/* Copyright (c) 2006 Kelvin Luck (kelvin AT kelvinluck DOT com || http://www.kelvinluck.com)

 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php) 

 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.

 * 

 * See http://kelvinluck.com/assets/jquery/jScrollPane/

 * $Id: jScrollPane.js 24 2008-11-29 07:08:14Z kelvin.luck $

 */



/**

 * Replace the vertical scroll bars on any matched elements with a fancy

 * styleable (via CSS) version. With JS disabled the elements will

 * gracefully degrade to the browsers own implementation of overflow:auto.

 * If the mousewheel plugin has been included on the page then the scrollable areas will also

 * respond to the mouse wheel.

 *

 * @example jQuery(".scroll-pane").jScrollPane();

 *

 * @name jScrollPane

 * @type jQuery

 * @param Object	settings	hash with options, described below.

 *								scrollbarWidth	-	The width of the generated scrollbar in pixels

 *								scrollbarMargin	-	The amount of space to leave on the side of the scrollbar in pixels

 *								wheelSpeed		-	The speed the pane will scroll in response to the mouse wheel in pixels

 *								showArrows		-	Whether to display arrows for the user to scroll with

 *								arrowSize		-	The height of the arrow buttons if showArrows=true

 *								animateTo		-	Whether to animate when calling scrollTo and scrollBy

 *								dragMinHeight	-	The minimum height to allow the drag bar to be

 *								dragMaxHeight	-	The maximum height to allow the drag bar to be

 *								animateInterval	-	The interval in milliseconds to update an animating scrollPane (default 100)

 *								animateStep		-	The amount to divide the remaining scroll distance by when animating (default 3)

 *								maintainPosition-	Whether you want the contents of the scroll pane to maintain it's position when you re-initialise it - so it doesn't scroll as you add more content (default true)

 *								scrollbarOnLeft	-	Display the scrollbar on the left side?  (needs stylesheet changes, see examples.html)

 *								reinitialiseOnImageLoad - Whether the jScrollPane should automatically re-initialise itself when any contained images are loaded

 * @return jQuery

 * @cat Plugins/jScrollPane

 * @author Kelvin Luck (kelvin AT kelvinluck DOT com || http://www.kelvinluck.com)

 */



(function($) {



$.jScrollPane = {

	active : []

};

$.fn.jScrollPane = function(settings)

{

	settings = $.extend({}, $.fn.jScrollPane.defaults, settings);



	var rf = function() { return false; };

	

	return this.each(

		function()

		{

			var $this = $(this);

			// Switch the element's overflow to hidden to ensure we get the size of the element without the scrollbars [http://plugins.jquery.com/node/1208]

			$this.css('overflow', 'hidden');

			var paneEle = this;

			

			if ($(this).parent().is('.jScrollPaneContainer')) {

				var currentScrollPosition = settings.maintainPosition ? $this.offset({relativeTo:$(this).parent()[0]}).top : 0;

				var $c = $(this).parent();

				var paneWidth = $c.innerWidth();

				var paneHeight = $c.outerHeight();

				var trackHeight = paneHeight;

				$('>.jScrollPaneTrack, >.jScrollArrowUp, >.jScrollArrowDown', $c).remove();

				$this.css({'top':0});

			} else {

				var currentScrollPosition = 0;

				this.originalPadding = $this.css('paddingTop') + ' ' + $this.css('paddingRight') + ' ' + $this.css('paddingBottom') + ' ' + $this.css('paddingLeft');

				this.originalSidePaddingTotal = (parseInt($this.css('paddingLeft')) || 0) + (parseInt($this.css('paddingRight')) || 0);

				var paneWidth = $this.innerWidth();

				var paneHeight = $this.innerHeight();

				var trackHeight = paneHeight;

				$this.wrap(

					$('<div></div>').attr(

						{'className':'jScrollPaneContainer'}

					).css(

						{

							'height':paneHeight+'px', 

							'width':paneWidth+'px'

						}

					)

				);

				// deal with text size changes (if the jquery.em plugin is included)

				// and re-initialise the scrollPane so the track maintains the

				// correct size

				$(document).bind(

					'emchange', 

					function(e, cur, prev)

					{

						$this.jScrollPane(settings);

					}

				);

				

			}

			

			if (settings.reinitialiseOnImageLoad) {

				// code inspired by jquery.onImagesLoad: http://plugins.jquery.com/project/onImagesLoad

				// except we re-initialise the scroll pane when each image loads so that the scroll pane is always up to size...

