typedef struct tagBITMAPINFO { /* bmi */
BITMAPINFOHEADER bmiHeader;
RGBQUAD bmiColors[1];
} BITMAPINFO;The BITMAPINFO structure fully defines the dimensions and color information for a Windows 3.0 or later device-independent bitmap (DIB).
bmiHeader
Specifies a BITMAPINFOHEADER structure that contains information about the dimensions and color format of a DIB.
bmiColors
Specifies an array of RGBQUAD structures that define the colors in the bitmap.
A Windows 3.0 or later DIB consists of two distinct parts: a BITMAPINFO structure, which describes the dimensions and colors of the bitmap, and an array of bytes defining the pixels of the bitmap. The bits in the array are packed together, but each scan line must be zero-padded to end on a LONG boundary. Segment boundaries, however, can appear anywhere in the bitmap. The origin of the bitmap is the lower-left corner.
The biBitCount member of the BITMAPINFOHEADER structure determines the number of bits which define each pixel and the maximum number of colors in the bitmap. This member may be set to any of the following values:
| Value | Meaning |
| 1 | The bitmap is monochrome, and the bmciColors member must contain two entries. Each bit in the bitmap array represents a pixel. If the bit is clear, the pixel is displayed with the color of the first entry in the bmciColors table. If the bit is set, the pixel has the color of the second entry in the table. |
| 4 | The bitmap has a maximum of 16 colors, and the bmciColors member contains 16 entries. Each pixel in the bitmap is represented by a four-bit index into the color table. |
| For example, if the first byte in the bitmap is 0x1F, the byte represents two pixels. The first pixel contains the color in the second table entry, and the second pixel contains the color in the sixteenth table entry. | |
| 8 | The bitmap has a maximum of 256 colors, and the bmciColors member contains 256 entries. In this case, each byte in the array represents a single pixel. |
| 24 | The bitmap has a maximum of 224 colors. The bmciColors member is NULL, and each 3-byte sequence in the bitmap array represents the relative intensities of red, green, and blue, respectively, of a pixel. |
The biClrUsed member of the BITMAPINFOHEADER structure specifies the number of color indexes in the color table actually used by the bitmap. If the biClrUsed member is set to zero, the bitmap uses the maximum number of colors corresponding to the value of the biBitCount member.
The colors in the bmiColors table should appear in order of importance.
Alternatively, for functions that use DIBs, the bmiColors member can be an array of 16-bit unsigned integers that specify an index into the currently realized logical palette instead of explicit RGB values. In this case, an application using the bitmap must call DIB functions with the wUsage parameter set to DIB_PAL_COLORS.
Note:
The bmiColors member should not contain palette indexes if the bitmap is to be stored in a file or transferred to another application. Unless the application uses the bitmap exclusively and under its complete control, the bitmap color table should contain explicit RGB values.