LDoubleBuffer::Begin

#include "ltwrappr.h"

virtual HDC LDoubleBuffer::Begin(hDC, cx, cy)

HDC hDC;	/* handle to the target device context */
L_INT cx;	/* width, in pixels, of the target device context */
L_INT cy;	/* height, in pixels of the target device context */

Returns a memory hDC that is used in the double buffering process. This function is available in the Document/Medical Toolkits.

Parameter	Description
hDC	Handle to the target device context.
cx	Width, in pixels, of the target device context.
cy	Height, in pixels, of the target device context.

Returns

<> 0	Memory hDC to use for double buffered paints
0	The function failed.

Comments

Use LDoubleBuffer::Begin to begin a double buffering process. All double buffered paint operations should be wrapped in LDoubleBuffer::Begin and LDoubleBuffer::End calls.

The hDC argument is the device context that you want to double buffer. The arguments cx and cy specify the pixel dimensions of the hDC. If the call to LDoubleBuffer::Begin is successful, a memory hDC is returned. Use this memory hDC for all subsequent paint operations. When you want the result of the memory hDC to appear on the target hDC, call LDoubleBuffer::End.

Note that you must create a double buffer handle with LDoubleBuffer::CreateHandle before calling this function.

For more information, see the topic Minimizing Flicker with Double Buffering.

Required DLLs and Libraries

LTDIS

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Functions:	Class Members
Topics:	Raster Image Functions: Displaying Images
	Minimizing Flicker with Double Buffering