b=600120; fix canvas composite.uncovered.image tests; r+a=vlad

content/canvas/src/nsCanvasRenderingContext2D.cpp

@@ -549,6 +549,19 @@ protected:
     PRUint32 mInvalidateCount;
     static const PRUint32 kCanvasMaxInvalidateCount = 100;
 
+    /**
+     * Returns true iff the the given operator should affect areas of the
+     * destination where the source is transparent. Among other things, this
+     * implies that a fully transparent source would still affect the canvas.
+     */
+    PRBool OperatorAffectsUncoveredAreas(gfxContext::GraphicsOperator op) const
+    {
+        return op == gfxContext::OPERATOR_IN ||
+               op == gfxContext::OPERATOR_OUT ||
+               op == gfxContext::OPERATOR_DEST_IN ||
+               op == gfxContext::OPERATOR_DEST_ATOP;
+    }
+
     /**
      * Returns true iff a shadow should be drawn along with a
      * drawing operation.
@@ -564,6 +577,22 @@ protected:
                (state.shadowOffset != gfxPoint(0, 0) || state.shadowBlur != 0);
     }
 
+    /**
+     * Checks the current state to determine if an intermediate surface would
+     * be necessary to complete a drawing operation. Does not check the
+     * condition pertaining to global alpha and patterns since that does not
+     * pertain to all drawing operations.
+     */
+    PRBool NeedToUseIntermediateSurface()
+    {
+        // certain operators always need an intermediate surface, except
+        // with quartz since quartz does compositing differently than cairo
+        return OperatorAffectsUncoveredAreas(mThebes->CurrentOperator());
+
+        // XXX there are other unhandled cases but they should be investigated
+        // first to ensure we aren't using an intermediate surface unecessarily
+    }
+
     /**
      * If the current operator is "source" then clear the destination before we
      * draw into it, to simulate the effect of an unbounded source operator.
@@ -1932,7 +1961,8 @@ nsCanvasRenderingContext2D::DrawPath(Style style, gfxRect *dirtyRect)
      * - globalAlpha != 1 and gradients/patterns are used (need to paint_with_alpha)
      * - certain operators are used
      */
-    PRBool doUseIntermediateSurface = NeedIntermediateSurfaceToHandleGlobalAlpha(style);
+    PRBool doUseIntermediateSurface = NeedToUseIntermediateSurface() ||
+                                      NeedIntermediateSurfaceToHandleGlobalAlpha(style);
 
     PRBool doDrawShadow = NeedToDrawShadow();
 
@@ -2751,7 +2781,7 @@ nsCanvasRenderingContext2D::DrawOrMeasureText(const nsAString& aRawText,
     // don't need to take care of these with stroke since Stroke() does that
     PRBool doDrawShadow = aOp == TEXT_DRAW_OPERATION_FILL && NeedToDrawShadow();
     PRBool doUseIntermediateSurface = aOp == TEXT_DRAW_OPERATION_FILL &&
-        NeedIntermediateSurfaceToHandleGlobalAlpha(STYLE_FILL);
+        (NeedToUseIntermediateSurface() || NeedIntermediateSurfaceToHandleGlobalAlpha(STYLE_FILL));
 
     // Clear the surface if we need to simulate unbounded SOURCE operator
     ClearSurfaceForUnboundedSource();
@@ -3559,11 +3589,25 @@ nsCanvasRenderingContext2D::DrawImage(nsIDOMElement *imgElt, float a1,
             }
         }
 
+        PRBool doUseIntermediateSurface = NeedToUseIntermediateSurface();
+
         mThebes->SetPattern(pattern);
         DirtyAllStyles();
 
-        /* Direct2D isn't very good at clipping so use Fill() when we can */
-        if (CurrentState().globalAlpha == 1.0f && mThebes->CurrentOperator() == gfxContext::OPERATOR_OVER) {
+        if (doUseIntermediateSurface) {
+            // draw onto a pushed group
+            mThebes->PushGroup(gfxASurface::CONTENT_COLOR_ALPHA);
+            mThebes->Clip(clip);
+
+            // don't want operators to be applied twice
+            mThebes->SetOperator(gfxContext::OPERATOR_SOURCE);
+
+            mThebes->Paint();
+            mThebes->PopGroupToSource();
+            mThebes->Paint(CurrentState().globalAlpha);
+        } else if (CurrentState().globalAlpha == 1.0f &&
+                   mThebes->CurrentOperator() == gfxContext::OPERATOR_OVER) {
+            /* Direct2D isn't very good at clipping so use Fill() when we can */
             mThebes->NewPath();
             mThebes->Rectangle(clip);
             mThebes->Fill();

content/canvas/test/Makefile.in

@@ -76,6 +76,10 @@ _TEST_FILES_0 = \
 	test_2d.composite.image.destination-in.html \
 	test_2d.composite.image.source-in.html \
 	test_2d.composite.image.source-out.html \
+	test_2d.composite.uncovered.image.destination-atop.html \
+	test_2d.composite.uncovered.image.destination-in.html \
+	test_2d.composite.uncovered.image.source-in.html \
+	test_2d.composite.uncovered.image.source-out.html \
 	test_mozGetAsFile.html \
 	$(NULL)
 
@@ -93,15 +97,6 @@ _TEST_FILES_0 = \
 #	test_2d.composite.clip.lighter.html \
 #
 
-# Temporarily disabled tests; unbounded operators changed behaviour, need to reevaluate tests.
-# At one point we were passing these accidentally, because the UpdateSurfaceClip at the end
-# of drawImage happened to clear the entire canvas with some operators, which is what these
-# tests were checking.
-#	test_2d.composite.uncovered.image.source-in.html \
-#	test_2d.composite.uncovered.image.destination-in.html \
-#	test_2d.composite.uncovered.image.source-out.html \
-#	test_2d.composite.uncovered.image.destination-atop.html \
-
 # Tests that fail on Mac (possibly because spec is underdefined?).  Bug 407105
 ifneq ($(MOZ_WIDGET_TOOLKIT),cocoa)
 # XXX vlad don't test these anywhere, cairo behaviour changed