Advanced Keyboard Features

In this section we’re going to introduce four new functions to deal with the keyboard. These functions work hand in hand to release us from the auto repeat problem that causes a small delay when waiting for the autorepeat to be operated.

The first function we’re going to present in here allows us to disable the keyboard repeat. The syntax is as follows:

Parameters:

• repeatMode – Enables, disables or restores the auto repeat mode. See bellow for possible values.

Possible values for repeatMode are as follows:

• GLUT_KEY_REPEAT_OFF – disable auto repeat mode


• GLUT_KEY_REPEAT_ON – enable auto repeat mode


• GLUT_KEY_REPEAT_DEFAULT – reset the auto repeat mode to its default state.

Note that this function works in a global basis, i.e. it will affect the repeat mode in all windows, not just the ones from our applications. So beware, when using this function to disable the auto repeat mode, it is convinient to reset it to its default state before terminating the application.

GLUT provides us with a safer approach, disabling callbacks for keyboard when the key repeat occurs. This allows us to safely ignore key repeats in our application without affecting the other apps. The function that provides this functionality is presented next:

• repeatMode – zero enables auto-repeat, non-zero disables it.

In any case, we’ll stop receiving callbacks when a key repeat occurs. However if you want to have an action performed while the key is being pressed, you’ll need to know when the key is released. GLUT provides two functions that register callbacks when a key is released.

Parameters:

• func – the name of the callback function.

The argument, a name of a function, will be the function that will handle these events. The parameters are the same as for when the user presses a key, so if a memory refresh is required look in the previous section.

In the next section we’ll show how to use this features to improve the application by revisiting the last example.