/**
 * Giant Scalable Image Viewer (GSIV) 1.0
 *
 * Generates a draggable and zoomable viewer for images that would
 * be otherwise too large for a browser window.  Examples would include
 * maps or high resolution document scans.
 *
 * Images must be precut into tiles, such as by the accompanying tilemaker.py
 * python library.
 *
 * <div class="viewer">
 *   <div class="well"><!-- --></div>
 *   <div class="surface"><!-- --></div>
 *   <div class="controls">
 *     <a href="#" class="zoomIn">+</a>
 *     <a href="#" class="zoomOut">-</a>
 *   </div>
 * </div>
 * 
 * The "well" node is where generated IMG elements are appended. It
 * should have the CSS rule "overflow: hidden", to occlude image tiles
 * that have scrolled out of view.
 * 
 * The "surface" node is the transparent mouse-responsive layer of the
 * image viewer, and should match the well in size.
 *
 * var viewerBean = new GSIV(element, 'tiles', 256, 3, 1);
 *
 * To disable the image toolbar in IE, be sure to add the following:
 * <meta http-equiv="imagetoolbar" content="no" />
 *
 * Copyright (c) 2005 Michal Migurski <mike-gsv@teczno.com>
 *                    Dan Allen <dan.allen@mojavelinux.com>
 * 
 * Redistribution and use in source form, with or without modification,
 * are permitted provided that the following conditions are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @author Michal Migurski <mike-gsv@teczno.com>
 * @author Dan Allen <dan.allen@mojavelinux.com>
 *
 * NOTE: if artifacts are appearing, then positions include half-pixels
 * TODO: additional jsdoc and package jsmin
 * TODO: Tile could be an object
 */
function GSIV(viewer, options) {

	// listeners that are notified on a move (pan) event
	this.viewerMovedListeners = [];
	this.viewerMoveStopedListeners = [];
	// listeners that are notified on a zoom event
	this.viewerZoomedListeners = [];

	if (typeof viewer == 'string') {
		this.viewer = document.getElementById(viewer);
	}
	else {
		this.viewer = viewer;
	}

	if (typeof options == 'undefined') {
		options = {};
	}

	if (typeof options.tileUrlProvider != 'undefined' &&
		GSIV.isInstance(options.tileUrlProvider, GSIV.TileUrlProvider)) {
		this.tileUrlProvider = options.tileUrlProvider;
	}
	else {
		this.tileUrlProvider = new GSIV.TileUrlProvider(
			options.tileBaseUri ? options.tileBaseUri : GSIV.TILE_BASE_URI,
			options.tilePrefix ? options.tilePrefix : GSIV.TILE_PREFIX,
			options.tileExtension ? options.tileExtension : GSIV.TILE_EXTENSION
		);
	}

	this.tileSize = (options.tileSize ? options.tileSize : GSIV.TILE_SIZE);

	// assign and do some validation on the zoom levels to ensure sanity
	this.zoomLevel = (typeof options.initialZoom == 'undefined' ? -1 : parseInt(options.initialZoom));
	this.maxZoomLevel = (typeof options.maxZoom == 'undefined' ? 0 : Math.abs(parseInt(options.maxZoom)));
	if (this.zoomLevel > this.maxZoomLevel) {
		this.zoomLevel = this.maxZoomLevel;
	}

	this.initialPan = (options.initialPan ? options.initialPan : GSIV.INITIAL_PAN);

	this.initialized = false;
	this.surface = null;
	this.well = null;
	this.width = 0;
	this.height = 0;
	this.top = 0;
	this.left = 0;
	this.x = 0;
	this.y = 0;
	this.currentX = 0;
	this.currentY = 0;
	this.border = -1;
	this.mark = { 'x' : 0, 'y' : 0 };
	this.pressed = false;
	this.tiles = [];
	this.cache = {};
	var blankTile = options.blankTile ? options.blankTile : GSIV.BLANK_TILE_IMAGE;
	var loadingTile = options.loadingTile ? options.loadingTile : GSIV.LOADING_TILE_IMAGE;
	this.cache['blank'] = new Image();
	this.cache['blank'].src = blankTile;
	if (blankTile != loadingTile) {
		this.cache['loading'] = new Image();
		this.cache['loading'].src = loadingTile;
	}
	else {
		this.cache['loading'] = this.cache['blank'];
	}

	// employed to throttle the number of redraws that
	// happen while the mouse is moving
	this.moveCount = 0;
	this.slideMonitor = 0;
	this.slideAcceleration = 0;

	// add to viewer registry
	GSIV.VIEWERS[GSIV.VIEWERS.length] = this;

	this.disableScroll = true;
}

GSIV.disableScroll = true;
// project specific variables
GSIV.PROJECT_NAME = 'GSIV';
GSIV.PROJECT_VERSION = '1.0.0';
GSIV.REVISION_FLAG = '';

// CSS definition settings
GSIV.SURFACE_STYLE_CLASS = 'surface';
GSIV.WELL_STYLE_CLASS = 'well';
GSIV.CONTROLS_STYLE_CLASS = 'controls'
GSIV.TILE_STYLE_CLASS = 'tile';

// language settings
//GSIV.MSG_BEYOND_MIN_ZOOM = 'Dosegli ste najbolj oddaljen pogled.';//'Cannot zoom out past the current level.';
//GSIV.MSG_BEYOND_MAX_ZOOM = 'Dosegli ste največjo povečavo.'; //'Cannot zoom in beyond the current level.';

