зеркало из https://github.com/mozilla/pjs.git
199 строки
5.1 KiB
C
199 строки
5.1 KiB
C
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/* Libart_LGPL - library of basic graphic primitives
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* Copyright (C) 1999-2000 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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/* Apply a dash style to a vector path. */
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#include <math.h>
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#include <stdlib.h>
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#include "art_misc.h"
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#include "art_vpath.h"
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#include "art_vpath_dash.h"
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/* Return the length of the largest subpath within vpath */
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static int
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art_vpath_dash_max_subpath (const ArtVpath *vpath)
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{
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int max_subpath;
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int i;
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int start;
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max_subpath = 0;
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start = 0;
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for (i = 0; vpath[i].code != ART_END; i++)
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{
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if (vpath[i].code == ART_MOVETO || vpath[i].code == ART_MOVETO_OPEN)
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{
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if (i - start > max_subpath)
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max_subpath = i - start;
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start = i;
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}
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}
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if (i - start > max_subpath)
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max_subpath = i - start;
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return max_subpath;
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}
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/**
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* art_vpath_dash: Add dash style to vpath.
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* @vpath: Original vpath.
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* @dash: Dash style.
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*
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* Creates a new vpath that is the result of applying dash style @dash
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* to @vpath.
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*
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* This implementation has two known flaws:
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*
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* First, it adds a spurious break at the beginning of the vpath. The
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* only way I see to resolve this flaw is to run the state forward one
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* dash break at the beginning, and fix up by looping back to the
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* first dash break at the end. This is doable but of course adds some
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* complexity.
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*
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* Second, it does not suppress output points that are within epsilon
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* of each other.
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*
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* Return value: Newly created vpath.
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**/
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ArtVpath *
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art_vpath_dash (const ArtVpath *vpath, const ArtVpathDash *dash)
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{
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int max_subpath;
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double *dists;
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ArtVpath *result;
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int n_result, n_result_max;
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int start, end;
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int i;
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double total_dist;
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/* state while traversing dasharray - offset is offset of current dash
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value, toggle is 0 for "off" and 1 for "on", and phase is the distance
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in, >= 0, < dash->dash[offset]. */
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int offset, toggle;
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double phase;
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/* initial values */
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int offset_init, toggle_init;
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double phase_init;
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max_subpath = art_vpath_dash_max_subpath (vpath);
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dists = art_new (double, max_subpath);
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n_result = 0;
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n_result_max = 16;
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result = art_new (ArtVpath, n_result_max);
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/* determine initial values of dash state */
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toggle_init = 1;
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offset_init = 0;
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phase_init = dash->offset;
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while (phase_init >= dash->dash[offset_init])
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{
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toggle_init = !toggle_init;
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phase_init -= dash->dash[offset_init];
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offset_init++;
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if (offset_init == dash->n_dash)
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offset_init = 0;
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}
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for (start = 0; vpath[start].code != ART_END; start = end)
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{
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for (end = start + 1; vpath[end].code == ART_LINETO; end++);
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/* subpath is [start..end) */
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total_dist = 0;
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for (i = start; i < end - 1; i++)
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{
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double dx, dy;
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dx = vpath[i + 1].x - vpath[i].x;
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dy = vpath[i + 1].y - vpath[i].y;
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dists[i - start] = sqrt (dx * dx + dy * dy);
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total_dist += dists[i - start];
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}
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if (total_dist <= dash->dash[offset_init] - phase_init)
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{
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/* subpath fits entirely within first dash */
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if (toggle_init)
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{
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for (i = start; i < end; i++)
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art_vpath_add_point (&result, &n_result, &n_result_max,
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vpath[i].code, vpath[i].x, vpath[i].y);
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}
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}
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else
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{
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/* subpath is composed of at least one dash - thus all
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generated pieces are open */
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double dist;
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phase = phase_init;
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offset = offset_init;
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toggle = toggle_init;
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dist = 0;
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i = start;
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if (toggle)
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art_vpath_add_point (&result, &n_result, &n_result_max,
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ART_MOVETO_OPEN, vpath[i].x, vpath[i].y);
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while (i != end - 1)
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{
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if (dists[i - start] - dist > dash->dash[offset] - phase)
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{
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/* dash boundary is next */
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double a;
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double x, y;
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dist += dash->dash[offset] - phase;
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a = dist / dists[i - start];
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x = vpath[i].x + a * (vpath[i + 1].x - vpath[i].x);
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y = vpath[i].y + a * (vpath[i + 1].y - vpath[i].y);
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art_vpath_add_point (&result, &n_result, &n_result_max,
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toggle ? ART_LINETO : ART_MOVETO_OPEN,
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x, y);
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/* advance to next dash */
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toggle = !toggle;
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phase = 0;
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offset++;
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if (offset == dash->n_dash)
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offset = 0;
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}
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else
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{
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/* end of line in vpath is next */
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phase += dists[i - start] - dist;
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i++;
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dist = 0;
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if (toggle)
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art_vpath_add_point (&result, &n_result, &n_result_max,
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ART_LINETO, vpath[i].x, vpath[i].y);
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}
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}
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}
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}
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art_vpath_add_point (&result, &n_result, &n_result_max,
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ART_END, 0, 0);
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art_free (dists);
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return result;
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}
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