The GetDIBits function retrieves the bits of the specified compatible bitmap and copies them into a buffer as a DIB using the specified format.
int GetDIBits(
HDC hdc,
HBITMAP hbm,
UINT start,
UINT cLines,
LPVOID lpvBits,
LPBITMAPINFO lpbmi,
UINT usage
);Parameters
hdc
A handle to the device context.
hbm
TBD
start
TBD
cLines
TBD
lpvBits
A pointer to a buffer to receive the bitmap data. If this parameter is NULL, the function passes the dimensions and format of the bitmap to the BITMAPINFO structure pointed to by the lpbi parameter.
lpbmi
TBD
usage
TBD
Return Value
If the lpvBits parameter is non-NULL and the function succeeds, the return value is the number of scan lines copied from the bitmap.
If the lpvBits parameter is NULL and GetDIBits successfully fills the BITMAPINFO structure, the return value is nonzero.
If the function fails, the return value is zero.
This function can return the following value.
Return code Description
ERROR_INVALID_PARAMETER
One or more of the input parameters is invalid.
Remarks
If the requested format for the DIB matches its internal format, the RGB values for the bitmap are copied. If the requested format doesn’t match the internal format, a color table is synthesized. The following table describes the color table synthesized for each format.
| Value | Meaning |
|---|---|
| 1_BPP | The color table consists of a black and a white entry. |
| 4_BPP | The color table consists of a mix of colors identical to the standard VGA palette. |
| 8_BPP | The color table consists of a general mix of 256 colors defined by GDI. (Included in these 256 colors are the 20 colors found in the default logical palette.) |
| 24_BPP | No color table is returned. |
If the lpvBits parameter is a valid pointer, the first six members of the BITMAPINFOHEADER structure must be initialized to specify the size and format of the DIB. The scan lines must be aligned on a DWORD except for RLE compressed bitmaps.
A bottom-up DIB is specified by setting the height to a positive number, while a top-down DIB is specified by setting the height to a negative number. The bitmap color table will be appended to the BITMAPINFO structure.
If lpvBits is NULL, GetDIBits examines the first member of the first structure pointed to by lpbi. This member must specify the size, in bytes, of a BITMAPCOREHEADER or a BITMAPINFOHEADER structure. The function uses the specified size to determine how the remaining members should be initialized.
If lpvBits is NULL and the bit count member of BITMAPINFO is initialized to zero, GetDIBits fills in a BITMAPINFOHEADER structure or BITMAPCOREHEADER without the color table. This technique can be used to query bitmap attributes.
The bitmap identified by the hbmp parameter must not be selected into a device context when the application calls this function.
The origin for a bottom-up DIB is the lower-left corner of the bitmap; the origin for a top-down DIB is the upper-left corner.
Examples
For an example, see Capturing an Image.
See Also
BITMAPCOREHEADER
BITMAPINFO
BITMAPINFOHEADER
Bitmap Functions
Bitmaps Overview
SetDIBits