m2_pad.h

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/*
 * Copyright (C) 2016 Robin Gareus <robin@gareus.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#ifndef _ardour_surfaces_m2pad_h_
#define _ardour_surfaces_m2pad_h_
 
#include <stdint.h>
#include "pbd/signals.h"
 
#include <cmath>
 
namespace ArdourSurface {
 
class M2PadInterface
{
        public:
                M2PadInterface () {}
                virtual ~M2PadInterface () {}
 
                /* user API */
                PBD::Signal<void(float)> pressed;
                PBD::Signal<void()> released;
                PBD::Signal<void(float)> aftertouch;
                PBD::Signal<void(float, bool)> event;
                PBD::Signal<void(float)> changed;
 
                virtual uint16_t value () const { return 0; }
                virtual float pressure () const { return 0.f; }
                virtual void set_color (uint32_t rgba) {}
 
                /* internal API - called from device thread */
                virtual void set_value (uint16_t v) {}
 
                virtual void color (uint8_t& r, uint8_t& g, uint8_t& b) const {
                        r = g = b = 0;
                }
};
 
class M2Pad : public M2PadInterface
{
        public:
                M2Pad ()
                        : M2PadInterface ()
                        , _pressed (false)
                        , _pressure (0)
                        , _last (0)
                        , _cnt (0)
                        , _rgba (0)
                {
                        for (int i = 0; i < 4; ++i) {
                                hist[i] = 0;
                        }
                }
 
                uint16_t value () const { return _raw; }
                float pressure () const { return _pressure; }
 
                void set_color (uint32_t rgba) { _rgba = rgba; }
 
                void color (uint8_t& r, uint8_t& g, uint8_t& b) const
                {
                        r = ((_rgba >> 24) & 0xff) >> 1;
                        g = ((_rgba >> 16) & 0xff) >> 1;
                        b = ((_rgba >>  8) & 0xff) >> 1;
                }
 
                void set_value (uint16_t v)
                {
                        // bleed to neighboring pads...
                        static const uint16_t high  = 159;
                        static const float    low   = 159 / 4095.f;
                        static const float mindelta = 32.f / 4096.f;
 
                        if (_raw != v) {
                                changed (v / 4095.f);
                                _raw = v;
                        }
 
                        // some pads never return to "0", and there's
                        // TODO map pressure from a min..max range,
                        // even hard hits rarely exceed 3400 or thereabouts.
                        // -> "pad sensitivity" config or "calibrate pads"
 
                        hist[_cnt] = v;
                        _cnt = (_cnt + 1) & 3;
 
                        if (_pressed) {
                                const float p = v / 4095.f;
                                _pressure += .1 * (p - _pressure);
                                if (_pressure < low) {
                                        _pressure = 0;
                                        _pressed = false;
                                        released (); /* EMIT SIGNAL */
                                        event (_pressure, true); /* EMIT SIGNAL */
                                } else {
                                        if (std::fabsf (_last - _pressure) > mindelta) {
                                                _last = _pressure;
                                                aftertouch (_pressure); /* EMIT SIGNAL */
                                                event (_pressure, false); /* EMIT SIGNAL */
                                        }
                                }
                        } else {
                                bool above_thresh = true;
                                uint16_t max = 0;
                                for (int i = 0; i < 4; ++i) {
                                        if (hist[i] < high) {
                                                above_thresh = false;
                                                break;
                                        }
                                        max = std::max (max, hist[i]);
                                }
                                if (above_thresh) {
                                        _pressed = true;
                                        _last = _pressure = max / 4095.f;
                                        pressed (_pressure);
                                        event (_pressure, true); /* EMIT SIGNAL */
                                }
                        }
                }
 
        protected:
                bool  _pressed;
                float _pressure;
                uint16_t _raw;
                float _last;
                uint16_t hist[4];
                unsigned int _cnt;
                uint32_t _rgba;
};
 
} /* namespace */
#endif /* _ardour_surfaces_m2pad_h_ */