The source code

    /*!
     * Ext JS Library 3.4.0
     * Copyright(c) 2006-2011 Sencha Inc.
     * licensing@sencha.com
     * http://www.sencha.com/license
     */
    /**
     * @class Ext.DataView
     * @extends Ext.BoxComponent
     * A mechanism for displaying data using custom layout templates and formatting. DataView uses an {@link Ext.XTemplate}
     * as its internal templating mechanism, and is bound to an {@link Ext.data.Store}
     * so that as the data in the store changes the view is automatically updated to reflect the changes.  The view also
     * provides built-in behavior for many common events that can occur for its contained items including click, doubleclick,
     * mouseover, mouseout, etc. as well as a built-in selection model. In order to use these features, an {@link #itemSelector}
     * config must be provided for the DataView to determine what nodes it will be working with.
     *
     * The example below binds a DataView to a {@link Ext.data.Store} and renders it into an {@link Ext.Panel}.
     *
    var store = new Ext.data.JsonStore({
        url: 'get-images.php',
        root: 'images',
        fields: [
            'name', 'url',
            {name:'size', type: 'float'},
            {name:'lastmod', type:'date', dateFormat:'timestamp'}
        ]
    });
    store.load();

    var tpl = new Ext.XTemplate(
        '<tpl for=".">',
            '<div class="thumb-wrap" id="{name}">',
            '<div class="thumb"><img src="{url}" title="{name}"></div>',
            '<span class="x-editable">{shortName}</span></div>',
        '</tpl>',
        '<div class="x-clear"></div>'
    );

    var panel = new Ext.Panel({
        id:'images-view',
        frame:true,
        width:535,
        autoHeight:true,
        collapsible:true,
        layout:'fit',
        title:'Simple DataView',

        items: new Ext.DataView({
            store: store,
            tpl: tpl,
            autoHeight:true,
            multiSelect: true,
            overClass:'x-view-over',
            itemSelector:'div.thumb-wrap',
            emptyText: 'No images to display'
        })
    });
    panel.render(document.body);

     * @constructor
     * Create a new DataView
     * @param {Object} config The config object
     * @xtype dataview
     */
    Ext.DataView = Ext.extend(Ext.BoxComponent, {
        /**
         * @cfg {String/Array} tpl
         * The HTML fragment or an array of fragments that will make up the template used by this DataView.  This should
         * be specified in the same format expected by the constructor of {@link Ext.XTemplate}.
         */
        /**
         * @cfg {Ext.data.Store} store
         * The {@link Ext.data.Store} to bind this DataView to.
         */
        /**
         * @cfg {String} itemSelector
         * This is a required setting. A simple CSS selector (e.g. div.some-class or
         * span:first-child) that will be used to determine what nodes this DataView will be
         * working with.
         */
        /**
         * @cfg {Boolean} multiSelect
         * True to allow selection of more than one item at a time, false to allow selection of only a single item
         * at a time or no selection at all, depending on the value of {@link #singleSelect} (defaults to false).
         */
        /**
         * @cfg {Boolean} singleSelect
         * True to allow selection of exactly one item at a time, false to allow no selection at all (defaults to false).
         * Note that if {@link #multiSelect} = true, this value will be ignored.
         */
        /**
         * @cfg {Boolean} simpleSelect
         * True to enable multiselection by clicking on multiple items without requiring the user to hold Shift or Ctrl,
         * false to force the user to hold Ctrl or Shift to select more than on item (defaults to false).
         */
        /**
         * @cfg {String} overClass
         * A CSS class to apply to each item in the view on mouseover (defaults to undefined).
         */
        /**
         * @cfg {String} loadingText
         * A string to display during data load operations (defaults to undefined).  If specified, this text will be
         * displayed in a loading div and the view's contents will be cleared while loading, otherwise the view's
         * contents will continue to display normally until the new data is loaded and the contents are replaced.
         */
        /**
         * @cfg {String} selectedClass
         * A CSS class to apply to each selected item in the view (defaults to 'x-view-selected').
         */
        selectedClass : "x-view-selected",
        /**
         * @cfg {String} emptyText
         * The text to display in the view when there is no data to display (defaults to '').
         */
        emptyText : "",

