L_SetOverlayCallback
#include "l_bitmap.h"
L_LTFIL_API L_INT L_SetOverlayCallback(pfnCallback, pUserData, uFlags)
OVERLAYCALLBACK pfnCallback; |
/* your callback function */ |
L_VOID* ppUserData; |
/* 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 |
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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. |
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pUserData |
Void pointer that you can use to pass one or more additional parameters that the callback function needs. |
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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. |
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If the additional parameters are not needed, you can pass NULL in this parameter. |
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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: |
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Value |
Meaning |
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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. |
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OVERLAY_CALLLOAD |
[0x0002] First, call the overlay callback. If the callback did not supply an overlay bitmap, try loading the overlay bitmap from disk. |
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OVERLAY_CALLONLY |
[0x003] Call the overlay callback. If there is no callback function set, there is no overlay bitmap. |
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OVERLAY_LOADONLY |
[0x0004] Try to load the overlay bitmap from disk. If the load fails, there is no overlay. |
Returns
SUCCESS |
The function was successful. |
< 1 |
An error occurred. Refer to Return Codes. |
Comments
The overlay callback set using L_SetOverlayCallback becomes the current callback. To get the current overlay callback, call L_GetOverlayCallback.
Required DLLs and Libraries
LTFIL 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: |
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Topics: |
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Example
For an example, refer to the OVERLAYCALLBACK function.