PAINTCALLBACK_PREPAINT Function (original) (raw)

Summary

This callback is used perform memory initialization or device initialization.

Syntax

#include "l_bitmap.h"

L_INT pEXT_CALLBACK YourFunction(pDisplay, pBitmap, prcDestClip, pUserData)

Parameters

L_VOID *pDisplay

Handle of the device context passed to the paint function.

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle structure holding the input data.

LPRECT prcDestClip

Pointer to the destination clipping rectangle.

L_VOID *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

Comments

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.

This callback is called after PAINTCALLBACK_ISCOMPATIBLEDC and before any other paint callbacks. This callback will be called exactly once for a paint operation.

You can use this callback to perform any device initialization or memory allocation needed for the current paint operation.

You can perform the device resetting or memory freeing in PAINTCALLBACK_POSTPAINT callback.

Required DLLs and Libraries

• 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.

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