    /**
     * The Ext.grid.plugin.CellEditing plugin injects editing at a cell level for a Grid. Only a single
     * cell will be editable at a time. The field that will be used for the editor is defined at the
     * {@link Ext.grid.column.Column#editor editor}. The editor can be a field instance or a field configuration.
     *
     * If an editor is not specified for a particular column then that cell will not be editable and it will
     * be skipped when activated via the mouse or the keyboard.
     *
     * The editor may be shared for each column in the grid, or a different one may be specified for each column.
     * An appropriate field type should be chosen to match the data structure that it will be editing. For example,
     * to edit a date, it would be useful to specify {@link Ext.form.field.Date} as the editor.
     *
     * ## Example
     *
     * A grid with editor for the name and the email columns:
     *
     *     @example
     *     Ext.create('Ext.data.Store', {
     *         storeId:'simpsonsStore',
     *         fields:['name', 'email', 'phone'],
     *         data:{'items':[
     *             {"name":"Lisa", "email":"lisa@simpsons.com", "phone":"555-111-1224"},
     *             {"name":"Bart", "email":"bart@simpsons.com", "phone":"555-222-1234"},
     *             {"name":"Homer", "email":"home@simpsons.com", "phone":"555-222-1244"},
     *             {"name":"Marge", "email":"marge@simpsons.com", "phone":"555-222-1254"}
     *         ]},
     *         proxy: {
     *             type: 'memory',
     *             reader: {
     *                 type: 'json',
     *                 root: 'items'
     *             }
     *         }
     *     });
     *
     *     Ext.create('Ext.grid.Panel', {
     *         title: 'Simpsons',
     *         store: Ext.data.StoreManager.lookup('simpsonsStore'),
     *         columns: [
     *             {header: 'Name',  dataIndex: 'name', editor: 'textfield'},
     *             {header: 'Email', dataIndex: 'email', flex:1,
     *                 editor: {
     *                     xtype: 'textfield',
     *                     allowBlank: false
     *                 }
     *             },
     *             {header: 'Phone', dataIndex: 'phone'}
     *         ],
     *         selType: 'cellmodel',
     *         plugins: [
     *             Ext.create('Ext.grid.plugin.CellEditing', {
     *                 clicksToEdit: 1
     *             })
     *         ],
     *         height: 200,
     *         width: 400,
     *         renderTo: Ext.getBody()
     *     });
     *
     * This requires a little explanation. We're passing in `store` and `columns` as normal, but
     * we also specify a {@link Ext.grid.column.Column#field field} on two of our columns. For the
     * Name column we just want a default textfield to edit the value, so we specify 'textfield'.
     * For the Email column we customized the editor slightly by passing allowBlank: false, which
     * will provide inline validation.
     *
     * To support cell editing, we also specified that the grid should use the 'cellmodel'
     * {@link Ext.grid.Panel#selType selType}, and created an instance of the CellEditing plugin,
     * which we configured to activate each editor after a single click.
     *
     */
    Ext.define('Ext.grid.plugin.CellEditing', {
        alias: 'plugin.cellediting',
        extend: 'Ext.grid.plugin.Editing',
        requires: ['Ext.grid.CellEditor', 'Ext.util.DelayedTask'],
        lockableScope: 'both',

