So after a callback function is written out, there must be a registered action that tells the caller how you found the function I wrote. So a lot of people say that the callback function is a bit like the BP machine you're carrying: Tell someone the number and call you when it's something! The callback function typically defines the type of parameters and return values as required by the caller, you provide the caller with the entry address of your callback function, and then you can call the function to notify you at any time when the caller has an event, and pass the parameters in a predetermined form. The callback function is written out not by its own program to invoke, but to let other things to invoke, such as the Windows operating system, such as other programs and so on. Using my method to control the window controls on other programs ' forms, you must first understand what isĬallback function。 My understanding is this: Delphi finds a window handle with a title known to traverse the window control handle (GO)

Delphi getwindowtext never works