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-rw-r--r--quantum/painter/qp_draw_circle.c172
1 files changed, 172 insertions, 0 deletions
diff --git a/quantum/painter/qp_draw_circle.c b/quantum/painter/qp_draw_circle.c
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+++ b/quantum/painter/qp_draw_circle.c
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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;
+}