// defaults if not provided as constructor options
GSIV.TILE_BASE_URI = 'tiles';
GSIV.TILE_PREFIX = 'tile-';
GSIV.TILE_EXTENSION = 'jpg';
GSIV.TILE_SIZE = 256;
GSIV.BLANK_TILE_IMAGE = 'blank.gif';
GSIV.LOADING_TILE_IMAGE = 'blank.gif';
GSIV.INITIAL_PAN = { 'x' : .5, 'y' : .5 };
GSIV.USE_LOADER_IMAGE = true;
GSIV.USE_SLIDE = true;
GSIV.USE_KEYBOARD = true;

//custom consts
GSIV.WORLD_X_OFFSET = 360000;
GSIV.WORLD_Y_OFFSET = 240000;
                        //pixel in m      //zoom 12 //tile size
GSIV.WORLDUNITCONST = (2.54 / 100 / 96) * 1000 * 256; // 68; //must be same value as in picture generator

// performance tuning variables
GSIV.MOVE_THROTTLE = 3;
GSIV.SLIDE_DELAY = 40;
GSIV.SLIDE_ACCELERATION_FACTOR = 5;

// the following are calculated settings
GSIV.DOM_ONLOAD = (navigator.userAgent.indexOf('KHTML') >= 0 ? false : true);
//GSIV.GRAB_MOUSE_CURSOR = '-moz-grab, crosshair'; //'hand'; //'crosshair'; //(navigator.userAgent.search(/KHTML|Opera/i) >= 0 ? 'pointer' : (document.attachEvent ? 'url(map/assets/gfx/grab.cur)' : '-moz-grab'));
//GSIV.GRABBING_MOUSE_CURSOR = '-moz-grabbing, pointer'; //(navigator.userAgent.search(/KHTML|Opera/i) >= 0 ? 'move' : (document.attachEvent ? 'url(map/assets/gfx/grabbing.cur)' : '-moz-grabbing'));

GSIV.GRAB_MOUSE_CURSOR = (document.attachEvent ? 'url(' + pirsApplicationPath + 'map/assets/gfx/grab.cur), crosshair' : '-moz-grab');
GSIV.GRABBING_MOUSE_CURSOR = (document.attachEvent ? 'url(' + pirsApplicationPath + 'map/assets/gfx/grabbing.cur), pointer' : '-moz-grabbing');



// registry of all known viewers
GSIV.VIEWERS = [];

// utility functions
GSIV.isInstance = function(object, clazz) {
	while (object != null) {
		if (object == clazz.prototype) {
			return true;
		}

		object = object.__proto__;
	}

	return false;
}

GSIV.prototype = {

	/**
	 * Resize the viewer to fit snug inside the browser window (or frame),
	 * spacing it from the edges by the specified border.
	 *
	 * This method should be called prior to init()
	 * FIXME: option to hide viewer to prevent scrollbar interference
	 */
	fitToWindow : function(border) {
		if (typeof border != 'number' || border < 0) {
			border = 0;
		}

		this.border = border;
		var calcWidth = 0;
		var calcHeight = 0;
		if (window.innerWidth) {
			calcWidth = window.innerWidth;
			calcHeight = window.innerHeight;
		}
		else {
			calcWidth = (document.compatMode == 'CSS1Compat' ? document.documentElement.clientWidth : document.body.clientWidth);
			calcHeight = (document.compatMode == 'CSS1Compat' ? document.documentElement.clientHeight : document.body.clientHeight);
		}
		
		/*calcHeight -= 28;
		calcWidth -= 12;*/
		
		calcWidth = Math.max(calcWidth - 2 * border, 0);
		calcHeight = Math.max(calcHeight - 2 * border, 0);
		
		if (calcWidth % 2) {
			calcWidth--;
		}

		if (calcHeight % 2) {
			calcHeight--;
		}

		this.width = calcWidth;
		this.height = calcHeight;
		this.viewer.style.width = this.width + 'px';
		this.viewer.style.height = this.height + 'px';
		this.viewer.style.top = border + 'px';
		this.viewer.style.left = border + 'px';
	},

	init : function() {
		if (document.attachEvent) {
			document.body.ondragstart = function() { return false; }
		}
		
		if (this.width == 0 && this.height == 0) {
			this.width = this.viewer.offsetWidth;
			this.height = this.viewer.offsetHeight;
		}

		var fullSize = this.tileSize;
		// explicit set of zoom level
		if (this.zoomLevel >= 0 && this.zoomLevel <= this.maxZoomLevel) {
			fullSize = this.tileSize * Math.pow(2, this.zoomLevel);
		}
		// calculate the zoom level based on what fits best in window
		else {
			this.zoomLevel = -1;
			fullSize = this.tileSize / 2;
			do {
				this.zoomLevel += 1;
				fullSize *= 2;
			} while (fullSize < Math.max(this.width, this.height));
		}

		// move top level up and to the left so that the image is centered
		this.x = Math.floor((fullSize - this.width) * -this.initialPan.x);
		this.y = Math.floor((fullSize - this.height) * -this.initialPan.y);

