L_DoubleBufferBegin

#include "l_bitmap.h"

HDC EXT_FUNCTION L_DoubleBufferBegin(hDoubleBufferHandle, hDC, cx, cy)

L_HANDLE hDoubleBufferHandle;	/* double buffering handle */
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
hDoubleBufferHandle	Handle that identifies the double buffering process.
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 L_DoubleBufferBegin to begin a double buffering process. All double buffered paint operations should be wrapped in L_DoubleBufferBegin and L_DoubleBufferEnd 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 L_DoubleBufferBegin 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 L_DoubleBufferEnd.

Note that you must create a double buffer handle with L_DoubleBufferCreateHandle 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.

Platforms

Windows 95 / 98 / Me, Windows 2000 / XP.

Functions:	L_DoubleBufferEnable, L_DoubleBufferCreateHandle, L_DoubleBufferDestroyHandle, L_DoubleBufferEnd
Topics:	Raster Image Functions: Displaying Images
	Minimizing Flicker With Double Buffering