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commit e5db2b1f3508e1630b9af36a397a68ef069a56a2 Author: Cyril Hrubis metan@ucw.cz Date: Sun Jan 8 18:53:24 2012 +0100
gfx: Add function for circle segment drawing.
diff --git a/include/gfx/GP_Gfx.h b/include/gfx/GP_CircleSeg.h similarity index 53% copy from include/gfx/GP_Gfx.h copy to include/gfx/GP_CircleSeg.h index 6503952..fddc5ef 100644 --- a/include/gfx/GP_Gfx.h +++ b/include/gfx/GP_CircleSeg.h @@ -16,41 +16,52 @@ * Foundation, Inc., 51 Franklin Street, Fifth Floor, * * Boston, MA 02110-1301 USA * * * - * Copyright (C) 2009-2010 Jiri "BlueBear" Dluhos * + * Copyright (C) 2009-2011 Jiri "BlueBear" Dluhos * * jiri.bluebear.dluhos@gmail.com * * * - * Copyright (C) 2009-2011 Cyril Hrubis metan@ucw.cz * + * Copyright (C) 2009-2012 Cyril Hrubis metan@ucw.cz * * * *****************************************************************************/
-/* +#ifndef GFX_GP_CIRCLE_H +#define GFX_GP_CIRCLE_H
- This is a main header for gfx part. +#include "core/GP_Context.h"
+/* + * Quadrants in cartesian space the center is set in the middle of the circle. + * + * First segment is where both x and y are possitive, second is where only y is + * possitive, third is for both x and y negative and the last one for only y + * negative. + * + * Note that on computer screen (and in in-memory bitmaps) cordinates for y + * grows in the opposite direction to the standard cartesian plane. + * + * So first segment is actually down right, second is down left, third is up + * left, and fourth is up right. */ +enum GP_CircleSegments { + GP_CIRCLE_SEG1 = 0x01, /* First Quadrant */ + GP_CIRCLE_SEG2 = 0x02, /* Second Quadrant */ + GP_CIRCLE_SEG3 = 0x04, /* Third Quadrant */ + GP_CIRCLE_SEG4 = 0x08, /* Fourth Quadrant */ +};
-#ifndef GP_GFX_H -#define GP_GFX_H +/* Circle Segment */
-/* basic definitions and structures */ -#include "core/GP_Context.h" -#include "core/GP_GetPutPixel.h" -#include "core/GP_WritePixel.h" - -/* public drawing API */ -#include "GP_Fill.h" -#include "GP_HLine.h" -#include "GP_VLine.h" -#include "GP_Line.h" -#include "GP_Rect.h" -#include "GP_Triangle.h" -#include "GP_Tetragon.h" -#include "GP_Circle.h" -#include "GP_Ellipse.h" -#include "GP_Arc.h" -#include "GP_Polygon.h" -#include "GP_Symbol.h" - -#include "GP_RectAA.h" - -#endif /* GP_GFX_H */ +void GP_CircleSeg(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, uint8_t seg_flag, GP_Pixel pixel); + +void GP_CircleSeg_Raw(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, uint8_t seg_flag, GP_Pixel pixel); + +/* Filled Circle Segment */ + +void GP_FillCircleSeg(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, uint8_t seg_flag, GP_Pixel pixel); + +void GP_FillCircleSeg_Raw(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, uint8_t seg_flag, GP_Pixel pixel); + +#endif /* GFX_GP_CIRCLE_H */ diff --git a/include/gfx/GP_Gfx.h b/include/gfx/GP_Gfx.h index 6503952..54648a8 100644 --- a/include/gfx/GP_Gfx.h +++ b/include/gfx/GP_Gfx.h @@ -46,6 +46,7 @@ #include "GP_Triangle.h" #include "GP_Tetragon.h" #include "GP_Circle.h" +#include "GP_CircleSeg.h" #include "GP_Ellipse.h" #include "GP_Arc.h" #include "GP_Polygon.h" diff --git a/libs/gfx/GP_CircleSeg.c b/libs/gfx/GP_CircleSeg.c new file mode 100644 index 0000000..56179c6 --- /dev/null +++ b/libs/gfx/GP_CircleSeg.c @@ -0,0 +1,108 @@ +/***************************************************************************** + * This file is part of gfxprim library. * + * * + * Gfxprim is free software; you can redistribute it and/or * + * modify it under the terms of the GNU Lesser General Public * + * License as published by the Free Software Foundation; either * + * version 2.1 of the