TextBoxBase.BeginChange 方法
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
开始更改块。
public:
void BeginChange();public void BeginChange ();member this.BeginChange : unit -> unitPublic Sub BeginChange ()示例
以下示例演示如何使用 BeginChange 和 EndChange 方法创建更改块。
TextBox myTextBox = new TextBox();
// Begin the change block. Once BeginChange() is called
// no text content or selection change events will be raised
// until EndChange is called. Also, all edits made within
// a BeginChange/EndChange block are wraped in a single undo block.
myTextBox.BeginChange();
// Put some initial text in the TextBox.
myTextBox.Text = "Initial text in TextBox";
// Make other changes if desired...
// Whenever BeginChange() is called EndChange() must also be
// called to end the change block.
myTextBox.EndChange();
Dim myTextBox As New TextBox()
' Begin the change block. Once BeginChange() is called
' no text content or selection change events will be raised
' until EndChange is called. Also, all edits made within
' a BeginChange/EndChange block are wraped in a single undo block.
myTextBox.BeginChange()
' Put some initial text in the TextBox.
myTextBox.Text = "Initial text in TextBox"
' Make other changes if desired...
' Whenever BeginChange() is called EndChange() must also be
' called to end the change block.
myTextBox.EndChange()
注解
备注
调用 BeginChange时，还必须调用 EndChange 以完成更改块，否则将引发异常。
更改块在逻辑上将多个更改分组到单个撤消单元中，并阻止在更改块之后引发文本内容或选择更改事件。 这样，便可以对文本元素进行多次编辑，而不会让另一个侦听器同时更改文本元素的危险。 通过调用 DeclareChangeBlock 方法创建更改块。 调用该方法 BeginChange 会导致指定更改块中包含所有后续更改，直到对方法进行相应的调用 EndChange 。