/*

  u8g_ellipse.c

  Utility to draw empty and filled ellipses.

  Universal 8bit Graphics Library

  Copyright (c) 2011, bjthom@gmail.com
  All rights reserved.

  Redistribution and use in source and binary forms, with or without modification,
  are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice, this list
    of conditions and the following disclaimer.

  * 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.

  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 HOLDER 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.

  Addition to the U8G Library as of 02/29/12
  Adapted from Bresenham's Algorithm and the following websites:
  http://free.pages.at/easyfilter/bresenham.html
  http://homepage.smc.edu/kennedy_john/belipse.pdf

*/

#include "u8g.h"

#ifdef WORK_IN_PROGRESS

  void u8g_DrawEllipseRect(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t x1, u8g_uint_t y1) {
    int a = abs(x1 - x0);
    int b = abs(y1 - y0); // get diameters
    int b1 = b & 1;
    long dx = 4 * (1 - a) * b * b;
    long dy = 4 * (b1 + 1) * a * a;
    long err = dx + dy + b1 * a * a;
    long e2;

    if (x0 > x1) { x0 = x1; x1 += a; }
    if (y0 > y1)   y0 = y1;
    y0 += (b + 1) / 2;
    y1 = y0 - b1;
    a *= 8 * a;
    b1 = 8 * b * b;

    do {
      u8g_DrawPixel(u8g, x1, y0);
      u8g_DrawPixel(u8g, x0, y0);
      u8g_DrawPixel(u8g, x0, y1);
      u8g_DrawPixel(u8g, x1, y1);
      e2 = 2 * err;
      if (e2 >= dx) {
        x0++;
        x1--;
        err += dx += b1;
      }
      if (e2 <= dy) {
        y0++;
        y1--;
        err += dy += a;
      }
    } while (x0 <= x1);

    while (y0 - y1 < b) {
      u8g_DrawPixel(u8g, x0 - 1, y0);
      u8g_DrawPixel(u8g, x1 + 1, y0++);
      u8g_DrawPixel(u8g, x0 - 1, y1);
      u8g_DrawPixel(u8g, x1 + 1, y1--);
    }
  }

  void u8g_DrawEllipse(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t xr, u8g_uint_t yr) {
    u8g_DrawPixel(u8g, x0, y0 + yr);
    u8g_DrawPixel(u8g, x0, y0 - yr);
    u8g_DrawPixel(u8g, x0 + xr, y0);
    u8g_DrawPixel(u8g, x0 - xr, y0);
  }

#endif // ifdef WORK_IN_PROGRESS

#ifdef U8G_16BIT
  typedef  int32_t u8g_long_t;
#else
  typedef  int16_t u8g_long_t;
#endif

/*
  Source:
    ftp://pc.fk0.name/pub/books/programming/bezier-ellipse.pdf
    Foley, Computer Graphics, p 90
*/
static void u8g_draw_ellipse_section(u8g_t *u8g, u8g_uint_t x, u8g_uint_t y, u8g_uint_t x0, u8g_uint_t y0, uint8_t option) {
  // upper right
  if (option & U8G_DRAW_UPPER_RIGHT)
    u8g_DrawPixel(u8g, x0 + x, y0 - y);

  // upper left
  if (option & U8G_DRAW_UPPER_LEFT)
    u8g_DrawPixel(u8g, x0 - x, y0 - y);

  // lower right
  if (option & U8G_DRAW_LOWER_RIGHT)
    u8g_DrawPixel(u8g, x0 + x, y0 + y);

  // lower left
  if (option & U8G_DRAW_LOWER_LEFT)
    u8g_DrawPixel(u8g, x0 - x, y0 + y);
}

void u8g_draw_ellipse(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t rx, u8g_uint_t ry, uint8_t option) {
  u8g_uint_t x, y;
  u8g_long_t xchg, ychg;
  u8g_long_t err;
  u8g_long_t rxrx2;
  u8g_long_t ryry2;
  u8g_long_t stopx, stopy;

  rxrx2 = rx;
  rxrx2 *= rx;
  rxrx2 *= 2;

  ryry2 = ry;
  ryry2 *= ry;
  ryry2 *= 2;

  x = rx;
  y = 0;

  xchg = 1;
  xchg -= rx;
  xchg -= rx;
  xchg *= ry;
  xchg *= ry;

  ychg = rx;
  ychg *= rx;

  err = 0;

  stopx = ryry2;
  stopx *= rx;
  stopy = 0;

  while (stopx >= stopy) {
    u8g_draw_ellipse_section(u8g, x, y, x0, y0, option);
    y++;
    stopy += rxrx2;
    err += ychg;
    ychg += rxrx2;
    if (2 * err + xchg > 0) {
      x--;
      stopx -= ryry2;
      err += xchg;
      xchg += ryry2;
    }
  }

