Question

A user selects a portion of an image for a cut and paste operation. I create a new bitmap, paste the selected portion in the new image, wipe the source array and paste it back into the old image. Works but at least half the time it hangs with Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Any thoughts or help?

public BitmapSource CutToNew(double left, double top, double width, double height, double pageWidth, double pageHeight)
{
    var destBmp = new Bitmap((int)pageWidth, (int)pageHeight);
    var g = Graphics.FromImage(destBmp);
    g.FillRectangle(new SolidBrush(Color.White), 0, 0, 
       (int)pageHeight, (int)pageWidth);
    g.Dispose();

    var croppedArea = new Rectangle((int)left, (int)top, (int)width, (int)height);
    BitmapData croppedSource = _bitmapImage.LockBits(croppedArea, 
          ImageLockMode.ReadWrite, BitmapImage.PixelFormat);
    var croppedDestArea = new Rectangle((int)left, (int)top, (int)width, (int)height);
    BitmapData croppedDest = destBmp.LockBits(croppedDestArea, 
          ImageLockMode.WriteOnly, BitmapImage.PixelFormat);

    // Create data array to hold bmpSource pixel data
    int stride = croppedSource.Stride;
    int numBytes = stride * (int)height;
    var srcData = new byte[numBytes];
    var destData = new byte[numBytes];

    Marshal.Copy(croppedSource.Scan0, srcData, 0, numBytes);
    //Tried creating a separate array in case that helped.
    Array.Copy(srcData, destData, srcData.Length);
    //Often hangs here with Attempted to read or write protected memory.
    Marshal.Copy(destData, 0, croppedDest.Scan0, numBytes);

    destBmp.UnlockBits(croppedDest);
    var retVal = new DocAppImage {BitmapImage = destBmp};
    destBmp.Dispose();

    //Blank the source area
    for (int y = 0; y < srcData.Length; y++)
        srcData[y] = 0xFF;

    Marshal.Copy(srcData, 0, croppedSource.Scan0, numBytes);
    _bitmapImage.UnlockBits(croppedSource);

    return retVal.bmpSource;
}

private Bitmap _bitmapImage;
public Bitmap BitmapImage
{
    get
    {
        if (_bitmapImage != null)
            return _bitmapImage;

        if (FileImage != null)
        {
            var stream = new MemoryStream(FileImage); //Fileimage=TIFF read from file.
            _bitmapImage = new Bitmap(stream);
            return _bitmapImage;
        }
        return null;
    }
    set
    {
        if (value != null)
        {

            ImageCodecInfo codecInfo = GetImageCodecInfo("TIFF");
             ... implementation to set the bitmap image.

Answer 1

You may want to try specifying your PixelFormat when you create the new object.

For example:

var destBmp = new Bitmap((int)pageWidth, (int)pageHeight, PixelFormat.Format24bppRgb);