| }; |
| |
| |
| /** |
| * When a scroll event occurs, compares the element's position to the current |
| * document scroll position, and stops or starts floating behavior if needed. |
| * @param {goog.events.Event=} opt_e The event, which is ignored. |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.handleScroll_ = function(opt_e) { |
| if (this.scrollingEnabled_) { |
| var scrollTop = this.getDomHelper().getDocumentScroll().y; |
| |
| if (this.originalBounds_.top - scrollTop >= this.viewportTopOffset_) { |
| this.dock_(); |
| return; |
| } |
| |
| var effectiveElementHeight = this.originalBounds_.height + |
| this.viewportTopOffset_; |
| |
| // If the element extends past the container, we need to pin it instead. |
| if (this.containerElement_) { |
| var containerBottom = this.containerBounds_.top + |
| this.containerBounds_.height; |
| |
| if (scrollTop > containerBottom - effectiveElementHeight) { |
| this.pin_(); |
| return; |
| } |
| } |
| |
| var windowHeight = this.getDomHelper().getViewportSize().height; |
| |
| // If the element is shorter than the window or the user uses IE < 7, |
| // float it at the top. |
| if (this.needsIePositionHack_() || effectiveElementHeight < windowHeight) { |
| this.float_(goog.ui.ScrollFloater.FloatMode_.TOP); |
| return; |
| } |
| |
| // If the element is taller than the window and is extending past the |
| // bottom, allow it scroll with the page until the bottom of the element is |
| // fully visible. |
| if (this.originalBounds_.height + this.originalTopOffset_ > |
| windowHeight + scrollTop) { |
| this.dock_(); |
| } else { |
| // Pin the element to the bottom of the page since the user has scrolled |
| // past it. |
| this.float_(goog.ui.ScrollFloater.FloatMode_.BOTTOM); |
| } |
| } |
| }; |
| |
| |
| /** |
| * Pins the element to the bottom of the container, making as much of the |
| * element visible as possible without extending past it. |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.pin_ = function() { |
| if (this.floating_ && !this.dock_()) { |
| return; |
| } |
| |
| // Ignore if the component is pinned or the PIN event is cancelled. |
| if (this.pinned_ || |
| !this.dispatchEvent(goog.ui.ScrollFloater.EventType.PIN)) { |
| return; |
| } |
| |
| var elem = this.getElement(); |
| |
| this.storeOriginalStyles_(); |
| |
| elem.style.position = 'relative'; |
| elem.style.top = this.containerBounds_.height - this.originalBounds_.height - |
| this.originalBounds_.top + this.containerBounds_.top + 'px'; |
| |
| this.pinned_ = true; |
| }; |
| |
| |
| /** |
| * Begins floating behavior, making the element position:fixed (or IE hacked |
| * equivalent) and inserting a placeholder where it used to be to keep the |
| * layout from shifting around. For IE < 7 users, we only support floating at |
| * the top. |
| * @param {goog.ui.ScrollFloater.FloatMode_} floatMode The position at which we |
| * should float. |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.float_ = function(floatMode) { |
| var isTop = floatMode == goog.ui.ScrollFloater.FloatMode_.TOP; |
| if (this.pinned_ && !this.dock_()) { |
| return; |
| } |
| |
| // Ignore if the component is floating or the FLOAT event is cancelled. |
| if (this.floating_ || |
| !this.dispatchEvent(goog.ui.ScrollFloater.EventType.FLOAT)) { |
| return; |
| } |
| |
| var elem = this.getElement(); |
| var doc = this.getDomHelper().getDocument(); |
| |
| // Read properties of element before modifying it. |
| var originalLeft_ = goog.style.getPageOffsetLeft(elem); |
| var originalWidth_ = goog.style.getContentBoxSize(elem).width; |
| |
| this.storeOriginalStyles_(); |
| |
| goog.style.setSize(this.placeholder_, elem.offsetWidth, elem.offsetHeight); |
| |
| // Make element float. |
| goog.style.setStyle(elem, { |
| 'left': originalLeft_ + 'px', |
| 'width': originalWidth_ + 'px', |
| 'cssFloat': 'none' |
| }); |
| |
| // If parents are the same, avoid detaching and reattaching elem. |
| // This prevents Flash embeds from being reloaded, for example. |
| if (elem.parentNode == this.parentElement_) { |
| elem.parentNode.insertBefore(this.placeholder_, elem); |
| } else { |
| elem.parentNode.replaceChild(this.placeholder_, elem); |
| this.parentElement_.appendChild(elem); |
| } |
| |
| // Versions of IE below 7-in-standards-mode don't handle 'position: fixed', |
| // so we must emulate it using an IE-specific idiom for JS-based calculated |
| // style values. These users will only ever float at the top (bottom floating |
