#include "l_bitmap.h"

L_LTFIL_API L_INT L_SetOverlayCallback(pfnCallback, pUserData, uFlags)


your callback function

L_VOID* pUserData;

pointer to more parameters for the callback

L_UINT uFlags;

procedure flag

Specifies how to load the overlay bitmap and optionally sets a callback function.

Parameter Description
pfnCallback Your callback function that asks the user for the overlay bitmap, when loading a file containing an overlay. The callback function must adhere to the syntax specified in OVERLAYCALLBACK. Pass NULL If there is no overlay callback function. If a callback function is set, the callback function will be used only if OVERLAY_LOADONLY is not set in uFlags.
pUserData Void pointer that you can use to pass one or more additional parameters that the callback function needs.
  To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID *. The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure.
  If the additional parameters are not needed, you can pass NULL in this parameter.
uFlags Flags that indicate the method(s) to use when loading an overlay bitmap and the order in which to perform those methods. Possible values are:
  Value Meaning
  OVERLAY_LOADCALL [0x0001] First, try loading the overlay bitmap from disk. If the load fails, the overlay callback will be asked to provide the overlay bitmap.
  OVERLAY_CALLLOAD [0x0002] First, call the overlay callback. If the callback did not supply an overlay bitmap, try loading the overlay bitmap from disk.
  OVERLAY_CALLONLY [0x003] Call the overlay callback. If there is no callback function set, there is no overlay bitmap.
  OVERLAY_LOADONLY [0x0004] Try to load the overlay bitmap from disk. If the load fails, there is no overlay.



The function was successful.

< 1

An error occurred. Refer to Return Codes.


The overlay callback set using L_SetOverlayCallback becomes the current callback. To get the current overlay callback, call L_GetOverlayCallback.

Required DLLs and Libraries


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


Win32, x64, Linux.

See Also




Raster Image Functions: Loading Files


Loading and Saving Images


For an example, refer to the OVERLAYCALLBACK function.

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