        /**
         * @cfg {Boolean} deferEmptyText True to defer emptyText being applied until the store's first load
         */
        deferEmptyText: true,
        /**
         * @cfg {Boolean} trackOver True to enable mouseenter and mouseleave events
         */
        trackOver: false,

        /**
         * @cfg {Boolean} blockRefresh Set this to true to ignore datachanged events on the bound store. This is useful if
         * you wish to provide custom transition animations via a plugin (defaults to false)
         */
        blockRefresh: false,

        //private
        last: false,

        // private
        initComponent : function(){
            Ext.DataView.superclass.initComponent.call(this);
            if(Ext.isString(this.tpl) || Ext.isArray(this.tpl)){
                this.tpl = new Ext.XTemplate(this.tpl);
            }

            this.addEvents(
                /**
                 * @event beforeclick
                 * Fires before a click is processed. Returns false to cancel the default action.
                 * @param {Ext.DataView} this
                 * @param {Number} index The index of the target node
                 * @param {HTMLElement} node The target node
                 * @param {Ext.EventObject} e The raw event object
                 */
                "beforeclick",
                /**
                 * @event click
                 * Fires when a template node is clicked.
                 * @param {Ext.DataView} this
                 * @param {Number} index The index of the target node
                 * @param {HTMLElement} node The target node
                 * @param {Ext.EventObject} e The raw event object
                 */
                "click",
                /**
                 * @event mouseenter
                 * Fires when the mouse enters a template node. trackOver:true or an overClass must be set to enable this event.
                 * @param {Ext.DataView} this
                 * @param {Number} index The index of the target node
                 * @param {HTMLElement} node The target node
                 * @param {Ext.EventObject} e The raw event object
                 */
                "mouseenter",
                /**
                 * @event mouseleave
                 * Fires when the mouse leaves a template node. trackOver:true or an overClass must be set to enable this event.
                 * @param {Ext.DataView} this
                 * @param {Number} index The index of the target node
                 * @param {HTMLElement} node The target node
                 * @param {Ext.EventObject} e The raw event object
                 */
                "mouseleave",
                /**
                 * @event containerclick
                 * Fires when a click occurs and it is not on a template node.
                 * @param {Ext.DataView} this
                 * @param {Ext.EventObject} e The raw event object
                 */
                "containerclick",
                /**
                 * @event dblclick
                 * Fires when a template node is double clicked.
                 * @param {Ext.DataView} this
                 * @param {Number} index The index of the target node
                 * @param {HTMLElement} node The target node
                 * @param {Ext.EventObject} e The raw event object
                 */
                "dblclick",
                /**
                 * @event contextmenu
                 * Fires when a template node is right clicked.
                 * @param {Ext.DataView} this
                 * @param {Number} index The index of the target node
                 * @param {HTMLElement} node The target node
                 * @param {Ext.EventObject} e The raw event object
                 */
                "contextmenu",
                /**
                 * @event containercontextmenu
                 * Fires when a right click occurs that is not on a template node.
                 * @param {Ext.DataView} this
                 * @param {Ext.EventObject} e The raw event object
                 */
                "containercontextmenu",
                /**
                 * @event selectionchange
                 * Fires when the selected nodes change.
                 * @param {Ext.DataView} this
                 * @param {Array} selections Array of the selected nodes
                 */
                "selectionchange",

                /**
                 * @event beforeselect
                 * Fires before a selection is made. If any handlers return false, the selection is cancelled.
                 * @param {Ext.DataView} this
                 * @param {HTMLElement} node The node to be selected
                 * @param {Array} selections Array of currently selected nodes
                 */
                "beforeselect"
            );

            this.store = Ext.StoreMgr.lookup(this.store);
            this.all = new Ext.CompositeElementLite();
            this.selected = new Ext.CompositeElementLite();
        },

