Keyboard buffer

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Buffer to read keystrokes synchronously.

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Functions

KeyBuf*	keybuf_create (void)
void	keybuf_destroy (...)
void	keybuf_OnUp (...)
void	keybuf_OnDown (...)
void	keybuf_clear (...)
bool_t	keybuf_pressed (...)
void	keybuf_str (...)
void	keybuf_dump (...)

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• Use keybuf_create to create the buffer.
• Use view_keybuf to bind the buffer to any graphical view.

The operating system generates events asynchronously every time the user presses or releases a key. We can capture such events using a callback function (see view_OnDown), but sometimes this is not enough. Let's think about a video game where we must read the state of a key in the update phase, which occurs synchronously. In these cases, the use of a keyboard buffer (Figure 1) will be very useful, which simply saves the state of each key based on the events that occur. This status can be read at any time during execution.

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keybuf_create ()

Create a buffer with keyboard status.

KeyBuf*
keybuf_create(void);

Return

The buffer.

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keybuf_destroy ()

Destroy the buffer.

void
keybuf_destroy(KeyBuf **bufer);

bufer

The buffer. It will be set to NULL after the destruction.

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keybuf_OnUp ()

Set the state of a key as released.

void
keybuf_OnUp(KeyBuf *bufer,
            const vkey_t key);

bufer	The buffer.
key	The key code.

Remarks

Normally it will not be necessary to call this function. It will be done by View or the module that captures keyboard events.

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keybuf_OnDown ()

Sets the state of a key as pressed.

void
keybuf_OnDown(KeyBuf *bufer,
              const vkey_t key);

bufer	The buffer.
key	The key code.

Remarks

Normally it will not be necessary to call this function. It will be done by View or the module that captures keyboard events.

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keybuf_clear ()

Clear the buffer. Set all keys as released.

void
keybuf_clear(KeyBuf *bufer);

bufer

The buffer.

Remarks

Normally it will not be necessary to call this function. It will be done by View or the module that captures keyboard events.

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keybuf_pressed ()

Returns the state of a key.

bool_t
keybuf_pressed(const KeyBuf *bufer,
               const vkey_t key);

bufer	The buffer.
key	The key code.

Return

Pulsed (TRUE) or released (FALSE).

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keybuf_str ()

Returns a text string associated with a key.

void
keybuf_str(const vkey_t key);

key	The key code.

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keybuf_dump ()

Dump the buffer status into the Log.

void
keybuf_dump(const KeyBuf *bufer);

bufer

The buffer.

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