TextBoxBase.SelectionLength 属性
定义
重要
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获取或设置文本框中选定的字符数。
public:
virtual property int SelectionLength { int get(); void set(int value); };[System.ComponentModel.Browsable(false)]
public virtual int SelectionLength { get; set; }[<System.ComponentModel.Browsable(false)>]
member this.SelectionLength : int with get, setPublic Overridable Property SelectionLength As Integer属性值
文本框中选定的字符数。
- 属性
例外
赋给的值小于零。
示例
下面的代码示例使用 TextBox，一个派生类。 它为MenuItem执行剪切、复制、粘贴和撤消操作的对象提供Click事件处理程序。 此示例要求已创建名为 TextBox 的 textBox1 控件。
private:
void Menu_Copy( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
// Ensure that text is selected in the text box.
if ( textBox1->SelectionLength > 0 )
{
// Copy the selected text to the Clipboard.
textBox1->Copy();
}
}
void Menu_Cut( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
// Ensure that text is currently selected in the text box.
if ( !textBox1->SelectedText->Equals( "" ) )
{
// Cut the selected text in the control and paste it into the Clipboard.
textBox1->Cut();
}
}
void Menu_Paste( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
// Determine if there is any text in the Clipboard to paste into the text box.
if ( Clipboard::GetDataObject()->GetDataPresent( DataFormats::Text ) == true )
{
// Determine if any text is selected in the text box.
if ( textBox1->SelectionLength > 0 )
{
// Ask user if they want to paste over currently selected text.
if ( MessageBox::Show( "Do you want to paste over current selection?",
"Cut Example", MessageBoxButtons::YesNo ) == ::DialogResult::No )
{
// Move selection to the point after the current selection and paste.
textBox1->SelectionStart = textBox1->SelectionStart + textBox1->SelectionLength;
}
}
// Paste current text in Clipboard into text box.
textBox1->Paste();
}
}
void Menu_Undo( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
// Determine if last operation can be undone in text box.
if ( textBox1->CanUndo == true )
{
// Undo the last operation.
textBox1->Undo();
// Clear the undo buffer to prevent last action from being redone.
textBox1->ClearUndo();
}
}
private void Menu_Copy(System.Object sender, System.EventArgs e)
{
// Ensure that text is selected in the text box.
if(textBox1.SelectionLength > 0)
// Copy the selected text to the Clipboard.
textBox1.Copy();
}
private void Menu_Cut(System.Object sender, System.EventArgs e)
{
// Ensure that text is currently selected in the text box.
if(textBox1.SelectedText != "")
// Cut the selected text in the control and paste it into the Clipboard.
textBox1.Cut();
}
private void Menu_Paste(System.Object sender, System.EventArgs e)
{
// Determine if there is any text in the Clipboard to paste into the text box.
if(Clipboard.GetDataObject().GetDataPresent(DataFormats.Text) == true)
{
// Determine if any text is selected in the text box.
if(textBox1.SelectionLength > 0)
{
// Ask user if they want to paste over currently selected text.
if(MessageBox.Show("Do you want to paste over current selection?", "Cut Example", MessageBoxButtons.YesNo) == DialogResult.No)
// Move selection to the point after the current selection and paste.
textBox1.SelectionStart = textBox1.SelectionStart + textBox1.SelectionLength;
}
// Paste current text in Clipboard into text box.
textBox1.Paste();
}
}
private void Menu_Undo(System.Object sender, System.EventArgs e)
{
// Determine if last operation can be undone in text box.
if(textBox1.CanUndo == true)
{
// Undo the last operation.
textBox1.Undo();
// Clear the undo buffer to prevent last action from being redone.
textBox1.ClearUndo();
}
}
Private Sub Menu_Copy(sender As System.Object, e As System.EventArgs)
' Ensure that text is selected in the text box.
If textBox1.SelectionLength > 0 Then
' Copy the selected text to the Clipboard.
textBox1.Copy()
End If
End Sub
Private Sub Menu_Cut(sender As System.Object, e As System.EventArgs)
' Ensure that text is currently selected in the text box.
If textBox1.SelectedText <> "" Then
' Cut the selected text in the control and paste it into the Clipboard.
textBox1.Cut()
End If
End Sub
Private Sub Menu_Paste(sender As System.Object, e As System.EventArgs)
' Determine if there is any text in the Clipboard to paste into the text box.
If Clipboard.GetDataObject().GetDataPresent(DataFormats.Text) = True Then
' Determine if any text is selected in the text box.
If textBox1.SelectionLength > 0 Then
' Ask user if they want to paste over currently selected text.
If MessageBox.Show("Do you want to paste over current selection?", _
"Cut Example", MessageBoxButtons.YesNo) = DialogResult.No Then
' Move selection to the point after the current selection and paste.
textBox1.SelectionStart = textBox1.SelectionStart + _
textBox1.SelectionLength
End If
End If
' Paste current text in Clipboard into text box.
textBox1.Paste()
End If
End Sub
Private Sub Menu_Undo(sender As System.Object, e As System.EventArgs)
' Determine if last operation can be undone in text box.
If textBox1.CanUndo = True Then
' Undo the last operation.
textBox1.Undo()
' Clear the undo buffer to prevent last action from being redone.
textBox1.ClearUndo()
End If
End Sub
注解
在对所选文本执行操作之前，可以使用此属性来确定文本框控件中当前是否选择了任何字符。 当属性的值SelectionLength设置为大于控件文本中的字符数的值时，如果为SelectionStart属性) 指定了任何值SelectionStart，则属性的值SelectionLength将设置为控件中文本的整个长度减去属性 (的值。
注意
可以通过编程方式移动文本框中的插入点，方法是将 设置为 SelectionStart 希望插入点移动到的文本框中的位置，并将 属性设置为 SelectionLength 零 (0) 的值。 文本框必须具有焦点才能移动插入点。