        /**
         * @event beforeedit
         * Fires before cell editing is triggered. Return false from event handler to stop the editing.
         *
         * @param {Ext.grid.plugin.CellEditing} editor
         * @param {Object} e An edit event with the following properties:
         *
         * - grid - The grid
         * - record - The record being edited
         * - field - The field name being edited
         * - value - The value for the field being edited.
         * - row - The grid table row
         * - column - The grid {@link Ext.grid.column.Column Column} defining the column that is being edited.
         * - rowIdx - The row index that is being edited
         * - colIdx - The column index that is being edited
         * - cancel - Set this to true to cancel the edit or return false from your handler.
         */
        /**
         * @event edit
         * Fires after a cell is edited. Usage example:
         *
         *     grid.on('edit', function(editor, e) {
         *         // commit the changes right after editing finished
         *         e.record.commit();
         *     });
         *
         * @param {Ext.grid.plugin.CellEditing} editor
         * @param {Object} e An edit event with the following properties:
         *
         * - grid - The grid
         * - record - The record that was edited
         * - field - The field name that was edited
         * - value - The value being set
         * - originalValue - The original value for the field, before the edit.
         * - row - The grid table row
         * - column - The grid {@link Ext.grid.column.Column Column} defining the column that was edited.
         * - rowIdx - The row index that was edited
         * - colIdx - The column index that was edited
         */
        /**
         * @event validateedit
         * Fires after a cell is edited, but before the value is set in the record. Return false from event handler to
         * cancel the change.
         *
         * Usage example showing how to remove the red triangle (dirty record indicator) from some records (not all). By
         * observing the grid's validateedit event, it can be cancelled if the edit occurs on a targeted row (for
         * example) and then setting the field's new value in the Record directly:
         *
         *     grid.on('validateedit', function(editor, e) {
         *       var myTargetRow = 6;
         *
         *       if (e.row == myTargetRow) {
         *         e.cancel = true;
         *         e.record.data[e.field] = e.value;
         *       }
         *     });
         *
         * @param {Ext.grid.plugin.CellEditing} editor
         * @param {Object} e An edit event with the following properties:
         *
         * - grid - The grid
         * - record - The record being edited
         * - field - The field name being edited
         * - value - The value being set
         * - originalValue - The original value for the field, before the edit.
         * - row - The grid table row
         * - column - The grid {@link Ext.grid.column.Column Column} defining the column that is being edited.
         * - rowIdx - The row index that is being edited
         * - colIdx - The column index that is being edited
         * - cancel - Set this to true to cancel the edit or return false from your handler.
         */
        /**
         * @event canceledit
         * Fires when the user started editing a cell but then cancelled the edit.
         * @param {Ext.grid.plugin.CellEditing} editor
         * @param {Object} e An edit event with the following properties:
         *
         * - grid - The grid
         * - record - The record that was edited
         * - field - The field name that was edited
         * - value - The value being set
         * - row - The grid table row
         * - column - The grid {@link Ext.grid.column.Column Column} defining the column that was edited.
         * - rowIdx - The row index that was edited
         * - colIdx - The column index that was edited
         */

        init: function(grid) {
            var me = this,
                lockingPartner = me.lockingPartner;

            me.callParent(arguments);

            // Share editor apparatus with lockingPartner becuse columns may move from side to side
            if (lockingPartner) {
                if (lockingPartner.editors) {
                    me.editors = lockingPartner.editors;
                } else {
                    me.editors = lockingPartner.editors = new Ext.util.MixedCollection(false, function(editor) {
                        return editor.editorId;
                    });
                }
            } else {
                me.editors = new Ext.util.MixedCollection(false, function(editor) {
                    return editor.editorId;
                });
            }
        },

        onReconfigure: function(grid, store, columns){
            // Only reconfigure editors if passed a new set of columns
            if (columns) {
                this.editors.clear();
            }
            this.callParent();
        },

        /**
         * @private
         * AbstractComponent calls destroy on all its plugins at destroy time.
         */
        destroy: function() {
            var me = this;
            if (me.editors) {
                me.editors.each(Ext.destroy, Ext);
                me.editors.clear();
            }
            me.callParent(arguments);
        },

        onBodyScroll: function() {
            var me = this,
                ed = me.getActiveEditor(),
                scroll = me.view.el.getScroll();

            // Scroll happened during editing...
            // If editing is on the other side of a lockable, then ignore it
            if (ed && ed.editing && ed.editingPlugin === me) {
                // Terminate editing only on vertical scroll. Horiz scroll can be caused by tabbing between cells.
                if (scroll.top !== me.scroll.top) {
                    if (ed.field) {
                        if (ed.field.triggerBlur) {
                            ed.field.triggerBlur();
                        } else {
                            ed.field.blur();
                        }
                    }
                }
                // Horiz scroll just requires that the editor be realigned.
                else {
                    ed.realign();
                }
            }
            me.scroll = scroll;
        },

        // @private
        // Template method called from base class's initEvents
        initCancelTriggers: function() {
            var me   = this,
                grid = me.grid,
                view = grid.view;

            me.mon(view, 'bodyscroll', me.onBodyScroll, me);
            me.mon(grid, {
                columnresize: me.cancelEdit,
                columnmove: me.cancelEdit,
                scope: me
            });
        },

        isCellEditable: function(record, columnHeader) {
            var me = this,
                context = me.getEditingContext(record, columnHeader);

            if (me.grid.view.isVisible(true) && context) {
                columnHeader = context.column;
                record = context.record;
                if (columnHeader && me.getEditor(record, columnHeader)) {
                    return true;
                }
            }
        },

