commit 1f2c0aadab8c573c4f0072cad09171f2dd7cffeb
Author: Martin Robinson <[email protected]>
Date:   Sat Jul 10 16:07:32 2010 -0700

    convex clip

diff --git a/WebCore/platform/graphics/cairo/GraphicsContextCairo.cpp b/WebCore/platform/graphics/cairo/GraphicsContextCairo.cpp
index 3226fe0..2f55f56 100644
--- a/WebCore/platform/graphics/cairo/GraphicsContextCairo.cpp
+++ b/WebCore/platform/graphics/cairo/GraphicsContextCairo.cpp
@@ -66,6 +66,14 @@

 namespace WebCore {

+static void addConvexPolygonToContext(cairo_t* context, size_t numPoints, const FloatPoint* points)
+{
+    cairo_move_to(context, points[0].x(), points[0].y());
+    for (size_t i = 1; i < numPoints; i++)
+        cairo_line_to(context, points[i].x(), points[i].y());
+    cairo_close_path(context);
+}
+
 static inline void setColor(cairo_t* cr, const Color& col)
 {
     float red, green, blue, alpha;
@@ -510,10 +518,7 @@ void GraphicsContext::drawConvexPolygon(size_t npoints, const FloatPoint* points
     m_data->saveCairoPath();

     cairo_set_antialias(cr, shouldAntialias ? CAIRO_ANTIALIAS_DEFAULT : CAIRO_ANTIALIAS_NONE);
-    cairo_move_to(cr, points[0].x(), points[0].y());
-    for (size_t i = 1; i < npoints; i++)
-        cairo_line_to(cr, points[i].x(), points[i].y());
-    cairo_close_path(cr);
+    addConvexPolygonToContext(cr, npoints, points);

     if (fillColor().alpha()) {
         setColor(cr, fillColor());
@@ -539,8 +544,21 @@ void GraphicsContext::clipConvexPolygon(size_t numPoints, const FloatPoint* poin

     if (numPoints <= 1)
         return;
-
-    // FIXME: IMPLEMENT!
+
+    cairo_t* cr = m_data->cr;
+    m_data->saveCairoPath();
+
+    cairo_fill_rule_t savedFillRule = cairo_get_fill_rule(cr);
+    cairo_antialias_t savedAntialiasRule = cairo_get_antialias(cr);
+    cairo_set_antialias(cr, CAIRO_ANTIALIAS_DEFAULT);
+    cairo_set_fill_rule(cr, CAIRO_FILL_RULE_WINDING);
+
+    addConvexPolygonToContext(cr, numPoints, points);
+    cairo_clip(cr);
+
+    cairo_set_antialias(cr, savedAntialiasRule);
+    cairo_set_fill_rule(cr, savedFillRule);
+    m_data->restoreCairoPath();
 }

 void GraphicsContext::fillPath()
diff --git a/WebCore/rendering/RenderObject.h b/WebCore/rendering/RenderObject.h
index 33271df..f3bb7a1 100644
--- a/WebCore/rendering/RenderObject.h
+++ b/WebCore/rendering/RenderObject.h
@@ -38,7 +38,7 @@
 #include "TransformationMatrix.h"
 #include <wtf/UnusedParam.h>

-#if PLATFORM(CG)
+#if PLATFORM(CG) || PLATFORM(GTK)
 #define HAVE_PATH_BASED_BORDER_RADIUS_DRAWING 1
 #endif