        // private
        afterRender : function(){
            Ext.DataView.superclass.afterRender.call(this);

    		this.mon(this.getTemplateTarget(), {
                "click": this.onClick,
                "dblclick": this.onDblClick,
                "contextmenu": this.onContextMenu,
                scope:this
            });

            if(this.overClass || this.trackOver){
                this.mon(this.getTemplateTarget(), {
                    "mouseover": this.onMouseOver,
                    "mouseout": this.onMouseOut,
                    scope:this
                });
            }

            if(this.store){
                this.bindStore(this.store, true);
            }
        },

        /**
         * Refreshes the view by reloading the data from the store and re-rendering the template.
         */
        refresh : function() {
            this.clearSelections(false, true);
            var el = this.getTemplateTarget(),
                records = this.store.getRange();

            el.update('');
            if(records.length < 1){
                if(!this.deferEmptyText || this.hasSkippedEmptyText){
                    el.update(this.emptyText);
                }
                this.all.clear();
            }else{
                this.tpl.overwrite(el, this.collectData(records, 0));
                this.all.fill(Ext.query(this.itemSelector, el.dom));
                this.updateIndexes(0);
            }
            this.hasSkippedEmptyText = true;
        },

        getTemplateTarget: function(){
            return this.el;
        },

        /**
         * Function which can be overridden to provide custom formatting for each Record that is used by this
         * DataView's {@link #tpl template} to render each node.
         * @param {Array/Object} data The raw data object that was used to create the Record.
         * @param {Number} recordIndex the index number of the Record being prepared for rendering.
         * @param {Record} record The Record being prepared for rendering.
         * @return {Array/Object} The formatted data in a format expected by the internal {@link #tpl template}'s overwrite() method.
         * (either an array if your params are numeric (i.e. {0}) or an object (i.e. {foo: 'bar'}))
         */
        prepareData : function(data){
            return data;
        },

        /**
         * Function which can be overridden which returns the data object passed to this
         * DataView's {@link #tpl template} to render the whole DataView.
         * This is usually an Array of data objects, each element of which is processed by an
         * {@link Ext.XTemplate XTemplate} which uses '<tpl for=".">' to iterate over its supplied
         * data object as an Array. However, named properties may be placed into the data object to
         * provide non-repeating data such as headings, totals etc.
         * @param {Array} records An Array of {@link Ext.data.Record}s to be rendered into the DataView.
         * @param {Number} startIndex the index number of the Record being prepared for rendering.
         * @return {Array} An Array of data objects to be processed by a repeating XTemplate. May also
         * contain named properties.
         */
        collectData : function(records, startIndex){
            var r = [],
                i = 0,
                len = records.length;
            for(; i < len; i++){
                r[r.length] = this.prepareData(records[i].data, startIndex + i, records[i]);
            }
            return r;
        },

        // private
        bufferRender : function(records, index){
            var div = document.createElement('div');
            this.tpl.overwrite(div, this.collectData(records, index));
            return Ext.query(this.itemSelector, div);
        },

        // private
        onUpdate : function(ds, record){
            var index = this.store.indexOf(record);
            if(index > -1){
                var sel = this.isSelected(index),
                    original = this.all.elements[index],
                    node = this.bufferRender([record], index)[0];

                this.all.replaceElement(index, node, true);
                if(sel){
                    this.selected.replaceElement(original, node);
                    this.all.item(index).addClass(this.selectedClass);
                }
                this.updateIndexes(index, index);
            }
        },

        // private
        onAdd : function(ds, records, index){
            if(this.all.getCount() === 0){
                this.refresh();
                return;
            }
            var nodes = this.bufferRender(records, index), n, a = this.all.elements;
            if(index < this.all.getCount()){
                n = this.all.item(index).insertSibling(nodes, 'before', true);
                a.splice.apply(a, [index, 0].concat(nodes));
            }else{
                n = this.all.last().insertSibling(nodes, 'after', true);
                a.push.apply(a, nodes);
            }
            this.updateIndexes(index);
        },

        // private
        onRemove : function(ds, record, index){
            this.deselect(index);
            this.all.removeElement(index, true);
            this.updateIndexes(index);
            if (this.store.getCount() === 0){
                this.refresh();
            }
        },

