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Description
Locks a rectangular portion of this bitmap and provides a temporary
buffer that you can use to read or write pixel data in a specified format. Any
pixel data that you write to the buffer is copied to the Bitmap object
when you call GdipBitmapUnlockBits.
Syntax
GpStatus WINGDIPAPI GdipBitmapLockBits(
GpBitmap*
bitmap,
GDIPCONST
GpRect* rect,
UINT flags,
PixelFormat
format,
BitmapData*
lockedBitmapData
);
PowerBASIC Syntax
DECLARE FUNCTION GdipBitmapLockBits ( _
BYVAL pbitmap
AS DWORD, _
BYREF prect AS
RECTL, _
BYVAL flags AS
LONG, _
BYVAL
PixelFormat AS LONG, _
BYREF
lockedBitmapData AS BitmapData _
) AS LONG
Parameters
bitmap
[in] Pointer to the Bitmap object.
rec
[in] Pointer to a rectangle that specifies the portion of the bitmap
to be locked.
flags
[in] Set of flags that specify whether the locked portion of the
bitmap is available for reading or for writing and whether the caller has
already allocated a buffer. Individual flags are defined in the ImageLockMode
enumeration.
format
[in] Long integer value that specifies the format of the pixel data
in the temporary buffer. The pixel format of the temporary buffer does not have
to be the same as the pixel format of this Bitmap object. Microsoft® Windows® GDI+ version 1.0 does not support processing of 16-bits-per-channel
images, so you should not set this parameter equal to PixelFormat48bppRGB,
PixelFormat64bppARGB, or PixelFormat64bppPARGB.
lockedBitmapData
[in, out] Pointer to a BitmapData object. If the ImageLockModeUserInputBuf
flag of the flags parameter is cleared, then lockedBitmapData serves
only as an output parameter. In that case, the Scan0 data member of the BitmapData
object receives a pointer to a temporary buffer, which is filled with the
values of the requested pixels. The other data members of the BitmapData
object receive attributes (width, height, format, and stride) of the pixel data
in the temporary buffer. If the pixel data is stored bottom-up, the Stride
data member is negative. If the pixel data is stored top-down, the Stride
data member is positive. If the ImageLockModeUserInputBuf flag of the
flags parameter is set, then lockedBitmapData serves as an input
parameter (and possibly as an output parameter). In that case, the caller must
allocate a buffer for the pixel data that will be read or written. The caller
also must create a BitmapData object, set the Scan0 data member
of that BitmapData object to the address of the buffer, and set the
other data members of the BitmapData object to specify the attributes
(width, height, format, and stride) of the buffer.
Remarks
GdipBitmapLockBits and GdipBitmapUnlockBits
must be used as a pair. A call to GdipBitmapLockBits establishes a temporary buffer that you can
use to read or write pixel data in a specified format. After you write
to the temporary buffer, a call to GdipBitmapUnlockBits
copies the pixel data in the buffer to the Bitmap
object. If the pixel format of the temporary buffer is different from
the pixel format of the Bitmap
object, the pixel data is converted appropriately.
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