L_DispContainerGetLowMemoryUsageCallBack

#include "l_bitmap.h"

L_LTIVW_API L_INT EXT_FUNCTION L_DispContainerGetLowMemoryUsageCallBack(hCon, ppfnCallBack, ppUserData)

HDISPCONTAINER hCon;	/* handle to the container */
DISPCONTAINERFRAMEREQUESTEDCALLBACK * ppfnCallBack;	/* pointer to the callback function */
LPVOID * ppUserData;	/* pointer to be updated with user data */

Gets a callback function, which will be fired every time the control requests a new frame when the low memory usage feature is enabled (for more information, refer to L_DispContainerEnableCellLowMemoryUsage).

Parameter	Description
hCon	Handle to the container.
ppfnCallBack	Pointer to a pointer to a callback function to be updated with the last low memory usage callback function set using the L_DispContainerSetLowMemoryUsageCallBack function.
ppUserData	Void pointer to be updated with the user defined data associated with the tag callback. If you are not interested in the user-defined data, pass NULL for this parameter.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

The low memory usage feature works by making the control stop from loading all of the frames at runtime. Instead, the control will load only the frames that are currently visible on the cell. The control will send a request each time the user scrolls down or up, changes the number of visible frames, etc. For example, suppose the cell layout is a 2X2 (See L_DispContainerSetCellProperties), and the user needs to load more than 100000 frames. Instead of loading them all, this function will send a callback (DISPCONTAINERFRAMEREQUESTEDCALLBACK) when the cell is loaded, requesting 4 frames (1, 2, 3 and 4) (because the cell is 2X2). Once the user scrolls down the cell to view frame number 5, frame number 1 will be disposed of because it is no longer visible, and the callback will be fired to request frame number 5. When frames are requested, the user is supposed to send them to the control by using L_DispContainerSetRequestedImage.

To set the current frames request callback function, call L_DispContainerSetLowMemoryUsageCallBack.

Required DLLs and Libraries

LTIVW

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 2000 /XP/Vista.

See Also

Functions:	L_DispContainerCreate, L_DispContainerDestroy, L_DispContainerEnableCellLowMemoryUsage, L_DispContainerInsertCell, L_DispContainerSetRequestedImage, L_DispContainerSetLowMemoryUsageCallBack, L_DispContainerSetCellBitmapList
Topics:	Using the Image Viewer
	Image Viewer Functions: Using the Image Viewer

Example

For an example, refer to L_DispContainerSetLowMemoryUsageCallBack.