Bug 796847 - Make AdjustInvalidAreaForSVGEffects correctly adjust for the coordinate space of the input rect. r=dholbert

layout/base/FrameLayerBuilder.cpp

@@ -2407,7 +2407,9 @@ FrameLayerBuilder::AddThebesDisplayItem(ThebesLayer* aLayer,
       props->MoveBy(-offset);
       nsIntRegion invalid = props->ComputeDifferences(layer, nullptr);
       if (aLayerState == LAYER_SVG_EFFECTS) {
-        invalid = nsSVGIntegrationUtils::AdjustInvalidAreaForSVGEffects(aItem->GetUnderlyingFrame(), invalid.GetBounds());
+        invalid = nsSVGIntegrationUtils::AdjustInvalidAreaForSVGEffects(aItem->GetUnderlyingFrame(),
+                                                                        aItem->ToReferenceFrame(),
+                                                                        invalid.GetBounds());
       }
       if (!invalid.IsEmpty()) {
 #ifdef DEBUG_INVALIDATIONS

layout/reftests/bugs/796847-1-ref.svg

@@ -0,0 +1,8 @@
+<svg xmlns="http://www.w3.org/2000/svg">
+  <filter id="f" x="0" y="0" width="100%" height="100%">
+    <feGaussianBlur in="SourceGraphic" stdDeviation="0.1"/>
+  </filter>
+  <g filter="url(#f)">
+    <rect x="0" y="0" width="100" height="100" style="fill: lime;"/>
+  </g>
+</svg>

layout/reftests/bugs/796847-1.svg

@@ -0,0 +1,25 @@
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<svg xmlns="http://www.w3.org/2000/svg" version="1.1" class="reftest-wait">
+  <title>Test that the area that's covered by a filtered elemnt is invalidated when content inside it changes</title>
+  <filter id="f" x="0" y="0" width="100%" height="100">
+    <feGaussianBlur in="SourceGraphic" stdDeviation="0.1"/>
+  </filter>
+  <script type="text/javascript">//<![CDATA[
+
+function doTest()
+{
+  var e = document.getElementsByTagName("rect")[0];
+  e.style.fill = "lime";
+  document.documentElement.removeAttribute('class');
+}
+
+document.addEventListener("MozReftestInvalidate", doTest, false);
+
+  //]]></script>
+  <g filter="url(#f)">
+    <rect x="0" y="0" width="100" height="100" style="fill: red;"/>
+  </g>
+</svg>

layout/reftests/bugs/reftest.list

@@ -1725,6 +1725,7 @@ fuzzy-if(true,17,5859) == 759036-2.html 759036-2-ref.html
 == 776265-2c.html 776265-2-ref.html
 == 776265-2d.html 776265-2-ref.html
 == 787947-1.html 787947-1-ref.html
+== 796847.svg 796847-ref.svg
 fuzzy(40,800) == 797797-1.html 797797-1-ref.html # 'opacity:N' and rgba(,,,N) text don't match precisely
 fuzzy(40,800) == 797797-2.html 797797-2-ref.html # 'opacity:N' and rgba(,,,N) text don't match precisely
 == 801994-1.html 801994-1-ref.html

layout/svg/nsSVGIntegrationUtils.cpp

@@ -282,6 +282,7 @@ nsRect
 
 nsIntRect
 nsSVGIntegrationUtils::AdjustInvalidAreaForSVGEffects(nsIFrame* aFrame,
+                                                      const nsPoint& aToReferenceFrame,
                                                       const nsIntRect& aInvalidRect)
 {
   // Don't bother calling GetEffectProperties; the filter property should
@@ -304,19 +305,25 @@ nsSVGIntegrationUtils::AdjustInvalidAreaForSVGEffects(nsIFrame* aFrame,
   if (!filterFrame) {
     // The frame is either not there or not currently available,
     // perhaps because we're in the middle of tearing stuff down.
-    // Be conservative.
-    nsRect overflow = aFrame->GetVisualOverflowRect();
+    // Be conservative, return our visual overflow rect relative
+    // to the reference frame.
+    nsRect overflow = aFrame->GetVisualOverflowRect() + aToReferenceFrame;
     return overflow.ToOutsidePixels(appUnitsPerDevPixel);
   }
 
   // Convert aInvalidRect into "user space" in app units:
   nsPoint toUserSpace =
     aFrame->GetOffsetTo(firstFrame) + GetOffsetToUserSpace(firstFrame);
+  // The initial rect was relative to the reference frame, so we need to
+  // remove that offset to get a rect relative to the current frame.
+  toUserSpace -= aToReferenceFrame;
   nsRect preEffectsRect = aInvalidRect.ToAppUnits(appUnitsPerDevPixel) + toUserSpace;
 
-  // Return ther result, relative to aFrame, not in user space:
+  // Adjust the dirty area for effects, and shift it back to being relative to
+  // the reference frame.
   nsRect result = filterFrame->GetPostFilterDirtyArea(firstFrame, preEffectsRect) -
            toUserSpace;
+  // Return the result, in pixels relative to the reference frame.
   return result.ToOutsidePixels(appUnitsPerDevPixel);
 }
 

layout/svg/nsSVGIntegrationUtils.h

@@ -115,9 +115,18 @@ public:
   /**
    * Used to adjust the area of a frame that needs to be invalidated to take
    * account of SVG effects.
+   *
+   * @param aFrame The effects frame.
+   * @param aToReferenceFrame The offset (in app units) from aFrame to its
+   * reference display item.
+   * @param aInvalidRect The pre-effects invalid rect in pixels relative to
+   * the reference display item.
+   * @return The post-effects invalid rect in pixels relative to the reference
+   * display item.
    */
   static nsIntRect
-  AdjustInvalidAreaForSVGEffects(nsIFrame* aFrame, const nsIntRect& aInvalidRect);
+  AdjustInvalidAreaForSVGEffects(nsIFrame* aFrame, const nsPoint& aToReferenceFrame,
+                                 const nsIntRect& aInvalidRect);
 
   /**
    * Figure out which area of the source is needed given an area to