Libpointing

An open-source cross-platform library to get raw events from pointing devices and master transfer functions.


Overview

Libpointing is an open-source cross-platform library that provides direct access to HID pointing devices and supports the design of pointing transfer functions.

The library


Minimalistic example

Once you correctly installed libpointing and linked it to your project, simply write #include <pointing/pointing.h> and start coding. Here is the console example which applies system specific transfer function to an input device and outputs the results to console:

#include <iostream>
#include <pointing/pointing.h>

using namespace pointing;

TransferFunction *func = 0;

// context is user data, timestamp is a moment at which the event was received
// input_dx, input_dy are displacements in horizontal and vertical directions
// buttons is a variable indicating which buttons of the pointing device were pressed.
void pointingCallback(void *, TimeStamp::inttime timestamp, int input_dx, int input_dy, int buttons) {
    if (!func) return;

    int output_dx = 0, output_dy = 0;
    // In order to use a particular transfer function, its applyi method must be called.
    func->applyi(input_dx, input_dy, &output_dx, &output_dy, timestamp);

    std::cout << "Displacements in x and y: " << input_dx << " " << input_dy << std::endl;
    std::cout << "Corresponding pixel displacements: " << output_dx << " " << output_dy << std::endl;
}

int main() {
    // Basically, to start using main functionality of libpointing
    // one needs to create objects of PointingDevice, DisplayDevice classes,
    // connect them passing to TransferFunction class object.

    // Any available pointing and display devices
    // if debugLevel > 0, the list of available devices
    // and extended information will be output.
    PointingDevice *input = PointingDevice::create("any:?debugLevel=1");
    DisplayDevice *output = DisplayDevice::create("any:?debugLevel=1");

    func = TransferFunction::create("sigmoid:?debugLevel=2", input, output);

    // To receive events from PointingDevice object, a callback function must be set.
    input->setPointingCallback(pointingCallback);
    while (1)
        PointingDevice::idle(100); // milliseconds

    delete input;
    delete output;
    delete func;

    return 0;
}

A more extended example can be found here.

That is it, in this manner you can apply any available transfer function on the chosen input. Enjoy!