Julien Templier

Updating resources files with BMP and PNG files (with managed code)

This only concerns Bitmap resources (RT_BITMAP). Updating others type of resources is easier and doesn’t require specific code.

  • BMP files

Inserting BMP files is quite easy. You only have to remove the header and you are good to go.

int BMP_HEADER_BYTES = 14;
FileStream stream = new FileStream(file, 

                                   FileMode.Open,
                                   FileAccess.Read,
                                   FileShare.Read);


BinaryReader reader = new BinaryReader(stream);


byte[] data = reader.ReadBytes((int)reader.BaseStream.Length);




GCHandle gcHandle = GCHandle.Alloc(data, GCHandleType.Pinned);


IntPtr bitmap = Marshal.UnsafeAddrOfPinnedArrayElement(data, BMP_HEADER_BYTES);




uint size = (uint)(data.GetLength(0) - BMP_HEADER_BYTES);


UpdateResource(hDll, 2, resourceId, LANG_ENGLISH_ID, bitmap, size);




gcHandle.Free();


stream.Close();


    

  • PNG files
    • 



It’s a bit more difficult with PNG files. You must add a header before inserting the image data. You also need to rotate the image before inserting because of the bitmap is copied and read (alternatively, you can insert a negative height into the header, but I haven’t tested it).


Also note that we do not set the compression to BI_PNG (5) and the size of the image in the BITMAPINFO header.


[StructLayout(LayoutKind.Sequential)] 


class BITMAPINFO {


public int biSize;


public int biWidth;


public int biHeight;


public short biPlanes;


public short biBitCount;     


public int biCompression;     


public int biSizeImage;     


public int biXPelsPerMeter;


public int biYPelsPerMeter;


public int biClrUsed;


public int biClrImportant; }




// Load file 


Bitmap pngFile = new Bitmap(file);


// Required due to the way bitmap is copied and read


pngFile.RotateFlip(RotateFlipType.RotateNoneFlipY);


BitmapData data = pngFile.LockBits(new Rectangle(0, 0,


                                                 pngFile.Width, pngFile.Height),


                                   ImageLockMode.ReadOnly,


                                   PixelFormat.Format32bppArgb); 




byte[] dataBuffer = new byte[data.Height * data.Stride]; 


Marshal.Copy(data.Scan0, dataBuffer, 0, data.Height * data.Stride); 


pngFile.UnlockBits(data);


// Setup Header 


BITMAPINFO header = new BITMAPINFO(); 


header.biSize = Marshal.SizeOf(typeof(BITMAPINFO));


header.biWidth = pngFile.Width; 


header.biHeight = pngFile.Height;


header.biPlanes = 1; 


header.biBitCount = 32; 




// Convert the structure to an array 


byte[] buffer = new byte[header.biSize];


GCHandle h = GCHandle.Alloc(buffer , GCHandleType.Pinned); 


Marshal.StructureToPtr(header, h.AddrOfPinnedObject(), false);


h.Free(); 




// Write header + data 


MemoryStream memory = new MemoryStream(); 


memory.Write(buffer, 0, buffer.Length);


memory.Write(dataBuffer, 0, dataBuffer.Length);


byte[] imageData = memory.GetBuffer(); 


GCHandle gcHandle = GCHandle.Alloc(imageData, GCHandleType.Pinned); 


IntPtr firstCopyElement = Marshal.UnsafeAddrOfPinnedArrayElement(imageData, 0);




UpdateResource(hDll, 2, resourceId, LANG_ENGLISH_ID,                


	       firstCopyElement, (uint)imageData.GetLength(0));




gcHandle.Free(); 


memory.Close();















Julien