		// offset of viewer in the window
		for (var node = this.viewer; node; node = node.offsetParent) {
			this.top += node.offsetTop;
			this.left += node.offsetLeft;
		}

		for (var child = this.viewer.firstChild; child; child = child.nextSibling) {
			if (child.className == GSIV.SURFACE_STYLE_CLASS) {
				this.surface = child;
				child.backingBean = this;
			}
			else if (child.className == GSIV.WELL_STYLE_CLASS) {
				this.well = child;
				child.backingBean = this;
			}
			else if (child.className == GSIV.CONTROLS_STYLE_CLASS) {
				for (var control = child.firstChild; control; control = control.nextSibling) {
				    if (control.name == 'navigator' || control.name == 'zoomerMap' || control.name == 'zoomGaugeMap' || control.name == 'moveGaugeMap')
				    {
				        for (var control2 = control.firstChild; control2; control2 = control2.nextSibling) {
				    		if (control2.className) {
						        control2.onclick = GSIV[control2.className + 'Handler'];
					        }
			        	}
				    }
					if (control.className) {
						control.onclick = GSIV[control.className + 'Handler'];
					}
				}
			}
		}

		this.viewer.backingBean = this;
		this.surface.style.cursor = GSIV.GRAB_MOUSE_CURSOR;
		this.prepareTiles();
		this.initialized = true;
	},

	prepareTiles : function() {
		var rows = Math.ceil(this.height / this.tileSize) + 1;
		var cols = Math.ceil(this.width / this.tileSize) + 1;

		for (var c = 0; c < cols; c++) {
			var tileCol = [];

			for (var r = 0; r < rows; r++) {
				/**
				 * element is the DOM element associated with this tile
				 * posx/posy are the pixel offsets of the tile
				 * xIndex/yIndex are the index numbers of the tile segment
				 * qx/qy represents the quadrant location of the tile
				 */
				var tileLayerCol = [];
				var tile = {
					'element' : null,
					'posx' : 0,
					'posy' : 0,
					'xIndex' : c,
					'yIndex' : r,
					'LayerIdx' : 0,
					'qx' : c,
					'qy' : r
				};

				tileLayerCol.push(tile);
				
				if (transparentTiles) //ie7, ff we can have trans layer
				{
				    var tile2 = {
					    'element' : null,
					    'posx' : 0,
					    'posy' : 0,
					    'xIndex' : c,
					    'yIndex' : r,
					    'LayerIdx' : 1,
					    'qx' : c,
					    'qy' : r
				    };

                    tileLayerCol.push(tile2);
                }
				tileCol.push(tileLayerCol);
				
				
			}
		
			this.tiles.push(tileCol);
		}

        this.surface.onmousemove = GSIV.mouseMovedHandlerNoGrab;
		this.surface.onmousedown = GSIV.mousePressedHandler;
		this.surface.onmouseup = this.surface.onmouseout = GSIV.mouseReleasedHandler;
		this.surface.ondblclick = GSIV.doubleClickHandler;
		this.surface.onmousewheel = GSIV.mouseWheelHandler;
		if (window.addEventListener)
           this.surface.addEventListener('DOMMouseScroll', GSIV.mouseWheelHandler, false); /** DOMMouseScroll is for mozilla. */

		
		//this.surface.oncontextmenu = "function() {alert(1); return false;};"
		//this.surface.onclick = GSIV.clickHandler;
		if (GSIV.USE_KEYBOARD) {
			window.onkeypress = GSIV.keyboardMoveHandler;
			window.onkeydown = GSIV.keyboardZoomHandler;
		}

		this.positionTiles();
	},

	/**
	 * Position the tiles based on the x, y coordinates of the
	 * viewer, taking into account the motion offsets, which
	 * are calculated by a motion event handler.
	 */
	positionTiles : function(motion, reset) {
		// default to no motion, just setup tiles
		if (typeof motion == 'undefined') {
			motion = { 'x' : 0, 'y' : 0 };
		}

		for (var c = 0; c < this.tiles.length; c++) {
			for (var r = 0; r < this.tiles[c].length; r++) {
			for (var l = 0; l < this.tiles[c][r].length; l++) {
				var tile =      this.tiles[c][r][l];

				tile.posx = (tile.xIndex * this.tileSize) + this.x + motion.x;
				tile.posy = (tile.yIndex * this.tileSize) + this.y + motion.y;

				var visible = true;

				if (tile.posx > this.width) {
					// tile moved out of view to the right
					// consider the tile coming into view from the left
					do {
						tile.xIndex -= this.tiles.length;
						tile.posx = (tile.xIndex * this.tileSize) + this.x + motion.x;
					} while (tile.posx > this.width);

					if (tile.posx + this.tileSize < 0) {
						visible = false;
					}

				} else {
					// tile may have moved out of view from the left
					// if so, consider the tile coming into view from the right
					while (tile.posx < -this.tileSize) {
						tile.xIndex += this.tiles.length;
						tile.posx = (tile.xIndex * this.tileSize) + this.x + motion.x;
					}

					if (tile.posx > this.width) {
						visible = false;
					}
				}

				if (tile.posy > this.height) {
					// tile moved out of view to the bottom
					// consider the tile coming into view from the top
					do {
						tile.yIndex -= this.tiles[c].length;
						tile.posy = (tile.yIndex * this.tileSize) + this.y + motion.y;
					} while (tile.posy > this.height);

					if (tile.posy + this.tileSize < 0) {
						visible = false;
					}

				} else {
					// tile may have moved out of view to the top
					// if so, consider the tile coming into view from the bottom
					while (tile.posy < -this.tileSize) {
						tile.yIndex += this.tiles[c].length;
						tile.posy = (tile.yIndex * this.tileSize) + this.y + motion.y;
					}

					if (tile.posy > this.height) {
						visible = false;
					}
				}

				// initialize the image object for this quadrant
				if (!this.initialized) {
					this.assignTileImage(tile, true);
					/*if (tile.LayerIdx == 1)
					    tile.element.style.zIndex = '100';*/
					    
					tile.element.style.top = tile.posy + 'px';
					tile.element.style.left = tile.posx + 'px';
				}

				// display the image if visible
				if (visible) {
					this.assignTileImage(tile);
				}

				// seems to need this no matter what
				tile.element.style.top = tile.posy + 'px';
				tile.element.style.left = tile.posx + 'px';
			}}
		}

