PiCar/joystick.hh

155 lines
3.5 KiB
C++

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Copyright Drew Noakes 2013-2016
#ifndef __JOYSTICK_HH__
#define __JOYSTICK_HH__
#include <string>
#include <iostream>
#define JS_EVENT_BUTTON 0x01 // button pressed/released
#define JS_EVENT_AXIS 0x02 // joystick moved
#define JS_EVENT_INIT 0x80 // initial state of device
/**
* Encapsulates all data relevant to a sampled joystick event.
*/
class JoystickEvent
{
public:
/** Minimum value of axes range */
static const short MIN_AXES_VALUE = -32768;
/** Maximum value of axes range */
static const short MAX_AXES_VALUE = 32767;
/**
* The timestamp of the event, in milliseconds.
*/
unsigned int time;
/**
* The value associated with this joystick event.
* For buttons this will be either 1 (down) or 0 (up).
* For axes, this will range between MIN_AXES_VALUE and MAX_AXES_VALUE.
*/
short value;
/**
* The event type.
*/
unsigned char type;
/**
* The axis/button number.
*/
unsigned char number;
/**
* Returns true if this event is the result of a button press.
*/
bool isButton()
{
return (type & JS_EVENT_BUTTON) != 0;
}
/**
* Returns true if this event is the result of an axis movement.
*/
bool isAxis()
{
return (type & JS_EVENT_AXIS) != 0;
}
/**
* Returns true if this event is part of the initial state obtained when
* the joystick is first connected to.
*/
bool isInitialState()
{
return (type & JS_EVENT_INIT) != 0;
}
/**
* The ostream inserter needs to be a friend so it can access the
* internal data structures.
*/
friend std::ostream& operator<<(std::ostream& os, const JoystickEvent& e);
};
/**
* Stream insertion function so you can do this:
* cout << event << endl;
*/
std::ostream& operator<<(std::ostream& os, const JoystickEvent& e);
/**
* Represents a joystick device. Allows data to be sampled from it.
*/
class Joystick
{
private:
void openPath(std::string devicePath, bool blocking=false);
int _fd;
public:
~Joystick();
/**
* Initialises an instance for the first joystick: /dev/input/js0
*/
Joystick();
/**
* Initialises an instance for the joystick with the specified,
* zero-indexed number.
*/
Joystick(int joystickNumber);
/**
* Initialises an instance for the joystick device specified.
*/
Joystick(std::string devicePath);
/**
* Joystick objects cannot be copied
*/
Joystick(Joystick const&) = delete;
/**
* Joystick objects can be moved
*/
Joystick(Joystick &&) = default;
/**
* Initialises an instance for the joystick device specified and provide
* the option of blocking I/O.
*/
Joystick(std::string devicePath, bool blocking);
/**
* Returns true if the joystick was found and may be used, otherwise false.
*/
bool isFound();
/**
* Attempts to populate the provided JoystickEvent instance with data
* from the joystick. Returns true if data is available, otherwise false.
*/
bool sample(JoystickEvent* event);
};
#endif