				// TODO: Do I even need to store it in $.data? Is a local variable here the same since I don't pass the reinitialiseOnImageLoad when I re-initialise?

				var $imagesToLoad = $.data(paneEle, 'jScrollPaneImagesToLoad') || $('img', $this);

				var loadedImages = [];

				

				if ($imagesToLoad.length) {

					$imagesToLoad.each(function(i, val)	{

						$(this).bind('load', function() {

							if($.inArray(i, loadedImages) == -1){ //don't double count images

								loadedImages.push(val); //keep a record of images we've seen

								$imagesToLoad = $.grep($imagesToLoad, function(n, i) {

									return n != val;

								});

								$.data(paneEle, 'jScrollPaneImagesToLoad', $imagesToLoad);

								settings.reinitialiseOnImageLoad = false;

								$this.jScrollPane(settings); // re-initialise

							}

						}).each(function(i, val) {

							if(this.complete || this.complete===undefined) { 

								//needed for potential cached images

								this.src = this.src; 

							} 

						});

					});

				};

			}



			var p = this.originalSidePaddingTotal;

			

			var cssToApply = {

				'height':'auto',

				'width':paneWidth - settings.scrollbarWidth - settings.scrollbarMargin - p + 'px'

			}



			if(settings.scrollbarOnLeft) {

				cssToApply.paddingLeft = settings.scrollbarMargin + settings.scrollbarWidth + 'px';

			} else {

				cssToApply.paddingRight = settings.scrollbarMargin + 'px';

			}



			$this.css(cssToApply);



			var contentHeight = $this.outerHeight();

			var percentInView = paneHeight / contentHeight;



			if (percentInView < .99) {

				var $container = $this.parent();

				$container.append(

					$('<div></div>').attr({'className':'jScrollPaneTrack'}).css({'width':settings.scrollbarWidth+'px'}).append(

						$('<div></div>').attr({'className':'jScrollPaneDrag'}).css({'width':settings.scrollbarWidth+'px'}).append(

							$('<div></div>').attr({'className':'jScrollPaneDragTop'}).css({'width':settings.scrollbarWidth+'px'}),

							$('<div></div>').attr({'className':'jScrollPaneDragBottom'}).css({'width':settings.scrollbarWidth+'px'})

						)

					)

				);

				

				var $track = $('>.jScrollPaneTrack', $container);

				var $drag = $('.jScrollPaneDrag', $container);
				

				if (settings.showArrows) {

					

					var currentArrowButton;

					var currentArrowDirection;

					var currentArrowInterval;

					var currentArrowInc;

					var whileArrowButtonDown = function()

					{

						if (currentArrowInc > 4 || currentArrowInc%4==0) {

							positionDrag(dragPosition + currentArrowDirection * mouseWheelMultiplier);

						}

						currentArrowInc ++;

					};

					var onArrowMouseUp = function(event)

					{

						$('html').unbind('mouseup', onArrowMouseUp);

						currentArrowButton.removeClass('jScrollActiveArrowButton');

						clearInterval(currentArrowInterval);

					};

					var onArrowMouseDown = function() {

						$('html').bind('mouseup', onArrowMouseUp);

						currentArrowButton.addClass('jScrollActiveArrowButton');

						currentArrowInc = 0;

						whileArrowButtonDown();

						currentArrowInterval = setInterval(whileArrowButtonDown, 100);

					};

					$container

						.append(

							$('<a></a>')

								.attr({'href':'javascript:;', 'className':'jScrollArrowUp'})

								.css({'width':settings.scrollbarWidth+'px'})

								.html('Scroll up')

								.bind('mousedown', function()

								{

									currentArrowButton = $(this);

									currentArrowDirection = -1;

									onArrowMouseDown();

									this.blur();

									return false;

								})

								.bind('click', rf),

							$('<a></a>')

								.attr({'href':'javascript:;', 'className':'jScrollArrowDown'})

								.css({'width':settings.scrollbarWidth+'px'})

								.html('Scroll down')

								.bind('mousedown', function()

								{

									currentArrowButton = $(this);

									currentArrowDirection = 1;

									onArrowMouseDown();

									this.blur();

									return false;

								})

