MFC – Keyboard Hook Filter Functions
The SDI sample, under the file menu, has two menu items called Hook CAPS Lock, Unhook CAPS Lock. When the user clicks the Hook Caps Lock menu item, the Keyboard hook is attached to the application and hooks the keyboard event. The UnHook CAPS Lock event removes installed hook from the application.
Our example SDI contains two menu items called First Dialog and Second Dialog under view menu. These menu items will bring up two dialogs with text boxes in it. When a hook is installed, you can type only the capital letters in the dialogs. After opting for the Un-Hook action, you will not have upper case constraint on the dialogs. Let us jump into the explanation-based walk-through.