Bug 1465619 - Part 4. Move the first frame refresh area calculation t…

…o frame commit. r=tnikkel

If we discard a frame during decoding, e.g. due to an error, then we
don't want to take that frame into account for the first frame refresh
area. We should also be handling partial frames here (the dirty rect
needs to encompass the rows that did not get written with actual pixel
data). The only place that can have the necessary information is at the
end rather than at the beginning.

Differential Revision: https://phabricator.services.mozilla.com/D7509

image/Decoder.cpp

@@ -361,26 +361,11 @@ Decoder::AllocateFrameInternal(const gfx::IntSize& aOutputSize,
   if (frameNum == 1) {
     MOZ_ASSERT(aPreviousFrame, "Must provide a previous frame when animated");
     aPreviousFrame->SetRawAccessOnly();
-
-    // If we dispose of the first frame by clearing it, then the first frame's
-    // refresh area is all of itself.
-    // RESTORE_PREVIOUS is invalid (assumed to be DISPOSE_CLEAR).
-    DisposalMethod prevDisposal = aPreviousFrame->GetDisposalMethod();
-    if (prevDisposal == DisposalMethod::CLEAR ||
-        prevDisposal == DisposalMethod::CLEAR_ALL ||
-        prevDisposal == DisposalMethod::RESTORE_PREVIOUS) {
-      mFirstFrameRefreshArea = aPreviousFrame->GetRect();
-    }
   }
 
   if (frameNum > 0) {
     ref->SetRawAccessOnly();
 
-    // Some GIFs are huge but only have a small area that they animate. We only
-    // need to refresh that small area when frame 0 comes around again.
-    mFirstFrameRefreshArea.UnionRect(mFirstFrameRefreshArea,
-                                     ref->GetBoundedBlendRect());
-
     if (ShouldBlendAnimation()) {
       if (aPreviousFrame->GetDisposalMethod() !=
           DisposalMethod::RESTORE_PREVIOUS) {
@@ -495,11 +480,34 @@ Decoder::PostFrameStop(Opacity aFrameOpacity)
 
   mLoopLength += mCurrentFrame->GetTimeout();
 
-  // If we're not sending partial invalidations, then we send an invalidation
-  // here when the first frame is complete.
-  if (!ShouldSendPartialInvalidations() && mFrameCount == 1) {
-    mInvalidRect.UnionRect(mInvalidRect,
-                           IntRect(IntPoint(), Size()));
+  if (mFrameCount == 1) {
+    // If we're not sending partial invalidations, then we send an invalidation
+    // here when the first frame is complete.
+    if (!ShouldSendPartialInvalidations()) {
+      mInvalidRect.UnionRect(mInvalidRect,
+                             IntRect(IntPoint(), Size()));
+    }
+
+    // If we dispose of the first frame by clearing it, then the first frame's
+    // refresh area is all of itself. RESTORE_PREVIOUS is invalid (assumed to
+    // be DISPOSE_CLEAR).
+    switch (mCurrentFrame->GetDisposalMethod()) {
+      default:
+        MOZ_FALLTHROUGH_ASSERT("Unexpected DisposalMethod");
+      case DisposalMethod::CLEAR:
+      case DisposalMethod::CLEAR_ALL:
+      case DisposalMethod::RESTORE_PREVIOUS:
+        mFirstFrameRefreshArea = IntRect(IntPoint(), Size());
+        break;
+      case DisposalMethod::KEEP:
+      case DisposalMethod::NOT_SPECIFIED:
+        break;
+    }
+  } else {
+    // Some GIFs are huge but only have a small area that they animate. We only
+    // need to refresh that small area when frame 0 comes around again.
+    mFirstFrameRefreshArea.UnionRect(mFirstFrameRefreshArea,
+                                     mCurrentFrame->GetBoundedBlendRect());
   }
 }
 

image/Decoder.h

@@ -451,6 +451,11 @@ class Decoder
     return mRecycleRect;
   }
 
+  const gfx::IntRect& GetFirstFrameRefreshArea() const
+  {
+    return mFirstFrameRefreshArea;
+  }
+
   bool HasFrameToTake() const { return mHasFrameToTake; }
   void ClearHasFrameToTake() {
     MOZ_ASSERT(mHasFrameToTake);