TextBoxBase.SelectionStart プロパティとは何？わかりやすく解説 Weblio辞書

.NET Framework クラスライブラリリファレンス

索引トップ用語の索引ランキング

TextBoxBase.SelectionStart プロパティ

テキストボックスで選択されているテキストの開始点を取得または設定します。

名前空間: System.Windows.Forms
アセンブリ: System.Windows.Forms (system.windows.forms.dll 内)
構文

Visual Basic (宣言)

Public Property SelectionStart As
 Integer

Visual Basic (使用法)

Dim instance As TextBoxBase
Dim value As Integer

value = instance.SelectionStart

instance.SelectionStart = value

public int SelectionStart { get;
 set; }

C++

public:
property int SelectionStart {
    int get ();
    void set (int value);
}

/** @property */
public int get_SelectionStart ()

/** @property */
public void set_SelectionStart (int
 value)

JScript

public function get SelectionStart
 () : int

public function set SelectionStart
 (value : int)

プロパティ値
テキストボックスで選択されているテキストの開始点。

例外

例外の種類	条件
ArgumentOutOfRangeException	割り当てられた値が 0 未満です。

解説

コントロールでテキストが選択されていない場合、このプロパティは新しいテキストの挿入位置を示します。このプロパティがコントロール内のテキストの長さを超えた位置に設定されている場合、開始点は最後の文字の後ろになります。テキストボックスコントロールでテキストが選択されているとき、このプロパティを変更すると SelectionLength プロパティの値が小さくなる場合があります。SelectionStart プロパティで示される位置より後ろにあるコントロール内の残りのテキストが SelectionLength プロパティの値未満の場合、SelectionLength プロパティの値は自動的に小さくなります。SelectionStart プロパティの値によって、SelectionLength プロパティの値が大きくなることはありません。

メモ
SelectionStart をカレットのテキストボックス内での移動先の位置に設定し、SelectionLength プロパティの値を 0 に設定すると、プログラムによってテキストボックス内でカレットを移動できます。カレットを移動するには、テキストボックスにフォーカスがあることが必要です。

使用例

派生クラス TextBox を使用するコード例を次に示します。切り取り、コピー、貼り付け、元に戻すなどの各操作を実行する MenuItem オブジェクトの Click イベントハンドラを用意します。この例では、textBox1 という名前の TextBox コントロールが作成されている必要があります。

Visual Basic

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

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();
    }
 }

C++

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(Object sender, System.EventArgs
 e)
{
    // Ensure that text is selected in the text box.   
    if (textBox1.get_SelectionLength() > 0) {
        // Copy the selected text to the Clipboard.
        textBox1.Copy();
    }
} //Menu_Copy

private void Menu_Cut(Object sender, System.EventArgs
 e)
{
    // Ensure that text is currently selected in the text box.   
    if (!(textBox1.get_SelectedText().Equals(""))) {
        // Cut the selected text in the control and paste it 
        //into the Clipboard.
        textBox1.Cut();
    }
} //Menu_Cut

private void Menu_Paste(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.get_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).Equals(get_DialogResult().No)) {
                // Move selection to the point after the current 
                // selection and paste.
                textBox1.set_SelectionStart(textBox1.get_SelectionStart() 
                    + textBox1.get_SelectionLength());
            }
        }
        // Paste current text in Clipboard into text box.
        textBox1.Paste();
    }
} //Menu_Paste

private void Menu_Undo(Object sender, System.EventArgs
 e)
{
    // Determine if last operation can be undone in text box.   
    if (textBox1.get_CanUndo() == true) {
        // Undo the last operation.
        textBox1.Undo();
        // Clear the undo buffer to prevent last action from being redone.
        textBox1.ClearUndo();
    }
} //Menu_Undo