								.bind('click', rf)

						);

					var $upArrow = $('>.jScrollArrowUp', $container);

					var $downArrow = $('>.jScrollArrowDown', $container);

					if (settings.arrowSize) {

						trackHeight = paneHeight - settings.arrowSize - settings.arrowSize;

						$track

							.css({'height': trackHeight+'px', top:settings.arrowSize+'px'})

					} else {

						var topArrowHeight = $upArrow.height();

						settings.arrowSize = topArrowHeight;

						trackHeight = paneHeight - topArrowHeight - $downArrow.height();

						$track

							.css({'height': trackHeight+'px', top:topArrowHeight+'px'})

					}

				}

				

				var $pane = $(this).css({'position':'absolute', 'overflow':'visible'});

				

				var currentOffset;

				var maxY;

				var mouseWheelMultiplier;

				// store this in a seperate variable so we can keep track more accurately than just updating the css property..

				var dragPosition = 0;

				var dragMiddle = percentInView*paneHeight/2;

				

				// pos function borrowed from tooltip plugin and adapted...

				var getPos = function (event, c) {

					var p = c == 'X' ? 'Left' : 'Top';

					return event['page' + c] || (event['client' + c] + (document.documentElement['scroll' + p] || document.body['scroll' + p])) || 0;

				};

				

				var ignoreNativeDrag = function() {	return false; };

				

				var initDrag = function()

				{

					ceaseAnimation();

					currentOffset = $drag.offset(false);

					currentOffset.top -= dragPosition;

					maxY = trackHeight - $drag[0].offsetHeight;

					mouseWheelMultiplier = 2 * settings.wheelSpeed * maxY / contentHeight;

				};

				

				var onStartDrag = function(event)

				{

					initDrag();

					dragMiddle = getPos(event, 'Y') - dragPosition - currentOffset.top;

					$('html').bind('mouseup', onStopDrag).bind('mousemove', updateScroll);

					if ($.browser.msie) {

						$('html').bind('dragstart', ignoreNativeDrag).bind('selectstart', ignoreNativeDrag);

					}

					return false;

				};

				var onStopDrag = function()

				{

					$('html').unbind('mouseup', onStopDrag).unbind('mousemove', updateScroll);

					dragMiddle = percentInView*paneHeight/2;

					if ($.browser.msie) {

						$('html').unbind('dragstart', ignoreNativeDrag).unbind('selectstart', ignoreNativeDrag);

					}

				};

				var positionDrag = function(destY)

				{

					destY = destY < 0 ? 0 : (destY > maxY ? maxY : destY);

					dragPosition = destY;

					$drag.css({'top':destY+'px'});

					var p = destY / maxY;

					$pane.css({'top':((paneHeight-contentHeight)*p) + 'px'});

					$this.trigger('scroll');

					if (settings.showArrows) {

						$upArrow[destY == 0 ? 'addClass' : 'removeClass']('disabled');

						$downArrow[destY == maxY ? 'addClass' : 'removeClass']('disabled');

					}

				};

				var updateScroll = function(e)

				{

					positionDrag(getPos(e, 'Y') - currentOffset.top - dragMiddle);

				};

				

				var dragH = Math.max(Math.min(percentInView*(paneHeight-settings.arrowSize*2), settings.dragMaxHeight), settings.dragMinHeight);

				

				$drag.css(

					{'height':dragH+'px'}

				).bind('mousedown', onStartDrag);

				

				var trackScrollInterval;

				var trackScrollInc;

				var trackScrollMousePos;

				var doTrackScroll = function()

				{

					if (trackScrollInc > 8 || trackScrollInc%4==0) {

						positionDrag((dragPosition - ((dragPosition - trackScrollMousePos) / 2)));

					}

					trackScrollInc ++;

				};

				var onStopTrackClick = function()

				{

					clearInterval(trackScrollInterval);

					$('html').unbind('mouseup', onStopTrackClick).unbind('mousemove', onTrackMouseMove);

				};

				var onTrackMouseMove = function(event)

				{

					trackScrollMousePos = getPos(event, 'Y') - currentOffset.top - dragMiddle;

				};

				var onTrackClick = function(event)

				{

					initDrag();

					onTrackMouseMove(event);

					trackScrollInc = 0;

