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/*
* 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 / 16;
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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)};
}
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};
struct Frame {
Samples pressure{};
Samples x{};
Samples y{};
bool touch{false};
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};
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>
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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;
}
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};
class Manager {
public:
std::function<void(ui::TouchEvent)> on_event{};
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void feed(const Frame& frame);
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private:
enum State {
NoTouch,
TouchDetected,
};
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static constexpr size_t touch_count_threshold{3};
static constexpr uint32_t touch_stable_bound{8};
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// 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{};
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// Debounce touch_debounce;
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State state{State::NoTouch};
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bool point_stable() const {
return filter_x.stable(touch_stable_bound) && filter_y.stable(touch_stable_bound);
}
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ui::Point filtered_point() const;
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void touch_started() {
fire_event(ui::TouchEvent::Type::Start);
}
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void touch_moved() {
fire_event(ui::TouchEvent::Type::Move);
}
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void touch_ended() {
fire_event(ui::TouchEvent::Type::End);
}
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void fire_event(ui::TouchEvent::Type type) {
if (on_event) {
on_event({filtered_point(), type});
}
}
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};
} /* namespace touch */
#endif /*__TOUCH_H__*/