License, or (at your option) any later version. * + * * + * Gfxprim is distributed in the hope that it will be useful, * + * but WITHOUT ANY WARRANTY; without even the implied warranty of * + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * + * Lesser General Public License for more details. * + * * + * You should have received a copy of the GNU Lesser General Public * + * License along with gfxprim; if not, write to the Free Software * + * Foundation, Inc., 51 Franklin Street, Fifth Floor, * + * Boston, MA 02110-1301 USA * + * * + * Copyright (C) 2009-2011 Jiri "BlueBear" Dluhos * + * jiri.bluebear.dluhos@gmail.com * + * * + * Copyright (C) 2009-2012 Cyril Hrubis metan@ucw.cz * + * * + *****************************************************************************/ + +#include "GP_CircleSeg.h" +#include "GP_HLine.h" + +#include "core/GP_GetPutPixel.h" +#include "core/GP_FnPerBpp.h" + +#include "algo/CircleSeg.algo.h" + +static uint8_t transform_segments(GP_Context *context, uint8_t seg_flags) +{ + uint8_t seg1 = seg_flags & GP_CIRCLE_SEG1; + uint8_t seg2 = seg_flags & GP_CIRCLE_SEG2; + uint8_t seg3 = seg_flags & GP_CIRCLE_SEG3; + uint8_t seg4 = seg_flags & GP_CIRCLE_SEG4; + + if (context->axes_swap) + GP_SWAP(seg2, seg4); + + if (context->x_swap) { + GP_SWAP(seg1, seg2); + GP_SWAP(seg3, seg4); + } + + if (context->y_swap) { + GP_SWAP(seg1, seg4); + GP_SWAP(seg2, seg3); + } + + seg1 = seg1 ? GP_CIRCLE_SEG1 : 0; + seg2 = seg2 ? GP_CIRCLE_SEG2 : 0; + seg3 = seg3 ? GP_CIRCLE_SEG3 : 0; + seg4 = seg4 ? GP_CIRCLE_SEG4 : 0; + + return seg1|seg2|seg3|seg4; +} + +/* Generate drawing functions for various bit depths. */ +GP_DEF_DRAW_FN_PER_BPP(GP_CircleSeg_Raw, DEF_CIRCLE_SEG_FN) + +void GP_CircleSeg_Raw(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, uint8_t seg_flag, GP_Pixel pixel) +{ + GP_CHECK_CONTEXT(context); + + GP_FN_PER_BPP_CONTEXT(GP_CircleSeg_Raw, context, context, + xcenter, ycenter, r, seg_flag, pixel); +} + +void GP_CircleSeg(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, uint8_t seg_flag, GP_Pixel pixel) +{ + GP_CHECK_CONTEXT(context); + + GP_TRANSFORM_POINT(context, xcenter, ycenter); + + GP_CircleSeg_Raw(context, xcenter, ycenter, r, + transform_segments(context, seg_flag), pixel); +} + +/* +#include "algo/FillCircle.algo.h" + +GP_DEF_FILL_FN_PER_BPP(GP_FillCircle_Raw, DEF_FILLCIRCLE_FN) + +void GP_FillCircle_Raw(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, GP_Pixel pixel) +{ + GP_CHECK_CONTEXT(context); + + GP_FN_PER_BPP_CONTEXT(GP_FillCircle_Raw, context, context, + xcenter, ycenter, r, pixel); +} + +void GP_FillCircle(GP_Context *context, GP_Coord xcenter, GP_Coord ycenter, + GP_Size r, GP_Pixel pixel) +{ + GP_CHECK_CONTEXT(context); + + GP_TRANSFORM_POINT(context, xcenter, ycenter); + + GP_FillCircle_Raw(context, xcenter, ycenter, r, pixel); +} +*/ diff --git a/libs/gfx/algo/CircleSeg.algo.h b/libs/gfx/algo/CircleSeg.algo.h new file mode 100644 index 0000000..9812888 --- /dev/null +++ b/libs/gfx/algo/CircleSeg.algo.h @@ -0,0 +1,108 @@ +/***************************************************************************** + * This file is part of gfxprim library. * + * * + * Gfxprim is free software; you can redistribute it and/or * + * modify it under the terms of the GNU Lesser General Public * + * License as published by the Free Software Foundation; either * + * version 2.1 of the License, or (at your option) any later version. * + * * + * Gfxprim is distributed in the hope that it will be useful, * + * but WITHOUT ANY WARRANTY; without even the implied warranty of * + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * + * Lesser General Public License for more details. * + * * + * You should