        /**
         * Refreshes an individual node's data from the store.
         * @param {Number} index The item's data index in the store
         */
        refreshNode : function(index){
            this.onUpdate(this.store, this.store.getAt(index));
        },

        // private
        updateIndexes : function(startIndex, endIndex){
            var ns = this.all.elements;
            startIndex = startIndex || 0;
            endIndex = endIndex || ((endIndex === 0) ? 0 : (ns.length - 1));
            for(var i = startIndex; i <= endIndex; i++){
                ns[i].viewIndex = i;
            }
        },

        /**
         * Returns the store associated with this DataView.
         * @return {Ext.data.Store} The store
         */
        getStore : function(){
            return this.store;
        },

        /**
         * Changes the data store bound to this view and refreshes it.
         * @param {Store} store The store to bind to this view
         */
        bindStore : function(store, initial){
            if(!initial && this.store){
                if(store !== this.store && this.store.autoDestroy){
                    this.store.destroy();
                }else{
                    this.store.un("beforeload", this.onBeforeLoad, this);
                    this.store.un("datachanged", this.onDataChanged, this);
                    this.store.un("add", this.onAdd, this);
                    this.store.un("remove", this.onRemove, this);
                    this.store.un("update", this.onUpdate, this);
                    this.store.un("clear", this.refresh, this);
                }
                if(!store){
                    this.store = null;
                }
            }
            if(store){
                store = Ext.StoreMgr.lookup(store);
                store.on({
                    scope: this,
                    beforeload: this.onBeforeLoad,
                    datachanged: this.onDataChanged,
                    add: this.onAdd,
                    remove: this.onRemove,
                    update: this.onUpdate,
                    clear: this.refresh
                });
            }
            this.store = store;
            if(store){
                this.refresh();
            }
        },

        /**
         * @private
         * Calls this.refresh if this.blockRefresh is not true
         */
        onDataChanged: function() {
            if (this.blockRefresh !== true) {
                this.refresh.apply(this, arguments);
            }
        },

        /**
         * Returns the template node the passed child belongs to, or null if it doesn't belong to one.
         * @param {HTMLElement} node
         * @return {HTMLElement} The template node
         */
        findItemFromChild : function(node){
            return Ext.fly(node).findParent(this.itemSelector, this.getTemplateTarget());
        },

        // private
        onClick : function(e){
            var item = e.getTarget(this.itemSelector, this.getTemplateTarget()),
                index;
            if(item){
                index = this.indexOf(item);
                if(this.onItemClick(item, index, e) !== false){
                    this.fireEvent("click", this, index, item, e);
                }
            }else{
                if(this.fireEvent("containerclick", this, e) !== false){
                    this.onContainerClick(e);
                }
            }
        },

        onContainerClick : function(e){
            this.clearSelections();
        },

        // private
        onContextMenu : function(e){
            var item = e.getTarget(this.itemSelector, this.getTemplateTarget());
            if(item){
                this.fireEvent("contextmenu", this, this.indexOf(item), item, e);
            }else{
                this.fireEvent("containercontextmenu", this, e);
            }
        },

        // private
        onDblClick : function(e){
            var item = e.getTarget(this.itemSelector, this.getTemplateTarget());
            if(item){
                this.fireEvent("dblclick", this, this.indexOf(item), item, e);
            }
        },

        // private
        onMouseOver : function(e){
            var item = e.getTarget(this.itemSelector, this.getTemplateTarget());
            if(item && item !== this.lastItem){
                this.lastItem = item;
                Ext.fly(item).addClass(this.overClass);
                this.fireEvent("mouseenter", this, this.indexOf(item), item, e);
            }
        },

        // private
        onMouseOut : function(e){
            if(this.lastItem){
                if(!e.within(this.lastItem, true, true)){
                    Ext.fly(this.lastItem).removeClass(this.overClass);
                    this.fireEvent("mouseleave", this, this.indexOf(this.lastItem), this.lastItem, e);
                    delete this.lastItem;
                }
            }
        },