| // not supported.) Also checked in handleScroll_. |
| if (this.needsIePositionHack_()) { |
| elem.style.position = 'absolute'; |
| elem.style.setExpression('top', |
| 'document.compatMode=="CSS1Compat"?' + |
| 'documentElement.scrollTop:document.body.scrollTop'); |
| } else { |
| elem.style.position = 'fixed'; |
| if (isTop) { |
| elem.style.top = this.viewportTopOffset_ + 'px'; |
| elem.style.bottom = 'auto'; |
| } else { |
| elem.style.top = 'auto'; |
| elem.style.bottom = 0; |
| } |
| } |
| |
| this.floating_ = true; |
| }; |
| |
| |
| /** |
| * Stops floating behavior, returning element to its original state. |
| * @return {boolean} True if the the element has been docked. False if the |
| * element is already docked or the event was cancelled. |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.dock_ = function() { |
| // Ignore if the component is docked or the DOCK event is cancelled. |
| if (!(this.floating_ || this.pinned_) || |
| !this.dispatchEvent(goog.ui.ScrollFloater.EventType.DOCK)) { |
| return false; |
| } |
| |
| var elem = this.getElement(); |
| |
| if (this.floating_) { |
| this.restoreOriginalStyles_(); |
| |
| if (this.needsIePositionHack_()) { |
| elem.style.removeExpression('top'); |
| } |
| |
| // If placeholder_ was inserted and didn't replace elem then elem has |
| // the right parent already, no need to replace (which removes elem before |
| // inserting it). |
| if (this.placeholder_.parentNode == this.parentElement_) { |
| this.placeholder_.parentNode.removeChild(this.placeholder_); |
| } else { |
| this.placeholder_.parentNode.replaceChild(elem, this.placeholder_); |
| } |
| } |
| |
| if (this.pinned_) { |
| this.restoreOriginalStyles_(); |
| } |
| |
| this.floating_ = this.pinned_ = false; |
| |
| return true; |
| }; |
| |
| |
| /** |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.storeOriginalStyles_ = function() { |
| var elem = this.getElement(); |
| this.originalStyles_ = {}; |
| |
| // Store styles while not floating so we can restore them when the |
| // element stops floating. |
| goog.array.forEach(goog.ui.ScrollFloater.STORED_STYLE_PROPS_, |
| function(property) { |
| this.originalStyles_[property] = elem.style[property]; |
| }, |
| this); |
| |
| // Copy relevant styles to placeholder so it will be layed out the same |
| // as the element that's about to be floated. |
| goog.array.forEach(goog.ui.ScrollFloater.PLACEHOLDER_STYLE_PROPS_, |
| function(property) { |
| this.placeholder_.style[property] = |
| elem.style[property] || |
| goog.style.getCascadedStyle(elem, property) || |
| goog.style.getComputedStyle(elem, property); |
| }, |
| this); |
| }; |
| |
| |
| /** |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.restoreOriginalStyles_ = function() { |
| var elem = this.getElement(); |
| for (var prop in this.originalStyles_) { |
| elem.style[prop] = this.originalStyles_[prop]; |
| } |
| }; |
| |
| |
| /** |
| * Determines whether we need to apply the position hack to emulated position: |
| * fixed on this browser. |
| * @return {boolean} Whether the current browser needs the position hack. |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.needsIePositionHack_ = function() { |
| return goog.userAgent.IE && |
| !(goog.userAgent.isVersionOrHigher('7') && |
| this.getDomHelper().isCss1CompatMode()); |
| }; |
| |
| |
| /** |
| * Sets some magic CSS properties that make float-scrolling work smoothly |
| * in IE6 (and IE7 in quirks mode). Without this hack, the floating element |
| * will appear jumpy when you scroll the document. This involves modifying |
| * the background of the HTML element (or BODY in quirks mode). If there's |
| * already a background image in use this is not required. |
| * For further reading, see |
| * http://annevankesteren.nl/2005/01/position-fixed-in-ie |
| * @private |
| */ |
| goog.ui.ScrollFloater.prototype.applyIeBgHack_ = function() { |
| if (this.needsIePositionHack_()) { |
| var doc = this.getDomHelper().getDocument(); |
| var topLevelElement = goog.style.getClientViewportElement(doc); |
| |
| if (topLevelElement.currentStyle.backgroundImage == 'none') { |
| // Using an https URL if the current windowbp is https avoids an IE |
| // "This page contains a mix of secure and nonsecure items" warning. |
| topLevelElement.style.backgroundImage = |
| this.getDomHelper().getWindow().location.protocol == 'https:' ? |
| 'url(https:///)' : 'url(about:blank)'; |
| topLevelElement.style.backgroundAttachment = 'fixed'; |
| } |
| } |
| }; |