GetDIBits function

The GetDIBits function retrieves the bits of the specified compatible bitmap and copies them into a buffer as a DIB using the specified format.

Syntax

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

A handle to the bitmap. This must be a compatible bitmap (DDB).

start

The first scan line to retrieve.

cLines

The number of scan lines to retrieve.

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

A pointer to a BITMAPINFO structure that specifies the desired format for the DIB data.

usage

The format of the bmiColors member of the BITMAPINFO structure. It must be one of the following values.

Value Meaning
DIB_PAL_COLORS
The color table should consist of an array of 16-bit indexes into the current logical palette.
DIB_RGB_COLORS
The color table should consist of literal red, green, blue (RGB) values.

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.

Requirements

   
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header wingdi.h (include Windows.h)
Library Gdi32.lib
DLL Gdi32.dll

See Also

BITMAPCOREHEADER

BITMAPINFO

BITMAPINFOHEADER

Bitmap Functions

Bitmaps Overview

SetDIBits