TextBoxBase.SelectionLength 屬性
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
取得或設定文字方塊中所選取的字元數。
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屬性值
文字方塊中所選取的字元數。
- 屬性
例外狀況
指派的值小於零。
範例
下列程式碼範例會使用 TextBox 衍生類別。 它會為 MenuItem 執行剪下、複製、貼上和復原作業的物件提供 Click 事件處理常式。 此範例會要求 TextBox 已建立名為 的 textBox1 控制項。
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
備註
您可以使用這個屬性來判斷文字方塊控制項中目前是否選取任何字元，然後再對選取的文字執行作業。 SelectionLength當屬性值設定為大於控制項文字中字元數的值時，屬性的值 SelectionLength 會設定為控制項內的整個文字長度減去 SelectionStart 屬性的值， (如果為 SelectionStart 屬性指定任何值，則為屬性) 。
注意
您可以透過程式設計方式移動文字方塊內的插入號，方法是將 設定 SelectionStart 為要移動插入號的文字方塊內的位置，並將 屬性設定 SelectionLength 為零 (0) 。 文字方塊必須有焦點，才能移動插入號。