        // private
        onItemClick : function(item, index, e){
            if(this.fireEvent("beforeclick", this, index, item, e) === false){
                return false;
            }
            if(this.multiSelect){
                this.doMultiSelection(item, index, e);
                e.preventDefault();
            }else if(this.singleSelect){
                this.doSingleSelection(item, index, e);
                e.preventDefault();
            }
            return true;
        },

        // private
        doSingleSelection : function(item, index, e){
            if(e.ctrlKey && this.isSelected(index)){
                this.deselect(index);
            }else{
                this.select(index, false);
            }
        },

        // private
        doMultiSelection : function(item, index, e){
            if(e.shiftKey && this.last !== false){
                var last = this.last;
                this.selectRange(last, index, e.ctrlKey);
                this.last = last; // reset the last
            }else{
                if((e.ctrlKey||this.simpleSelect) && this.isSelected(index)){
                    this.deselect(index);
                }else{
                    this.select(index, e.ctrlKey || e.shiftKey || this.simpleSelect);
                }
            }
        },

        /**
         * Gets the number of selected nodes.
         * @return {Number} The node count
         */
        getSelectionCount : function(){
            return this.selected.getCount();
        },

        /**
         * Gets the currently selected nodes.
         * @return {Array} An array of HTMLElements
         */
        getSelectedNodes : function(){
            return this.selected.elements;
        },

        /**
         * Gets the indexes of the selected nodes.
         * @return {Array} An array of numeric indexes
         */
        getSelectedIndexes : function(){
            var indexes = [],
                selected = this.selected.elements,
                i = 0,
                len = selected.length;

            for(; i < len; i++){
                indexes.push(selected[i].viewIndex);
            }
            return indexes;
        },

        /**
         * Gets an array of the selected records
         * @return {Array} An array of {@link Ext.data.Record} objects
         */
        getSelectedRecords : function(){
            return this.getRecords(this.selected.elements);
        },

        /**
         * Gets an array of the records from an array of nodes
         * @param {Array} nodes The nodes to evaluate
         * @return {Array} records The {@link Ext.data.Record} objects
         */
        getRecords : function(nodes){
            var records = [],
                i = 0,
                len = nodes.length;

            for(; i < len; i++){
                records[records.length] = this.store.getAt(nodes[i].viewIndex);
            }
            return records;
        },

        /**
         * Gets a record from a node
         * @param {HTMLElement} node The node to evaluate
         * @return {Record} record The {@link Ext.data.Record} object
         */
        getRecord : function(node){
            return this.store.getAt(node.viewIndex);
        },

        /**
         * Clears all selections.
         * @param {Boolean} suppressEvent (optional) True to skip firing of the selectionchange event
         */
        clearSelections : function(suppressEvent, skipUpdate){
            if((this.multiSelect || this.singleSelect) && this.selected.getCount() > 0){
                if(!skipUpdate){
                    this.selected.removeClass(this.selectedClass);
                }
                this.selected.clear();
                this.last = false;
                if(!suppressEvent){
                    this.fireEvent("selectionchange", this, this.selected.elements);
                }
            }
        },

        /**
         * Returns true if the passed node is selected, else false.
         * @param {HTMLElement/Number/Ext.data.Record} node The node, node index or record to check
         * @return {Boolean} True if selected, else false
         */
        isSelected : function(node){
            return this.selected.contains(this.getNode(node));
        },

        /**
         * Deselects a node.
         * @param {HTMLElement/Number/Record} node The node, node index or record to deselect
         */
        deselect : function(node){
            if(this.isSelected(node)){
                node = this.getNode(node);
                this.selected.removeElement(node);
                if(this.last == node.viewIndex){
                    this.last = false;
                }
                Ext.fly(node).removeClass(this.selectedClass);
                this.fireEvent("selectionchange", this, this.selected.elements);
            }
        },

