GetDIBits

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

int GetDIBits(
  HDC hdc,           // handle to device context
  HBITMAP hbmp,      // handle to bitmap
  UINT uStartScan,   // first scan line to set in destination bitmap
  UINT cScanLines,   // number of scan lines to copy
  LPVOID lpvBits,    // address of array for bitmap bits
  LPBITMAPINFO lpbi, // address of structure with bitmap data
  UINT uUsage        // RGB or palette index
);
 

Parameters

hdc

Handle to the device context.

hbmp

Handle to the bitmap.

uStartScan

Specifies the first scan line to retrieve.

cScanLines

Specifies the number of scan lines to retrieve.

lpvBits

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.

lpbi

Pointer to a BITMAPINFO structure that specifies the desired format for the device-independent bitmap (DIB) data.

uUsage

Specifies 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 Values

If the lpvBits parameter is non-NULL and the function succeeds, the return value is the number of scan lines copied from the bitmap.

Windows 95 and Windows 98: If the lpvBits parameter is NULL and GetDIBits successfully fills the BITMAPINFO structure, the return value is the total number of scan lines in the bitmap.

Windows NT: If the lpvBits parameter is NULL and GetDIBits successfully fills the BITMAPINFO structure, the return value is non-zero.

If the function fails, the return value is zero.

Windows NT: To get extended error information, call GetLastError.

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.

If the lpvBits parameter is a valid pointer, the first six members of the bitmap information header structure must be initialized to specify the size and format of the DIB.

Note  A bitmap information header structure may be one of the following:

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's 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 bitmap information header 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 bitmap information header 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.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in wingdi.h.
  Import Library: Use gdi32.lib.

See Also

Bitmaps Overview, Bitmap Functions, SetDIBits