我在計時器控制元件下使用 Windows.Media.Ocr 掃描螢屏中的一些文本，每 200 毫秒觸發一次滴答事件。然后我在一個不幸閃爍的富文本框中顯示輸出..
我制作了一個 gif 來顯示這個問題（ocr 是故意用 M 掃描值）
有什么辦法可以阻止這種行為？謝謝
我在計時器內部使用的代碼是：
Dim softwareBmp As Windows.Graphics.Imaging.SoftwareBitmap
Using bmp As Bitmap = New Bitmap(PictureBox1.Width, PictureBox1.Height)
Using g As Graphics = Graphics.FromImage(bmp)
Dim pt As Point = Me.PointToScreen(New Point(PictureBox1.Left, PictureBox1.Top))
g.CopyFromScreen(pt.X, pt.Y, 0, 0, bmp.Size, CopyPixelOperation.SourceCopy)
Using memStream = New Windows.Storage.Streams.InMemoryRandomAccessStream()
bmp.Save(memStream.AsStream(), System.Drawing.Imaging.ImageFormat.Bmp)
Dim decoder As Windows.Graphics.Imaging.BitmapDecoder = Await Windows.Graphics.Imaging.BitmapDecoder.CreateAsync(memStream)
softwareBmp = Await decoder.GetSoftwareBitmapAsync(decoder.BitmapPixelFormat, BitmapAlphaMode.Ignore)
End Using
End Using
End Using
Dim ocrEng = OcrEngine.TryCreateFromLanguage(New Windows.Globalization.Language("en-US"))
Dim languages As IReadOnlyList(Of Windows.Globalization.Language) = ocrEng.AvailableRecognizerLanguages
For Each language In languages
Console.WriteLine(language.LanguageTag)
Next
Dim r = ocrEng.RecognizerLanguage
Dim n = ocrEng.MaxImageDimension
Dim ocrResult = Await ocrEng.RecognizeAsync(softwareBmp)
RichTextBox1.Clear()
Dim wordList As List(Of cText) = New List(Of cText)()
Dim lines As IReadOnlyList(Of OcrLine) = ocrResult.Lines
For Each line In lines
For Each word In line.Words
Dim nY As Double = CLng(word.BoundingRect.Bottom / 10) * 10
wordList.Add(New cText() With {.Text = word.Text, .LocY = nY, .LocX = word.BoundingRect.Left})
Next
Next
wordList.Sort(New WordComparer())
Dim oldLocY As Double = 0
For Each item As cText In wordList
If (item.LocY > oldLocY And oldLocY <> 0) Then
RichTextBox1.Text = Environment.NewLine
End If
RichTextBox1.Text = (item.Text " ")
oldLocY = item.LocY
Next
uj5u.com熱心網友回復：
我使用WM_SETREDRAW解決了
<DllImport("User32.dll", SetLastError:=True, CharSet:=CharSet.Unicode)>
Public Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, ByVal lParam As IntPtr) As Integer
End Function
Public Const WM_SETREDRAW As Integer = &HB
添加行之前（在RichTextBox1.Clear() 之前）
If (RichTextBox1.IsHandleCreated) Then
SendMessage(RichTextBox1.Handle, WM_SETREDRAW, 0, IntPtr.Zero)
End If
添加行后：
If (RichTextBox1.IsHandleCreated) Then
SendMessage(RichTextBox1.Handle, WM_SETREDRAW, 1, IntPtr.Zero)
RichTextBox1.Invalidate()
End If
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