		// reset the x, y coordinates of the viewer according to motion
		if (reset) {
			this.x += motion.x;
			this.y += motion.y;
			this.currentX = this.x;
			this.currentY = this.y;
		}
		else
		{
		    this.currentX = this.x + motion.x;
		    this.currentY = this.y + motion.y;
		}
		
		
		
	},

	/**
	 * Determine the source image of the specified tile based
	 * on the zoom level and position of the tile.  If forceBlankImage
	 * is specified, the source should be automatically set to the
	 * null tile image.  This method will also setup an onload
	 * routine, delaying the appearance of the tile until it is fully
	 * loaded, if configured to do so.
	 */
	assignTileImage : function(tile, forceBlankImage) {
		var tileImgId, src;
		var useBlankImage = (forceBlankImage ? true : false);

		// check if image has been scrolled too far in any particular direction
		// and if so, use the null tile image
		if (!useBlankImage) {
			var left = tile.xIndex < 0;
			var high = tile.yIndex < 0;
			var right = tile.xIndex >= Math.pow(2, this.zoomLevel);
			var low = tile.yIndex >= Math.pow(2, this.zoomLevel);
			if (high || left || low || right) {
				useBlankImage = true;
			}
		}

		if (useBlankImage) {
			tileImgId = 'blank:' + tile.qx + ':' + tile.qy + ':' + tile.LayerIdx;
			src = this.cache['blank'].src;
		} else {
		    if (tile.LayerIdx == 1 && (trajekt == false && icons == "0" && MapPath.RouteID == "" || transparentTiles == false))
		    {
		        //empty transparent layer
		        tileImgId = 'blank:' + tile.qx + ':' + tile.qy + ':' + tile.LayerIdx;
			    src = this.cache['blank'].src;
		    }
		    else
		        tileImgId = src = this.tileUrlProvider.assembleUrl(tile.xIndex, tile.yIndex, this.zoomLevel, tile.LayerIdx);
		}

		// only remove tile if identity is changing
		if (tile.element != null &&
			tile.element.parentNode != null &&
			tile.element.relativeSrc != src) {
			this.well.removeChild(tile.element);
		}

		var tileImg = this.cache[tileImgId];
		// create cache if not exist
		if (tileImg == null) {
			tileImg = this.cache[tileImgId] = this.createPrototype(src, tile.LayerIdx);
		}
                                                    
		if (useBlankImage || !GSIV.USE_LOADER_IMAGE || tileImg.complete || (tileImg.image && tileImg.image.complete)) {
			tileImg.onload = function() {};
			if (tileImg.image) {
				tileImg.image.onload = function() {};
			}

			if (tileImg.parentNode == null) {
				tile.element = this.well.appendChild(tileImg);
			}
		}
		else {
			var loadingImgId = 'loading:' + tile.qx + ':' + tile.qy + ':' + tile.LayerIdx;
			var loadingImg = this.cache[loadingImgId];
			if (loadingImg == null) {
				loadingImg = this.cache[loadingImgId] = this.createPrototype(this.cache['loading'].src, tile.LayerIdx);
			}

			loadingImg.targetSrc = tileImgId;

			var well = this.well;
			tile.element = well.appendChild(loadingImg);
			tileImg.onload = function() {
				// make sure our destination is still present
				if (loadingImg.parentNode && loadingImg.targetSrc == tileImgId) {
					tileImg.style.top = loadingImg.style.top;
					tileImg.style.left = loadingImg.style.left;
					well.replaceChild(tileImg, loadingImg);
					tile.element = tileImg;
				}

				tileImg.onload = function() {};
				return false;
			}

			// konqueror only recognizes the onload event on an Image
			// javascript object, so we must handle that case here
			if (!GSIV.DOM_ONLOAD) {
				tileImg.image = new Image();
				tileImg.image.onload = tileImg.onload;
				tileImg.image.src = tileImg.src;
			}
		}
	},

	createPrototype : function(src, layer) {
		var img = document.createElement('img');
		img.src = src;
		//img.relativeSrc = src;
		img.className = GSIV.TILE_STYLE_CLASS;
		img.style.width = this.tileSize + 'px';
		img.style.height = this.tileSize + 'px';
		/*
		//tooo slow use just one transparent layer
		if (layer == 1 && src != this.cache['blank'].src)
		{
		    img.src = this.cache['blank'].src;
		    img.relativeSrc = this.cache['blank'].src;
		   // runtimeStyle (better?) style
		    img.runtimeStyle.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+src+"', sizingMethod='scale', enabled='true')" ;
		}*/
		return img;
	},

	addViewerMovedListener : function(listener) {
		this.viewerMovedListeners.push(listener);
	},
	
	addViewerMoveStopedListener : function(listener) {
		this.viewerMoveStopedListeners.push(listener);
	},

	addViewerZoomedListener : function(listener) {
		this.viewerZoomedListeners.push(listener);
	},

	/**
	 * Notify listeners of a zoom event on the viewer.
	 */
	notifyViewerZoomed : function() {
		var percentage = (100/(this.maxZoomLevel + 1)) * (this.zoomLevel + 1);
		for (var i = 0; i < this.viewerZoomedListeners.length; i++) {
			this.viewerZoomedListeners[i].viewerZoomed(
				new GSIV.ZoomEvent(this.x, this.y, this.zoomLevel, percentage)
			);
		}
	},

	/**
	 * Notify listeners of a move event on the viewer.
	 */
	notifyViewerMoved : function(coords) {
		if (typeof coords == 'undefined') {
			coords = { 'x' : 0, 'y' : 0 };
		}

		for (var i = 0; i < this.viewerMovedListeners.length; i++) {
			this.viewerMovedListeners[i].viewerMoved(
				new GSIV.MoveEvent(
					this.x + (coords.x - this.mark.x),
					this.y + (coords.y - this.mark.y)
				)
			);
		}
	},
	
