public void LockBitsAndUnpad()
{
//Get width and height of bitmap.
Width = _source.PixelWidth;
Height = _source.PixelHeight;
//Get total locked pixels count.
var pixelCount = Width * Height;
//Get source bitmap pixel format size.
Depth = _source.Format.BitsPerPixel;
if (Depth != 32 && Depth != 24)
{
throw new ArgumentException("Only 24 and 32 bpp images are supported.");
}
_data = new WriteableBitmap(_source);
//Lock bitmap and return bitmap data.
_data.Lock();
/*
* https://doanvublog.wordpress.com/tag/32bpp/
* 1,4,8 and 16bpp uses a color table.
*
* 1bpp : 1 byte, 8 pixels, 2 colors
* 4bpp : 1 byte, 2 pixels, 16 colors
* 8bpp : 1 byte, 1 pixel, 256 colors
* 16bpp : 2 bytes, 1 pixel
* 24bpp : 3 bytes, 1 pixel
* 32bpp : 4 bytes, 1 pixel
*
* So, bpp/8 = color chunk size.
*/
//Create byte array to copy pixel values.
var step = Depth / 8;
//Adjust to necessary padding.
var bytesPerRow = Width * step;
var pad = bytesPerRow % 4 != 0 ? 4 - bytesPerRow % 4 : 0;
Pixels = new byte[pixelCount * step];
BackBuffer = _data.BackBuffer;
//Copy data from pointer to array normally, if it has no padding.
if (pad == 0)
{
Marshal.Copy(BackBuffer, Pixels, 0, Pixels.Length);
return;
}
//Removes the pad from the pixel array.
for (var row = 0; row < Height; row++)
{
Marshal.Copy(new IntPtr(BackBuffer.ToInt64() + row * (bytesPerRow + pad)), Pixels, row * bytesPerRow, bytesPerRow);
}
}
