Clipping operations
[GDI functions]

Functions

Function Documentation

void GUIAPI ClipRectIntersect ( HDC  hdc,
const RECT *  prc 
)

Intersects the specified rectangle with the visible region of the DC.

This function intersects the specified rectangle prc with the visible region of the device context hdc.

Parameters:
hdc The device context.
prc Pointer to the rectangle.
See also:
IncludeClipRect, ExcludeClipRect, Region operations
void GUIAPI ExcludeClipRect ( HDC  hdc,
const RECT *  prc 
)

Excludes the specified rectangle from the current visible region of a DC.

This function excludes the specified rect prc from the current visible region of the device context hdc.

Parameters:
hdc The device context.
prc The rectangle to be excluded.
See also:
IncludeClipRect, Region operations
void GUIAPI GetBoundsRect ( HDC  hdc,
RECT *  pRect 
)

Retrieves the bounding rectangle of the current visible region of a DC.

This function retrieves the bounding rectangle of the current visible region of the specified device context hdc, and returned through pRect.

Parameters:
hdc The device context.
pRect The bounding rectangle will be returned through this buffer.
See also:
Region operations
int GetClipBox ( HDC  hdc,
RECT *  clipbox 
)

Retrieves the bounding rectangle of the current clipping region of a DC.

This function retrieves the bounding rectangle of the current clipping region of the specified device context hdc, and returned through clipbox.

Parameters:
hdc The device context.
clipbox The bounding rectangle will be returned through this buffer.
Returns:
-1 for error, else the type of clipping region, can be one of the following values:
  • NULLREGION
    A null region.
  • SIMPLEREGION
    A simple region.
  • COMPLEXREGION
    A complex region.
See also:
GetBoundsRect
void GUIAPI IncludeClipRect ( HDC  hdc,
const RECT *  prc 
)

Includes the specified rectangle to the current visible region of a DC.

This function includes the specified rectangle prc to the current visible region of the device context hdc.

Parameters:
hdc The device context.
prc The rectangle to be included.
See also:
ExcludeClipRect, Region operations
int GUIAPI OffsetClipRegion ( HDC  hdc,
int  off_x,
int  off_y 
)

Moves the clipping region of a device context by the specified offsets.

This function moves the clipping region of a device context hdc by the specified offsets (off_x, off_y).

Parameters:
hdc Handle to the device context.
off_x Specifies the number of device units to move left or right.
off_y pecifies the number of device units to move up or down.
Returns:
The return value specifies the new clipping region's complexity; it can be one of the following values.

NULLREGION Region is empty. SIMPLEREGION Region is a single rectangle. COMPLEXREGION Region is more than one rectangle. -1 An error occurred.

See also:
SelectClipRegion
BOOL GUIAPI PtVisible ( HDC  hdc,
int  x,
int  y 
)

Checks whether a point is visible.

This function checks whether the point specified by (x,y) is visible, i.e. it is within the current visible clipping region of the device context hdc.

Parameters:
hdc The device context.
x x,y: The coordinates of the point.
y x,y: The coordinates of the point.
Returns:
TRUE for visible, else for not.
See also:
RectVisible, Region operations
BOOL GUIAPI RectVisible ( HDC  hdc,
const RECT *  pRect 
)

Checks whether the specified rectangle is visible.

This function checks whether the rectangle pointed to by pRect is visible, i.e. it is intersected with the current visible region of the device context hdc.

Parameters:
hdc The device context.
pRect Pointer to the rectangle.
See also:
PtVisible, Region operations

Example:

/*
 * Use RectVisible to optimize the repaint of the window.
 */
MSG_PAINT:
{
        HDC hdc = BeginPaint (hWnd);

        for (j = 0; j < 10; j ++) {
                if (RectVisible  (hdc, rcs + j)) {
                        FillBox (hdc, rcs[j].left, rcs[j].top, rcs [j].right, rcs [j].bottom);
                }
        }

        EndPaint (hWnd, hdc);
        return 0;
}
void GUIAPI SelectClipRect ( HDC  hdc,
const RECT *  prc 
)

Sets the visible region of a DC to be a rectangle.

This function sets the visible region of the device context hdc to the rectangle pointed to by prc.

Parameters:
hdc The device context.
prc Pointer to the rectangle.
See also:
SelectClipRegion, Region operations
void GUIAPI SelectClipRegion ( HDC  hdc,
const CLIPRGN *  pRgn 
)

Sets the visible region of a DC to be a region.

This function sets the visible region of the device context hdc to the region pointed to by pRgn.

Parameters:
hdc The device context.
pRgn Pointer to the region.
See also:
SelectClipRect, GetClipRegion, Region operations
int GUIAPI SelectClipRegionEx ( HDC  hdc,
const CLIPRGN *  pRgn,
int  fnMode 
)

Combines the specified region with the current clipping region using the specified mode.

This function combines the specified region with the current clipping region using the specified mode.

If an error occurs when this function is called, the previous clipping region for the specified device context is not affected.

The SelectClipRegionEx function assumes that the coordinates for the specified region are specified in device units.

Only a copy of the region identified by the pRgn parameter is used. The region itself can be reused after this call or it can be deleted.

Parameters:
hdc Handle to the device context.
pRgn Pointer to the region to be selected. This handle can only be NULL when the RGN_COPY mode is specified.
Specifies the operation to be performed. It must be one of the following values:
  • RGN_AND
    The new clipping region combines the overlapping areas of the current clipping region and the region identified by pRgn.
  • RGN_COPY
    The new clipping region is a copy of the region identified by pRgn. This is identical to SelectClipRegion. If the region identified by pRgn is NULL, the new clipping region is the default clipping region (the default clipping region is a null region).
  • RGN_DIFF
    The new clipping region combines the areas of the current clipping region with those areas excluded from the region identified by hrgn.
  • RGN_OR
    The new clipping region combines the current clipping region and the region identified by hrgn.
  • RGN_XOR
    The new clipping region combines the current clipping region and the region identified by hrgn but excludes any overlapping areas.
Returns:
The return value specifies the new clipping region's complexity; it can be one of the following values.

NULLREGION Region is empty. SIMPLEREGION Region is a single rectangle. COMPLEXREGION Region is more than one rectangle. -1 An error occurred.

See also:
SelectClipRect, SelectClipRegion, GetClipRegion, Region operations
Generated on Thu Apr 7 15:58:38 2011 for MiniGUI V3.0.12 API Reference by  doxygen 1.6.3