	/**
	 * Notify listeners of a move event on the viewer.
	 */
	notifyViewerMoveStoped : function(coords) {
		if (typeof coords == 'undefined') {
			coords = { 'x' : 0, 'y' : 0 };
		}

		for (var i = 0; i < this.viewerMoveStopedListeners.length; i++) {
			this.viewerMoveStopedListeners[i].viewerMoveStoped(
				new GSIV.MoveEvent(
					this.x + (coords.x - this.mark.x),
					this.y + (coords.y - this.mark.y)
				)
			);
		}
	},

	zoom : function(direction) {
		// ensure we are not zooming out of range
		if (this.zoomLevel + direction < 0) {
			direction = 0 - this.zoomLevel;
			if (this.zoomLevel == 0)
			{
			    alert(GSIV.MSG_BEYOND_MIN_ZOOM);
			    return;
			}
		}
		else if (this.zoomLevel + direction > this.maxZoomLevel) {
			direction = this.maxZoomLevel - this.zoomLevel;
			if (this.maxZoomLevel == this.zoomLevel)
			{
			    alert(GSIV.MSG_BEYOND_MAX_ZOOM);
			    return;
			}
		}

		this.blank();

		var coords = { 'x' : Math.floor(this.width / 2), 'y' : Math.floor(this.height / 2) };

		var before = {
			'x' : (coords.x - this.x),
			'y' : (coords.y - this.y)
		};

		var after = {
			'x' : Math.floor(before.x * Math.pow(2, direction)),
			'y' : Math.floor(before.y * Math.pow(2, direction))
		};

		this.x = coords.x - after.x;
		this.y = coords.y - after.y;
		this.zoomLevel += direction;
		this.positionTiles();

		this.notifyViewerZoomed();
	},

	/** 
	 * Clear all the tiles from the well for a complete reinitialization of the
	 * viewer. At this point the viewer is not considered to be initialized.
	 */
	clear : function() {
		this.blank();
		this.initialized = false;
		this.tiles = [];
	},

	/**
	 * Remove all tiles from the well, which effectively "hides"
	 * them for a repaint.
	 */
	blank : function() {
		for (imgId in this.cache) {
			var img = this.cache[imgId];
			img.onload = function() {};
			if (img.image) {
				img.image.onload = function() {};
			}

			if (img.parentNode != null) {
				this.well.removeChild(img);
			}
		}
	},

	/**
	 * Method specifically for handling a mouse move event.  A direct
	 * movement of the viewer can be achieved by calling positionTiles() directly.
	 */
	moveViewer : function(coords) {
		this.positionTiles({ 'x' : (coords.x - this.mark.x), 'y' : (coords.y - this.mark.y) });
		this.notifyViewerMoved(coords);
	},

	/**
	 * Make the specified coords the new center of the image placement.
	 * This method is typically triggered as the result of a double-click
	 * event.  The calculation considers the distance between the center
	 * of the viewable area and the specified (viewer-relative) coordinates.
	 * If absolute is specified, treat the point as relative to the entire
	 * image, rather than only the viewable portion.
	 */
	recenter : function(coords, absolute) {
		if (absolute) {
			coords.x += this.x;
			coords.y += this.y;
		}

		var motion = {
			'x' : Math.floor((this.width / 2) - coords.x),
			'y' : Math.floor((this.height / 2) - coords.y)
		};

		if (motion.x == 0 && motion.y == 0) {
		    this.notifyViewerMoveStoped();
			return;
		}

		if (GSIV.USE_SLIDE) {
			var target = motion;
			var x, y;
			// handle special case of vertical movement
			if (target.x == 0) {
				x = 0;
				y = this.slideAcceleration;
			}
			else {
				var slope = Math.abs(target.y / target.x);
				x = Math.round(Math.pow(Math.pow(this.slideAcceleration, 2) / (1 + Math.pow(slope, 2)), .5));
				y = Math.round(slope * x);
			}
			
			motion = {
				'x' : Math.min(x, Math.abs(target.x)) * (target.x < 0 ? -1 : 1),
				'y' : Math.min(y, Math.abs(target.y)) * (target.y < 0 ? -1 : 1)
			}
		}

		this.positionTiles(motion, true);
		this.notifyViewerMoved();

		if (!GSIV.USE_SLIDE) {
			return;
		}

		var newcoords = {
			'x' : coords.x + motion.x,
			'y' : coords.y + motion.y
		};

		var self = this;
		// TODO: use an exponential growth rather than linear (should also depend on how far we are going)
		// FIXME: this could be optimized by calling positionTiles directly perhaps
		this.slideAcceleration += GSIV.SLIDE_ACCELERATION_FACTOR;
		this.slideMonitor = setTimeout(function() { self.recenter(newcoords); }, GSIV.SLIDE_DELAY );
	},

	resize : function() {
		// IE fires a premature resize event
		if (!this.initialized) {
			return;
		}

		this.viewer.style.display = 'none';
		this.clear();

		var before = {
			'x' : Math.floor(this.width / 2),
			'y' : Math.floor(this.height / 2)
		};

		if (this.border >= 0) {
			this.fitToWindow(this.border);
		}
		
		this.prepareTiles();

		var after = {
			'x' : Math.floor(this.width / 2),
			'y' : Math.floor(this.height / 2)
		};

		this.x += (after.x - before.x);
		this.y += (after.y - before.y);
		this.positionTiles();
		this.viewer.style.display = '';
		this.initialized = true;
		this.notifyViewerMoved();
	},

