source: Dev/trunk/src/client/dojox/widget/Selection.js

define(["dojo/_base/declare", "dojo/_base/array", "dojo/_base/lang", "dojo/Stateful"], 
        function(declare, arr, lang, Stateful){
                
        return declare("dojox.widget.Selection", Stateful, {
                // summary:
                //              Base class for widgets that manage a list of selected data items.

                constructor: function(){
                        this.selectedItems = [];
                },
                
                // selectionMode: String
                //              Valid values are:
                //
                //              1. "none": No selection can be done.
                //              2. "single": Only one item can be selected at a time.
                //              3. "multiple": Several item can be selected using the control key modifier.
                //              Default value is "single".
                selectionMode: "single",
                
                _setSelectionModeAttr: function(value){
                        if(value != "none" && value != "single" && value != "multiple"){
                                value = "single"; //default value
                        }                       
                        if(value != this.selectionMode){
                                this.selectionMode = value;
                                if(value == "none"){
                                        this.set("selectedItems", null);
                                }else if(value == "single"){
                                        this.set("selectedItem", this.selectedItem); // null or last selected item 
                                }
                        }
                },
                
                // selectedItem: Object
                //              In single selection mode, the selected item or in multiple selection mode the last selected item.
                //              Warning: Do not use this property directly, make sure to call set() or get() methods.
                selectedItem: null,
                
                _setSelectedItemAttr: function(value){
                        if(this.selectedItem != value){
                                this._set("selectedItem", value);
                                this.set("selectedItems", value ? [value] : null);
                        }
                },
                
                // selectedItems: Object[]
                //              The list of selected items.
                //              Warning: Do not use this property directly, make sure to call set() or get() methods.
                selectedItems: null,
                
                _setSelectedItemsAttr: function(value){
                        var oldSelectedItems = this.selectedItems;
                        
                        this.selectedItems = value;
                        this.selectedItem = null;
                        
                        if(oldSelectedItems != null && oldSelectedItems.length>0){
                                this.updateRenderers(oldSelectedItems, true);
                        }
                        if(this.selectedItems && this.selectedItems.length>0){
                                this.selectedItem = this.selectedItems[0];
                                this.updateRenderers(this.selectedItems, true);
                        }
                },
                
                _getSelectedItemsAttr: function(){
                        return this.selectedItems == null ? [] : this.selectedItems.concat();
                },
                
                isItemSelected: function(item){
                        // summary:
                        //              Returns wether an item is selected or not.
                        // item: Object
                        //              The item to test the selection for.                     
                        if(this.selectedItems == null || this.selectedItems.length== 0){
                                return false;
                        }
                         
                        return arr.some(this.selectedItems, lang.hitch(this, function(sitem){
                                return this.getIdentity(sitem) == this.getIdentity(item);
                        }));
                },
                
                getIdentity: function(item){
                        // summary:
                        //              This function must be implemented to return the id of a item.
                        // item: Object
                        //              The item to query the identity for.
                },
                
                setItemSelected: function(item, value){
                        // summary:
                        //              Change the selection state of an item.
                        // item: Object
                        //              The item to change the selection state for.
                        // value: Boolean
                        //              True to select the item, false to deselect it. 
                        
                        if(this.selectionMode == "none" || item == null){
                                return;
                        }

                        // copy is returned
                        var sel = this.get("selectedItems");
                        var old = this.get("selectedItems");
                        
                        if(this.selectionMode == "single"){
                                if(value){
                                        this.set("selectedItem", item);
                                }else if(this.isItemSelected(item)){
                                        this.set("selectedItems", null);
                                }
                        }else{ // multiple
                                if(value){
                                        if(this.isItemSelected(item)){
                                                return; // already selected
                                        }
                                        if(sel == null){
                                                sel = [item];
                                        }else{
                                                sel.unshift(item);
                                        }
                                        this.set("selectedItems", sel);
                                }else{
                                        var res = arr.filter(sel, function(sitem){
                                                return sitem.id != item.id; 
                                        });
                                        if(res == null || res.length == sel.length){
                                                return; // already not selected
                                        }
                                        this.set("selectedItems", res);
                                }
                        }
                },
                
                selectFromEvent: function(e, item, renderer, dispatch){
                        // summary:
                        //              Applies selection triggered by an user interaction
                        // e: Event
                        //              The source event of the user interaction.
                        // item: Object
                        //              The render item that has been selected/deselected.
                        // renderer: Object
                        //              The visual renderer of the selected/deselected item.                    
                        // dispatch: Boolean
                        //              Whether an event must be dispatched or not.
                        // returns: Boolean
                        //              Returns true if the selection has changed and false otherwise.
                        // tags:
                        //              protected
                        
                        if(this.selectionMode == "none"){
                                return false;
                        }
                        
                        var changed;
                        var oldSelectedItem = this.get("selectedItem");
                        var selected = item ? this.isItemSelected(item): false;
                        
                        if(item == null){
                                if(!e.ctrlKey && this.selectedItem != null){
                                        this.set("selectedItem", null);
                                        changed = true;
                                }
                        }else if(this.selectionMode == "multiple"){
                                 if(e.ctrlKey){
                                        this.setItemSelected(item, !selected);
                                        changed = true;
                                }else{
                                        this.set("selectedItem", item);                                 
                                        changed = true;                                         
                                }                                                                                               
                        }else{ // single
                                if(e.ctrlKey){                                  
                                        //if the object is selected deselects it.
                                        this.set("selectedItem", selected ? null : item);
                                        changed = true;                                 
                                }else{
                                        if(!selected){                                                  
                                                this.set("selectedItem", item);
                                                changed = true;
                                        }
                                }
                        }                                               
                        
                        if(dispatch && changed){
                                this.dispatchChange(oldSelectedItem, this.get("selectedItem"), renderer, e);
                        }
                        
                        return changed;
                },
                
                dispatchChange: function(oldSelectedItem, newSelectedItem, renderer, triggerEvent){
                        // summary:
                        //              Dispatch a selection change event.
                        // oldSelectedItem: Object
                        //              The previously selectedItem.
                        // newSelectedItem: Object
                        //              The new selectedItem.
                        // renderer: Object
                        //              The visual renderer of the selected/deselected item.
                        // triggerEvent: Event
                        //              The event that lead to the selection of the item.                       
                        this.onChange({
                                oldValue: oldSelectedItem,
                                newValue: newSelectedItem,
                                renderer: renderer,
                                triggerEvent: triggerEvent
                        });
                },
                
                onChange: function(){
                        // summary:
                        //              Called when the selection changed.
                        // tags:
                        //              callback                        
                }
        });
});