[S.P.] Don't draw frames of animated images that are offscreen.

Source/core/layout/LayoutObject.cpp

Index: Source/core/layout/LayoutObject.cpp
diff --git a/Source/core/layout/LayoutObject.cpp b/Source/core/layout/LayoutObject.cpp
index 2fa594d795b58033d5ff04abe59b35de5c51df22..f6b846aa3c2d2a2c392b0a520c657810f31417c3 100644
--- a/Source/core/layout/LayoutObject.cpp
+++ b/Source/core/layout/LayoutObject.cpp
@@ -1198,8 +1198,14 @@ void LayoutObject::invalidateTreeIfNeeded(const PaintInvalidationState& paintInv
     if (!shouldCheckForPaintInvalidation(paintInvalidationState))
         return;
 
-    invalidatePaintIfNeeded(paintInvalidationState, paintInvalidationState.paintInvalidationContainer());
-    clearPaintInvalidationState(paintInvalidationState);
+    PaintInvalidationReason reason = invalidatePaintIfNeeded(paintInvalidationState, paintInvalidationState.paintInvalidationContainer());
+    if (reason != PaintInvalidationDelayedFull) {
+        clearPaintInvalidationState(paintInvalidationState);
+    } else {
+        // Mark this object as needing paint invalidation again in the next frame, due to the request for delayed paint invalidation.
+        setShouldDoFullPaintInvalidation();

[Xianzhu, 2015/03/17 23:34:01]

Should we let this be for slimming-paint only?

[chrishtr, 2015/03/17 23:55:56]

In this CL it only takes effect if PaintInvalidationDelayedFull, which only
happens when Slimming Paint is on.

I suppose I could change the logic to treat "delayed" as PaintInvalidationFull
when Slimmming Paint is off, if you want.

Also, to respond to your global comment: line 1206 is there in order to set the
bits up the tree so that the next time paint invalidation happens, it recurses
down to this LayoutObject. I agree that the mechanism is a little fragile, since
it depends on the bits being cleared top-to-bottom along with the recursion,
suggestions welcome.

[Xianzhu, 2015/03/18 16:37:01]

Acknowledged.
My bad. I thought we cleared the paint invalidation state after we walk the
subtrees.

+    }
+
     invalidatePaintOfSubtreesIfNeeded(paintInvalidationState);
 }
 
@@ -1269,8 +1275,9 @@ void LayoutObject::invalidateSelectionIfNeeded(const LayoutBoxModelObject& paint
 PaintInvalidationReason LayoutObject::invalidatePaintIfNeeded(const PaintInvalidationState& paintInvalidationState, const LayoutBoxModelObject& paintInvalidationContainer)
 {
     LayoutView* v = view();
-    if (v->document().printing())
+    if (v->document().printing()) {
         return PaintInvalidationNone; // Don't invalidate paints if we're printing.
+    }

[Xianzhu, 2015/03/18 19:24:53]

Nit: unnecessary change

[chrishtr, 2015/03/19 22:01:27]

Done.

 
     const LayoutRect oldBounds = previousPaintInvalidationRect();
     const LayoutPoint oldLocation = previousPositionFromPaintInvalidationBacking();
@@ -1289,15 +1296,17 @@ PaintInvalidationReason LayoutObject::invalidatePaintIfNeeded(const PaintInvalid
     // paint invalidations. We can then skip issuing of paint invalidations for the child
     // renderers as they'll be covered by the LayoutView.
     // However, slimming paint mode requires paint invalidation of the child renderers.
-    if (view()->doingFullPaintInvalidation() && !RuntimeEnabledFeatures::slimmingPaintEnabled())
+    if (view()->doingFullPaintInvalidation() && !RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         return invalidationReason;
+    }

[Xianzhu, 2015/03/18 19:24:53]

Ditto.

[chrishtr, 2015/03/19 22:01:27]

Done.

 
     TRACE_EVENT2(TRACE_DISABLED_BY_DEFAULT("blink.invalidation"), "LayoutObject::invalidatePaintIfNeeded()",
         "object", this->debugName().ascii(),
         "info", jsonObjectForOldAndNewRects(oldBounds, oldLocation, newBounds, newLocation));
 
-    if (invalidationReason == PaintInvalidationNone)
+    if (invalidationReason == PaintInvalidationNone) {
         return invalidationReason;
+    }

[Xianzhu, 2015/03/18 19:24:53]

Ditto.

[chrishtr, 2015/03/19 22:01:26]

Done.

 
     if (RuntimeEnabledFeatures::slimmingPaintEnabled())
         invalidateDisplayItemClients(paintInvalidationContainer);
@@ -3109,7 +3118,6 @@ void LayoutObject::setShouldDoFullPaintInvalidation(PaintInvalidationReason reas
         m_bitfields.setFullPaintInvalidationReason(reason);
     }
 
-    ASSERT(document().lifecycle().state() != DocumentLifecycle::InPaintInvalidation);
     frame()->page()->animator().scheduleVisualUpdate(); // In case that this is called outside of FrameView::updateLayoutAndStyleForPainting().
     markContainerChainForPaintInvalidation();
 }