have received a copy of the GNU Lesser General Public * + * License along with gfxprim; if not, write to the Free Software * + * Foundation, Inc., 51 Franklin Street, Fifth Floor, * + * Boston, MA 02110-1301 USA * + * * + * Copyright (C) 2009-2011 Jiri "BlueBear" Dluhos * + * jiri.bluebear.dluhos@gmail.com * + * * + * Copyright (C) 2009-2012 Cyril Hrubis metan@ucw.cz * + * * + *****************************************************************************/ + +/* + * Circle drawing algorithm. + * + * The circle is drawn in a top-down manner. We start from the top, and + * at each line, we iterate X until we accumulate enough changes to Y + * to pass to the next line. In each step, 4 pixels are drawn: + * (X, Y), (-X, Y), (X, -Y) and (-X, -Y). + * + * The math: + * From the circle equation, for every point applies: + * + * x^2 + y^2 = r^2 -> x^2 + y^2 - r^2 = 0 + * + * which has an exact solution for a non-integer x. + * For an integer approximation, we want to find x + * for which + * + * x^2 + y^2 - r^2 = error + * + * where error should be as close to 0 as possible. + * We find the x by incrementing its value until + * we cross the zero error boundary. + * + * Optimization: + * Significant amount of multiplications can be + * saved when calculating error by re-using previous + * error values. For error(x+1) we have: + * + * error(x+1) = (x+1)^2 + y^2 - r^2 + * + * which can be expanded to (expanding (x+1)^2): + * + * error(x+1) = x^2 + 2*x + 1 + y^2 - r^2 + * + * and after substituting the error(x) we already know: + * + * error(x+1) = error(x) + 2*x + 1 + * + * The same can be done for calculating + * error(y-1) from error(y). + */ + +/* + * This macro defines a circle drawing function. + * Arguments: + * CONTEXT_T - user-defined type of drawing context (passed to PUTPIXEL) + * PIXVAL_T - user-defined pixel value type (passed to PUTPIXEL) + * PUTPIXEL - a pixel drawing function f(context, x, y, pixval) + * FN_NAME - name of the function to be defined + */ +#define DEF_CIRCLE_SEG_FN(FN_NAME, CONTEXT_T, PIXVAL_T, PUTPIXEL) +void FN_NAME(CONTEXT_T context, int xcenter, int ycenter, unsigned int r, + uint8_t seg_flags, PIXVAL_T pixval) +{ + int x, y, error; + for (x = 0, error = -r, y = r; y >= 0; y--) { ++ /* Iterate X until we can pass to the next line. */ + while (error < 0) { + error += 2*x + 1; + x++; + if (seg_flags & GP_CIRCLE_SEG3) + PUTPIXEL(context, xcenter-x+1, ycenter-y, pixval); + if (seg_flags & GP_CIRCLE_SEG4) + PUTPIXEL(context, xcenter+x-1, ycenter-y, pixval); + if (seg_flags & GP_CIRCLE_SEG2) + PUTPIXEL(context, xcenter-x+1, ycenter+y, pixval); + if (seg_flags & GP_CIRCLE_SEG1) + PUTPIXEL(context, xcenter+x-1, ycenter+y, pixval); + } ++ /* Enough changes accumulated, go to next line. */ + error += -2*y + 1; + if (seg_flags & GP_CIRCLE_SEG3) + PUTPIXEL(context, xcenter-x+1, ycenter-y, pixval); + if (seg_flags & GP_CIRCLE_SEG4) + PUTPIXEL(context, xcenter+x-1, ycenter-y, pixval); + if (seg_flags & GP_CIRCLE_SEG2) + PUTPIXEL(context, xcenter-x+1, ycenter+y, pixval); + if (seg_flags & GP_CIRCLE_SEG1) + PUTPIXEL(context, xcenter+x-1, ycenter+y, pixval); + } +}
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Summary of changes: include/gfx/{GP_Triangle.h => GP_CircleSeg.h} | 52 +++++++---- include/gfx/GP_Gfx.h | 1 + libs/gfx/{GP_Circle.c => GP_CircleSeg.c} | 98 ++++++++++----------- libs/gfx/algo/{Circle.algo.h => CircleSeg.algo.h} | 30 ++++--- 4 files changed, 99 insertions(+), 82 deletions(-) copy include/gfx/{GP_Triangle.h => GP_CircleSeg.h} (55%) copy libs/gfx/{GP_Circle.c => GP_CircleSeg.c} (59%) copy libs/gfx/algo/{Circle.algo.h => CircleSeg.algo.h} (85%)
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