portapack-mayhem/firmware/application/touch.hpp
2023-05-03 11:18:37 +02:00

263 lines
5.9 KiB
C++

/*
* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
*
* This file is part of PortaPack.
*
* 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, 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef __TOUCH_H__
#define __TOUCH_H__
#include <cstdint>
#include <cstddef>
#include <algorithm>
#include <array>
#include <functional>
#include "debounce.hpp"
#include "ui.hpp"
namespace touch {
using sample_t = uint16_t;
constexpr sample_t sample_max = 1023;
constexpr sample_t touch_threshold = sample_max / 5;
struct Samples {
sample_t xp;
sample_t xn;
sample_t yp;
sample_t yn;
constexpr Samples(
) : Samples { 0 }
{
}
constexpr Samples(
uint32_t v
) : xp { static_cast<sample_t>(v) },
xn { static_cast<sample_t>(v) },
yp { static_cast<sample_t>(v) },
yn { static_cast<sample_t>(v) }
{
}
constexpr Samples(
uint32_t xp,
uint32_t xn,
uint32_t yp,
uint32_t yn
) : xp { static_cast<sample_t>(xp) },
xn { static_cast<sample_t>(xn) },
yp { static_cast<sample_t>(yp) },
yn { static_cast<sample_t>(yn) }
{
}
Samples& operator +=(const Samples& r) {
xp += r.xp;
xn += r.xn;
yp += r.yp;
yn += r.yn;
return *this;
}
Samples operator/(const unsigned int r) const {
return {
static_cast<sample_t>(xp / r),
static_cast<sample_t>(xn / r),
static_cast<sample_t>(yp / r),
static_cast<sample_t>(yn / r)
};
}
Samples operator>>(const size_t n) const {
return {
static_cast<sample_t>(xp >> n),
static_cast<sample_t>(xn >> n),
static_cast<sample_t>(yp >> n),
static_cast<sample_t>(yn >> n)
};
}
};
struct Frame {
Samples pressure { };
Samples x { };
Samples y { };
bool touch { false };
};
struct Metrics {
const float x;
const float y;
const float r;
};
Metrics calculate_metrics(const Frame& frame);
struct DigitizerPoint {
int32_t x;
int32_t y;
};
struct Calibration {
/* Touch screen calibration matrix, based on article by Carlos E. Vidales:
* http://www.embedded.com/design/system-integration/4023968/How-To-Calibrate-Touch-Screens
*/
constexpr Calibration(
const std::array<DigitizerPoint, 3>& s,
const std::array<ui::Point, 3>& d
) : k { (s[0].x - s[2].x) * (s[1].y - s[2].y) - (s[1].x - s[2].x) * (s[0].y - s[2].y) },
a { (d[0].x() - d[2].x()) * (s[1].y - s[2].y) - (d[1].x() - d[2].x()) * (s[0].y - s[2].y) },
b { (s[0].x - s[2].x) * (d[1].x() - d[2].x()) - (d[0].x() - d[2].x()) * (s[1].x - s[2].x) },
c { s[0].y * (s[2].x * d[1].x() - s[1].x * d[2].x()) + s[1].y * (s[0].x * d[2].x() - s[2].x * d[0].x()) + s[2].y * (s[1].x * d[0].x() - s[0].x * d[1].x()) },
d { (d[0].y() - d[2].y()) * (s[1].y - s[2].y) - (d[1].y() - d[2].y()) * (s[0].y - s[2].y) },
e { (s[0].x - s[2].x) * (d[1].y() - d[2].y()) - (d[0].y() - d[2].y()) * (s[1].x - s[2].x) },
f { s[0].y * (s[2].x * d[1].y() - s[1].x * d[2].y()) + s[1].y * (s[0].x * d[2].y() - s[2].x * d[0].y()) + s[2].y * (s[1].x * d[0].y() - s[0].x * d[1].y()) }
{
}
constexpr Calibration() :
Calibration(
/* Values derived from one PortaPack H1 unit. */
{ { { 256, 731 }, { 880, 432 }, { 568, 146 } } },
{ { { 32, 48 }, { 208, 168 }, { 120, 288 } } }
)
{
}
ui::Point translate(const DigitizerPoint& p) const;
private:
int32_t k;
int32_t a;
int32_t b;
int32_t c;
int32_t d;
int32_t e;
int32_t f;
};
template<size_t N>
class Filter {
public:
constexpr Filter() = default;
void reset() {
history.fill(0);
history_history = 0;
accumulator = 0;
n = 0;
}
void feed(const sample_t value) {
accumulator = accumulator + value - history[n];
history[n] = value;
n = (n + 1) % history.size();
history_history = (history_history << 1) | 1U;
}
int32_t value() const {
return accumulator / N;
}
bool stable(const uint32_t bound) const {
if( history_valid() ) {
const auto minmax = std::minmax_element(history.cbegin(), history.cend());
const auto min = *minmax.first;
const auto max = *minmax.second;
const uint32_t delta = max - min;
return (delta < bound);
} else {
return false;
}
}
private:
static constexpr uint32_t history_history_mask { (1U << N) - 1 };
std::array<sample_t, N> history { };
uint32_t history_history { 0 };
int32_t accumulator { 0 };
size_t n { 0 };
bool history_valid() const {
return (history_history & history_history_mask) == history_history_mask;
}
};
class Manager {
public:
std::function<void(ui::TouchEvent)> on_event { };
void feed(const Frame& frame);
private:
enum State {
NoTouch,
TouchDetected,
};
static constexpr size_t touch_count_threshold { 3 };
static constexpr uint32_t touch_stable_bound { 8 };
// Ensure filter length is equal or less than touch_count_threshold,
// or coordinates from the last touch will be in the initial averages.
Filter<touch_count_threshold> filter_x { };
Filter<touch_count_threshold> filter_y { };
//Debounce touch_debounce;
State state { State::NoTouch };
bool point_stable() const {
return filter_x.stable(touch_stable_bound)
&& filter_y.stable(touch_stable_bound);
}
ui::Point filtered_point() const;
void touch_started() {
fire_event(ui::TouchEvent::Type::Start);
}
void touch_moved() {
fire_event(ui::TouchEvent::Type::Move);
}
void touch_ended() {
fire_event(ui::TouchEvent::Type::End);
}
void fire_event(ui::TouchEvent::Type type) {
if( on_event ) {
on_event({ filtered_point(), type });
}
}
};
} /* namespace touch */
#endif/*__TOUCH_H__*/