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// Copyright 2021 Paul Cotter (@gr1mr3aver)
// Copyright 2021 Nick Brassel (@tzarc)
// SPDX-License-Identifier: GPL-2.0-or-later
#include "qp_internal.h"
#include "qp_comms.h"
#include "qp_draw.h"
// Utilize 4-way symmetry to draw an ellipse
static bool qp_ellipse_helper_impl(painter_device_t device, uint16_t centerx, uint16_t centery, uint16_t offsetx, uint16_t offsety, bool filled) {
/*
Ellipses have the property of 4-way symmetry, so four pixels can be drawn
for each computed [offsetx,offsety] given the center coordinates
represented by [centerx,centery].
For filled ellipses, we can draw horizontal lines between each pair of
pixels with the same final value of y.
When offsetx == 0 only two pixels can be drawn for filled or unfilled ellipses
*/
int16_t xpx = ((int16_t)centerx) + ((int16_t)offsetx);
int16_t xmx = ((int16_t)centerx) - ((int16_t)offsetx);
int16_t ypy = ((int16_t)centery) + ((int16_t)offsety);
int16_t ymy = ((int16_t)centery) - ((int16_t)offsety);
if (offsetx == 0) {
if (!qp_internal_setpixel_impl(device, xpx, ypy)) {
return false;
}
if (!qp_internal_setpixel_impl(device, xpx, ymy)) {
return false;
}
} else if (filled) {
if (!qp_internal_fillrect_helper_impl(device, xpx, ypy, xmx, ypy)) {
return false;
}
if (offsety > 0 && !qp_internal_fillrect_helper_impl(device, xpx, ymy, xmx, ymy)) {
return false;
}
} else {
if (!qp_internal_setpixel_impl(device, xpx, ypy)) {
return false;
}
if (!qp_internal_setpixel_impl(device, xpx, ymy)) {
return false;
}
if (!qp_internal_setpixel_impl(device, xmx, ypy)) {
return false;
}
if (!qp_internal_setpixel_impl(device, xmx, ymy)) {
return false;
}
}
return true;
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Quantum Painter External API: qp_ellipse
bool qp_ellipse(painter_device_t device, uint16_t x, uint16_t y, uint16_t sizex, uint16_t sizey, uint8_t hue, uint8_t sat, uint8_t val, bool filled) {
qp_dprintf("qp_ellipse: entry\n");
painter_driver_t *driver = (painter_driver_t *)device;
if (!driver->validate_ok) {
qp_dprintf("qp_ellipse: fail (validation_ok == false)\n");
return false;
}
int16_t aa = ((int16_t)sizex) * ((int16_t)sizex);
int16_t bb = ((int16_t)sizey) * ((int16_t)sizey);
int16_t fa = 4 * ((int16_t)aa);
int16_t fb = 4 * ((int16_t)bb);
int16_t dx = 0;
int16_t dy = ((int16_t)sizey);
qp_internal_fill_pixdata(device, QP_MAX(sizex, sizey), hue, sat, val);
if (!qp_comms_start(device)) {
qp_dprintf("qp_ellipse: fail (could not start comms)\n");
return false;
}
bool ret = true;
for (int16_t delta = (2 * bb) + (aa * (1 - (2 * sizey))); bb * dx <= aa * dy; dx++) {
if (!qp_ellipse_helper_impl(device, x, y, dx, dy, filled)) {
ret = false;
break;
}
if (delta >= 0) {
delta += fa * (1 - dy);
dy--;
}
delta += bb * (4 * dx + 6);
}
dx = sizex;
dy = 0;
for (int16_t delta = (2 * aa) + (bb * (1 - (2 * sizex))); aa * dy <= bb * dx; dy++) {
if (!qp_ellipse_helper_impl(device, x, y, dx, dy, filled)) {
ret = false;
break;
}
if (delta >= 0) {
delta += fb * (1 - dx);
dx--;
}
delta += aa * (4 * dy + 6);
}
qp_dprintf("qp_ellipse: %s\n", ret ? "ok" : "fail");
qp_comms_stop(device);
return ret;
}
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