In This Topic ▼

PANWNDCALLBACK

Summary

Called to notify the main window of changes to the associated Pan Window.

Syntax

#include "l_bitmap.h"

L_VOID pEXT_CALLBACK YourFunction(hPanWindow, hWndParent, uFlags, prcPan, pUserData)

Parameters

HWND hPanWindow

Handle to the Pan Window which has changed.

HWND hWndParent

Handle to the associated main window.

L_UINT uFlags

Flag indicating the reason for the Pan Window notification. Possible values are:

Value	Meaning
PANWIN_CREATED	[0] Pan Window was created.
PANWIN_UPDATED	[1] Pan Window was updated/repainted.
PANWIN_DESTROYED	[2] Pan Window was destroyed.
PANWIN_MOVED	[3] Pan Window was moved.
PANWIN_REPAINTED	[4] Pan Window was repainted.

LPRECT prcPan

Pointer to a RECT that contains the current coordinates of the Pan Rect in 1:1 zoom factor, when uFlags = PANWIN_UPDATED. Otherwise, this will be NULL. You must convert these coordinates to match your main windows current zoom factor.

L_VOID* pUserData

A 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 calling function.)

Keep in mind that this is a void pointer, which must be cast to the appropriate data type within your callback function.

Returns

None.

Comments

This function will be called when the Pan Window updates itself when responding to end-user input, or when the Pan Window repaints itself after being invalidated.

You can use this callback as a notification that the Pan Window has been updated by the end-user. You can also use this function to do your own custom painting in the Pan Window, for example render annotation objects to the Pan Window using the L_AnnDraw function.

You must set a PANWNDCALLBACK callback function when you create the Pan Window using the L_CreatePanWindow function in order to be notified of updates to the Pan Window.