	/**
	 * Resolve the coordinates from this mouse event by subtracting the
	 * offset of the viewer in the browser window (or frame).  This does
	 * take into account the scroll offset of the page.
	 */
	resolveCoordinates : function(e) {
		return {
			'x': ((e.pageX || (e.clientX + (document.documentElement.scrollLeft || document.body.scrollLeft))) - this.left)/* + (maximized ? 380 : 0)*/,    // hardcoded corrections when maximized
			'y': ((e.pageY || (e.clientY + (document.documentElement.scrollTop || document.body.scrollTop))) - this.top)/* + (maximized ? 403 : 0)*/
		}
	},

	press : function(coords) {
		this.activate(true);
		this.mark = coords;
	},

	release : function(coords) {
		this.activate(false);
		var motion = {
			'x' : (coords.x - this.mark.x),
			'y' : (coords.y - this.mark.y)
		};

		this.x += motion.x;
		this.y += motion.y;
		this.mark = { 'x' : 0, 'y' : 0 };
		    
        this.positionTiles({'x': 0,'y': 0}, true);	 //bugfixDD
        this.notifyViewerMoved();
		this.notifyViewerMoveStoped();
	},
	
	moveToPosition : function(xc, yc, zoom2, disableSlide) {
	
	    if (zoom2 < 0) {
			alert(GSIV.MSG_BEYOND_MIN_ZOOM);
			zoom2 = 0;
			//return;
		}
		else if (zoom2 > this.maxZoomLevel) {
			alert(GSIV.MSG_BEYOND_MAX_ZOOM);
			zoom2 = this.maxZoomLevel;
			//return;
		}
		
		this.zoomLevel = zoom2;
		this.notifyViewerZoomed();
		
	    var unit = GSIV.WORLDUNITCONST * Math.pow(2,12 - this.zoomLevel);
	    var xInd = (xc - GSIV.WORLD_X_OFFSET)/unit;
	    var yInd = (GSIV.WORLD_Y_OFFSET - yc)/unit;
	 
    	var slideOld = GSIV.USE_SLIDE;

    	if (/*this.zoomLevel > 5 || */disableSlide)
    	    GSIV.USE_SLIDE = false;
	    
	    this.recenter({'x': xInd * this.tileSize, 'y': yInd * this.tileSize}, true);
	    
	    GSIV.USE_SLIDE = slideOld;
	},

    getCenterWorldCoord : function() {
        var xc = (this.x*(-1)) + this.width/2;
        var yc = (this.y*(-1)) + this.height/2;
        
        var a = this.getWorldCoord(xc, yc);
        //window.status = a.x + " - " + a.y + " - " + " - " + a.cx + " - " + a.cy;
        return a;
    },
    
    getCurrentWorldCoord : function(xc, yc) {
        var xc = (this.x*(-1)) + xc;
        var yc = (this.y*(-1)) + yc;
        
        var a = this.getWorldCoord(xc, yc);
        //window.status = a.x + " - " + a.y + " - " + " - " + a.cx + " - " + a.cy;
        return a;
    },
    
    getWorldCoord : function(xc, yc) {
        var unit = GSIV.WORLDUNITCONST * Math.pow(2,12 - this.zoomLevel);
       
	    var wx = Math.round( (xc/this.tileSize)*unit + GSIV.WORLD_X_OFFSET);
	    var wy = GSIV.WORLD_Y_OFFSET - Math.round((yc/this.tileSize)*unit);
	 
    	return {'x': wx, 'y': wy, 'cx': xc, 'cy' : yc};
	},
	
	getImageCoord : function(xc, yc) {
	    var unit = GSIV.WORLDUNITCONST * Math.pow(2,12 - this.zoomLevel);
       
        var x = Math.round( this.tileSize * (xc - GSIV.WORLD_X_OFFSET) / unit);
        var y = Math.round((GSIV.WORLD_Y_OFFSET - yc) * this.tileSize / unit);
	
    	return {'x': x, 'y': y, 'cx': xc, 'cy' : yc};
	},
	
	getScreenCoord : function(xc, yc) {
	    var a = this.getImageCoord(xc, yc);
	    //not finished yet
	    var x = (this.x) + a.x;
        var y = (this.y) + a.y;
	
    	return {'x': x, 'y': y, 'cx': xc, 'cy' : yc};
	},
	
	

	/**
	 * Activate the viewer into motion depending on whether the mouse is pressed or
	 * not pressed.  This method localizes the changes that must be made to the
	 * layers.
	 */
	activate : function(pressed) {
		this.pressed = pressed;
		this.surface.style.cursor = (pressed ? GSIV.GRABBING_MOUSE_CURSOR : GSIV.GRAB_MOUSE_CURSOR);
		this.surface.onmousemove = (pressed ? GSIV.mouseMovedHandler : GSIV.mouseMovedHandlerNoGrab);
	},

	/**
	 * Check whether the specified point exceeds the boundaries of
	 * the viewer's primary image.
	 */
	pointExceedsBoundaries : function(coords) {
	    return false;
		return (coords.x < this.x ||
			coords.y < this.y ||
			coords.x > (this.tileSize * Math.pow(2, this.zoomLevel) + this.x) ||
			coords.y > (this.tileSize * Math.pow(2, this.zoomLevel) + this.y));
	},

	// QUESTION: where is the best place for this method to be invoked?
	resetSlideMotion : function() {
		if (this.slideMonitor != 0) {
			clearTimeout(this.slideMonitor);
			this.slideMonitor = 0;
		}

		this.slideAcceleration = 0;
	}
	
};

GSIV.TileUrlProvider = function(baseUri, prefix, extension) {
	this.baseUri = baseUri;
	this.prefix = prefix;
	this.extension = extension;
}