  x = 0;
  y = ry;

  xchg = ry;
  xchg *= ry;

  ychg = 1;
  ychg -= ry;
  ychg -= ry;
  ychg *= rx;
  ychg *= rx;

  err = 0;

  stopx = 0;

  stopy = rxrx2;
  stopy *= ry;

  while (stopx <= stopy) {
    u8g_draw_ellipse_section(u8g, x, y, x0, y0, option);
    x++;
    stopx += ryry2;
    err += xchg;
    xchg += ryry2;
    if (2 * err + ychg > 0) {
      y--;
      stopy -= rxrx2;
      err += ychg;
      ychg += rxrx2;
    }
  }

}

void u8g_DrawEllipse(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t rx, u8g_uint_t ry, uint8_t option) {
  // check for bounding box
  {
    u8g_uint_t rxp, rxp2;
    u8g_uint_t ryp, ryp2;

    rxp = rx;
    rxp++;
    rxp2 = rxp;
    rxp2 *= 2;

    ryp = ry;
    ryp++;
    ryp2 = ryp;
    ryp2 *= 2;

    if (u8g_IsBBXIntersection(u8g, x0 - rxp, y0 - ryp, rxp2, ryp2) == 0)
      return;
  }

  u8g_draw_ellipse(u8g, x0, y0, rx, ry, option);
}

static void u8g_draw_filled_ellipse_section(u8g_t *u8g, u8g_uint_t x, u8g_uint_t y, u8g_uint_t x0, u8g_uint_t y0, uint8_t option) {
  // upper right
  if (option & U8G_DRAW_UPPER_RIGHT)
    u8g_DrawVLine(u8g, x0 + x, y0 - y, y + 1);

  // upper left
  if (option & U8G_DRAW_UPPER_LEFT)
    u8g_DrawVLine(u8g, x0 - x, y0 - y, y + 1);

  // lower right
  if (option & U8G_DRAW_LOWER_RIGHT)
    u8g_DrawVLine(u8g, x0 + x, y0, y + 1);

  // lower left
  if (option & U8G_DRAW_LOWER_LEFT)
    u8g_DrawVLine(u8g, x0 - x, y0, y + 1);
}

void u8g_draw_filled_ellipse(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t rx, u8g_uint_t ry, uint8_t option) {
  u8g_uint_t x, y;
  u8g_long_t xchg, ychg;
  u8g_long_t err;
  u8g_long_t rxrx2;
  u8g_long_t ryry2;
  u8g_long_t stopx, stopy;

  rxrx2 = rx;
  rxrx2 *= rx;
  rxrx2 *= 2;

  ryry2 = ry;
  ryry2 *= ry;
  ryry2 *= 2;

  x = rx;
  y = 0;

  xchg = 1;
  xchg -= rx;
  xchg -= rx;
  xchg *= ry;
  xchg *= ry;

  ychg = rx;
  ychg *= rx;

  err = 0;

  stopx = ryry2;
  stopx *= rx;
  stopy = 0;

  while (stopx >= stopy) {
    u8g_draw_filled_ellipse_section(u8g, x, y, x0, y0, option);
    y++;
    stopy += rxrx2;
    err += ychg;
    ychg += rxrx2;
    if (2 * err + xchg > 0) {
      x--;
      stopx -= ryry2;
      err += xchg;
      xchg += ryry2;
    }
  }

  x = 0;
  y = ry;

  xchg = ry;
  xchg *= ry;

  ychg = 1;
  ychg -= ry;
  ychg -= ry;
  ychg *= rx;
  ychg *= rx;

  err = 0;

  stopx = 0;

  stopy = rxrx2;
  stopy *= ry;

  while (stopx <= stopy) {
    u8g_draw_filled_ellipse_section(u8g, x, y, x0, y0, option);
    x++;
    stopx += ryry2;
    err += xchg;
    xchg += ryry2;
    if (2 * err + ychg > 0) {
      y--;
      stopy -= rxrx2;
      err += ychg;
      ychg += rxrx2;
    }
  }

}

void u8g_DrawFilledEllipse(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t rx, u8g_uint_t ry, uint8_t option) {
  // check for bounding box
  {
    u8g_uint_t rxp, rxp2;
    u8g_uint_t ryp, ryp2;

    rxp = rx;
    rxp++;
    rxp2 = rxp;
    rxp2 *= 2;

    ryp = ry;
    ryp++;
    ryp2 = ryp;
    ryp2 *= 2;

    if (u8g_IsBBXIntersection(u8g, x0 - rxp, y0 - ryp, rxp2, ryp2) == 0)
      return;
  }

  u8g_draw_filled_ellipse(u8g, x0, y0, rx, ry, option);
}
