TextBoxBase.SelectionStart TextBoxBase.SelectionStart TextBoxBase.SelectionStart TextBoxBase.SelectionStart Property

Определение

Получает или задает начальную позицию текста, выбранного в текстовом поле.Gets or sets the starting point of text selected in the text box.

public:
 property int SelectionStart { int get(); void set(int value); };
[System.ComponentModel.Browsable(false)]
public int SelectionStart { get; set; }
member this.SelectionStart : int with get, set
Public Property SelectionStart As Integer

Значение свойства

Начальная позиция текста, выбранного в текстовом поле.The starting position of text selected in the text box.

Исключения

Присвоенное значение меньше нуля.The assigned value is less than zero.

Примеры

Пример 1Example 1

В следующем примере кода используется TextBoxпроизводный класс.The following code example uses TextBox, a derived class. Он предоставляет Click обработчики событий MenuItem для объектов, выполняющих операции вырезания, копирования, вставки и отмены.It provides Click event handlers for MenuItem objects that perform Cut, Copy, Paste, and Undo operations. Для этого примера требуется, TextBox чтобы был textBox1 создан элемент управления с именем.This example requires that a TextBox control named textBox1 has been created.

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

Пример 2Example 2

В следующем примере SelectionStart задается свойство TextBox объекта, которому ReadOnly Focus присваивается первое значение.The following example sets the SelectionStart property of a TextBox that is ReadOnly by giving it the Focus first.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        this.button1.Click += new System.EventHandler(this.ButtonClickWork);
    }

    private void ButtonClickWork(object sender, EventArgs e)
    {
        this.textBox1.Text = "Hello world!";
        this.textBox1.ReadOnly = true;

        this.textBox1.Focus();
        this.textBox1.SelectionStart = this.textBox1.SelectionStart + 1;
        this.textBox1.SelectionLength = 1;
    }
}
Public Class Form1

    Private Sub ButtonClickWork(ByVal sender As System.Object, ByVal e As System.EventArgs) _
        Handles Button1.Click

        Me.TextBox1.Text = "Hello world!"
        Me.TextBox1.ReadOnly = True

        Me.TextBox1.Focus()
        Me.TextBox1.SelectionStart = Me.TextBox1.SelectionStart + 1
        Me.TextBox1.SelectionLength = 1
    End Sub
End Class

Комментарии

Если в элементе управления не выбран текст, это свойство указывает точку вставки или курсор для нового текста.If no text is selected in the control, this property indicates the insertion point, or caret, for new text. Если задать для этого свойства расположение, превышающее длину текста в элементе управления, начальная позиция будет помещена после последнего символа.If you set this property to a location beyond the length of the text in the control, the selection start position will be placed after the last character. При выборе текста в элементе управления "текстовое поле" изменение этого свойства может привести к уменьшению значения SelectionLength свойства.When text is selected in the text box control, changing this property might decrease the value of the SelectionLength property. Если оставшийся текст в элементе управления после расположения, указанного SelectionStart свойством SelectionLength , меньше значения SelectionLength свойства, значение свойства уменьшается автоматически.If the remaining text in the control after the position indicated by the SelectionStart property is less than the value of the SelectionLength property, the value of the SelectionLength property is automatically decreased. Значение SelectionStart свойства никогда не приводит к увеличению SelectionLength свойства.The value of the SelectionStart property never causes an increase in the SelectionLength property.

Можно программно переместить выделенный фрагмент в текстовое поле, задав SelectionStart SelectionLength свойства и.You can programmatically move the selection within the text box by setting the SelectionStart and the SelectionLength properties.

Вы можете программно перемещать курсор внутри текстового поля, присвоив SelectionStart SelectionLength свойству значение, которое нужно переместить курсору, и установить для свойства нулевое (0).You can programmatically move the caret within the text box by setting the SelectionStart to the position within the text box where you want the caret to move to and set the SelectionLength property to a value of zero (0).

Для перемещения выделения или курсора долженбытьустановленфокус.TextBoxThe TextBox must have focus in order for the selection or the caret to be moved. SelectionStart Свойство ReadOnly объекта можно задать Focus , предоставив ему первое значение. TextBoxYou can set the SelectionStart property of a TextBox that is ReadOnly by giving it the Focus first.

Применяется к