Adding upstream version 1.23.0.upstream/1.23.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 180 insertions, 0 deletions

diff --git a/src/libs/libgroff/geometry.cpp b/src/libs/libgroff/geometry.cpp
new file mode 100644
index 0000000..c4665c4
--- /dev/null
+++ b/src/libs/libgroff/geometry.cpp
@@ -0,0 +1,180 @@
+// -*- C++ -*-
+/* Copyright (C) 1989-2020 Free Software Foundation, Inc.
+     Written by Gaius Mulley <gaius@glam.ac.uk>
+     using adjust_arc_center() from printer.cpp, written by James Clark.
+
+This file is part of groff.
+
+groff is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+groff 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 General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <math.h>
+
+#undef	MAX
+#define MAX(a, b)  (((a) > (b)) ? (a) : (b))
+
+#undef	MIN
+#define MIN(a, b)  (((a) < (b)) ? (a) : (b))
+
+
+// This utility function adjusts the specified center of the
+// arc so that it is equidistant between the specified start
+// and end points.  (p[0], p[1]) is a vector from the current
+// point to the center; (p[2], p[3]) is a vector from the 
+// center to the end point.  If the center can be adjusted,
+// a vector from the current point to the adjusted center is
+// stored in c[0], c[1] and 1 is returned.  Otherwise 0 is
+// returned.
+
+#if 1
+int adjust_arc_center(const int *p, double *c)
+{
+  // We move the center along a line parallel to the line between
+  // the specified start point and end point so that the center
+  // is equidistant between the start and end point.
+  // It can be proved (using Lagrange multipliers) that this will
+  // give the point nearest to the specified center that is equidistant
+  // between the start and end point.
+
+  double x = p[0] + p[2];	// (x, y) is the end point
+  double y = p[1] + p[3];
+  double n = x*x + y*y;
+  if (n != 0) {
+    c[0]= double(p[0]);
+    c[1] = double(p[1]);
+    double k = .5 - (c[0]*x + c[1]*y)/n;
+    c[0] += k*x;
+    c[1] += k*y;
+    return 1;
+  }
+  else
+    return 0;
+}
+#else
+int printer::adjust_arc_center(const int *p, double *c)
+{
+  int x = p[0] + p[2];	// (x, y) is the end point
+  int y = p[1] + p[3];
+  // Start at the current point; go in the direction of the specified
+  // center point until we reach a point that is equidistant between
+  // the specified starting point and the specified end point.  Place
+  // the center of the arc there.
+  double n = p[0]*double(x) + p[1]*double(y);
+  if (n > 0) {
+    double k = (double(x)*x + double(y)*y)/(2.0*n);
+    // (cx, cy) is our chosen center
+    c[0] = k*p[0];
+    c[1] = k*p[1];
+    return 1;
+  }
+  else {
+    // We would never reach such a point.  So instead start at the
+    // specified end point of the arc.  Go towards the specified
+    // center point until we reach a point that is equidistant between
+    // the specified start point and specified end point.  Place
+    // the center of the arc there.
+    n = p[2]*double(x) + p[3]*double(y);
+    if (n > 0) {
+      double k = 1 - (double(x)*x + double(y)*y)/(2.0*n);
+      // (c[0], c[1]) is our chosen center
+      c[0] = p[0] + k*p[2];
+      c[1] = p[1] + k*p[3];
+      return 1;
+    }
+    else
+      return 0;
+  }
+}  
+#endif
+
+
+/*
+ *  check_output_arc_limits - works out the smallest box that will encompass
+ *                            an arc defined by an origin (x, y) and two
+ *                            vectors (p0, p1) and (p2, p3).
+ *                            (x1, y1) -> start of arc
+ *                            (x1, y1) + (xv1, yv1) -> center of circle
+ *                            (x1, y1) + (xv1, yv1) + (xv2, yv2) -> end of arc
+ *
+ *                            Works out in which quadrant the arc starts and
+ *                            stops, and from this it determines the x, y
+ *                            max/min limits.  The arc is drawn clockwise.
+ */
+
+void check_output_arc_limits(int x_1, int y_1,
+			     int xv_1, int yv_1,
+			     int xv_2, int yv_2,
+			     double c_0, double c_1,
+			     int *minx, int *maxx,
+			     int *miny, int *maxy)
+{
+  int radius = (int)sqrt(c_0 * c_0 + c_1 * c_1);
+  // clockwise direction
+  int xcenter = x_1 + xv_1;
+  int ycenter = y_1 + yv_1;
+  int xend = xcenter + xv_2;
+  int yend = ycenter + yv_2;
+  // for convenience, transform to counterclockwise direction,
+  // centered at the origin
+  int xs = xend - xcenter;
+  int ys = yend - ycenter;
+  int xe = x_1 - xcenter;
+  int ye = y_1 - ycenter;
+  *minx = *maxx = xs;
+  *miny = *maxy = ys;
+  if (xe > *maxx)
+    *maxx = xe;
+  else if (xe < *minx)
+    *minx = xe;
+  if (ye > *maxy)
+    *maxy = ye;
+  else if (ye < *miny)
+    *miny = ye;
+  int qs, qe;			// quadrants 0..3
+  if (xs >= 0)
+    qs = (ys >= 0) ? 0 : 3;
+  else
+    qs = (ys >= 0) ? 1 : 2;
+  if (xe >= 0)
+    qe = (ye >= 0) ? 0 : 3;
+  else
+    qe = (ye >= 0) ? 1 : 2;
+  // make qs always smaller than qe
+  if ((qs > qe)
+      || ((qs == qe) && (double(xs) * ye < double(xe) * ys)))
+    qe += 4;
+  for (int i = qs; i < qe; i++)
+    switch (i % 4) {
+    case 0:
+      *maxy = radius;
+      break;
+    case 1:
+      *minx = -radius;
+      break;
+    case 2:
+      *miny = -radius;
+      break;
+    case 3:
+      *maxx = radius;
+      break;
+    }
+  *minx += xcenter;
+  *maxx += xcenter;
+  *miny += ycenter;
+  *maxy += ycenter;
+}