bitmap.cpp

#include "bitmap.h"

static void errhandler(TCHAR* e, HWND hwnd) {
    MessageBox(hwnd, e, "error", MB_OK);
}

PBITMAPINFO CreateBitmapInfoStruct(HWND hwnd, HBITMAP hBmp)
{
    BITMAP bmp;
    PBITMAPINFO pbmi;
    WORD    cClrBits;

    // Retrieve the bitmap color format, width, and height.  
    if (!GetObject(hBmp, sizeof(BITMAP), (LPSTR)&bmp))
        errhandler("GetObject", hwnd);

    // Convert the color format to a count of bits.  
    cClrBits = (WORD)(bmp.bmPlanes * bmp.bmBitsPixel);
    if (cClrBits == 1)
        cClrBits = 1;
    else if (cClrBits <= 4)
        cClrBits = 4;
    else if (cClrBits <= 8)
        cClrBits = 8;
    else if (cClrBits <= 16)
        cClrBits = 16;
    else if (cClrBits <= 24)
        cClrBits = 24;
    else cClrBits = 32;

    // Allocate memory for the BITMAPINFO structure. (This structure  
    // contains a BITMAPINFOHEADER structure and an array of RGBQUAD  
    // data structures.)  

    if (cClrBits < 24)
        pbmi = (PBITMAPINFO)LocalAlloc(LPTR,
            sizeof(BITMAPINFOHEADER) +
            sizeof(RGBQUAD) * ((__int64)1 << cClrBits));

    // There is no RGBQUAD array for these formats: 24-bit-per-pixel or 32-bit-per-pixel 

    else
        pbmi = (PBITMAPINFO)LocalAlloc(LPTR,
            sizeof(BITMAPINFOHEADER));

    // Initialize the fields in the BITMAPINFO structure.  

    pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    pbmi->bmiHeader.biWidth = bmp.bmWidth;
    pbmi->bmiHeader.biHeight = bmp.bmHeight;
    pbmi->bmiHeader.biPlanes = bmp.bmPlanes;
    pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel;
    if (cClrBits < 24)
        pbmi->bmiHeader.biClrUsed = (1 << cClrBits);

    // If the bitmap is not compressed, set the BI_RGB flag.  
    pbmi->bmiHeader.biCompression = BI_RGB;

    // Compute the number of bytes in the array of color  
    // indices and store the result in biSizeImage.  
    // The width must be DWORD aligned unless the bitmap is RLE 
    // compressed. 
    pbmi->bmiHeader.biSizeImage = ((pbmi->bmiHeader.biWidth * cClrBits + 31) & ~31) / 8
        * pbmi->bmiHeader.biHeight;
    // Set biClrImportant to 0, indicating that all of the  
    // device colors are important.  
    pbmi->bmiHeader.biClrImportant = 0;
    return pbmi;
}

void CreateBMPFile(HWND hwnd, LPTSTR pszFile, PBITMAPINFO pbi,
    HBITMAP hBMP, HDC hDC)
{
    HANDLE hf;                 // file handle  
    BITMAPFILEHEADER hdr;       // bitmap file-header  
    PBITMAPINFOHEADER pbih;     // bitmap info-header  
    LPBYTE lpBits;              // memory pointer  
    DWORD dwTotal;              // total count of bytes  
    DWORD cb;                   // incremental count of bytes  
    BYTE* hp;                   // byte pointer  
    DWORD dwTmp;

    pbih = (PBITMAPINFOHEADER)pbi;
    lpBits = (LPBYTE)GlobalAlloc(GMEM_FIXED, pbih->biSizeImage);

    if (!lpBits)
        errhandler("GlobalAlloc", hwnd);

    // Retrieve the color table (RGBQUAD array) and the bits  
    // (array of palette indices) from the DIB.  
    if (!GetDIBits(hDC, hBMP, 0, (WORD)pbih->biHeight, lpBits, pbi,
        DIB_RGB_COLORS))
    {
        errhandler("GetDIBits", hwnd);
    }

    // Create the .BMP file.  
    hf = CreateFile(pszFile,
        GENERIC_READ | GENERIC_WRITE,
        (DWORD)0,
        NULL,
        CREATE_ALWAYS,
        FILE_ATTRIBUTE_NORMAL,
        (HANDLE)NULL);
    if (hf == INVALID_HANDLE_VALUE)
        errhandler("CreateFile", hwnd);
    hdr.bfType = 0x4d42;        // 0x42 = "B" 0x4d = "M"  
    // Compute the size of the entire file.  
    hdr.bfSize = (DWORD)(sizeof(BITMAPFILEHEADER) +
        pbih->biSize + pbih->biClrUsed
        * sizeof(RGBQUAD) + pbih->biSizeImage);
    hdr.bfReserved1 = 0;
    hdr.bfReserved2 = 0;

    // Compute the offset to the array of color indices.  
    hdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) +
        pbih->biSize + pbih->biClrUsed
        * sizeof(RGBQUAD);

    // Copy the BITMAPFILEHEADER into the .BMP file.  
    if (!WriteFile(hf, (LPVOID)&hdr, sizeof(BITMAPFILEHEADER),
        (LPDWORD)&dwTmp, NULL))
    {
        errhandler("WriteFile", hwnd);
    }

    // Copy the BITMAPINFOHEADER and RGBQUAD array into the file.  
    if (!WriteFile(hf, (LPVOID)pbih, sizeof(BITMAPINFOHEADER)
        + pbih->biClrUsed * sizeof(RGBQUAD),
        (LPDWORD)&dwTmp, (NULL)))
        errhandler("WriteFile", hwnd);

    // Copy the array of color indices into the .BMP file.  
    dwTotal = cb = pbih->biSizeImage;
    hp = lpBits;
    if (!WriteFile(hf, (LPSTR)hp, (int)cb, (LPDWORD)&dwTmp, NULL))
        errhandler("WriteFile", hwnd);

    // Close the .BMP file.  
    if (!CloseHandle(hf))
        errhandler("CloseHandle", hwnd);

    // Free memory.  
    GlobalFree((HGLOBAL)lpBits);
}