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typedef struct tagPBITMAP {
    short bmType;
    short bmWidth;
    short bmHeight;
    short bmWidthBytes;
    BYTE  bmPlanes;
    BYTE  bmBitsPixel;
    long  bmBits;
    long  bmWidthPlanes;
    long  bmlpPDevice;
    short bmSegmentIndex;
    short bmScanSegment;
    short bmFillBytes;
    short reserved1;
    short reserved2;
} PBITMAP;
 
A PBITMAP structure specifies the dimensions, attributes, and bits of a
physical bitmap.
 
Member          Description
────────────────────────────────────────────────────────────────────────────
 
bmType          Specifies a physical bitmap. The member must be set to
                zero.
 
bmWidth         Specifies the width of the bitmap in pixels.
 
bmHeight        Specifies the height of the bitmap in raster lines.
 
bmWidthBytes    Specifies the number of bytes in each raster line of this
                bitmap. The number of bytes must be even; all raster lines
                must be aligned on 16-bit boundaries.
 
bmPlanes        Specifies the number of color planes.
 
bmBitsPixel     Specifies the number of color bits for each pixel.
 
bmBits          Points to an array of bits specifying the pixels of the
                bitmap. The array must be aligned on a 16-bit boundary.
 
bmWidthPlanes   Specifies the size in bytes of each color plane. It is equal
                to the product of bmWidthBytes*bmHeight.
 
bmlpPDevice     Points to the PDEVICE structure specifying the device for
                which this bitmap is compatible.
 
bmSegmentIndex  Specifies the segment or selector offset for segments in the
                bitmap array. If the bitmap is less than 64K bytes, this
                member is zero.
 
bmScanSegment   Specifies the number of raster lines contained in each
                segment of the bitmap array. If the bitmap is less than 64K
                bytes, this member is zero.
 
bmFillBytes     Specifies the number of extra bytes in each segment.
                Graphics-device interface (GDI) allocates storage for the
                bitmap array in 16-byte multiples.
 
reserved1       Reserved; do not use.
 
reserved2       Reserved; do not use.
 
Comments
 
If the bitmap bits exceed 64K bytes, GDI allocates a two or more segments to
store the bitmap. In such cases, the bmScanSegment member specifies the
number of raster lines stored in each segment, with bmFillBytes specifying
any additional bytes needed to round the segment size out to a multiple of
16; no segment contains more than 64K bytes. The total number of segments is
equal to the quotient of bmHeight divided by bmScanSegment rounded up by one
if the remainder is not zero. The selector (or segment address) for each
segment is a multiple of bmSegmentIndex.
 
GDI stores the bits in the bitmap array as raster lines, with the raster
line representing the top of the bitmap stored first. If the bitmap has more
than one plane, GDI stores the first raster lines for all planes at the
beginning of the array, stores the second raster lines next, and so on. The
following shows the layout for a 4-plane bitmap:
 
Plane 0, first raster line
Plane 1, first raster line
Plane 2, first raster line
Plane 3, first raster line
Plane 0, second raster line
        .
        .
        .
Plane 0, last raster line
Plane 1, last raster line
Plane 2, last raster line
Plane 3, last raster line
 
If the bitmap array exceeds 64K bytes, GDI splits the raster lines across
several segments but retains the storage order, giving the first raster
lines in the first segment and the last raster lines in the last segment.
When GDI splits the raster lines, it ensures that matching raster lines from
the various planes are always in the same segment. If necessary, GDI leaves
a number of empty bytes (as specified by bmFillBytes) at the end of the
segment to round out the segment size to a multiple of 16.
 
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