From: Tony Cook <tony@develop-help.com>
Date: Mon, 10 Oct 2011 11:53:40 +0000 (+1100)
Subject: [rt #71309] fix combine=0 fill color anti-aliasing
X-Git-Tag: v0.85_02~26
X-Git-Url: http://git.imager.perl.org/imager.git/commitdiff_plain/7a98c44258fc1de05eab8ff856be1d96ed92c13e

[rt #71309] fix combine=0 fill color anti-aliasing
---

diff --git a/render.im b/render.im
index e17da1cf..4f9bbd38 100644
--- a/render.im
+++ b/render.im
@@ -333,8 +333,8 @@ i_render_fill(i_render *r, i_img_dim x, i_img_dim y, i_img_dim width,
 	}
 	else if (*src) {
 	  for (ch = 0; ch < im->channels; ++ch) {
-	    IM_WORK_T work = (destc->channel[ch] * (IM_SAMPLE_MAX - *src)
-			      + srcc->channel[ch] * *src) / IM_SAMPLE_MAX;
+	    IM_WORK_T work = (destc->channel[ch] * (255 - *src)
+			      + srcc->channel[ch] * *src) / 255.0;
 	    destc->channel[ch] = IM_LIMIT(work);
 	  }
 	}
diff --git a/t/t20fill.t b/t/t20fill.t
index e060b0fa..bdf57252 100644
--- a/t/t20fill.t
+++ b/t/t20fill.t
@@ -1,6 +1,6 @@
 #!perl -w
 use strict;
-use Test::More tests => 156;
+use Test::More tests => 157;
 
 use Imager ':handy';
 use Imager::Fill;
@@ -638,6 +638,34 @@ SKIP:
   }
 }
 
+{ # RT 71309
+  my $fount = Imager::Fountain->simple(colors => [ '#804041', '#804041' ],
+				       positions => [ 0, 1 ]);
+  my $im = Imager->new(xsize => 40, ysize => 40);
+  $im->box(filled => 1, color => '#804040');
+  my $fill = Imager::Fill->new
+    (
+     combine => 0,
+     fountain => "linear",
+     segments => $fount,
+     xa => 0, ya => 0,
+     xb => 40, yb => 40,
+    );
+  $im->polygon(fill => $fill,
+	       points => 
+	       [
+		[ 0, 0 ],
+		[ 40, 20 ],
+		[ 20, 40 ],
+	       ]
+	      );
+  # the bug magnified the differences between the source and destination
+  # color, blending between the background and fill colors here only allows
+  # for those 2 colors in the result.
+  # with the bug extra colors appeared along the edge of the polygon.
+  is($im->getcolorcount, 2, "only original and fill color");
+}
+
 sub color_close {
   my ($c1, $c2) = @_;