libs/libnx/nx/nx_drawcircle.c

/****************************************************************************
 * libs/libnx/nx/nx_drawcircle.c
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <debug.h>
#include <errno.h>

#include <nuttx/nx/nxglib.h>
#include <nuttx/nx/nx.h>

/****************************************************************************
 * Pre-Processor Definitions
 ****************************************************************************/

/* 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

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: nx_drawcircle
 *
 * Description:
 *  Draw a circular outline using the specified line thickness and color.
 *
 * Input Parameters:
 *   hwnd   - The window handle
 *   center - A pointer to the point that is the center of the circle
 *   radius - The radius of the circle in pixels.
 *   width  - The width of the line
 *   color  - The color to use to fill the line
 *
 * Returned Value:
 *   OK on success; ERROR on failure with errno set appropriately
 *
 ****************************************************************************/

int nx_drawcircle(NXWINDOW hwnd, FAR const struct nxgl_point_s *center,
                  nxgl_coord_t radius, nxgl_coord_t width,
                  nxgl_mxpixel_t color[CONFIG_NX_NPLANES])
{
  struct nxgl_point_s pts[NCIRCLE_POINTS];
  FAR struct nxgl_vector_s vector;
  int i;
  int ret;

  /* Convert the circle to a set of 16 points */

  nxgl_circlepts(center, radius, pts);

  /* Draw each pair of points as a vector */

  for (i = POINT_0p0; i < POINT_337p5; i++)
    {
      /* Draw one line segment */

      vector.pt1.x = pts[i].x;
      vector.pt1.y = pts[i].y;
      vector.pt2.x = pts[i + 1].x;
      vector.pt2.y = pts[i + 1].y;

      ret = nx_drawline(hwnd, &vector, width, color, NX_LINECAP_PT1);
      if (ret != OK)
        {
          return ret;
        }
    }

  /* The final, closing vector is a special case */

  vector.pt1.x = pts[POINT_337p5].x;
  vector.pt1.y = pts[POINT_337p5].y;
  vector.pt2.x = pts[POINT_0p0].x;
  vector.pt2.y = pts[POINT_0p0].y;
  return nx_drawline(hwnd, &vector, width, color, NX_LINECAP_PT1);
}