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LVectorWindow::StartChanging

#include "ltwrappr.h"

virtual L_INT LVectorWindow::StartChanging(nChangeType, nChangeCategory)

L_UINT nChangeType;	/* type of change */
L_UINT nChangeCategory;	/* the change category */

This function is called by every function that affects the vector.

Parameter	Description
nChangeType	The type of change to be done to the vector. For a list of all the change types and notifications refer to Bitmap and Vector Change Notifications and Notification Categories.
nChangeCategory	The change category. For a list of all the change types and notifications refer to Bitmap and Vector Change Notifications and Notification Categories.

Returns

SUCCESS	Continue the operation without interrupting it.
< 1	An error occurred. Refer to Return Codes. This will stop the operation.

Comments

This function is called by every function that affects the vector. You can override this function to have control over the different operations that are done to the vector. This function is called before doing any changes to the vector. If you want to cancel the operation, you can return an error code that is less than SUCCESS. If you return SUCCESS, the operation will continue executing. For a list of all the change types and notifications refer to Vector Change Notifications and Notification Categories.

The high level window classes override this function so it will be notified of any changing done to the vector object. This allows these classes to do some special processing before starting the changing operation.

If you override this function you must do one of the following:

• To stop an operation, return an error code (anything other than SUCCESS). In this case the operation will stop and the parent class will not have a chance to do any default processing for the operation.

• Do your customer processing, and then call the parent-class implementation for this function to let the parent do default processing for this function.

Override this function to be notified of any scaling on the displayed vector.

A scale can be requested by:

• the user pressing one of the keys defined for scaling

• calling the LVectorWindow::ScaleIn or LVectorWindow::ScaleOut functions

Required DLLs and Libraries

LVKRN For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

See Also

Functions:

Bitmap and Vector Change Notifications and Notification Categories, LVectorWindow::EndChanging, Class Members

Example

For an example, refer to LVectorWindow::MsgProcCallBack.