Is there a fast alternative to creating a Texture2D from a Bitmap object in XNA?

Question

I've looked around a lot and the only methods I've found for creating a Texture2D from a Bitmap are:

using  (MemoryStream s = new  MemoryStream())
{
   bmp.Save(s, System.Drawing.Imaging.ImageFormat.Png);
   s.Seek(0, SeekOrigin.Begin);
   Texture2D tx = Texture2D.FromFile(device, s);
}

and

Texture2D tx = new Texture2D(device, bmp.Width, bmp.Height,
                        0, TextureUsage.None, SurfaceFormat.Color);
tx.SetData<byte>(rgbValues, 0, rgbValues.Length, SetDataOptions.NoOverwrite);

Where rgbValues is a byte array containing the bitmap's pixel data in 32-bit ARGB format.

My question is, are there any faster approaches that I can try?

I am writing a map editor which has to read in custom-format images (map tiles) and convert them into Texture2D textures to display. The previous version of the editor, which was a C++ implementation, converted the images first into bitmaps and then into textures to be drawn using DirectX. I have attempted the same approach here, however both of the above approaches are significantly too slow. To load into memory all of the textures required for a map takes for the first approach ~250 seconds and for the second approach ~110 seconds on a reasonable spec computer (for comparison, C++ code took approximately 5 seconds). If there is a method to edit the data of a texture directly (such as with the Bitmap class's LockBits method) then I would be able to convert the custom-format images straight into a Texture2D and hopefully save processing time.

Any help would be very much appreciated.

Thanks

Answer 1

You want LockBits? You get LockBits.

In my implementation I passed in the GraphicsDevice from the caller so I could make this method generic and static.

public static Texture2D GetTexture2DFromBitmap(GraphicsDevice device, Bitmap bitmap)
{
    Texture2D tex = new Texture2D(device, bitmap.Width, bitmap.Height, 1, TextureUsage.None, SurfaceFormat.Color);

    BitmapData data = bitmap.LockBits(new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, bitmap.PixelFormat);

    int bufferSize = data.Height * data.Stride;

    //create data buffer 
    byte[] bytes = new byte[bufferSize];    

    // copy bitmap data into buffer
    Marshal.Copy(data.Scan0, bytes, 0, bytes.Length);

    // copy our buffer to the texture
    tex.SetData(bytes);

    // unlock the bitmap data
    bitmap.UnlockBits(data);

    return tex;
}

Answer 2

they have changed the format from bgra to rgba in XNA 4.0, so that method gives strange colors, the red and blue channels needs to be switched. Here's a method i wrote that is super fast! (loads 1500x 256x256 pixel textures in about 3 seconds).

    private Texture2D GetTexture(GraphicsDevice dev, System.Drawing.Bitmap bmp)
    {
        int[] imgData = new int[bmp.Width * bmp.Height];
        Texture2D texture = new Texture2D(dev, bmp.Width, bmp.Height);

        unsafe
        {
            // lock bitmap
            System.Drawing.Imaging.BitmapData origdata = 
                bmp.LockBits(new System.Drawing.Rectangle(0, 0, bmp.Width, bmp.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, bmp.PixelFormat);

            uint* byteData = (uint*)origdata.Scan0;

            // Switch bgra -> rgba
            for (int i = 0; i < imgData.Length; i++)
            {
                byteData[i] = (byteData[i] & 0x000000ff) << 16 | (byteData[i] & 0x0000FF00) | (byteData[i] & 0x00FF0000) >> 16 | (byteData[i] & 0xFF000000);                        
            }                

            // copy data
            System.Runtime.InteropServices.Marshal.Copy(origdata.Scan0, imgData, 0, bmp.Width * bmp.Height);

            byteData = null;

            // unlock bitmap
            bmp.UnlockBits(origdata);
        }

        texture.SetData(imgData);

        return texture;
    }