GSIV.TileUrlProvider.prototype = {
    assembleUrl: function(xIndex, yIndex, zoom, layer) {
        var curZoom = 1000 * Math.pow(2, 12 - zoom);

        var unit = GSIV.WORLDUNITCONST * Math.pow(2, 12 - zoom);
        var x = Math.round((xIndex * unit + (xIndex + 1) * unit) / 2) + GSIV.WORLD_X_OFFSET;
        var y = GSIV.WORLD_Y_OFFSET - Math.round((yIndex * unit + (yIndex + 1) * unit) / 2);

        var params = "zoom=" + curZoom + "&x=" + x + "&y=" + y + "&size=" + 256;

        if (layer != 1 && layer != '1') {
            //layer 0 --> map
            params += "&theme=" + theme + "S:Tile" + "&xIdx=" + xIndex + "&yIdx=" + yIndex + "&zoomIdx=" + zoom;
        } else {
            //layer 1 --> additional stuff: trajekt, path,...
            params += "&theme=TransparentViewS:Tile&icon=" + icons + "&RouteID=" + MapPath.RouteID;
            if (trajekt)
                params += "&t=1";
        }

        var address = pirsApplicationPath + "GetMap.ashx?" + "type=map&" + params;

        /*	var address="";
        //	if ((xIndex + yIndex) % 2 == 0)
        address="GetMap.ashx?" + "type=map&"+params;
        //	else
        //	    address= secondMapUrl + "GetMap.ashx?" + "type=map&"+params;*/


        return address;
        /*return this.baseUri + '/' +
        this.prefix + zoom + '-' + xIndex + '-' + yIndex + '.' + this.extension +
        (GSIV.REVISION_FLAG ? '?r=' + GSIV.REVISION_FLAG : '');*/
    }
}

GSIV.mousePressedHandler = function(e) {
	e = e ? e : window.event;
	// only grab on left-click
	if (e.button < 2) {
		var self = this.backingBean;
		var coords = self.resolveCoordinates(e);
		if (self.pointExceedsBoundaries(coords)) {
			e.cancelBubble = true;
		}
		else {
			self.press(coords);
		}
	}
	
	// NOTE: MANDATORY! must return false so event does not propagate to well!
	e.returnValue = false; 
    e.cancelBubble = true;
	return false;
};

disableScroll = true;
GSIV.disableScroll = true;
this.disableScroll = true;

GSIV.mouseWheelHandler = function(e) {
    e = e ? e : window.event;
    if (disableScroll == true) {
        return;
    }
    delta = 0;
    if (e.wheelDelta) { /* IE/Opera. */
        delta = e.wheelDelta / 120;
        /** In Opera 9, delta differs in sign as compared to IE.
        */
        if (window.opera)
            delta = -delta;
    } else if (e.detail) { /** Mozilla case. */
        /** In Mozilla, sign of delta is different than in IE.
        * Also, delta is multiple of 3.
        */
        delta = -e.detail / 3;
    }
    /** If delta is nonzero, handle it.
    * Basically, delta is now positive if wheel was scrolled up,
    * and negative, if wheel was scrolled down.
    */
    if (delta) {
        var self = this.backingBean;
        if (delta < 0)
            self.zoom(getZoomStep(-1));
        else
            self.zoom(getZoomStep(1));
    }

    /** Prevent default actions caused by mouse wheel.
    * That might be ugly, but we handle scrolls somehow
    * anyway, so don't bother here..
    */
    if (e.preventDefault)
        e.preventDefault();
    e.returnValue = false;
};

GSIV.mouseReleasedHandler = function(e) {
    e = e ? e : window.event;

    var self = this.backingBean;
    if (self.pressed) {
        disableScroll = false;
        // OPTION: could decide to move viewer only on release, right here
        var coord = self.resolveCoordinates(e);
        if ((self.mark.x == coord.x && self.mark.y == coord.y) || e.button >= 2) {
            //only click

            if (e.button == 4) {
                hideContextMenu();
                var slideOld = GSIV.USE_SLIDE;
                GSIV.USE_SLIDE = false;
                self.recenter(self.resolveCoordinates(e));
                GSIV.USE_SLIDE = slideOld;
                self.zoom(getZoomStep(-1));

            }
            else if (e.button >= 2) {

                //  var self = this.backingBean;
                //  self.zoom(getZoomStep(-1));
                e.returnValue = false;
                e.cancelBubble = true;
                showContextMenu(coord, e);
                return false;
            }
            else {
                hideContextMenu();
                var slideOld = GSIV.USE_SLIDE;
                GSIV.USE_SLIDE = false;
                self.recenter(self.resolveCoordinates(e));
                GSIV.USE_SLIDE = slideOld;
                self.zoom(getZoomStep(1));
            }
        }
        self.release(coord);
    }
    else {
        if (e.button == 4) {
            hideContextMenu();
            var slideOld = GSIV.USE_SLIDE;
            GSIV.USE_SLIDE = false;
            self.recenter(self.resolveCoordinates(e));
            GSIV.USE_SLIDE = slideOld;
            self.zoom(getZoomStep(-1));

        }
        else if (e.button >= 2) {
            var coord = self.resolveCoordinates(e);
            //    var self = this.backingBean;
            //    self.zoom(getZoomStep(-1));
            e.returnValue = false;
            e.cancelBubble = true;
            showContextMenu(coord, e);
            return false;
        }
    }

    e.returnValue = false;
    e.cancelBubble = true;
    return false;
};

GSIV.mouseMovedHandler = function(e) {
	e = e ? e : window.event;
	var self = this.backingBean;
	self.moveCount++;
	if (self.moveCount % GSIV.MOVE_THROTTLE == 0) {
		self.moveViewer(self.resolveCoordinates(e));
	}
};

