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).


#include "ltivw.h"

L_LTIVW_API L_INT EXT_FUNCTION L_DispContainerGetLowMemoryUsageCallBack(hCellWnd, ppfnCallBack, ppUserData)


L_HWND hCellWnd

A handle to the window that represents the Medical Viewer Cell.


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.

LPVOID * 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.


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


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


The toolkit comes in Win32 and x64 editions that can support development of software applications for any of the following environments:

Windows 10

Windows 8

Windows 7

Windows Vista

Windows XP

Windows 2000

See Also




For an example, refer to L_DispContainerSetLowMemoryUsageCallBack.

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LEADTOOLS Medical Image Viewer C API Help

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