Re: fill-opacity bug fix

On Tue, 9 Mar 2004, Yi Zhang wrote:
>
> I had problem with applying fill-opacity and stroke-opacity at the same
> time. When I set fill-opacity to 0.0, and stroke-opacity to 1.0, the
> object's (e.g. rectangle) outline will not be drawn. Someone on the
> ImageMagick mailing list had a similar experience:
> http://studio.imagemagick.org/pipermail/magick-users/2003-November/011301.ht
> ml
>
> Eventually, I fixed my problem with the following patch (the first patch
> chunk is in DrawGetFillOpacity(), the second chunk is in
> DrawSetFillOpacity()):

These are the fixes I finally ended up applying.  The opacity is
stored inverted internally, but must be passed non-inverted for the
MVG.

Index: draw.c
===================================================================
RCS file: /GraphicsMagick/GraphicsMagick/magick/draw.c,v
retrieving revision 1.612
diff -u -r1.612 draw.c
--- draw.c	22 Dec 2003 01:06:31 -0000	1.612
+++ draw.c	9 Mar 2004 17:18:56 -0000
@@ -1546,7 +1546,7 @@
   assert(context != (DrawContext)NULL);
   assert(context->signature == MagickSignature);

-  return ((double)CurrentContext->opacity/MaxRGB);
+  return (((double)(MaxRGB-CurrentContext->fill.opacity))/MaxRGB);
 }

 /*
@@ -1578,17 +1578,21 @@
                                      const double fill_opacity)
 {
   Quantum
-    opacity;
+    quantum_opacity;
+
+  double
+    validated_opacity;

   assert(context != (DrawContext)NULL);
   assert(context->signature == MagickSignature);

-  opacity = (Quantum)((double) MaxRGB*(1.0-(fill_opacity <= 1.0 ? fill_opacity : 1.0 ))+0.5);
+  validated_opacity=(fill_opacity < 0.0 ? 0.0 : (fill_opacity > 1.0 ? 1.0 : fill_opacity));
+  quantum_opacity = (Quantum) (((double) MaxRGB*(1.0-validated_opacity))+0.5);

-  if (context->filter_off || (CurrentContext->opacity != opacity))
+  if (context->filter_off || (CurrentContext->fill.opacity != quantum_opacity))
     {
-      CurrentContext->opacity = opacity;
-      MvgPrintf(context, "fill-opacity %.4g\n", fill_opacity);
+      CurrentContext->fill.opacity = quantum_opacity;
+      MvgPrintf(context, "fill-opacity %.4g\n", validated_opacity);
     }
 }

@@ -5398,18 +5402,22 @@
 MagickExport void DrawSetStrokeOpacity(DrawContext context,
                                        const double stroke_opacity)
 {
+  Quantum
+    quantum_opacity;
+
   double
-    opacity;
+    validated_opacity;

   assert(context != (DrawContext)NULL);
   assert(context->signature == MagickSignature);

-  opacity = (Quantum)((double) MaxRGB*(1.0-(stroke_opacity <= 1.0 ? stroke_opacity : 1.0 ))+0.5);
+  validated_opacity=(stroke_opacity < 0.0 ? 0.0 : (stroke_opacity > 1.0 ? 1.0 : stroke_opacity));
+  quantum_opacity = (Quantum) (((double) MaxRGB*(1.0-validated_opacity))+0.5);

-  if (context->filter_off || (CurrentContext->stroke.opacity != opacity))
+  if (context->filter_off || (CurrentContext->stroke.opacity != quantum_opacity))
     {
-      CurrentContext->stroke.opacity = (Quantum) ceil(opacity);
-      MvgPrintf(context, "stroke-opacity %.4g\n", stroke_opacity);
+      CurrentContext->stroke.opacity = quantum_opacity;
+      MvgPrintf(context, "stroke-opacity %.4g\n", validated_opacity);
     }
 }


======================================
Bob Friesenhahn
[email protected]
http://www.simplesystems.org/users/bfriesen



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