143 lines
5.1 KiB
C
143 lines
5.1 KiB
C
/****************************************************************************
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* graphics/nxglib/nxglib_circlepts.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <string.h>
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#include <errno.h>
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#include <fixedmath.h>
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#include <nuttx/nx/nxglib.h>
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/****************************************************************************
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* Pre-Processor Definitions
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****************************************************************************/
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/* Trigonometry */
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#define SIN_0p0 0 /* sin(0) = 0 */
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#define COS_0p0 1 /* cos(0) = 1 */
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#define SIN_22p5 25080 /* sin(22.5) = 25080 / 65536 */
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#define COS_22p5 60547 /* cos(22.5) = 60547 / 65536 */
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#define SIN_45p0 46341 /* sin(45) = 46341 / 65536 */
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#define COS_45p0 SIN_45p0 /* cos(45) = sin(45) */
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/* Named indices into the 16 circle points generated by nxgl_circlepts */
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#define POINT_0p0 0
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#define POINT_22p5 1
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#define POINT_45p0 2
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#define POINT_67p5 3
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#define POINT_90p0 4
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#define POINT_112p5 5
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#define POINT_135p0 6
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#define POINT_157p5 7
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#define POINT_180p0 8
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#define POINT_202p5 9
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#define POINT_225p0 10
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#define POINT_247p5 11
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#define POINT_270p0 12
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#define POINT_292p5 13
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#define POINT_315p0 14
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#define POINT_337p5 15
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#define NCIRCLE_POINTS 16
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxgl_circlepts
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*
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* Description:
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* Given a description of a circle, return a set of 16 points on the
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* circumference of the circle. These points may then be used by
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* nx_drawcircle() or related APIs to draw a circle outline.
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*
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* Input Parameters:
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* center - A pointer to the point that is the center of the circle
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* radius - The radius of the circle in pixels.
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* circle - A pointer the first entry in an array of 16 points where the
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* circle points will be returned.
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void nxgl_circlepts(FAR const struct nxgl_point_s *center,
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nxgl_coord_t radius,
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FAR struct nxgl_point_s *circle)
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{
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nxgl_coord_t xoffs;
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nxgl_coord_t yoffs;
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/* 0, 90, 180, and 270 degrees are the easiest */
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circle[POINT_0p0].x = center->x + radius;
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circle[POINT_0p0].y = center->y;
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circle[POINT_90p0].x = center->x;
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circle[POINT_90p0].y = center->y + radius;
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circle[POINT_180p0].x = center->x - radius;
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circle[POINT_180p0].y = center->y;
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circle[POINT_270p0].x = center->x;
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circle[POINT_270p0].y = center->y - radius;
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/* Now 22.5, 67.5, 112.5, 157.5, 202.5, 247.5, 292.5, and 337.5 */
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xoffs = b16toi(b16muli(COS_22p5, radius) + b16HALF);
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yoffs = b16toi(b16muli(SIN_22p5, radius) + b16HALF);
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circle[POINT_22p5].x = center->x + xoffs;
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circle[POINT_22p5].y = center->y + yoffs;
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circle[POINT_157p5].x = center->x - xoffs;
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circle[POINT_157p5].y = center->y + yoffs;
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circle[POINT_202p5].x = center->x - xoffs;
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circle[POINT_202p5].y = center->y - yoffs;
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circle[POINT_337p5].x = center->x + xoffs;
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circle[POINT_337p5].y = center->y - yoffs;
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circle[POINT_67p5].x = center->x + yoffs;
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circle[POINT_67p5].y = center->y + xoffs;
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circle[POINT_112p5].x = center->x - yoffs;
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circle[POINT_112p5].y = center->y + xoffs;
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circle[POINT_247p5].x = center->x - yoffs;
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circle[POINT_247p5].y = center->y - xoffs;
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circle[POINT_292p5].x = center->x + yoffs;
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circle[POINT_292p5].y = center->y - xoffs;
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/* Finally, 45.0, 135.0, 225.0, 315.0 */
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xoffs = b16toi(b16muli(COS_45p0, radius) + b16HALF);
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circle[POINT_45p0].x = center->x + xoffs;
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circle[POINT_45p0].y = center->y + xoffs;
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circle[POINT_135p0].x = center->x - xoffs;
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circle[POINT_135p0].y = center->y + xoffs;
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circle[POINT_225p0].x = center->x - xoffs;
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circle[POINT_225p0].y = center->y - xoffs;
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circle[POINT_315p0].x = center->x + xoffs;
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circle[POINT_315p0].y = center->y - xoffs;
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}
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