root/galaxy-central/static/scripts/jquery.event.drag.js @ 2

/*! 
jquery.event.drag.js ~ v1.4 ~ Copyright (c) 2008, Three Dub Media (http://threedubmedia.com)  
Liscensed under the MIT License ~ http://threedubmedia.googlecode.com/files/MIT-LICENSE.txt
*/
;(function($){ // secure $ jQuery alias
/*******************************************************************************************/
// Created: 2008-06-04 | Updated: 2009-01-26
/*******************************************************************************************/
// Events: drag, dragstart, dragend
/*******************************************************************************************/

// jquery method
$.fn.drag = function( fn1, fn2, fn3 ){
        if ( fn2 ) this.bind('dragstart', fn1 ); // 2+ args
        if ( fn3 ) this.bind('dragend', fn3 ); // 3 args
        return !fn1 ? this.trigger('drag') // 0 args
                : this.bind('drag', fn2 ? fn2 : fn1 ); // 1+ args
        };

// local refs
var $event = $.event, $special = $event.special,

// special event configuration
drag = $special.drag = {
        not: ':input', // don't begin to drag on event.targets that match this selector
        distance: 0, // distance dragged before dragstart
        which: 1, // mouse button pressed to start drag sequence
        setup: function( data ){
                data = $.extend({ 
                        distance: drag.distance, 
                        which: drag.which, 
                        not: drag.not
                        }, data || {});
                data.distance = squared( data.distance ); //  xｲ + yｲ = distanceｲ
                $event.add( this, "mousedown", handler, data );
                },
        teardown: function(){
                $event.remove( this, "mousedown", handler );
                if ( this === drag.dragging ) drag.dragging = drag.proxy = null; // deactivate element
                selectable( this, true ); // enable text selection
                }
        };

// handle drag-releatd DOM events
function handler ( event ){ 
        var elem = this, returned, data = event.data || {};
        // mousemove or mouseup
        if ( data.elem ){ 
                // update event properties...
                elem = event.dragTarget = data.elem; // drag source element
                event.dragProxy = drag.proxy || elem; // proxy element or source
                event.cursorOffsetX = data.pageX - data.left; // mousedown offset
                event.cursorOffsetY = data.pageY - data.top; // mousedown offset
                event.offsetX = event.pageX - event.cursorOffsetX; // element offset
                event.offsetY = event.pageY - event.cursorOffsetY; // element offset
                }
        // mousedown, check some initial props to avoid the switch statement
        else if ( drag.dragging || ( data.which>0 && event.which!=data.which ) || 
                $( event.target ).is( data.not ) ) return;
        // handle various events
        switch ( event.type ){
                // mousedown, left click, event.target is not restricted, init dragging
                case 'mousedown':
                        $.extend( data, $( elem ).offset(), { 
                                elem: elem, target: event.target,
                                pageX: event.pageX, pageY: event.pageY
                                }); // store some initial attributes
                        $event.add( document, "mousemove mouseup", handler, data );
                        selectable( elem, false ); // disable text selection
                        return false; // prevents text selection in safari 
                // mousemove, check distance, start dragging
                case !drag.dragging && 'mousemove': 
                        if ( squared( event.pageX-data.pageX ) 
                                + squared( event.pageY-data.pageY ) //  xｲ + yｲ = distanceｲ
                                < data.distance ) break; // distance tolerance not reached
                        event.target = data.target; // force target from "mousedown" event (fix distance issue)
                        returned = hijack( event, "dragstart", elem ); // trigger "dragstart", return proxy element
                        if ( returned !== false ){ // "dragstart" not rejected
                                drag.dragging = elem; // activate element
                                drag.proxy = event.dragProxy = $( returned || elem )[0]; // set proxy
                                }
                // mousemove, dragging
                case 'mousemove': 
                        if ( drag.dragging ){
                                returned = hijack( event, "drag", elem ); // trigger "drag"             
                                if ( $special.drop ){ // manage drop events
                                        $special.drop.allowed = ( returned !== false ); // prevent drop
                                        $special.drop.handler( event ); // "dropstart", "dropend"
                                        }
                                if ( returned !== false ) break; // "drag" not rejected, stop           
                                event.type = "mouseup"; // helps "drop" handler behave
                                }
                // mouseup, stop dragging
                case 'mouseup': 
                        $event.remove( document, "mousemove mouseup", handler ); // remove page events
                        if ( drag.dragging ) {
                                if ( $special.drop ) $special.drop.handler( event ); // "drop"
                                hijack( event, "dragend", elem ); // trigger "dragend"  
                        } else {
                                hijack( event, "dragclickonly", elem );
                        }
                        selectable( elem, true ); // enable text selection
                        drag.dragging = drag.proxy = data.elem = null; // deactivate element
                        break;
                } 
        };

// set event type to custom value, and handle it
function hijack ( event, type, elem ){
        event.type = type; // force the event type
        var result = $event.handle.call( elem, event );
        return result===false ? false : result || event.result;
        };
        
// return the value squared     
function squared ( value ){ return Math.pow( value, 2 ); };
        
// toggles text selection attributes    
function selectable ( elem, bool ){ 
        if ( !elem ) return; // maybe element was removed ? 
        elem.unselectable = bool ? "off" : "on"; // IE
        elem.onselectstart = function(){ return bool; }; // IE
        if ( document.selection && document.selection.empty ) document.selection.empty(); // IE
        if ( elem.style ) elem.style.MozUserSelect = bool ? "" : "none"; // FF
        };      
        
/*******************************************************************************************/
})( jQuery ); // confine scope