        /**
         * Starts editing the specified record, using the specified Column definition to define which field is being edited.
         * @param {Ext.data.Model/Number} record The Store data record which backs the row to be edited, or index of the record.
         * @param {Ext.grid.column.Column/Number} columnHeader The Column object defining the column to be edited, or index of the column.
         * @return {Boolean} `true` if editing was started, `false` otherwise.
         */
        startEdit: function(record, columnHeader, /* private */ context) {
            var me = this,
                ed;

            if (!context) {
                me.preventBeforeCheck = true;
                context = me.callParent(arguments);
                delete me.preventBeforeCheck;
                if (context === false) {
                    return false;
                }
            }

            // Cancel editing if EditingContext could not be found (possibly because record has been deleted by an intervening listener),
            // or if the grid view is not currently visible
            if (context && me.grid.view.isVisible(true)) {

                record = context.record;
                columnHeader = context.column;

                // Complete the edit now, before getting the editor's target cell DOM element.
                // Completing the edit hides the editor, causes a row update and sets up a delayed focus on the row.
                // Also allows any post-edit events to take effect before continuing
                me.completeEdit();

                // See if the field is editable for the requested record
                if (columnHeader && !columnHeader.getEditor(record)) {
                    return false;
                }

                // Switch to new context *after* completing the current edit
                me.context = context;

                context.originalValue = context.value = record.get(columnHeader.dataIndex);

                if (me.beforeEdit(context) === false || me.fireEvent('beforeedit', me, context) === false || context.cancel) {
                    return false;
                }

                ed = me.getEditor(record, columnHeader);

                // Whether we are going to edit or not, ensure the edit cell is scrolled into view
                me.grid.view.cancelFocus();
                me.view.scrollCellIntoView(me.getCell(record, columnHeader));
                if (ed) {
                    me.showEditor(ed, context, context.value);
                    return true;
                }
                return false;
            }
        },

        showEditor: function(ed, context, value) {
            var me = this,
                record = context.record,
                columnHeader = context.column,
                sm = me.grid.getSelectionModel(),
                selection = sm.getCurrentPosition(),
                otherView = selection && selection.view;

            // Selection is for another view.
            // This can happen in a lockable grid where there are two grids, each with a separate Editing plugin
            if (otherView && otherView !== me.view) {
                return me.lockingPartner.showEditor(ed, me.lockingPartner.getEditingContext(selection.record, selection.columnHeader), value);
            }

            me.setEditingContext(context);
            me.setActiveEditor(ed);
            me.setActiveRecord(record);
            me.setActiveColumn(columnHeader);

            // Select cell on edit only if it's not the currently selected cell
            if (sm.selectByPosition && (!selection || selection.column !== context.colIdx || selection.row !== context.rowIdx)) {
                sm.selectByPosition({
                    row: context.rowIdx,
                    column: context.colIdx,
                    view: me.view
                });
            }

            ed.startEdit(me.getCell(record, columnHeader), value, context);
            me.editing = true;
            me.scroll = me.view.el.getScroll();
        },

        completeEdit: function() {
            var activeEd = this.getActiveEditor();
            if (activeEd) {
                activeEd.completeEdit();
                this.editing = false;
            }
        },

        // internal getters/setters
        setEditingContext: function(context) {
            this.context = context;
            if (this.lockingPartner) {
                this.lockingPartner.context = context;
            }
        },

        setActiveEditor: function(ed) {
            this.activeEditor = ed;
            if (this.lockingPartner) {
                this.lockingPartner.activeEditor = ed;
            }
        },

        getActiveEditor: function() {
            return this.activeEditor;
        },

        setActiveColumn: function(column) {
            this.activeColumn = column;
            if (this.lockingPartner) {
                this.lockingPartner.activeColumn = column;
            }
        },

        getActiveColumn: function() {
            return this.activeColumn;
        },

        setActiveRecord: function(record) {
            this.activeRecord = record;
            if (this.lockingPartner) {
                this.lockingPartner.activeRecord = record;
            }
        },

        getActiveRecord: function() {
            return this.activeRecord;
        },

        getEditor: function(record, column) {
            var me = this,
                editors = me.editors,
                editorId = column.getItemId(),
                editor = editors.getByKey(editorId),
                // Add to top level grid if we are editing one side of a locking system
                editorOwner = me.grid.ownerLockable || me.grid;

            if (!editor) {
                editor = column.getEditor(record);
                if (!editor) {
                    return false;
                }

