From 4280d5421ce48482a67e07bcfdd2f98d6ce9f116 Mon Sep 17 00:00:00 2001
From: Cristy <urban-warrior@imagemagick.org>
Date: Sat, 11 Jun 2016 12:48:49 -0400
Subject: [PATCH] https://github.com/ImageMagick/ImageMagick/issues/218

---
 ChangeLog         |  2 ++
 MagickCore/draw.c | 56 ++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 538bee414..ed3d95e3b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,8 @@
 2016-06-09  7.0.2-0 Cristy  <quetzlzacatenango@image...>
   * Backoff finite precision epsilon (reference
     https://github.com/ImageMagick/ImageMagick/issues/215).
+  * Fix drawing glitch for stroke widths greater than 2 (reference
+    https://github.com/ImageMagick/ImageMagick/issues/218).
 
 2016-06-05  7.0.1-10 Cristy  <quetzlzacatenango@image...>
   * Release ImageMagick version 7.0.1-10, GIT revision 18406:ba4ad2d:20160607.
diff --git a/MagickCore/draw.c b/MagickCore/draw.c
index 6f174779b..5d6c5f140 100644
--- a/MagickCore/draw.c
+++ b/MagickCore/draw.c
@@ -432,10 +432,10 @@ static void LogPolygonInfo(const PolygonInfo *polygon_info)
     (void) LogMagickEvent(DrawEvent,GetMagickModule(),"      ghostline: %s",
       p->ghostline != MagickFalse ? "transparent" : "opaque");
     (void) LogMagickEvent(DrawEvent,GetMagickModule(),
-      "      bounds: %g %g - %g %g",p->bounds.x1,p->bounds.y1,
+      "      bounds: %g,%g - %g,%g",p->bounds.x1,p->bounds.y1,
       p->bounds.x2,p->bounds.y2);
     for (j=0; j < (ssize_t) p->number_points; j++)
-      (void) LogMagickEvent(DrawEvent,GetMagickModule(),"        %g %g",
+      (void) LogMagickEvent(DrawEvent,GetMagickModule(),"        %g,%g",
         p->points[j].x,p->points[j].y);
     p++;
   }
@@ -699,7 +699,7 @@ static void LogPathInfo(const PathInfo *path_info)
   (void) LogMagickEvent(DrawEvent,GetMagickModule(),"    begin vector-path");
   for (p=path_info; p->code != EndCode; p++)
     (void) LogMagickEvent(DrawEvent,GetMagickModule(),
-      "      %g %g %s",p->point.x,p->point.y,p->code == GhostlineCode ?
+      "      %g,%g %s",p->point.x,p->point.y,p->code == GhostlineCode ?
       "moveto ghostline" : p->code == OpenCode ? "moveto open" :
       p->code == MoveToCode ? "moveto" : p->code == LineToCode ? "lineto" :
       "?");
@@ -4314,7 +4314,7 @@ MagickExport MagickBooleanType DrawPrimitive(Image *image,
       (void) LogMagickEvent(DrawEvent,GetMagickModule(),
         "  begin draw-primitive");
       (void) LogMagickEvent(DrawEvent,GetMagickModule(),
-        "    affine: %g %g %g %g %g %g",draw_info->affine.sx,
+        "    affine: %g,%g,%g,%g,%g,%g",draw_info->affine.sx,
         draw_info->affine.rx,draw_info->affine.ry,draw_info->affine.sy,
         draw_info->affine.tx,draw_info->affine.ty);
     }
@@ -6023,8 +6023,28 @@ static PrimitiveInfo *TraceStrokePolygon(const DrawInfo *draw_info,
   }
   if (n == (ssize_t) number_vertices)
     n=(ssize_t) number_vertices-1L;
-  slope.p=DrawEpsilonReciprocal(dx.p)*dy.p;
-  inverse_slope.p=(-1.0*DrawEpsilonReciprocal(slope.p));
+  slope.p=0.0;
+  inverse_slope.p=0.0;
+  if (fabs(dx.p) < MagickEpsilon)
+    {
+      if (dx.p >= 0.0)
+        slope.p=dy.p < 0.0 ? -1.0/MagickEpsilon : 1.0/MagickEpsilon;
+      else
+        slope.p=dy.p < 0.0 ? 1.0/MagickEpsilon : -1.0/MagickEpsilon;
+    }
+  else
+    if (fabs(dy.p) < MagickEpsilon)
+      {
+        if (dy.p >= 0.0)
+          inverse_slope.p=dx.p < 0.0 ? -1.0/MagickEpsilon : 1.0/MagickEpsilon;
+        else
+          inverse_slope.p=dx.p < 0.0 ? 1.0/MagickEpsilon : -1.0/MagickEpsilon;
+      }
+    else
+      {
+        slope.p=dy.p/dx.p;
+        inverse_slope.p=(-1.0/slope.p);
+      }
   mid=ExpandAffine(&draw_info->affine)*draw_info->stroke_width/2.0;
   miterlimit=(double) (draw_info->miterlimit*draw_info->miterlimit*
     mid*mid);
@@ -6071,8 +6091,28 @@ static PrimitiveInfo *TraceStrokePolygon(const DrawInfo *draw_info,
     dot_product=dx.q*dx.q+dy.q*dy.q;
     if (dot_product < 0.25)
       continue;
-    slope.q=DrawEpsilonReciprocal(dx.q)*dy.q;
-    inverse_slope.q=(-1.0*DrawEpsilonReciprocal(slope.q));
+    slope.q=0.0;
+    inverse_slope.q=0.0;
+    if (fabs(dx.q) < MagickEpsilon)
+      { 
+        if (dx.q >= 0.0) 
+          slope.q=dy.q < 0.0 ? -1.0/MagickEpsilon : 1.0/MagickEpsilon;
+        else
+          slope.q=dy.q < 0.0 ? 1.0/MagickEpsilon : -1.0/MagickEpsilon;
+      }
+    else 
+      if (fabs(dy.q) < MagickEpsilon)
+        { 
+          if (dy.q >= 0.0)
+            inverse_slope.q=dx.q < 0.0 ? -1.0/MagickEpsilon : 1.0/MagickEpsilon;
+          else
+            inverse_slope.q=dx.q < 0.0 ? 1.0/MagickEpsilon : -1.0/MagickEpsilon;
+        }
+      else
+        { 
+          slope.q=dy.q/dx.q;
+          inverse_slope.q=(-1.0/slope.q);
+        }
     offset.x=sqrt((double) (mid*mid/(inverse_slope.q*inverse_slope.q+1.0)));
     offset.y=(double) (offset.x*inverse_slope.q);
     dot_product=dy.q*offset.x-dx.q*offset.y;
-- 
2.49.0