问题
I have a RichTextBox.
lets say I want to draw every word "test" in the text. My problem is not to find the "test" in the text, My problem is when I color the word I can see the RichTextBox Selection process.
My color function:
Private Sub DrawSubPart(ByVal StartIndex As Integer, ByVal EndIndex As Integer, ByVal col As Color)
Dim save As Integer = TextScreen.SelectionStart
TextScreen.SelectionStart = StartIndex 'Here I can see the selection, And I dont want to see it.
TextScreen.SelectionLength = EndIndex - EndIndex + 1
TextScreen.SelectionColor = col
TextScreen.SelectionLength = 0
TextScreen.SelectionStart = save
End Sub
I tried to catch the Selection process and it look like that:
And after one millisecond it looks ok:
So how can I stop the Selection "flickering" ?
回答1:
Try using a custom RichTextBox control that turns off the drawing and scrolling events while you reformat the contents:
Public Class RichTextBoxEx
Inherits RichTextBox
<DllImport("user32.dll")> _
Private Shared Function SendMessage(hWnd As IntPtr, wMsg As Int32, wParam As Int32, ByRef lParam As Point) As IntPtr
End Function
<DllImport("user32.dll")> _
Private Shared Function SendMessage(hWnd As IntPtr, wMsg As Int32, wParam As Int32, lParam As IntPtr) As IntPtr
End Function
Const WM_USER As Integer = &H400
Const WM_SETREDRAW As Integer = &HB
Const EM_GETEVENTMASK As Integer = WM_USER + 59
Const EM_SETEVENTMASK As Integer = WM_USER + 69
Const EM_GETSCROLLPOS As Integer = WM_USER + 221
Const EM_SETSCROLLPOS As Integer = WM_USER + 222
Private _ScrollPoint As Point
Private _Painting As Boolean = True
Private _EventMask As IntPtr
Private _SuspendIndex As Integer = 0
Private _SuspendLength As Integer = 0
Public Sub SuspendPainting()
If _Painting Then
_SuspendIndex = Me.SelectionStart
_SuspendLength = Me.SelectionLength
SendMessage(Me.Handle, EM_GETSCROLLPOS, 0, _ScrollPoint)
SendMessage(Me.Handle, WM_SETREDRAW, 0, IntPtr.Zero)
_EventMask = SendMessage(Me.Handle, EM_GETEVENTMASK, 0, IntPtr.Zero)
_Painting = False
End If
End Sub
Public Sub ResumePainting()
If Not _Painting Then
Me.Select(_SuspendIndex, _SuspendLength)
SendMessage(Me.Handle, EM_SETSCROLLPOS, 0, _ScrollPoint)
SendMessage(Me.Handle, EM_SETEVENTMASK, 0, _EventMask)
SendMessage(Me.Handle, WM_SETREDRAW, 1, IntPtr.Zero)
_Painting = True
Me.Invalidate()
End If
End Sub
End Class
Then your usage would be:
RichTextBoxEx1.SuspendPainting()
Dim save As Integer = RichTextBoxEx1.SelectionStart
RichTextBoxEx1.SelectionStart = StartIndex
RichTextBoxEx1.SelectionLength = EndIndex - StartIndex + 1
RichTextBoxEx1.SelectionColor = Color.Green
RichTextBoxEx1.SelectionLength = 0
RichTextBoxEx1.SelectionStart = save
RichTextBoxEx1.ResumePainting()
来源:https://stackoverflow.com/questions/29038072/richtextbox-flickers-while-coloring-words