Gird事件机制初级读本

原文地址 文章日期：2006/09/25/

新版.32 的YUI-EXT包含了GIRD事件机制的重要升级。许多新事件现在可以用了，监听事件的机制也改变了（尽管它仍然向后兼容）。

侦听事件的方法

鉴于 YAHOO.util.CustomEvent只提供简单的访问，Grid和相关的对象扩展了新的方法来侦听事件，这些事件你应该是熟悉的。它们是：

• addListener(eventName, fn, scope, override) - "eventName" should be one of the events defined below. "fn" is the function to call when the event occurs. "scope" is an optional object providing the scope (this) of the function. "override" is whether or not to apply that scope and is only there for backwards compatibility.
  
• removeListener(eventName, fn, scope) -移除前先提交的事件侦听
  
• on(eventName, fn, scope, override) - addListener 快捷方式

这些方法与YAHOO.uitl.Event一样，有相同的署名（signatures）。

onRowSelect事件的侦听：

var sm = grid.getSelectionModel();

sm.addListener('rowselect', myHandler);

这是GIRD暴露事件的列表和参数简介：

- "this" 指的是Grid对象；

- "e" 指的是 YAHOO.ext.EventObject (常规化事件对象) ，除了Drag & Drop对象是标准浏览器事件对象。

- "dd" 指的是Grid的YAHOO.ext.GridDD对象。

译注：下面事件解释以原文方式提供以便读者准确理解：

• cellclick - (this, rowIndex, columnIndex, e) - Fires when a cell is clicked
  
• celldblclick - (this, rowIndex, columnIndex, e) - Fires when a cell is double clicked
  
• rowclick - (this, rowIndex, e) - Fires when a row is clicked
  
• rowdblclick - (this, rowIndex, e) - Fires when a row is double clicked
  
• headerclick - (this, columnIndex, e) - Fires when a header is clicked
  
• rowcontextmenu - (this, rowIndex, e) - Fires when a row is right clicked
  
• headercontextmenu - (this, columnIndex, e) - Fires when a header is right clicked
  
• beforeedit - (this, rowIndex, columnIndex, e) - Fires just before editing is started on a cell
  
• afteredit - (this, rowIndex, columnIndex, e) - Fires immediately after a cell is edited
  
• bodyscroll - (scrollLeft, scrollTop) - Fires when the grid's body is scrolled
  
• columnresize - (columnIndex, newSize) Fires when the user resizes a column.
  
• startdrag - (this, dd, e) - Fires when row(s) start being dragged
  
• enddrag - (this, dd, e) - Fires when a drag operation is complete
  
• dragdrop - (this, dd, targetId, e) - Fires when dragged row(s) are dropped on a valid DD target
  
• dragover - (this, dd, targetId, e) Fires while row(s) are being dragged. "targetId" is the id of the Yahoo.util.DD object the selected rows are being dragged over.
  
• dragenter - (this, dd, targetId, e) - Fires when the dragged row(s) first cross another DD target while being dragged
  
• dragout - (this, dd, targetId, e) - Fires when the dragged row(s) leave another DD target while being dragged

Gird事件的例子

function onCellClick(grid, rowIndex, colIndex, e){

 alert('Cell at row ' + rowIndex + ', column ' + colIndex + ' was clicked!');

 }

 var grid = ... // 这里注册事件 grid.addListener('cellclick', onCellClick);

普通Grid事件

Since there is no way to envision everything you may want to do with the grid, I've also exposed direct access to many of the grid's raw events. All of these events pass one parameter to their handler: "e" a YAHOO.ext.EventObject.

• click
  
• dblclick
  
• mousedown
  
• mouseup
  
• mouseover
  
• mouseout
  
• keypress
  
• keydown

LoadableDataModel (from which XMLDataModel and JSONDataModel are derived) picked up a useful new event:

beforeload - Fires right before the model starts fetching remote data.

You could use this event combined with the load event to hide/show a loading indicator.

var img = getEl('loading-indicator'); var dm = grid.getDataModel(); dm.addListener('beforeload', img.show, img, true); dm.addListener('load', img.hide, img, true);

Hopefully this can get you started with the new event system. If you have any questions, feel free to post in the Help Forum and I will help you out.

Jack