graphic::IKeyboard Interface Reference

Keyboard interface. More...

#include <IKeyboard.hpp>

Public Types
enum	Keys {   KEY_UNKNOWN = -1 , KEY_ESCAPE , KEY_F1 , KEY_F2 ,   KEY_F3 , KEY_F4 , KEY_F5 , KEY_F6 ,   KEY_F7 , KEY_F8 , KEY_F9 , KEY_F10 ,   KEY_F11 , KEY_F12 , KEY_1 , KEY_2 ,   KEY_3 , KEY_4 , KEY_5 , KEY_6 ,   KEY_7 , KEY_8 , KEY_9 , KEY_0 ,   KEY_MINUS , KEY_EQUAL , KEY_BACKSPACE , KEY_TAB ,   KEY_Q , KEY_W , KEY_E , KEY_R ,   KEY_T , KEY_Y , KEY_U , KEY_I ,   KEY_O , KEY_P , KEY_LEFT_BRACKET , KEY_RIGHT_BRACKET ,   KEY_CAPS_LOCK , KEY_LEFT_CONTROL , KEY_A , KEY_S ,   KEY_D , KEY_F , KEY_G , KEY_H ,   KEY_J , KEY_K , KEY_L , KEY_SEMICOLON ,   KEY_APOSTROPHE , KEY_BACKTICK , KEY_ENTER , KEY_LEFT_SHIFT ,   KEY_BACKSLASH , KEY_Z , KEY_X , KEY_C ,   KEY_V , KEY_B , KEY_N , KEY_M ,   KEY_COMMA , KEY_PERIOD , KEY_SLASH , KEY_RIGHT_SHIFT ,   KEY_LEFT_ALT , KEY_LEFT_SUPER , KEY_SPACE , KEY_RIGHT_ALT ,   KEY_RIGHT_SUPER , KEY_RIGHT_CONTROL , KEY_PAD_0 , KEY_PAD_1 ,   KEY_PAD_2 , KEY_PAD_3 , KEY_PAD_4 , KEY_PAD_5 ,   KEY_PAD_6 , KEY_PAD_7 , KEY_PAD_8 , KEY_PAD_9 ,   KEY_PAD_MINUS , KEY_PAD_PLUS , KEY_PAD_DOT , KEY_PAD_ENTER ,   KEY_UP , KEY_DOWN , KEY_LEFT , KEY_RIGHT ,   KEY_COUNT }
	Scan codes. More...

Public Member Functions
virtual	~IKeyboard ()
	Destroy the IKeyboard object.
virtual std::vector< Keys >	whichKeyDown () const =0
	Every key HELD right now - like isKeyDown, without having to name the key.
virtual bool	isKeyPressed (Keys key) const =0
	Check if the key is pressed.
virtual bool	isKeyReleased (Keys key) const =0
	Check if the key is released.
virtual bool	isKeyDown (Keys key) const =0
	Check if the key is down.
virtual bool	isKeyUp (Keys key) const =0
	Check if the key is up.

Detailed Description

Keyboard interface.

Four methods, two behaviours.

isKeyPressed / isKeyReleased are true for ONE FRAME only, the one where the key changes state. Holding a key does not re-trigger isKeyPressed, even when the OS sends key repeat.

isKeyDown / isKeyUp are true EVERY FRAME for as long as the key is held (or released).

For a key pressed on frame 3 and released on frame 6 :

key             ______/‾‾‾‾‾‾‾‾‾‾‾\______
frame            1   2   3   4   5   6   7

isKeyDown        0   0   1   1   1   0   0
isKeyUp          1   1   0   0   0   1   1
isKeyPressed     0   0   1   0   0   0   0
isKeyReleased    0   0   0   0   0   1   0

Hence the run / jump pair : isKeyDown(KEY_W) keeps moving while W is held, isKeyPressed(KEY_SPACE) jumps once. Jumping on isKeyDown jumps sixty times a second.

All four are readable ANYWHERE in the frame, on every vendor : the window drains its queue once in pollEvent() and folds it into state, so nothing has to be read at a particular moment.

while (window->isOpen()) {
    if (window->pollEvent()) {             // the frame's event pump
        window->eventClose();
        if (kb->isKeyPressed(KEY_SPACE))   // a front
            jump();
    }
 
    if (kb->isKeyDown(KEY_W))              // a state, outside
        walk();
 
    window->beginDraw();
    // ...
    window->endDraw();                     // end of frame
}

The condition is an optimisation, not a rule : with no event the fronts are false anyway. It only holds for the fronts - isKeyDown, isKeyUp and whichKeyDown() are true across frames where nothing happened, so putting them inside would silently drop them on a vendor that has a queue and keep them on one that has not.

