diff options
Diffstat (limited to 'src/libs/libgroff/geometry.cc')
| -rw-r--r-- | src/libs/libgroff/geometry.cc | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/src/libs/libgroff/geometry.cc b/src/libs/libgroff/geometry.cc index 7aa0d2b8..58a94a4a 100644 --- a/src/libs/libgroff/geometry.cc +++ b/src/libs/libgroff/geometry.cc @@ -1,5 +1,5 @@ // -*- C++ -*- -/* Copyright (C) 1989, 1990, 1991, 1992, 2000, 2001 +/* Copyright (C) 1989, 1990, 1991, 1992, 2000, 2001, 2002 Free Software Foundation, Inc. Written by Gaius Mulley <gaius@glam.ac.uk> using adjust_arc_center() from printer.cc, written by James Clark. @@ -136,14 +136,22 @@ void check_output_arc_limits(int x1, int y1, *miny = y1 + yv1 - radius; *maxy = y1 + yv1 + radius; - // now see which min/max can be reduced and increased for the limits of - // the arc - // - // Q2 | Q1 - // -----+----- - // Q3 | Q4 - // - if (xv1 >= 0 && yv1 >= 0) { + /* now to see which min/max can be reduced and increased for the limits of + * the arc + * + * Q2 | Q1 + * -----+----- + * Q3 | Q4 + * + * + * NB. (x1+xv1, y1+yv1) is at the origin + * + * below we ask a nested question + * (i) from which quadrant does the first vector start? + * (ii) into which quadrant does the second vector go? + * from the 16 possible answers we determine the limits of the arc + */ + if (xv1 > 0 && yv1 > 0) { // first vector in Q3 if (xv2 >= 0 && yv2 >= 0 ) { // second in Q1 @@ -172,7 +180,7 @@ void check_output_arc_limits(int x1, int y1, } } } - else if (xv1 >= 0 && yv1 < 0) { + else if (xv1 > 0 && yv1 < 0) { // first vector in Q2 if (xv2 >= 0 && yv2 >= 0) { // second in Q1 @@ -202,7 +210,7 @@ void check_output_arc_limits(int x1, int y1, *minx = MIN(x1, x2); } } - else if (xv1 < 0 && yv1 < 0) { + else if (xv1 <= 0 && yv1 <= 0) { // first vector in Q1 if (xv2 >= 0 && yv2 >= 0) { // second in Q1 @@ -232,7 +240,7 @@ void check_output_arc_limits(int x1, int y1, *maxy = y1; } } - else if (xv1 < 0 && yv1 >= 0) { + else if (xv1 <= 0 && yv1 > 0) { // first vector in Q4 if (xv2 >= 0 && yv2 >= 0) { // second in Q1 |