1 files changed, 32 insertions, 16 deletions

diff --git a/Source/WebCore/css/CSSGradientValue.cpp b/Source/WebCore/css/CSSGradientValue.cpp
index b6b9ebe..ede76da 100644
--- a/Source/WebCore/css/CSSGradientValue.cpp
+++ b/Source/WebCore/css/CSSGradientValue.cpp
@@ -41,27 +41,28 @@ using namespace std;
 
 namespace WebCore {
 
-Image* CSSGradientValue::image(RenderObject* renderer, const IntSize& size)
+PassRefPtr<Image> CSSGradientValue::image(RenderObject* renderer, const IntSize& size)
 {
-    if (!m_clients.contains(renderer))
-        return 0;
-
-    // Need to look up our size.  Create a string of width*height to use as a hash key.
-    // FIXME: hashing based only on size is not sufficient. Color stops may use context-sensitive units (like em)
-    // that should force the color stop positions to be recomputed.
-    Image* result = getImage(renderer, size);
-    if (result)
-        return result;
-
     if (size.isEmpty())
         return 0;
 
+    bool cacheable = isCacheable();
+    if (cacheable) {
+        if (!m_clients.contains(renderer))
+            return 0;
+
+        // Need to look up our size.  Create a string of width*height to use as a hash key.
+        Image* result = getImage(renderer, size);
+        if (result)
+            return result;
+    }
+    
     // We need to create an image.
     RefPtr<Image> newImage = GeneratedImage::create(createGradient(renderer, size), size);
-    result = newImage.get();
-    putImage(size, newImage.release());
+    if (cacheable)
+        putImage(size, newImage);
 
-    return result;
+    return newImage.release();
 }
 
 // Should only ever be called for deprecated gradients.
@@ -280,7 +281,7 @@ void CSSGradientValue::addStops(Gradient* gradient, RenderObject* renderer, Rend
             float lastOffset = stops[stops.size() - 1].offset;
             if (lastOffset < maxExtent) {
                 float currOffset = lastOffset;
-                size_t srcStopOrdinal = 0;
+                size_t srcStopOrdinal = originalFirstStopIndex;
 
                 while (true) {
                     GradientStop newStop = stops[srcStopOrdinal];
@@ -289,7 +290,7 @@ void CSSGradientValue::addStops(Gradient* gradient, RenderObject* renderer, Rend
                     if (currOffset > maxExtent)
                         break;
                     if (srcStopOrdinal < originalNumStops - 1)
-                        currOffset += stops[originalFirstStopIndex + srcStopOrdinal + 1].offset - stops[originalFirstStopIndex + srcStopOrdinal].offset;
+                        currOffset += stops[srcStopOrdinal + 1].offset - stops[srcStopOrdinal].offset;
                     srcStopOrdinal = (srcStopOrdinal + 1) % originalNumStops;
                 }
             }
@@ -406,6 +407,21 @@ FloatPoint CSSGradientValue::computeEndPoint(CSSPrimitiveValue* first, CSSPrimit
     return result;
 }
 
+bool CSSGradientValue::isCacheable() const
+{
+    for (size_t i = 0; i < m_stops.size(); ++i) {
+        const CSSGradientColorStop& stop = m_stops[i];
+        if (!stop.m_position)
+            continue;
+
+        unsigned short unitType = stop.m_position->primitiveType();
+        if (unitType == CSSPrimitiveValue::CSS_EMS || unitType == CSSPrimitiveValue::CSS_EXS || unitType == CSSPrimitiveValue::CSS_REMS)
+            return false;
+    }
+    
+    return true;
+}
+
 String CSSLinearGradientValue::cssText() const
 {
     String result;