        /**
         * Selects a set of nodes.
         * @param {Array/HTMLElement/String/Number/Ext.data.Record} nodeInfo An HTMLElement template node, index of a template node,
         * id of a template node, record associated with a node or an array of any of those to select
         * @param {Boolean} keepExisting (optional) true to keep existing selections
         * @param {Boolean} suppressEvent (optional) true to skip firing of the selectionchange vent
         */
        select : function(nodeInfo, keepExisting, suppressEvent){
            if(Ext.isArray(nodeInfo)){
                if(!keepExisting){
                    this.clearSelections(true);
                }
                for(var i = 0, len = nodeInfo.length; i < len; i++){
                    this.select(nodeInfo[i], true, true);
                }
                if(!suppressEvent){
                    this.fireEvent("selectionchange", this, this.selected.elements);
                }
            } else{
                var node = this.getNode(nodeInfo);
                if(!keepExisting){
                    this.clearSelections(true);
                }
                if(node && !this.isSelected(node)){
                    if(this.fireEvent("beforeselect", this, node, this.selected.elements) !== false){
                        Ext.fly(node).addClass(this.selectedClass);
                        this.selected.add(node);
                        this.last = node.viewIndex;
                        if(!suppressEvent){
                            this.fireEvent("selectionchange", this, this.selected.elements);
                        }
                    }
                }
            }
        },

        /**
         * Selects a range of nodes. All nodes between start and end are selected.
         * @param {Number} start The index of the first node in the range
         * @param {Number} end The index of the last node in the range
         * @param {Boolean} keepExisting (optional) True to retain existing selections
         */
        selectRange : function(start, end, keepExisting){
            if(!keepExisting){
                this.clearSelections(true);
            }
            this.select(this.getNodes(start, end), true);
        },

        /**
         * Gets a template node.
         * @param {HTMLElement/String/Number/Ext.data.Record} nodeInfo An HTMLElement template node, index of a template node,
         * the id of a template node or the record associated with the node.
         * @return {HTMLElement} The node or null if it wasn't found
         */
        getNode : function(nodeInfo){
            if(Ext.isString(nodeInfo)){
                return document.getElementById(nodeInfo);
            }else if(Ext.isNumber(nodeInfo)){
                return this.all.elements[nodeInfo];
            }else if(nodeInfo instanceof Ext.data.Record){
                var idx = this.store.indexOf(nodeInfo);
                return this.all.elements[idx];
            }
            return nodeInfo;
        },

        /**
         * Gets a range nodes.
         * @param {Number} start (optional) The index of the first node in the range
         * @param {Number} end (optional) The index of the last node in the range
         * @return {Array} An array of nodes
         */
        getNodes : function(start, end){
            var ns = this.all.elements,
                nodes = [],
                i;

            start = start || 0;
            end = !Ext.isDefined(end) ? Math.max(ns.length - 1, 0) : end;
            if(start <= end){
                for(i = start; i <= end && ns[i]; i++){
                    nodes.push(ns[i]);
                }
            } else{
                for(i = start; i >= end && ns[i]; i--){
                    nodes.push(ns[i]);
                }
            }
            return nodes;
        },

        /**
         * Finds the index of the passed node.
         * @param {HTMLElement/String/Number/Record} nodeInfo An HTMLElement template node, index of a template node, the id of a template node
         * or a record associated with a node.
         * @return {Number} The index of the node or -1
         */
        indexOf : function(node){
            node = this.getNode(node);
            if(Ext.isNumber(node.viewIndex)){
                return node.viewIndex;
            }
            return this.all.indexOf(node);
        },

        // private
        onBeforeLoad : function(){
            if(this.loadingText){
                this.clearSelections(false, true);
                this.getTemplateTarget().update(''+this.loadingText+'');
                this.all.clear();
            }
        },

        onDestroy : function(){
            this.all.clear();
            this.selected.clear();
            Ext.DataView.superclass.onDestroy.call(this);
            this.bindStore(null);
        }
    });

    /**
     * Changes the data store bound to this view and refreshes it. (deprecated in favor of bindStore)
     * @param {Store} store The store to bind to this view
     */
    Ext.DataView.prototype.setStore = Ext.DataView.prototype.bindStore;

    Ext.reg('dataview', Ext.DataView);