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BITMAPINFOHEADER Structure Members

Summary

The following tables list the members exposed by BITMAPINFOHEADER.

Public Fields

Name Description
Public Field biBitCount Specifies the number of bits per pixel. The biBitCount member of the BITMAPINFOHEADER structure determines the number of bits that define each pixel and the maximum number of colors in the bitmap. This member must be one of the following values.
Public Field biClrImportant Specifies the number of color indexes required for displaying the bitmap. If this value is zero, all colors are required.
Public Field biClrUsed Specifies the number of color indexes in the color table that are actually used by the bitmap. If this value is zero, the bitmap uses the maximum number of colors corresponding to the value of the biBitCount member for the compression mode specified by biCompression. If biClrUsed is nonzero and the biBitCount member is less than 16, the biClrUsed member specifies the actual number of colors the graphics engine or device driver accesses. If biBitCount is 16 or greater, the biClrUsed member specifies the size of the color table used to optimize performance of the system color palettes. If biBitCount equals 16 or 32, the optimal color palette starts immediately following the three DWORD masks. If the bitmap is a packed bitmap (a bitmap in which the bitmap array immediately follows the BITMAPINFO header and is referenced by a single pointer), the biClrUsed member must be either zero or the actual size of the color table.
Public Field biCompression Specifies the type of compression for a compressed bottom-up bitmap (top-down DIBs cannot be compressed). This member can be one of the following values. BI_RGB An uncompressed format. BI_BITFIELDS Specifies that the bitmap is not compressed and that the color table consists of three DWORD color masks that specify the red, green, and blue components of each pixel. This is valid when used with 16-bit and 32-bpp bitmaps. BI_ALPHABITFIELDS Specifies that the bitmap is not compressed and that the color table consists of four DWORD color masks that specify the red, green, blue, and alpha components of each pixel. This is valid when used with 16-bit and 32-bpp bitmaps. You can OR any of the values in the above table with BI_SRCPREROTATE to specify that the source DIB section has the same rotation angle as the destination.
Public Field biHeight Specifies the height of the bitmap, in pixels. If biHeight is positive, the bitmap is a bottom-up DIB and its origin is the lower left corner. If biHeight is negative, the bitmap is a top-down DIB and its origin is the upper left corner. If biHeight is negative, indicating a top-down DIB, biCompression must be either BI_RGB or BI_BITFIELDS. Top-down DIBs cannot be compressed.
Public Field biPlanes Specifies the number of planes for the target device. This value must be set to 1.
Public Field biSize Specifies the size of the structure, in bytes. This size does not include the color table or the masks mentioned in the biClrUsed member.
Public Field biSizeImage Specifies the size, in bytes, of the image. This may be set to zero for BI_RGB bitmaps.
Public Field biWidth Specifies the width of the bitmap, in pixels.
Public Field biXPelsPerMeter Specifies the horizontal resolution, in pixels per meter, of the target device for the bitmap. An application can use this value to select a bitmap from a resource group that best matches the characteristics of the current device.
Public Field biYPelsPerMeter Specifies the vertical resolution, in pixels per meter, of the target device for the bitmap.
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