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- // Copyright 2021 Paul Cotter (@gr1mr3aver)
- // Copyright 2021 Nick Brassel (@tzarc)
- // SPDX-License-Identifier: GPL-2.0-or-later
-
- #include "qp.h"
- #include "qp_internal.h"
- #include "qp_comms.h"
- #include "qp_draw.h"
-
- // Utilize 8-way symmetry to draw circles
- static bool qp_circle_helper_impl(painter_device_t device, uint16_t centerx, uint16_t centery, uint16_t offsetx, uint16_t offsety, bool filled) {
- /*
- Circles have the property of 8-way symmetry, so eight pixels can be drawn
- for each computed [offsetx,offsety] given the center coordinates
- represented by [centerx,centery].
-
- For filled circles, we can draw horizontal lines between each pair of
- pixels with the same final value of y.
-
- Two special cases exist and have been optimized:
- 1) offsetx == offsety (the final point), makes half the coordinates
- equivalent, so we can omit them (and the corresponding fill lines)
- 2) offsetx == 0 (the starting point) means that some horizontal lines
- would be a single pixel in length, so we write individual pixels instead.
- This also makes half the symmetrical points identical to their twins,
- so we only need four points or two points and one line
- */
-
- int16_t xpx = ((int16_t)centerx) + ((int16_t)offsetx);
- int16_t xmx = ((int16_t)centerx) - ((int16_t)offsetx);
- int16_t xpy = ((int16_t)centerx) + ((int16_t)offsety);
- int16_t xmy = ((int16_t)centerx) - ((int16_t)offsety);
- int16_t ypx = ((int16_t)centery) + ((int16_t)offsetx);
- int16_t ymx = ((int16_t)centery) - ((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, centerx, ypy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, centerx, ymy)) {
- return false;
- }
- if (filled) {
- if (!qp_internal_fillrect_helper_impl(device, xpy, centery, xmy, centery)) {
- return false;
- }
- } else {
- if (!qp_internal_setpixel_impl(device, xpy, centery)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xmy, centery)) {
- return false;
- }
- }
- } else if (offsetx == offsety) {
- if (filled) {
- if (!qp_internal_fillrect_helper_impl(device, xpy, ypy, xmy, ypy)) {
- return false;
- }
- if (!qp_internal_fillrect_helper_impl(device, xpy, ymy, xmy, ymy)) {
- return false;
- }
- } else {
- if (!qp_internal_setpixel_impl(device, xpy, ypy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xmy, ypy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xpy, ymy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xmy, ymy)) {
- return false;
- }
- }
-
- } else {
- if (filled) {
- if (!qp_internal_fillrect_helper_impl(device, xpx, ypy, xmx, ypy)) {
- return false;
- }
- if (!qp_internal_fillrect_helper_impl(device, xpx, ymy, xmx, ymy)) {
- return false;
- }
- if (!qp_internal_fillrect_helper_impl(device, xpy, ypx, xmy, ypx)) {
- return false;
- }
- if (!qp_internal_fillrect_helper_impl(device, xpy, ymx, xmy, ymx)) {
- return false;
- }
- } else {
- if (!qp_internal_setpixel_impl(device, xpx, ypy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xmx, ypy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xpx, ymy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xmx, ymy)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xpy, ypx)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xmy, ypx)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xpy, ymx)) {
- return false;
- }
- if (!qp_internal_setpixel_impl(device, xmy, ymx)) {
- return false;
- }
- }
- }
-
- return true;
- }
-
- ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- // Quantum Painter External API: qp_circle
-
- bool qp_circle(painter_device_t device, uint16_t x, uint16_t y, uint16_t radius, uint8_t hue, uint8_t sat, uint8_t val, bool filled) {
- qp_dprintf("qp_circle: entry\n");
- struct painter_driver_t *driver = (struct painter_driver_t *)device;
- if (!driver->validate_ok) {
- qp_dprintf("qp_circle: fail (validation_ok == false)\n");
- return false;
- }
-
- // plot the initial set of points for x, y and r
- int16_t xcalc = 0;
- int16_t ycalc = (int16_t)radius;
- int16_t err = ((5 - (radius >> 2)) >> 2);
-
- qp_internal_fill_pixdata(device, (radius * 2) + 1, hue, sat, val);
-
- if (!qp_comms_start(device)) {
- qp_dprintf("qp_circle: fail (could not start comms)\n");
- return false;
- }
-
- bool ret = true;
- if (!qp_circle_helper_impl(device, x, y, xcalc, ycalc, filled)) {
- ret = false;
- }
-
- if (ret) {
- while (xcalc < ycalc) {
- xcalc++;
- if (err < 0) {
- err += (xcalc << 1) + 1;
- } else {
- ycalc--;
- err += ((xcalc - ycalc) << 1) + 1;
- }
- if (!qp_circle_helper_impl(device, x, y, xcalc, ycalc, filled)) {
- ret = false;
- break;
- }
- }
- }
-
- qp_dprintf("qp_circle: %s\n", ret ? "ok" : "fail");
- qp_comms_stop(device);
- return ret;
- }
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