portapack-mayhem/firmware/application/touch.cpp
2016-02-06 16:44:19 -08:00

120 lines
3.3 KiB
C++

/*
* Copyright (C) 2015 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.
*/
#include "touch.hpp"
namespace touch {
struct Metrics {
const float x;
const float y;
const float r;
};
static Metrics calculate_metrics(const Frame& frame) {
/* TODO: Yikes! M0 doesn't have floating point, so this code is
* expensive! On the other hand, it seems to be working well (and
* fast *enough*?), so maybe leave it alone at least for now.
*/
const auto x_max = frame.x.xp;
const auto x_min = frame.x.xn;
const auto x_range = x_max - x_min;
const auto x_position = (frame.x.yp + frame.x.yn) / 2;
const float x_norm = float(x_position - x_min) / x_range;
const auto y_max = frame.y.yn;
const auto y_min = frame.y.yp;
const auto y_range = y_max - y_min;
const auto y_position = (frame.y.xp + frame.y.xn) / 2;
const float y_norm = float(y_position - y_min) / y_range;
const auto z_max = frame.pressure.yp;
const auto z_min = frame.pressure.xn;
const auto z_range = z_max - z_min;
const auto z1_position = frame.pressure.xp;
const float z1_norm = float(z1_position - z_min) / z_range;
const auto z2_position = frame.pressure.yn;
const float z2_norm = float(z2_position - z_min) / z_range;
const float r_x_plate = 330.0f;
//const float r_y_plate = 600.0f;
const float r_touch = r_x_plate * x_norm * (z2_norm / z1_norm - 1.0f);
return {
.x = x_norm,
.y = y_norm,
.r = r_touch,
};
}
void Manager::feed(const Frame& frame) {
// touch_debounce.feed(touch_raw);
const auto touch_raw = frame.touch;
//const auto touch_stable = touch_debounce.state();
const auto touch_stable = frame.touch;
bool touch_pressure = false;
// Only feed coordinate averaging if there's a touch.
// TODO: Separate threshold to gate coordinates for filtering?
if( touch_raw ) {
const auto metrics = calculate_metrics(frame);
// TODO: Add touch pressure hysteresis?
touch_pressure = (metrics.r < r_touch_threshold);
if( touch_pressure ) {
const float x = width_pixels * (metrics.x - calib_x_low) / calib_x_range;
filter_x.feed(x);
const float y = height_pixels * (calib_y_high - metrics.y) / calib_y_range;
filter_y.feed(y);
}
} else {
filter_x.reset();
filter_y.reset();
}
switch(state) {
case State::NoTouch:
if( touch_stable && touch_pressure ) {
if( point_stable() ) {
state = State::TouchDetected;
touch_started();
}
}
break;
case State::TouchDetected:
if( touch_stable && touch_pressure ) {
touch_moved();
} else {
state = State::NoTouch;
touch_ended();
}
break;
default:
state = State::NoTouch;
break;
}
}
} /* namespace touch */