Remove BufferContentType and add ValidBufferSize (bug 1399692 part 3, r=bas)

BufferContentType and BufferSizeOkFor make more sense as general functions for
any RotatedBuffer, and this helps out in a later patch.

MozReview-Commit-ID: EAVodvl4WTu

--HG--
extra : rebase_source : 6b3406713414a5fe5c1ace6cd0db86c811557323
extra : source : b57a3f0d08478f094328b5a50c57eed35798fdf0

gfx/layers/RotatedBuffer.cpp

@@ -389,6 +389,12 @@ RotatedBuffer::AdjustTo(const gfx::IntRect& aDestBufferRect,
   return true;
 }
 
+RotatedBuffer::ContentType
+RotatedBuffer::GetContentType() const
+{
+  return ContentForFormat(GetFormat());
+}
+
 DrawTarget*
 RotatedBuffer::BorrowDrawTargetForQuadrantUpdate(const IntRect& aBounds,
                                                  ContextSource aSource,

gfx/layers/RotatedBuffer.h

@@ -203,6 +203,11 @@ public:
    */
   void ClearDidSelfCopy() { mDidSelfCopy = false; }
 
+  /**
+   * Gets the content type for this buffer.
+   */
+  ContentType GetContentType() const;
+
   virtual bool IsLocked() = 0;
   virtual bool Lock(OpenMode aMode) = 0;
   virtual void Unlock() = 0;

gfx/layers/client/ContentClient.cpp

@@ -127,17 +127,17 @@ ContentClient::BeginPaint(PaintedLayer* aLayer,
     MOZ_ASSERT(dest.mValidRegion.IsEmpty());
 
     result.mRegionToInvalidate = aLayer->GetValidRegion();
-    Clear();
 
 #if defined(MOZ_DUMP_PAINTING)
     if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
-      if (result.mContentType != BufferContentType()) {
+      if (result.mContentType != mBuffer->GetContentType()) {
         printf_stderr("Invalidating entire rotated buffer (layer %p): content type changed\n", aLayer);
       } else if ((dest.mBufferMode == SurfaceMode::SURFACE_COMPONENT_ALPHA) != mBuffer->HaveBufferOnWhite()) {
         printf_stderr("Invalidating entire rotated buffer (layer %p): component alpha changed\n", aLayer);
       }
     }
 #endif
+    Clear();
   }
 
   result.mRegionToDraw.Sub(dest.mNeededRegion,
@@ -380,7 +380,9 @@ ContentClient::CalculateBufferForPaint(PaintedLayer* aLayer,
   while (true) {
     mode = aLayer->GetSurfaceMode();
     neededRegion = aLayer->GetVisibleRegion().ToUnknownRegion();
-    canReuseBuffer = canReuseBuffer && BufferSizeOkFor(neededRegion.GetBounds().Size());
+    canReuseBuffer = canReuseBuffer && ValidBufferSize(mBufferSizePolicy,
+                                                       mBuffer->BufferRect().Size(),
+                                                       neededRegion.GetBounds().Size());
     contentType = layerContentType;
 
     if (canReuseBuffer) {
@@ -433,7 +435,7 @@ ContentClient::CalculateBufferForPaint(PaintedLayer* aLayer,
     // have transitioned into/out of component alpha, then we need to recreate it.
     if (canKeepBufferContents &&
         mBuffer &&
-        (contentType != BufferContentType() ||
+        (contentType != mBuffer->GetContentType() ||
         (mode == SurfaceMode::SURFACE_COMPONENT_ALPHA) != mBuffer->HaveBufferOnWhite()))
     {
       // Restart the decision process; we won't re-enter since we guard on
@@ -461,22 +463,14 @@ ContentClient::CalculateBufferForPaint(PaintedLayer* aLayer,
   return dest;
 }
 
-gfxContentType
-ContentClient::BufferContentType()
-{
-  if (mBuffer) {
-    return ContentForFormat(mBuffer->GetFormat());
-  }
-  return gfxContentType::SENTINEL;
-}
-
 bool
-ContentClient::BufferSizeOkFor(const IntSize& aSize)
+ContentClient::ValidBufferSize(BufferSizePolicy aPolicy,
+                               const gfx::IntSize& aBufferSize,
+                               const gfx::IntSize& aVisibleBoundsSize)
 {
-  MOZ_ASSERT(mBuffer);
-  return (aSize == mBuffer->BufferRect().Size() ||
-          (SizedToVisibleBounds != mBufferSizePolicy &&
-           aSize < mBuffer->BufferRect().Size()));
+  return (aVisibleBoundsSize == aBufferSize ||
+          (SizedToVisibleBounds != aPolicy &&
+           aVisibleBoundsSize < aBufferSize));
 }
 
 void

gfx/layers/client/ContentClient.h

@@ -203,15 +203,9 @@ protected:
   BufferDecision CalculateBufferForPaint(PaintedLayer* aLayer,
                                          uint32_t aFlags);
 
-  /**
-   * Return the buffer's content type.  Requires a valid buffer.
-   */
-  gfxContentType BufferContentType();
-  /**
-   * Returns whether the specified size is adequate for the current
-   * buffer and buffer size policy.
-   */
-  bool BufferSizeOkFor(const gfx::IntSize& aSize);
+  static bool ValidBufferSize(BufferSizePolicy aPolicy,
+                              const gfx::IntSize& aBufferSize,
+                              const gfx::IntSize& aVisibleBoundsSize);
 
   /**
    * Any actions that should be performed at the last moment before we begin