TextBoxBase.SelectionStart Propriété

Définition

Obtient ou définit le point de départ du texte sélectionné dans la zone de texte.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

Valeur de propriété

Position de départ du texte sélectionné dans la zone de texte.The starting position of text selected in the text box.

Attributs

Exceptions

La valeur assignée est inférieure à zéro.The assigned value is less than zero.

Exemples

Exemple 1Example 1

L’exemple de code suivant TextBoxutilise, une classe dérivée.The following code example uses TextBox, a derived class. Il fournit Click des gestionnaires d’événements MenuItem pour les objets qui effectuent des opérations couper, copier, coller et annuler.It provides Click event handlers for MenuItem objects that perform Cut, Copy, Paste, and Undo operations. Cet exemple nécessite qu’un TextBox contrôle nommé textBox1 ait été créé.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

Exemple 2Example 2

L’exemple suivant définit la SelectionStart propriété d’un TextBox qui est ReadOnly en lui donnant le Focus premier.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

Remarques

Si aucun texte n’est sélectionné dans le contrôle, cette propriété indique le point d’insertion, ou signe insertion, pour le nouveau texte.If no text is selected in the control, this property indicates the insertion point, or caret, for new text. Si vous définissez cette propriété sur un emplacement situé au-delà de la longueur du texte dans le contrôle, la position de début de la sélection sera placée après le dernier caractère.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. Quand du texte est sélectionné dans le contrôle zone de texte, la modification de cette propriété peut diminuer SelectionLength la valeur de la propriété.When text is selected in the text box control, changing this property might decrease the value of the SelectionLength property. Si le texte restant dans le contrôle après la position indiquée par la SelectionStart propriété est inférieur à la valeur de la SelectionLength propriété, la valeur de la SelectionLength propriété est automatiquement réduite.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. La valeur de la SelectionStart propriété n’entraîne jamais l’augmentation de SelectionLength la propriété.The value of the SelectionStart property never causes an increase in the SelectionLength property.

Vous pouvez déplacer par programmation la sélection dans la zone de texte en définissant SelectionStart les SelectionLength propriétés et.You can programmatically move the selection within the text box by setting the SelectionStart and the SelectionLength properties.

Vous pouvez déplacer par programmation le signe insertion dans la zone de texte en affectant SelectionStart à la position dans la zone de texte où vous souhaitez déplacer le point d’insertion et affecter à SelectionLength la propriété une valeur de zéro (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).

Le TextBox doit avoir le focus pour que la sélection ou le signe insertion soient déplacés.The TextBox must have focus in order for the selection or the caret to be moved. Vous pouvez définir la SelectionStart propriété d’un TextBox qui est ReadOnly en lui donnant le Focus premier.You can set the SelectionStart property of a TextBox that is ReadOnly by giving it the Focus first.

S’applique à