PAINTCALLBACK_SELECTPALETTE Function - Raster Imaging C API Help

PAINTCALLBACK_SELECTPALETTE Function

#include "l_bitmap.h"

L_HPALETTE pEXT_CALLBACK YourFunction(pDisplay, hPal, bForceBackground, pUserData)

L_VOID *pDisplay;

device context handle

HPALETTE hPal;

handle to logical palette

L_BOOL bForceBackground;

foreground or background mode

L_VOID *pUserData;

pointer to additional data

This is the callback that replaces the SelectPalette GDI function.

Parameter

Description

pDisplay

Handle of the device context passed to the paint function.

hPalette

Handle to the logical palette to be selected.

bForceBackground

Specifies whether the logical palette is forced to be a background palette.

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

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.

Help Version 20.0.2018.7.30
Products | Support | Contact Us | Copyright Notices
© 1991-2018 LEAD Technologies, Inc. All Rights Reserved.

LEADTOOLS Raster Imaging C API Help