SetBoundsRect
The SetBoundsRect
function controls the accumulation of bounding rectangle information for the
specified device context. Windows can maintain a bounding rectangle for all drawing
operations. An application can examine and set this rectangle. The drawing
boundaries are useful for invalidating bitmap caches.
UINT SetBoundsRect(
|
HDC hdc, |
// handle of device
context |
|
CONST RECT *lprcBounds, |
// address of
rectangle coordinates |
|
UINT flags |
// controls
rectangle combination |
|
); |
|
Parameters
hdc
Identifies
the device context for which to accumulate bounding rectangles.
lprcBounds
Points to a RECT structure used to set the
bounding rectangle. Rectangle dimensions are in logical coordinates. This
parameter can be NULL.
flags
Specifies how
the new rectangle will be combined with the accumulated rectangle. This
parameter can be a combination of the following values:
|
Value |
Description |
|
DCB_ACCUMULATE |
Adds the
rectangle specified by the lprcBounds parameter to the bounding
rectangle (using a rectangle union operation). Using both DCB_RESET and
DCB_ACCUMULATE sets the bounding rectangle to the rectangle specified by the lprcBounds
parameter. |
|
DCB_DISABLE |
Turns off
boundary accumulation. |
|
DCB_ENABLE |
Turns on
boundary accumulation, which is disabled by default. |
|
DCB_RESET |
Clears the
bounding rectangle. |
Return Values
If the
function succeeds, the return value specifies the previous state of the
bounding rectangle. This state can be a combination of the following values:
|
Value |
Meaning |
|
DCB_DISABLE |
Boundary
accumulation is off. |
|
DCB_ENABLE |
Boundary
accumulation is on. DCB_ENABLE and DCB_DISABLE are mutually exclusive. |
|
DCB_RESET |
Bounding
rectangle is empty. |
|
DCB_SET |
Bounding
rectangle is not empty. DCB_SET and DCB_RESET are mutually exclusive. |
Remarks
The DCB_SET
value is a combination of the bit values DCB_ACCUMULATE and DCB_RESET.
Applications that check the DCB_RESET bit to determine whether the bounding
rectangle is empty must also check the DCB_ACCUMULATE bit. The bounding
rectangle is empty only if the DCB_RESET bit is 1 and the DCB_ACCUMULATE bit is
0.
See Also