/*******************************************************************************
 *  Copyright: 2004, 2010 1&1 Internet AG, Germany, http://www.1und1.de,
 *                        and EclipseSource
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this
 * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html
 *
 *  Contributors:
 *    1&1 Internet AG and others - original API and implementation
 *    EclipseSource - adaptation for the Eclipse Rich Ajax Platform
 *
 * This class contains code based on the following work:
 *
 *  * Yahoo! UI Library
 *      http://developer.yahoo.com/yui
 *      Version 2.2.0
 *
 *    Copyright:
 *      (c) 2007, Yahoo! Inc.
 *
 *    License:
 *      BSD: http://developer.yahoo.com/yui/license.txt
 *
 ******************************************************************************/

/**
 * Includes library functions to work with the client's viewport (window).
 */
qx.Class.define("qx.bom.Viewport",
{
  statics :
  {
    /**
     * Returns the current width of the viewport (excluding a eventually visible scrollbar).
     *
     * <code>clientWidth</code> is the inner width of an element in pixels. It includes padding
     * but not the vertical scrollbar (if present, if rendered), border or margin.
     *
     * The property <code>innerWidth</code> is not useable as defined by the standard as it includes the scrollbars
     * which is not the indented behavior of this method. We can decrement the size by the scrollbar
     * size but there are easier possibilities to work around this.
     *
     * Safari 2 and 3 beta (3.0.2) do not correctly implement <code>clientWidth</code> on documentElement/body,
     * but <code>innerWidth</code> works there. Interesting is that webkit do not correctly implement
     * <code>innerWidth</code>, too. It calculates the size excluding the scroll bars and this
     * differs from the behavior of all other browsers - but this is exactly what we want to have
     * in this case.
     *
     * Opera as of 9.21 only works well using <code>body.clientWidth</code>.
     *
     * Verified to correctly work with:
     *
     * * Mozilla Firefox 2.0.0.4
     * * Opera 9.2.1
     * * Safari 3.0 beta (3.0.2)
     * * Internet Explorer 7.0
     *
     * @type static
     * @signature function(win)
     * @param win {Window?window} The window to query
     * @return {Integer} The width of the viewable area of the page (excludes scrollbars).
     */
    getWidth : qx.core.Variant.select("qx.client",
    {
      "opera" : function(win) {
        return (win||window).document.body.clientWidth;
      },

      "webkit" : function(win) {
        return (win||window).innerWidth;
      },

      "default" : function(win)
      {
        var doc = (win||window).document;
        return doc.compatMode === "CSS1Compat" ? doc.documentElement.clientWidth : doc.body.clientWidth;
      }
    }),


    /**
     * Returns the current height of the viewport (excluding a eventually visible scrollbar).
     *
     * <code>clientHeight</code> is the inner height of an element in pixels. It includes padding
     * but not the vertical scrollbar (if present, if rendered), border or margin.
     *
     * The property <code>innerHeight</code> is not useable as defined by the standard as it includes the scrollbars
     * which is not the indented behavior of this method. We can decrement the size by the scrollbar
     * size but there are easier possibilities to work around this.
     *
     * Safari 2 and 3 beta (3.0.2) do not correctly implement <code>clientHeight</code> on documentElement/body,
     * but <code>innerHeight</code> works there. Interesting is that webkit do not correctly implement
     * <code>innerHeight</code>, too. It calculates the size excluding the scroll bars and this
     * differs from the behavior of all other browsers - but this is exactly what we want to have
     * in this case.
     *
     * Opera as of 9.21 only works well using <code>body.clientHeight</code>.
     *
     * Verified to correctly work with:
     *
     * * Mozilla Firefox 2.0.0.4
     * * Opera 9.2.1
     * * Safari 3.0 beta (3.0.2)
     * * Internet Explorer 7.0
     *
     * @type static
     * @signature function(win)
     * @param win {Window?window} The window to query
     * @return {Integer} The Height of the viewable area of the page (excludes scrollbars).
     */
    getHeight : qx.core.Variant.select("qx.client",
    {
      "opera" : function(win) {
        return (win||window).document.body.clientHeight;
      },

      "webkit" : function(win) {
        return (win||window).innerHeight;
      },

      "default" : function(win)
      {
        var doc = (win||window).document;
        return doc.compatMode === "CSS1Compat" ? doc.documentElement.clientHeight : doc.body.clientHeight;
      }
    }),


    /**
     * Returns the scroll position of the viewport
     *
     * All clients except MSHTML supports the non-standard property <code>pageXOffset</code>.
     * As this is easier to evaluate we prefer this property over <code>scrollLeft</code>.
     *
     * For MSHTML the access method differs between standard and quirks mode;
     * as this can differ from document to document this test must be made on
     * each query.
     *
     * Verified to correctly work with:
     *
     * * Mozilla Firefox 2.0.0.4
     * * Opera 9.2.1
     * * Safari 3.0 beta (3.0.2)
     * * Internet Explorer 7.0
     *
     * @type static
     * @signature function(win)
     * @param win {Window?window} The window to query
     * @return {Integer} Scroll position from left edge, always a positive integer
     */
    getScrollLeft : qx.core.Variant.select("qx.client",
    {
      "mshtml" : function(win)
      {
        var doc = (win||window).document;
        return doc.documentElement.scrollLeft || doc.body.scrollLeft;
      },

      "default" : function(win) {
        return (win||window).pageXOffset;
      }
    }),


    /**
     * Returns the scroll position of the viewport
     *
     * All clients except MSHTML supports the non-standard property <code>pageYOffset</code>.
     * As this is easier to evaluate we prefer this property over <code>scrollTop</code>.
     *
     * For MSHTML the access method differs between standard and quirks mode;
     * as this can differ from document to document this test must be made on
     * each query.
     *
     * Verified to correctly work with:
     *
     * * Mozilla Firefox 2.0.0.4
     * * Opera 9.2.1
     * * Safari 3.0 beta (3.0.2)
     * * Internet Explorer 7.0
     *
     * @type static
     * @signature function(win)
     * @param win {Window?window} The window to query
     * @return {Integer} Scroll position from left edge, always a positive integer
     */
    getScrollTop : qx.core.Variant.select("qx.client",
    {
      "mshtml" : function(win)
      {
        var doc = (win||window).document;
        return doc.documentElement.scrollTop || doc.body.scrollTop;
      },

      "default" : function(win) {
        return (win||window).pageYOffset;
      }
    })
  }
});