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Annotation of generator/main/dib.c, revision 1.1

1.1     ! root        1: /* Generator is (c) James Ponder, 1997-2001 http://www.squish.net/generator/ */
        !             2: 
        !             3: #include <assert.h>
        !             4: #include <stdlib.h>
        !             5: 
        !             6: #include "generator.h"
        !             7: 
        !             8: #include "dib.h"
        !             9: 
        !            10: /* From http://www.jmcgowan.com/avitech.html */
        !            11: 
        !            12: /*
        !            13:  * The DIB files have a standard header that identifies the format, size,
        !            14:  * color palette (if applicable) of the bitmapped image.  The header
        !            15:  * is a BITMAPINFO structure.
        !            16:  * 
        !            17:  * typedef struct tagBITMAPINFO {
        !            18:  *     BITMAPINFOHEADER    bmiHeader;
        !            19:  *     RGBQUAD             bmiColors[1];
        !            20:  * } BITMAPINFO;
        !            21:  * 
        !            22:  * The BITMAPINFOHEADER is a structure of the form:
        !            23:  * 
        !            24:  * typedef struct tagBITMAPINFOHEADER{ // bmih 
        !            25:  *    DWORD  biSize; 
        !            26:  *    LONG   biWidth; 
        !            27:  *    LONG   biHeight; 
        !            28:  *    WORD   biPlanes; 
        !            29:  *    WORD   biBitCount 
        !            30:  *    DWORD  biCompression; // a DIB can be compressed using run length encoding
        !            31:  *    DWORD  biSizeImage; 
        !            32:  *    LONG   biXPelsPerMeter; 
        !            33:  *    LONG   biYPelsPerMeter; 
        !            34:  *    DWORD  biClrUsed; 
        !            35:  *    DWORD  biClrImportant; 
        !            36:  * } BITMAPINFOHEADER; 
        !            37:  *  
        !            38:  * bmiColors[1] is the first entry in an optional color palette or color
        !            39:  * table of RGBQUAD data structures.  True color (24 bit RGB) images
        !            40:  * do not need a color table.  4 and 8 bit color images use a color table.
        !            41:  * 
        !            42:  * typedef struct tagRGBQUAD { // rgbq 
        !            43:  *     BYTE    rgbBlue; 
        !            44:  *     BYTE    rgbGreen; 
        !            45:  *     BYTE    rgbRed; 
        !            46:  *     BYTE    rgbReserved; // always zero
        !            47:  * } RGBQUAD; 
        !            48:  *  
        !            49:  * A DIB consists of
        !            50:  * 
        !            51:  *   (BITMAPINFOHEADER)(optional color table of RGBQUAD's)(data for the
        !            52:  * bitmapped image)
        !            53:  * 
        !            54:  */
        !            55: 
        !            56: /*
        !            57:  * Other useful links:
        !            58:  * http://www.cwi.nl/ftp/audio/RIFF-format
        !            59:  *
        !            60:  */
        !            61: 
        !            62: void dib_setheader(t_bmih *bmih, uint32 x, uint32 y)
        !            63: {
        !            64:   uint8 pad = 4 - ((x * 3) & 3); /* must align to 32 bits (4 bytes) */
        !            65: 
        !            66:   if (pad == 4)
        !            67:     pad = 0; 
        !            68:   bmih->biSize = sizeof(t_bmih);
        !            69:   bmih->biWidth = x;
        !            70:   bmih->biHeight = y;
        !            71:   bmih->biPlanes = 1;
        !            72:   bmih->biBitCount = 24;
        !            73:   bmih->biCompression = 0; /* BI_RGB */
        !            74:   bmih->biSizeImage = ((x * 3) + pad) * y;
        !            75:   bmih->biXPelsPerMeter = 0;
        !            76:   bmih->biYPelsPerMeter = 0;
        !            77:   bmih->biClrUsed = 0; /* no palette in 24 bit mode */
        !            78:   bmih->biClrImportant = 0; /* no palette in 24 bit mode */
        !            79:   assert(bmih->biSize == 40);
        !            80: }

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