The boundary between two frames is endDraw(). A press + release inside the same frame is lost, on every vendor.

Modifiers are keys like any other : Shift+E is isKeyDown(KEY_LEFT_SHIFT) and isKeyPressed(KEY_E), composed by the caller.

Member Enumeration Documentation

Keys

enum graphic::IKeyboard::Keys

Scan codes.

Enumerator
KEY_UNKNOWN
KEY_ESCAPE	Line 0.
KEY_F1
KEY_F2
KEY_F3
KEY_F4
KEY_F5
KEY_F6
KEY_F7
KEY_F8
KEY_F9
KEY_F10
KEY_F11
KEY_F12
KEY_1	Line 1.
KEY_2
KEY_3
KEY_4
KEY_5
KEY_6
KEY_7
KEY_8
KEY_9
KEY_0
KEY_MINUS
KEY_EQUAL
KEY_BACKSPACE
KEY_TAB	Line 2.
KEY_Q
KEY_W
KEY_E
KEY_R
KEY_T
KEY_Y
KEY_U
KEY_I
KEY_O
KEY_P
KEY_LEFT_BRACKET
KEY_RIGHT_BRACKET
KEY_CAPS_LOCK	Line 3.
KEY_LEFT_CONTROL
KEY_A
KEY_S
KEY_D
KEY_F
KEY_G
KEY_H
KEY_J
KEY_K
KEY_L
KEY_SEMICOLON
KEY_APOSTROPHE
KEY_BACKTICK
KEY_ENTER
KEY_LEFT_SHIFT	Line 4.
KEY_BACKSLASH
KEY_Z
KEY_X
KEY_C
KEY_V
KEY_B
KEY_N
KEY_M
KEY_COMMA
KEY_PERIOD
KEY_SLASH
KEY_RIGHT_SHIFT
KEY_LEFT_ALT	Line 5.
KEY_LEFT_SUPER
KEY_SPACE
KEY_RIGHT_ALT
KEY_RIGHT_SUPER
KEY_RIGHT_CONTROL
KEY_PAD_0	KEYPAD.
KEY_PAD_1
KEY_PAD_2
KEY_PAD_3
KEY_PAD_4
KEY_PAD_5
KEY_PAD_6
KEY_PAD_7
KEY_PAD_8
KEY_PAD_9
KEY_PAD_MINUS
KEY_PAD_PLUS
KEY_PAD_DOT
KEY_PAD_ENTER
KEY_UP	ARROWS.
KEY_DOWN
KEY_LEFT
KEY_RIGHT
KEY_COUNT

Constructor & Destructor Documentation

~IKeyboard()

virtual graphic::IKeyboard::~IKeyboard ( )

inlinevirtual

Destroy the IKeyboard object.

Member Function Documentation

isKeyDown()

virtual bool graphic::IKeyboard::isKeyDown ( Keys  key ) const

pure virtual

Check if the key is down.

Parameters

key

Returns

bool

isKeyPressed()

virtual bool graphic::IKeyboard::isKeyPressed ( Keys  key ) const

pure virtual

Check if the key is pressed.

Parameters

key

Returns

bool

isKeyReleased()

virtual bool graphic::IKeyboard::isKeyReleased ( Keys  key ) const

pure virtual

Check if the key is released.

Parameters

key

Returns

bool

isKeyUp()

virtual bool graphic::IKeyboard::isKeyUp ( Keys  key ) const

pure virtual

Check if the key is up.

Parameters

key

Returns

bool

whichKeyDown()

virtual std::vector< Keys > graphic::IKeyboard::whichKeyDown ( ) const

pure virtual

Every key HELD right now - like isKeyDown, without having to name the key.

A held key stays in the list every frame. For a debug overlay, a state readout, chord detection.

Walks the whole keyboard : avoid in a hot loop, isKeyDown is a direct lookup.

Returns

std::vector<Keys>

---

The documentation for this interface was generated from the following file:

• includes/event/IKeyboard.hpp