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