keyboard.md

Keyboard

The Keyboard is not a node, it is a set of functions available by default for each Robot node to read the keyboard input. It is therefore not a device and the functions do not require any WbDeviceTag.

Note [Python]: In C++, Python and Java the keyboard functions are in a dedicated class called Keyboard. In order to get the Keyboard instance, you should call the getKeyboard function of the Robot class.

Keyboard Functions

wb_keyboard_enable

wb_keyboard_disable

wb_keyboard_get_sampling_period

wb_keyboard_get_key

%tab-component "language"

%tab "C"

#include <webots/keyboard.h>

enum {
  WB_KEYBOARD_END,
  WB_KEYBOARD_HOME,
  WB_KEYBOARD_LEFT,
  WB_KEYBOARD_UP,
  WB_KEYBOARD_RIGHT,
  WB_KEYBOARD_DOWN,
  WB_KEYBOARD_PAGEUP,
  WB_KEYBOARD_PAGEDOWN,
  WB_KEYBOARD_NUMPAD_HOME,
  WB_KEYBOARD_NUMPAD_LEFT,
  WB_KEYBOARD_NUMPAD_UP,
  WB_KEYBOARD_NUMPAD_RIGHT,
  WB_KEYBOARD_NUMPAD_DOWN,
  WB_KEYBOARD_NUMPAD_END,
  WB_KEYBOARD_KEY,
  WB_KEYBOARD_SHIFT,
  WB_KEYBOARD_CONTROL,
  WB_KEYBOARD_ALT
};

void wb_keyboard_enable(int sampling_period);
void wb_keyboard_disable();
int wb_keyboard_get_sampling_period();
int wb_keyboard_get_key();

%tab-end

%tab "C++"

#include <webots/Keyboard.hpp>

namespace webots {
  class Keyboard {
    enum {
      END, HOME, LEFT, UP, RIGHT, DOWN,
      PAGEUP, PAGEDOWN, NUMPAD_HOME, NUMPAD_LEFT,
      NUMPAD_UP, NUMPAD_RIGHT, NUMPAD_DOWN, NUMPAD_END,
      KEY, SHIFT, CONTROL, ALT
    };

    virtual void enable(int samplingPeriod);
    virtual void disable();
    int getSamplingPeriod() const;
    int getKey() const;
  }
}

%tab-end

%tab "Python"

from controller import Keyboard

class Keyboard:
    END, HOME, LEFT, UP, RIGHT, DOWN, PAGEUP,
    PAGEDOWN, NUMPAD_HOME, NUMPAD_LEFT, NUMPAD_UP,
    NUMPAD_RIGHT, NUMPAD_DOWN, NUMPAD_END, KEY, SHIFT,
    CONTROL, ALT

    def enable(self, samplingPeriod):
    def disable(self):
    def getSamplingPeriod(self):
    def getKey(self):

%tab-end

%tab "Java"

import com.cyberbotics.webots.controller.Keyboard;

public class Keyboard {
  public final static int END, HOME, LEFT, UP, RIGHT,
    DOWN, PAGEUP, PAGEDOWN, NUMPAD_HOME, NUMPAD_LEFT,
    NUMPAD_UP, NUMPAD_RIGHT, NUMPAD_DOWN, NUMPAD_END,
    KEY, SHIFT, CONTROL, ALT;

  public void enable(int samplingPeriod);
  public void disable();
  public int getSamplingPeriod();
  public int getKey();
}

%tab-end

%tab "MATLAB"

WB_KEYBOARD_END, WB_KEYBOARD_HOME, WB_KEYBOARD_LEFT, WB_KEYBOARD_UP,
WB_KEYBOARD_RIGHT, WB_KEYBOARD_DOWN, WB_KEYBOARD_PAGEUP, WB_KEYBOARD_PAGEDOWN,
WB_KEYBOARD_NUMPAD_HOME, WB_KEYBOARD_NUMPAD_LEFT, WB_KEYBOARD_NUMPAD_UP,
WB_KEYBOARD_NUMPAD_RIGHT, WB_KEYBOARD_NUMPAD_DOWN, WB_KEYBOARD_NUMPAD_END,
WB_KEYBOARD_KEY, WB_KEYBOARD_SHIFT, WB_KEYBOARD_CONTROL, WB_KEYBOARD_ALT

wb_keyboard_enable(sampling_period)
wb_keyboard_disable()
period = wb_keyboard_get_sampling_period()
key = wb_keyboard_get_key()

%tab-end

%end

Description

keyboard reading function

These functions allow a controller program to read keys pressed on the computer keyboard when the 3D window of Webots is selected and the simulation is running. You may have to click inside the 3D window, so that it gets selected (e.g., active) and the key press events can be sent to the controller program. First, it is necessary to enable keyboard input by calling the wb_keyboard_enable function. The sampling_period parameter is expressed in milliseconds, and defines how frequently readings are updated. Note that the first key will be available only after the first sampling period elapsed. After that, values can be read by calling the wb_keyboard_get_key function repeatedly until this function returns -1. The returned value, if non-negative, is a key code corresponding to a key currently pressed. If no modifier (shift, control or alt) key is pressed, the key code is the ASCII code of the corresponding key or a special value (e.g., for the arrow keys). However, if a modifier key was pressed, the ASCII code (or special value) can be obtained by applying a binary AND between to the WB_KEYBOARD_KEY mask and the returned value. In this case, the returned value is the result of a binary OR between one of WB_KEYBOARD_SHIFT, WB_KEYBOARD_CONTROL or WB_KEYBOARD_ALT and the ASCII code (or the special value) of the pressed key according to which modifier key was pressed simultaneously. If no key is currently pressed, the function will return -1. Calling the wb_keyboard_get_key function a second time will return either -1 or the key code of another key which is currently simultaneously pressed. The function can be called up to 7 times to detect up to 7 simultaneous keys pressed. The wb_keyboard_disable function should be used to stop the keyboard readings.

Note [C++]: The keyboard predefined values are located into a (static) enumeration of the Keyboard class. For example, Keyboard.CONTROL corresponds to the ctrl key stroke.

Note [Java]: The keyboard predefined values are final integers located in the Keyboard class. For example, ctrl-B can be tested like this:

int key=keyboard.getKey()
if (key==Keyboard.CONTROL+'B')
  System.out.Println("Ctrl+B is pressed");

Note [Python]: The keyboard predefined values are integers located into the Keyboard class. For example, ctrl-B can be tested like this:

key=keyboard.getKey()
if (key==Keyboard.CONTROL+ord('B')):
  print('Ctrl+B is pressed')