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122 lines
3.4 KiB
C
122 lines
3.4 KiB
C
/* Libart_LGPL - library of basic graphic primitives
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* Copyright (C) 1998 Raph Levien
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/* Render a sorted vector path into a graymap. */
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#include <string.h> /* for memset */
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#include "art_misc.h"
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#include "art_svp.h"
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#include "art_svp_render_aa.h"
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#include "art_gray_svp.h"
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typedef struct _ArtGraySVPData ArtGraySVPData;
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struct _ArtGraySVPData {
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art_u8 *buf;
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int rowstride;
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int x0, x1;
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};
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static void
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art_gray_svp_callback (void *callback_data, int y,
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int start, ArtSVPRenderAAStep *steps, int n_steps)
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{
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ArtGraySVPData *data = (ArtGraySVPData *)callback_data;
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art_u8 *linebuf;
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int run_x0, run_x1;
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int running_sum = start;
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int x0, x1;
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int k;
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#if 0
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printf ("start = %d", start);
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running_sum = start;
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for (k = 0; k < n_steps; k++)
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{
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running_sum += steps[k].delta;
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printf (" %d:%d", steps[k].x, running_sum >> 16);
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}
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printf ("\n");
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#endif
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linebuf = data->buf;
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x0 = data->x0;
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x1 = data->x1;
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if (n_steps > 0)
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{
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run_x1 = steps[0].x;
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if (run_x1 > x0)
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memset (linebuf, running_sum >> 16, run_x1 - x0);
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for (k = 0; k < n_steps - 1; k++)
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{
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running_sum += steps[k].delta;
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run_x0 = run_x1;
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run_x1 = steps[k + 1].x;
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if (run_x1 > run_x0)
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memset (linebuf + run_x0 - x0, running_sum >> 16, run_x1 - run_x0);
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}
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running_sum += steps[k].delta;
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if (x1 > run_x1)
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memset (linebuf + run_x1 - x0, running_sum >> 16, x1 - run_x1);
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}
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else
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{
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memset (linebuf, running_sum >> 16, x1 - x0);
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}
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data->buf += data->rowstride;
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}
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/**
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* art_gray_svp_aa: Render the vector path into the bytemap.
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* @svp: The SVP to render.
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* @x0: The view window's left coord.
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* @y0: The view window's top coord.
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* @x1: The view window's right coord.
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* @y1: The view window's bottom coord.
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* @buf: The buffer where the bytemap is stored.
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* @rowstride: the rowstride for @buf.
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*
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* Each pixel gets a value proportional to the area within the pixel
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* overlapping the (filled) SVP. Pixel (x, y) is stored at:
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*
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* @buf[(y - * @y0) * @rowstride + (x - @x0)]
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*
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* All pixels @x0 <= x < @x1, @y0 <= y < @y1 are generated. A
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* stored value of zero is no coverage, and a value of 255 is full
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* coverage. The area within the pixel (x, y) is the region covered
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* by [x..x+1] and [y..y+1].
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**/
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void
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art_gray_svp_aa (const ArtSVP *svp,
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int x0, int y0, int x1, int y1,
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art_u8 *buf, int rowstride)
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{
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ArtGraySVPData data;
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data.buf = buf;
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data.rowstride = rowstride;
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data.x0 = x0;
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data.x1 = x1;
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art_svp_render_aa (svp, x0, y0, x1, y1, art_gray_svp_callback, &data);
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}
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