Bug 1343436 - Fix filter result for baseFrequency="0" type="fractalNoise". r=longsonr+218550

MozReview-Commit-ID: LLAr9ifux98

--HG--
extra : rebase_source : 7e70fa361b2377ba180f96862d19ce22a2725438

dom/svg/SVGFETurbulenceElement.cpp

@@ -133,7 +133,14 @@ SVGFETurbulenceElement::GetPrimitiveDescription(nsSVGFilterInstance* aInstance,
   uint16_t stitch = mEnumAttributes[STITCHTILES].GetAnimValue();
 
   if (fX == 0 || fY == 0) {
-    return FilterPrimitiveDescription(PrimitiveType::Empty);
+    // A base frequency of zero results in transparent black for
+    // type="turbulence" and in 50% alpha 50% gray for type="fractalNoise".
+    if (type == SVG_TURBULENCE_TYPE_TURBULENCE) {
+      return FilterPrimitiveDescription(PrimitiveType::Empty);
+    }
+    FilterPrimitiveDescription descr(PrimitiveType::Flood);
+    descr.Attributes().Set(eFloodColor, Color(0.5, 0.5, 0.5, 0.5));
+    return descr;
   }
 
   // We interpret the base frequency as relative to user space units. In other

layout/reftests/svg/filters/feTurbulence-zero-baseFreq-ref.svg

@@ -0,0 +1,13 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!--
+     This is the reference image for feTurbulence-zero-baseFreq.svg.
+-->
+<svg xmlns="http://www.w3.org/2000/svg">
+  <rect x="0" y="0" width="400" height="100" fill="blue"/>
+  <rect x="0" y="100" width="400" height="100" fill="lime"/>
+  <!-- nothing in place of the type="turbulence" filter -->
+  <rect x="200" y="50" width="100" height="100" fill="rgba(128, 128, 128, 0.5)"/>
+</svg>

layout/reftests/svg/filters/feTurbulence-zero-baseFreq.svg

@@ -0,0 +1,23 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!--
+     This test verifies that feTurbulence with baseFrequency="0" creates
+     a transparent black result for type="turbulence" and a 50% alpha
+     50% gray result for type="fractalNoise".
+-->
+<svg xmlns="http://www.w3.org/2000/svg">
+  <filter id="filterTurbulence" primitiveUnits="objectBoundingBox" color-interpolation-filters="sRGB">
+    <feTurbulence type="turbulence" baseFrequency="0" numOctaves="1"
+                  x="0%" y="0%" width="100%" height="100%"/>
+  </filter>
+  <filter id="filterFractalNoise" primitiveUnits="objectBoundingBox" color-interpolation-filters="sRGB">
+    <feTurbulence type="fractalNoise" baseFrequency="0" numOctaves="1"
+                  x="0%" y="0%" width="100%" height="100%"/>
+  </filter>
+  <rect x="0" y="0" width="400" height="100" fill="blue"/>
+  <rect x="0" y="100" width="400" height="100" fill="lime"/>
+  <rect x="50" y="50" width="100" height="100" filter="url(#filterTurbulence)"/>
+  <rect x="200" y="50" width="100" height="100" filter="url(#filterFractalNoise)"/>
+</svg>

layout/reftests/svg/filters/reftest.list

@@ -119,6 +119,7 @@ fuzzy(2,2659) skip-if(d2d) == feSpecularLighting-1.svg feSpecularLighting-1-ref.
 == fePointLight-zoomed-page.svg fePointLight-zoomed-page-ref.svg
 
 == feTurbulence-offset.svg feTurbulence-offset-ref.svg
+fuzzy(1,10000) == feTurbulence-zero-baseFreq.svg feTurbulence-zero-baseFreq-ref.svg
 
 == outside-sourcegraphic-1.svg outside-sourcegraphic-ref.svg
 == outside-sourcegraphic-2.svg outside-sourcegraphic-ref.svg