101 lines
2.7 KiB
C
101 lines
2.7 KiB
C
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/*
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u8g_ellipse.c
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Utility to draw empty and filled ellipses.
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Universal 8bit Graphics Library
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Copyright (c) 2011, bjthom@gmail.com
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All rights reserved.
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Redistribution and use in source and binary forms, with or without modification,
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are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this list
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of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice, this
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list of conditions and the following disclaimer in the documentation and/or other
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materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Addition to the U8G Library as of 02/29/12
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Adapted from Bresenham's Algorithm and the following websites:
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http://free.pages.at/easyfilter/bresenham.html
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http://homepage.smc.edu/kennedy_john/belipse.pdf
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*/
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#include "u8g.h"
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#ifdef WORK_IN_PROGRESS
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void u8g_DrawEllipseRect(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t x1, u8g_uint_t y1)
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{
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int a = abs(x1 - x0);
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int b = abs(y1 - y0); //get diameters
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int b1 = b&1;
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long dx = 4*(1-a)*b*b;
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long dy = 4*(b1+1)*a*a;
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long err = dx+dy+b1*a*a;
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long e2;
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if (x0 > x1) { x0 = x1; x1 += a; }
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if (y0 > y1) { y0 = y1; }
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y0 += (b+1)/2;
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y1 = y0-b1;
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a *= 8*a;
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b1 = 8*b*b;
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do {
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u8g_DrawPixel(u8g, x1, y0);
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u8g_DrawPixel(u8g, x0, y0);
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u8g_DrawPixel(u8g, x0, y1);
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u8g_DrawPixel(u8g, x1, y1);
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e2 = 2*err;
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if (e2 >= dx) {
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x0++;
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x1--;
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err += dx += b1;
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}
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if (e2 <= dy) {
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y0++;
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y1--;
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err += dy += a;
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}
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} while (x0 <= x1);
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while (y0-y1 < b) {
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u8g_DrawPixel(u8g, x0-1, y0);
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u8g_DrawPixel(u8g, x1+1, y0++);
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u8g_DrawPixel(u8g, x0-1, y1);
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u8g_DrawPixel(u8g, x1+1, y1--);
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}
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}
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void u8g_DrawEllipse(u8g_t *u8g, u8g_uint_t x0, u8g_uint_t y0, u8g_uint_t xr, u8g_uint_t yr)
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{
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u8g_DrawPixel(u8g, x0, y0+yr);
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u8g_DrawPixel(u8g, x0, y0-yr);
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u8g_DrawPixel(u8g, x0+xr, y0);
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u8g_DrawPixel(u8g, x0-xr, y0);
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}
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#endif
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