GSIV.mouseMovedHandlerNoGrab = function(e) {
	e = e ? e : window.event;
	var self = this.backingBean;
	
    var mc = self.resolveCoordinates(e);
    checkIconPosition(mc.x, mc.y);
};

GSIV.zoomInHandler = function(e) {
	e = e ? e : window.event;
	var self = this.parentNode.parentNode.parentNode.backingBean;
	self.zoom(getZoomStep(1));
	return false;
};

GSIV.zoomOutHandler = function(e) {
	e = e ? e : window.event;
	var self = this.parentNode.parentNode.parentNode.backingBean;
	self.zoom(getZoomStep(-1));
	return false;
};

GSIV.doubleClickHandler = function(e) {
	e = e ? e : window.event;
	var self = this.backingBean;
	coords = self.resolveCoordinates(e);
	if (!self.pointExceedsBoundaries(coords)) {
		self.resetSlideMotion();
		self.recenter(coords);
	}
};

GSIV.clickHandler = function(e) {
	e = e ? e : window.event;
	var self = this.backingBean;
	coords = self.resolveCoordinates(e);
	if (!self.pointExceedsBoundaries(coords)) {
		//self.resetSlideMotion();
		//self.recenter(coords);
		//setTimeout(function() { self.zoom(getZoomStep(1)); }, 2000 );
		/*
		var slideOld = GSIV.USE_SLIDE;
		GSIV.USE_SLIDE = false;
	    self.recenter(coords);
	    GSIV.USE_SLIDE = slideOld;
		self.zoom(getZoomStep(1));*/
	}
	return false;
};

GSIV.keyboardMoveHandler = function(e) {
	e = e ? e : window.event;
	for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
		if (e.keyCode == 38)
		{
				viewer.positionTiles({'x': 0,'y': GSIV.MOVE_THROTTLE}, true);
				viewer.notifyViewerMoved();
	    }
		if (e.keyCode == 39)
		{
				viewer.positionTiles({'x': -GSIV.MOVE_THROTTLE,'y': 0}, true);
				viewer.notifyViewerMoved();
		}
		if (e.keyCode == 40)
		{
				viewer.positionTiles({'x': 0,'y': -GSIV.MOVE_THROTTLE}, true);
				viewer.notifyViewerMoved();
		}
		if (e.keyCode == 37)
		{
				viewer.positionTiles({'x': GSIV.MOVE_THROTTLE,'y': 0}, true);
				viewer.notifyViewerMoved();
		}
	}
}

GSIV.moveDownHandler = function(e) {
	e = e ? e : window.event;
	for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
		viewer.positionTiles({'x': 0,'y': -GSIV.MOVE_THROTTLE}, true);
		viewer.notifyViewerMoved();
		//viewer.notifyViewerMoveStoped();
	}
}

GSIV.moveUpHandler = function(e) {
	e = e ? e : window.event;
	for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
		viewer.positionTiles({'x': 0,'y': GSIV.MOVE_THROTTLE}, true);
		viewer.notifyViewerMoved();
		//viewer.notifyViewerMoveStoped();
	}
}

GSIV.moveLeftHandler = function(e) {
	e = e ? e : window.event;
	for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
		viewer.positionTiles({'x': GSIV.MOVE_THROTTLE,'y': 0}, true);
		viewer.notifyViewerMoved();
		//viewer.notifyViewerMoveStoped();
	}
}

GSIV.moveRightHandler = function(e) {
	e = e ? e : window.event;
	for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
		viewer.positionTiles({'x': -GSIV.MOVE_THROTTLE,'y': 0}, true);
		viewer.notifyViewerMoved();
		//viewer.notifyViewerMoveStoped();
	}
}

GSIV.moveRightSlideHandler = function(e) {
   
    for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
	    viewer.resetSlideMotion();
	    viewer.recenter({'x': viewer.width, 'y':viewer.height/2});
	}
}

GSIV.moveLeftSlideHandler = function(e) {
    for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
	    viewer.resetSlideMotion();
	    viewer.recenter({'x': 0, 'y':viewer.height/2});
	}
}

GSIV.moveUpSlideHandler = function(e) {
    for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
	    viewer.resetSlideMotion();
	    viewer.recenter({'x': viewer.width/2, 'y':0});
	}
}

GSIV.moveDownSlideHandler = function(e) {
    for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
	    viewer.resetSlideMotion();
	    viewer.recenter({'x': viewer.width/2, 'y':viewer.height});
	}
}

GSIV.moveDefaultPosHandler = function(e) {
    for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
		
		var slideOld = GSIV.USE_SLIDE;
        
       // if (viewer.zoomLevel > 4)
            GSIV.USE_SLIDE = false;
        
    	viewer.zoomLevel = 1
    	viewer.notifyViewerZoomed();
    	viewer.recenter({'x': 256, 'y':256}, true);

	    GSIV.USE_SLIDE = slideOld;

	    viewer.notifyViewerMoveStoped();
	}
}

GSIV.keyboardZoomHandler = function(e) {
	e = e ? e : window.event;
	for (var i = 0; i < GSIV.VIEWERS.length; i++) {
		var viewer = GSIV.VIEWERS[i];
		if (e.keyCode == 109)
				viewer.zoom(getZoomStep(-1));
		if (e.keyCode == 107)
				viewer.zoom(getZoomStep(1));
	}
}

GSIV.MoveEvent = function(x, y) {
	this.x = x;
	this.y = y;
};

GSIV.ZoomEvent = function(x, y, level, percentage) {
	this.x = x;
	this.y = y;
	this.percentage = percentage;
	this.level = level;
};