					$('html').bind('mouseup', onStopTrackClick).bind('mousemove', onTrackMouseMove);

					trackScrollInterval = setInterval(doTrackScroll, 100);

					doTrackScroll();

				};

				

				$track.bind('mousedown', onTrackClick);

				

				$container.bind(

					'mousewheel',

					function (event, delta) {

						initDrag();

						ceaseAnimation();

						var d = dragPosition;

						positionDrag(dragPosition - delta * mouseWheelMultiplier);

						var dragOccured = d != dragPosition;

						return !dragOccured;

					}

				);



				var _animateToPosition;

				var _animateToInterval;

				function animateToPosition()

				{

					var diff = (_animateToPosition - dragPosition) / settings.animateStep;

					if (diff > 1 || diff < -1) {

						positionDrag(dragPosition + diff);

					} else {

						positionDrag(_animateToPosition);

						ceaseAnimation();

					}

				}

				var ceaseAnimation = function()

				{

					if (_animateToInterval) {

						clearInterval(_animateToInterval);

						delete _animateToPosition;

					}

				};

				var scrollTo = function(pos, preventAni)

				{

					if (typeof pos == "string") {

						$e = $(pos, this);

						if (!$e.length) return;

						pos = $e.offset().top - $this.offset().top;

					}

					ceaseAnimation();

					var destDragPosition = -pos/(paneHeight-contentHeight) * maxY;

					if (preventAni || !settings.animateTo) {

						positionDrag(destDragPosition);

					} else {

						_animateToPosition = destDragPosition;

						_animateToInterval = setInterval(animateToPosition, settings.animateInterval);

					}

				};

				$this[0].scrollTo = scrollTo;

				

				$this[0].scrollBy = function(delta)

				{

					var currentPos = -parseInt($pane.css('top')) || 0;

					scrollTo(currentPos + delta);

				};

				

				initDrag();

				

				scrollTo(-currentScrollPosition, true);

			

				// Deal with it when the user tabs to a link or form element within this scrollpane

				$('*', this).bind(

					'focus',

					function(event)

					{

						var eleTop = $(this).position().top;

						var viewportTop = -parseInt($pane.css('top')) || 0;

						var maxVisibleEleTop = viewportTop + paneHeight;

						var eleInView = eleTop > viewportTop && eleTop < maxVisibleEleTop;

						if (!eleInView) {

							$container.scrollTop(0);

							var destPos = eleTop - settings.scrollbarMargin;

							if (eleTop > viewportTop) { // element is below viewport - scroll so it is at bottom.

								destPos += $(this).height() + 15+ settings.scrollbarMargin - paneHeight;

							}

							scrollTo(destPos);

						}

					}

				)

				

				

				if (location.hash) {

					// the timeout needs to be longer in IE when not loading from cache...

					setTimeout(function() {

						$(location.hash, $this).trigger('focus');

					}, $.browser.msie ? 100 : 0);

				}

				

				// use event delegation to listen for all clicks on links and hijack them if they are links to

				// anchors within our content...

				$(document).bind(

					'click',

					function(e)

					{

						$target = $(e.target);

						if ($target.is('a')) {

							var h = $target.attr('href');

							if (h.substr(0, 1) == '#') {

								$linkedEle = $(h, $this);

								if ($linkedEle.length) {

									$linkedEle.trigger('focus');

									return false;

								}

							}

						}

					}

				);

				

				$.jScrollPane.active.push($this[0]);

				

			} else {

				$this.css(

					{

						'height':paneHeight+'px',

						'width':paneWidth-this.originalSidePaddingTotal+'px',

						'padding':this.originalPadding

					}

				);

				// remove from active list?

			}

			

		}

	)

};



$.fn.jScrollPane.defaults = {

	scrollbarWidth : 525,

	scrollbarMargin : 5,

	wheelSpeed : 18,

	showArrows : false,

	arrowSize : 0,

	animateTo : false,

	dragMinHeight : 1,

	dragMaxHeight : 99999,

	animateInterval : 100,

	animateStep: 3,

	maintainPosition: true,

	scrollbarOnLeft: false,

	reinitialiseOnImageLoad: false

};



// clean up the scrollTo expandos

$(window)

	.bind('unload', function() {

		var els = $.jScrollPane.active; 

		for (var i=0; i<els.length; i++) {

			els[i].scrollTo = els[i].scrollBy = null;

		}

	}

);



})(jQuery);