Muestra la barra de desplazamiento en el cuadro de texto cuando el contenido está más allá de los límites C #
Pregunta
¿Es posible mostrar / ocultar la barra de desplazamiento en un cuadro de texto solo cuando el recuento de líneas en el cuadro de texto es mayor que el número de líneas mostradas?
Solución
Considere el uso de RichTextBox - tiene ese comportamiento incorporado.
Otros consejos
Public Class TextBoxScrollbarPlugin
Private WithEvents mTarget As TextBox
''' <summary>
''' After the Handle is created, mTarget.IsHandleCreated always returns
''' TRUE, even after HandleDestroyed is fired.
''' </summary>
''' <remarks></remarks>
Private mIsHandleCreated As Boolean = False
Public Sub New(item As TextBox)
mTarget = item
mIsHandleCreated = mTarget.IsHandleCreated
End Sub
Private Sub Update()
If Not mTarget.IsHandleCreated Then
Return
ElseIf Not mIsHandleCreated Then
Return
End If
Dim textBoxRect = TextRenderer.MeasureText(mTarget.Text,
mTarget.Font,
New Size(mTarget.Width, Integer.MaxValue),
TextFormatFlags.WordBreak + TextFormatFlags.TextBoxControl)
Try
If textBoxRect.Height > mTarget.Height Then
mTarget.ScrollBars = ScrollBars.Vertical
Else
mTarget.ScrollBars = ScrollBars.None
End If
Catch ex As System.ComponentModel.Win32Exception
'this sometimes throws a "failure to create window handle"
'error.
'This might happen if the TextBox is unvisible and/or
'to small to display a toolbar.
If mLog.IsWarnEnabled Then mLog.Warn("Update()", ex)
End Try
End Sub
Private Sub mTarget_HandleCreated(sender As Object, e As System.EventArgs) Handles mTarget.HandleCreated
mIsHandleCreated = True
End Sub
Private Sub mTarget_HandleDestroyed(sender As Object, e As System.EventArgs) Handles mTarget.HandleDestroyed
mIsHandleCreated = False
End Sub
Private Sub mTarget_SizeChanged(sender As Object, e As System.EventArgs) Handles mTarget.SizeChanged
Update()
End Sub
Private Sub mTarget_TextChanged(sender As Object, e As System.EventArgs) Handles mTarget.TextChanged
Update()
End Sub
End Class
Private mPlugins As New List(Of Object)
Private Sub Form_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
mPlugins.Add(New TextBoxScrollbarPlugin(txtBoxOne))
mPlugins.Add(New TextBoxScrollbarPlugin(txtBoxTwo))
mPlugins.Add(New TextBoxScrollbarPlugin(txtBoxThree))
End Sub
Gracias maniquí, funciona! Aquí la versión corta de la respuesta ficticia en c #
Llame a este código al final de sus controladores SizeChanged y TextChanged:
Size textBoxRect = TextRenderer.MeasureText(
this.YourTextBox.Text,
this.YourTextBox.Font,
new Size(this.YourTextBox.Width, int.MaxValue),
TextFormatFlags.WordBreak | TextFormatFlags.TextBoxControl);
try
{
this.YourTextBox.ScrollBars = textBoxRect.Height > this.YourTextBox.Height ?
ScrollBars.Vertical :
ScrollBars.None;
} catch (System.ComponentModel.Win32Exception)
{
// this sometimes throws a "failure to create window handle" error.
// This might happen if the TextBox is unvisible and/or
// too small to display a toolbar.
}
Tengo una solución tnimas trabajando en vb. Funciona bastante bien como está escrito y no he visto los errores.
Private Sub TextBoxSizeChanged(sender As Object, e As EventArgs) Handles Me.SizeChanged
Dim textBoxRect As Size = TextRenderer.MeasureText(TextBox.Text, TextBox.Font, New Size(TextBox.Width, Integer.MaxValue), TextFormatFlags.WordBreak Or TextFormatFlags.TextBoxControl)
Try
TextBox.ScrollBar = If(textBoxRect.Height > TextBox.Height, ScrollBars.Vertical, ScrollBars.None)
Catch ex As Exception
'handle error
End Try
End Sub
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