c# - How to avoid from richTextBox to being flickering? - Stack Overflow

I call the method UpdateRichTextBox inside a pictureBox mouse move event.

private void pbImage_MouseMove(object sender, MouseEventArgs e)
{
    if (pbImage.Image == null) return;

    Bitmap img = new Bitmap(pbImage.Image);
    int imgWidth = img.Width;
    int imgHeight = img.Height;
    int pbWidth = pbImage.Width;
    int pbHeight = pbImage.Height;

    // Compute scale to fit in PictureBox while maintaining aspect ratio
    float scaleX = (float)pbWidth / imgWidth;
    float scaleY = (float)pbHeight / imgHeight;
    float scale = Math.Min(scaleX, scaleY); // Maintain aspect ratio

    // Calculate the actual displayed image size in PictureBox
    int displayWidth = (int)(imgWidth * scale);
    int displayHeight = (int)(imgHeight * scale);

    // Compute offsets (padding) due to aspect ratio
    int offsetX = (pbWidth - displayWidth) / 2;
    int offsetY = (pbHeight - displayHeight) / 2;

    // Adjust mouse coordinates relative to image
    int imgX = (int)((e.X - offsetX) / scale);
    int imgY = (int)((e.Y - offsetY) / scale);

    // Ensure coordinates are within the image bounds
    if (imgX >= 0 && imgX < imgWidth && imgY >= 0 && imgY < imgHeight)
    {
        // LockBits for fast pixel reading
        BitmapData bmpData = img.LockBits(new Rectangle(0, 0, imgWidth, imgHeight),
                                          ImageLockMode.ReadOnly,
                                          PixelFormat.Format24bppRgb);

        IntPtr ptr = bmpData.Scan0;
        int stride = bmpData.Stride;
        int bytesPerPixel = 3;

        int index = (imgY * stride) + (imgX * bytesPerPixel);
        byte[] pixelData = new byte[3];

        Marshal.Copy(ptr + index, pixelData, 0, 3);

        img.UnlockBits(bmpData);

        Color pixelColor = Color.FromArgb(pixelData[2], pixelData[1], pixelData[0]);
        string hexColor = $"#{pixelColor.R:X2}{pixelColor.G:X2}{pixelColor.B:X2}";
        string colorName = GetClosestColorName(pixelColor);
        string mouseInfoText =
            $"