                // Allow them to specify a CellEditor in the Column
                if (editor instanceof Ext.grid.CellEditor) {
                    editor.floating = true;
                }
                // But if it's just a Field, wrap it.
                else {
                    editor = new Ext.grid.CellEditor({
                        floating: true,
                        editorId: editorId,
                        field: editor
                    });
                }
                // Add the Editor as a floating child of the grid
                editorOwner.add(editor);
                editor.on({
                    scope: me,
                    specialkey: me.onSpecialKey,
                    complete: me.onEditComplete,
                    canceledit: me.cancelEdit
                });
                column.on('removed', me.cancelActiveEdit, me);
                editors.add(editor);
            }

            if (column.isTreeColumn) {
                editor.isForTree = column.isTreeColumn;
                editor.addCls(Ext.baseCSSPrefix + 'tree-cell-editor')
            }
            editor.grid = me.grid;

            // Keep upward pointer correct for each use - editors are shared between locking sides
            editor.editingPlugin = me;
            return editor;
        },

        cancelActiveEdit: function(column){
            var context = this.context
            if (context && context.column === column) {
                this.cancelEdit();
            }
        },

        // inherit docs
        setColumnField: function(column, field) {
            var ed = this.editors.getByKey(column.getItemId());
            Ext.destroy(ed, column.field);
            this.editors.removeAtKey(column.getItemId());
            this.callParent(arguments);
        },

        /**
         * Gets the cell (td) for a particular record and column.
         * @param {Ext.data.Model} record
         * @param {Ext.grid.column.Column} column
         * @private
         */
        getCell: function(record, column) {
            return this.grid.getView().getCell(record, column);
        },

        onSpecialKey: function(ed, field, e) {
            var sm;

            if (e.getKey() === e.TAB) {
                e.stopEvent();

                if (ed) {
                    // Allow the field to act on tabs before onEditorTab, which ends
                    // up calling completeEdit. This is useful for picker type fields.
                    ed.onEditorTab(e);
                }

                sm = ed.up('tablepanel').getSelectionModel();
                if (sm.onEditorTab) {
                    return sm.onEditorTab(ed.editingPlugin, e);
                }
            }
        },

        onEditComplete : function(ed, value, startValue) {
            var me = this,
                activeColumn = me.getActiveColumn(),
                context = me.context,
                record;

            if (activeColumn) {
                record = context.record;

                me.setActiveEditor(null);
                me.setActiveColumn(null);
                me.setActiveRecord(null);

                context.value = value;
                if (!me.validateEdit()) {
                    return;
                }

                // Only update the record if the new value is different than the
                // startValue. When the view refreshes its el will gain focus
                if (!record.isEqual(value, startValue)) {
                    record.set(activeColumn.dataIndex, value);
                }

                // Restore focus back to the view.
                // Use delay so that if we are completing due to tabbing, we can cancel the focus task
                context.view.focus(false, true);
                me.fireEvent('edit', me, context);
                me.editing = false;
            }
        },

        /**
         * Cancels any active editing.
         */
        cancelEdit: function() {
            var me = this,
                activeEd = me.getActiveEditor();

            me.setActiveEditor(null);
            me.setActiveColumn(null);
            me.setActiveRecord(null);
            if (activeEd) {
                activeEd.cancelEdit();
                me.context.view.focus();
                me.callParent(arguments);
                return;
            }
            // If we aren't editing, return true to allow the event to bubble
            return true;
        },

        /**
         * Starts editing by position (row/column)
         * @param {Object} position A position with keys of row and column.
         */
        startEditByPosition: function(position) {

            // If a raw {row:0, column:0} object passed.
            if (!position.isCellContext) {
                position = new Ext.grid.CellContext(this.view).setPosition(position);
            }

            // Coerce the edit column to the closest visible column
            position.setColumn(this.view.getHeaderCt().getVisibleHeaderClosestToIndex(position.column).getIndex());

            return this.startEdit(position.record, position.columnHeader);
        }
    });