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- /****************************************************************************
- * graphics/nxglib/nxglib_circlepts.c
- *
- * Copyright (C) 2011 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <string.h>
- #include <errno.h>
- #include <fixedmath.h>
- #include <nuttx/nx/nxglib.h>
- /****************************************************************************
- * Pre-Processor Definitions
- ****************************************************************************/
- /* Trigonometry */
- #define SIN_0p0 0 /* sin(0) = 0 */
- #define COS_0p0 1 /* cos(0) = 1 */
- #define SIN_22p5 25080 /* sin(22.5) = 25080 / 65536 */
- #define COS_22p5 60547 /* cos(22.5) = 60547 / 65536 */
- #define SIN_45p0 46341 /* sin(45) = 46341 / 65536 */
- #define COS_45p0 SIN_45p0 /* cos(45) = sin(45) */
- /* Named indices into the 16 circle points generated by nxgl_circlepts */
- #define POINT_0p0 0
- #define POINT_22p5 1
- #define POINT_45p0 2
- #define POINT_67p5 3
- #define POINT_90p0 4
- #define POINT_112p5 5
- #define POINT_135p0 6
- #define POINT_157p5 7
- #define POINT_180p0 8
- #define POINT_202p5 9
- #define POINT_225p0 10
- #define POINT_247p5 11
- #define POINT_270p0 12
- #define POINT_292p5 13
- #define POINT_315p0 14
- #define POINT_337p5 15
- #define NCIRCLE_POINTS 16
- /****************************************************************************
- * Private Types
- ****************************************************************************/
- /****************************************************************************
- * Private Data
- ****************************************************************************/
- /****************************************************************************
- * Public Data
- ****************************************************************************/
- /****************************************************************************
- * Private Functions
- ****************************************************************************/
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: nxgl_circlepts
- *
- * Description:
- * Given a description of a circle, return a set of 16 points on the
- * circumference of the circle. These points may then be used by
- * nx_drawcircle() or related APIs to draw a circle outline.
- *
- * Input parameters:
- * center - A pointer to the point that is the center of the circle
- * radius - The radius of the circle in pixels.
- * circle - A pointer the first entry in an array of 16 points where the
- * circle points will be returned.
- *
- * Returned value:
- * None
- *
- ****************************************************************************/
- void nxgl_circlepts(FAR const struct nxgl_point_s *center, nxgl_coord_t radius,
- FAR struct nxgl_point_s *circle)
- {
- nxgl_coord_t xoffs;
- nxgl_coord_t yoffs;
- /* 0, 90, 180, and 270 degrees are the easiest */
- circle[POINT_0p0].x = center->x + radius;
- circle[POINT_0p0].y = center->y;
- circle[POINT_90p0].x = center->x;
- circle[POINT_90p0].y = center->y + radius;
- circle[POINT_180p0].x = center->x - radius;
- circle[POINT_180p0].y = center->y;
- circle[POINT_270p0].x = center->x;
- circle[POINT_270p0].y = center->y - radius;
- /* Now 22.5, 67.5, 112.5, 157.5, 202.5, 247.5, 292.5, and 337.5 */
- xoffs = b16toi(b16muli(COS_22p5, radius) + b16HALF);
- yoffs = b16toi(b16muli(SIN_22p5, radius) + b16HALF);
- circle[POINT_22p5].x = center->x + xoffs;
- circle[POINT_22p5].y = center->y + yoffs;
- circle[POINT_157p5].x = center->x - xoffs;
- circle[POINT_157p5].y = center->y + yoffs;
- circle[POINT_202p5].x = center->x - xoffs;
- circle[POINT_202p5].y = center->y - yoffs;
- circle[POINT_337p5].x = center->x + xoffs;
- circle[POINT_337p5].y = center->y - yoffs;
- circle[POINT_67p5].x = center->x + yoffs;
- circle[POINT_67p5].y = center->y + xoffs;
- circle[POINT_112p5].x = center->x - yoffs;
- circle[POINT_112p5].y = center->y + xoffs;
- circle[POINT_247p5].x = center->x - yoffs;
- circle[POINT_247p5].y = center->y - xoffs;
- circle[POINT_292p5].x = center->x + yoffs;
- circle[POINT_292p5].y = center->y - xoffs;
- /* Finally, 45.0, 135.0, 225.0, 315.0 */
- xoffs = b16toi(b16muli(COS_45p0, radius) + b16HALF);
- circle[POINT_45p0].x = center->x + xoffs;
- circle[POINT_45p0].y = center->y + xoffs;
- circle[POINT_135p0].x = center->x - xoffs;
- circle[POINT_135p0].y = center->y + xoffs;
- circle[POINT_225p0].x = center->x - xoffs;
- circle[POINT_225p0].y = center->y - xoffs;
- circle[POINT_315p0].x = center->x + xoffs;
- circle[POINT_315p0].y = center->y - xoffs;
- }
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