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Available in LEADTOOLS Document and Medical Imaging toolkits. |
#include "l_bitmap.h"
L_INT pEXT_CALLBACK YourFunction(pDisplay, nIndex, pUserData)
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L_VOID *pDisplay; |
/* device context handle */ |
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L_INT nIndex; |
/* index of the capability to retrieve */ |
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L_VOID *pUserData; |
/* pointer to additional data */ |
This is the callback that replaces the GetDeviceCaps GDI function.
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Parameter |
Description |
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pDisplay |
Handle of the device context passed to the paint function. |
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nIndex |
The index of the capability to retrieve. |
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pUserData |
Void pointer that you can use to access a variable or structure containing data that your callback function needs. This gives you a way to receive data indirectly from the function that uses this callback function. (This is the same pointer that you pass in the pUserData parameter of the PAINTCALLBACKDATA structure.) |
Returns
The return values are the same as the return values for the corresponding GDI function.
Comments
The internal display engine calls your callback function if you override the corresponding GDI function in the PAINTCALLBACKDATA structure.
pDisplay is the pDisplay member from the PAINTCALLBACKDATA structure that you passed to the paint function. The default callbacks expect it to be a HDC handle. But, if you override all the paint callbacks, it can be a pointer of any type you want.
Please see the Microsoft documentation for the values you are expected to return and for the meaning of the parameters before pUserData.
Required DLLs and Libraries
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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 |
Example
For an example, refer to L_PaintDCCallback.
