array[byte] to HBITMAP or CBitmap - c++

Question

I have an array of bytes (which I read through a stream directly from a .bmp and then store as a BLOB in a database) which I want to display as icons in a CImageList. Therefore I want to somehow load my data into an HBITMAP or CBitmap. I have done it like this up to now, reading from a file:
hPic = (HBITMAP)LoadImage(NULL, strPath, IMAGE_BITMAP, dwWidth, dwHeight, LR_LOADFROMFILE | LR_VGACOLOR);
...
CBitmap bitmap;
bitmap.Attach(hPicRet);
But obviously, that only works for files, but not for byte-arrays. How can I get the same result, but reading from an array of byte?
Edit:
Note that my array does not contain just the colour information, but rather the complete file as it is written on disk, including all headers and meta-data. It seems to me that discarding all that information is a bad idea.

Answer 1

Assuming you have the information loaded into a BYTE array named bytes....
BITMAPFILEHEADER* bmfh;
bmfh = (BITMAPFILEHEADER*)bytes;
BITMAPINFOHEADER* bmih;
bmih = (BITMAPINFOHEADER*)(bytes + sizeof(BITMAPFILEHEADER));
BITMAPINFO* bmi;
bmi = (BITMAPINFO*)bmih;
void* bits;
bits = (void*)(bytes + bmfh->bfOffBits);
HDC hdc = ::GetDC(NULL);
HBITMAP hbmp = CreateDIBitmap(hdc, bmih, CBM_INIT, bits, bmi, DIB_RGB_COLORS) ;
::ReleaseDC(NULL, hdc);
It's a little messy and could use a hefty dose of error checking, but the basic idea is sound.

Answer 2

Following sample could help you.
BITMAPINFO bmInfo;
BITMAPINFOHEADER &bmInfohdr = (BITMAPINFOHEADER)bmInfo.bmiHeader;
bmInfohdr.biSize = 40 + 255; //I think it's not of use
bmInfohdr.biWidth = x;
bmInfohdr.biHeight = y;
bmInfohdr.biPlanes=1;
bmInfohdr.biBitCount=8;
bmInfohdr.biCompression=0;
bmInfohdr.biSizeImage=0;
bmInfohdr.biXPelsPerMeter = 0;
bmInfohdr.biYPelsPerMeter = 0;
bmInfohdr.biClrUsed = 0;
bmInfohdr.biClrImportant = 0;
// should I allocate memory further than the
// bmColors[1]?? anyway the compiler gives an
// error for type mismatch!
//bmInfo.bmiColors = (RGBQUAD *)
malloc(sizeof(RGBQUAD) * 256);
// here I define the 256 graylevel palette
for (int i=0; i<256; i++)
{
bmInfo.bmiColors[i].rgbRed = i;
bmInfo.bmiColors[i].rgbGreen = i;
bmInfo.bmiColors[i].rgbBlue = i;
}
BYTE *matrix;
matrix = (BYTE*)malloc(size*sizeof(BYTE));
// here I put the BYTE values of the pixels
CDC *pdcDest = this->GetDC();
HBITMAP hBmp = CreateDIBitmap( pdcDest->m_hDC,
&bmInfohdr,
CBM_INIT,
matrix,
&bmInfo,
DIB_RGB_COLORS);
m_bmpBitmap.Attach( hBmp );

Answer 3

Something like this worked for me:
int bitmap[WX*WY]; // truecolor bitmap data
BITMAPINFO bm = { sizeof(BITMAPINFOHEADER), WX, WY, 1, 32, BI_RGB, 0, 0, 0, 0, 0 };
HBITMAP bmp = CreateDIBSection( GetDC(win), &bm, DIB_RGB_COLORS, (void**)&bitmap, 0,0 );
(This is specifically configured for 32-bit colors, but you can specify any kind).

Answer 4

Ok, here's a complete example: http://nishi.dreamhosters.com/u/so_bmp_v0.zip
#include <stdio.h>
#include <windows.h>
#pragma comment(lib,"gdi32.lib")
#pragma comment(lib,"user32.lib")
char buf[1<<22];
int main( int argc, char **argv ) {
FILE* f = fopen( "winnt.bmp", "rb" ); if( f==0 ) return 1;
fread( buf, 1,sizeof(buf), f );
fclose(f);
BITMAPFILEHEADER& bfh = (BITMAPFILEHEADER&)buf[0];
BITMAPINFO& bi = (BITMAPINFO&)buf[sizeof(BITMAPFILEHEADER)];
BITMAPINFOHEADER& bih = bi.bmiHeader;
char* bitmap = &buf[bfh.bfOffBits];
int WX=1024, WY=512; // window's width/height
int SX=bih.biWidth, SY=bih.biHeight;
HWND win = CreateWindow( "STATIC", "Bitmap test", 0x90C0, 0,0, WX,WY, 0,0, GetModuleHandle(0), 0 );
MSG msg;
PAINTSTRUCT ps;
HDC DC = GetDC(win); // window's DC
HBITMAP dib = CreateDIBitmap( DC, &bih, CBM_INIT, bitmap, &bi, DIB_RGB_COLORS );
HDC dibDC = CreateCompatibleDC( DC ); SelectObject( dibDC, dib );
ShowWindow( win, SW_SHOWNOACTIVATE );
SetFocus( win );
while( GetMessage(&msg,win,0,0) ) {
int m = msg.message;
if( m==WM_PAINT ) {
DC = BeginPaint( win, &ps );
StretchBlt( DC, 0,0,WX,WY, dibDC,0,0,SX,SY, SRCCOPY );
EndPaint( win, &ps );
} else if( (m==WM_KEYDOWN) || (m==WM_SYSKEYDOWN) ) {
break;
} else {
DispatchMessage(&msg);
}
}
return 0;
}