let's say i have painted something on a dc created with CreateCompatibleDC (later CreateCompatibleBitmap and SelectObject). how can i save the content as a bitmap? and why does rc.exe say that the bitmap painted with "Paint" isn't a windows 3.0 bitmap or whatever? bye
Posted on 2001-04-21 14:01:00 by [SaFc0n]
A bitmap file consists of a few structures and the image data. At the start of the file, there's an BITMAPFILEHEADER structure, followed by a BITMAPINFO structure. The BITMAPINFO is a BITMAPINFOHEADER structure (with size, color, etc) information, followed by the raw image data. So all you have to do is fill in a BITMAPFILEHEADER and a BITMAPINFOHEADER structure, write both to a file and then write all the image data. GetDIBits can be a usefull function. Thomas
Posted on 2001-04-21 15:20:00 by Thomas
ok, so i've to open a new file, write the BITMAPFILEHEADER structure and then the BITMAPINFOHEADER to it, and then the raw bitmap data. but how to write the raw bitmap data exactly? e.g.

invoke CreateCompatibleDC,NULL
mov hBackBuffer,eax
invoke GetDC,hWin
push eax
invoke CreateCompatibleBitmap,eax,157,150
mov hBackBitmap,eax
pop eax
invoke ReleaseDC,hWin,eax
invoke SelectObject,hBackBuffer,hBackBitmap
invoke Ellipse,hBackBuffer,5,5,50,50
how can i write the DC (hBackBuffer) to the file now? i don't understand that. tnx
Posted on 2001-04-22 04:35:00 by [SaFc0n]
I'll write some code for you today. Thomas
Posted on 2001-04-23 03:48:00 by Thomas
Here's some code:

SaveDCToBitmap  proc uses ebx   hDC:DWORD, hBitmap:DWORD, lpFileName:DWORD
LOCAL   BytesWritten:DWORD
LOCAL   hTempMem:DWORD, pTempMem:DWORD
LOCAL   hImageMem:DWORD, pImageMem:DWORD
LOCAL   HeaderAndPaletteSize:DWORD
LOCAL   retval:DWORD

    ;--- Create new file (NOTE: CREATE_ALWAYS overwrites old file!!!!!) ---
    invoke  CreateFile, lpFileName, GENERIC_WRITE, 0, \
        xor     eax, eax
    mov     hFile, eax
    ;--- The bitmap file header will be written at the end, so skip it now ---
    invoke  SetFilePointer, hFile, SIZEOF BITMAPFILEHEADER, 0, FILE_BEGIN

    ;--- allocate memory for bitmapinfoheader and palette if available ---
    ; get number of bytes to allocate for the palette in eax
    ; eax=0 if no palette (full color image or 16-bit color)
    invoke  GetDeviceCaps, hDC, BITSPIXEL   
    mov     ecx, eax
    .IF     ecx<16
        xor     eax, eax
        inc     eax
        shl     eax, cl
        shl     eax, 2
        xor     eax, eax
    ; add size of BITMAPINFOHEADER
    add         eax, SIZEOF BITMAPINFOHEADER
    mov         HeaderAndPaletteSize, eax
    ; allocate memory
    invoke      GlobalAlloc, GMEM_MOVEABLE or GMEM_ZEROINIT, eax
    mov         hTempMem, eax
    invoke      GlobalLock, eax
    mov         pTempMem, eax
    mov         ebx, pTempMem
    ;Get bitmapinfoheader:  
    assume      ebx:PTR BITMAPINFOHEADER
    mov         .biSize, SIZEOF BITMAPINFOHEADER
    invoke      GetDIBits, hDC, hBitmap, 0, 0, NULL, ebx, DIB_RGB_COLORS
    ; Get size of image data:
    mov         eax, .biSizeImage
    ; allocate memory for image data:
    invoke      GlobalAlloc, GMEM_MOVEABLE, eax
    mov         hImageMem, eax
    invoke      GlobalLock, eax
    mov         pImageMem, eax
    ; get image data and full bitmap info header + palette if available:
    mov         ecx, .biHeight
    invoke      GetDIBits, hDC, hBitmap, 0, ecx, pImageMem, pTempMem, DIB_RGB_COLORS
    ; write header and palette to file
    invoke      WriteFile, hFile, pTempMem, HeaderAndPaletteSize, ADDR BytesWritten, 0
    .IF         eax==0
        mov     retval, eax
        jmp     @return1
    ; write image data to file:
    invoke      WriteFile, hFile, pImageMem,  .biSizeImage, ADDR BytesWritten, 0
    .IF         eax==0
        mov     retval, eax
        jmp     @return1
    ;fill bitmapfileheader:
    mov     bfh.bfType, "MB"        ;"BM", reversed
    mov     eax, HeaderAndPaletteSize
    mov     bfh.bfOffBits, eax

    add     eax,  .biSizeImage 
    mov     bfh.bfSize, eax
    and     bfh.bfReserved1, 0
    and     bfh.bfReserved2, 0
    ;write bitmapfileheader:
    invoke  SetFilePointer, hFile, 0, 0, FILE_BEGIN
    invoke  WriteFile, hFile, ADDR bfh, SIZEOF BITMAPFILEHEADER, ADDR BytesWritten, 0
    .IF     eax==0
        mov     retval, eax
        jmp     @return1
    mov         retval, 1
    assume      ebx:nothing
    ;--- clear memory handles ---
    invoke      GlobalUnlock, hTempMem
    invoke      GlobalFree, hTempMem
    invoke      GlobalUnlock, hImageMem
    invoke      GlobalFree, hImageMem
    ;--- Close file handle ---
    invoke  CloseHandle, hFile   
    mov     eax, retval
SaveDCToBitmap  endp
I don't know if it works perfectly for all color formats, paint had some troubles with reading the bitmap when it's a 16-bit or 32-bit color image. 8-bit and 24-bit worked fine. But paint shop pro read all the bitmaps the program wrote. Hope this helps, Thomas
Posted on 2001-04-23 10:16:00 by Thomas