Bug 1368386 - Make ProgressiveUpdate's aValidRegion parameter const to make it a bit easier to reason about. r=mattwoodrow

MozReview-Commit-ID: DOfJ8TTuL1t

--HG--
extra : rebase_source : d4e6a1dc8aedb9f6b446c43aeded6823944c497a

gfx/layers/client/ClientTiledPaintedLayer.cpp

@@ -322,8 +322,12 @@ ClientTiledPaintedLayer::RenderHighPrecision(const nsIntRegion& aInvalidRegion,
 
     TILING_LOG("TILING %p: Progressive update with old valid region %s\n", this, Stringify(oldValidRegion).c_str());
 
-    return mContentClient->GetTiledBuffer()->ProgressiveUpdate(mValidRegion, aInvalidRegion,
-                      oldValidRegion, &mPaintData, aCallback, aCallbackData);
+    nsIntRegion drawnRegion;
+    bool updatedBuffer =
+      mContentClient->GetTiledBuffer()->ProgressiveUpdate(mValidRegion, aInvalidRegion,
+                      oldValidRegion, drawnRegion, &mPaintData, aCallback, aCallbackData);
+    mValidRegion.OrWith(drawnRegion);
+    return updatedBuffer;
   }
 
   // Otherwise do a non-progressive paint. We must do this even when
@@ -388,9 +392,11 @@ ClientTiledPaintedLayer::RenderLowPrecision(const nsIntRegion& aInvalidRegion,
     TILING_LOG("TILING %p: Progressive paint: low-precision old valid region is %s\n", this, Stringify(oldValidRegion).c_str());
 
     if (!invalidRegion.IsEmpty()) {
+      nsIntRegion drawnRegion;
       updatedBuffer = mContentClient->GetLowPrecisionTiledBuffer()->ProgressiveUpdate(
                             mLowPrecisionValidRegion, invalidRegion, oldValidRegion,
-                            &mPaintData, aCallback, aCallbackData);
+                            drawnRegion, &mPaintData, aCallback, aCallbackData);
+      mLowPrecisionValidRegion.OrWith(drawnRegion);
     }
 
     TILING_LOG("TILING %p: Progressive paint: low-precision new valid region is %s\n", this, Stringify(mLowPrecisionValidRegion).c_str());

gfx/layers/client/SingleTiledContentClient.h

@@ -45,9 +45,10 @@ public:
                    bool aIsProgressive = false) override;
  
   bool SupportsProgressiveUpdate() override { return false; }
-  bool ProgressiveUpdate(nsIntRegion& aValidRegion,
+  bool ProgressiveUpdate(const nsIntRegion& aValidRegion,
                          const nsIntRegion& aInvalidRegion,
                          const nsIntRegion& aOldValidRegion,
+                         nsIntRegion& aOutDrawnRegion,
                          BasicTiledLayerPaintData* aPaintData,
                          LayerManager::DrawPaintedLayerCallback aCallback,
                          void* aCallbackData) override

gfx/layers/client/TiledContentClient.cpp

@@ -1336,9 +1336,10 @@ ClientMultiTiledLayerBuffer::ComputeProgressiveUpdateRegion(const nsIntRegion& a
 }
 
 bool
-ClientMultiTiledLayerBuffer::ProgressiveUpdate(nsIntRegion& aValidRegion,
+ClientMultiTiledLayerBuffer::ProgressiveUpdate(const nsIntRegion& aValidRegion,
                                                const nsIntRegion& aInvalidRegion,
                                                const nsIntRegion& aOldValidRegion,
+                                               nsIntRegion& aOutDrawnRegion,
                                                BasicTiledLayerPaintData* aPaintData,
                                                LayerManager::DrawPaintedLayerCallback aCallback,
                                                void* aCallbackData)
@@ -1350,6 +1351,7 @@ ClientMultiTiledLayerBuffer::ProgressiveUpdate(nsIntRegion& aValidRegion,
   bool repeat = false;
   bool isBufferChanged = false;
   nsIntRegion remainingInvalidRegion = aInvalidRegion;
+  nsIntRegion updatedValidRegion = aValidRegion;
   do {
     // Compute the region that should be updated. Repeat as many times as
     // is required.
@@ -1370,13 +1372,14 @@ ClientMultiTiledLayerBuffer::ProgressiveUpdate(nsIntRegion& aValidRegion,
     isBufferChanged = true;
 
     // Keep track of what we're about to refresh.
-    aValidRegion.Or(aValidRegion, regionToPaint);
+    aOutDrawnRegion.OrWith(regionToPaint);
+    updatedValidRegion.OrWith(regionToPaint);
 
     // aValidRegion may have been altered by InvalidateRegion, but we still
     // want to display stale content until it gets progressively updated.
     // Create a region that includes stale content.
     nsIntRegion validOrStale;
-    validOrStale.Or(aValidRegion, aOldValidRegion);
+    validOrStale.Or(updatedValidRegion, aOldValidRegion);
 
     // Paint the computed region and subtract it from the invalid region.
     PaintThebes(validOrStale, regionToPaint, remainingInvalidRegion,
@@ -1384,7 +1387,7 @@ ClientMultiTiledLayerBuffer::ProgressiveUpdate(nsIntRegion& aValidRegion,
     remainingInvalidRegion.SubOut(regionToPaint);
   } while (repeat);
 
-  TILING_LOG("TILING %p: Progressive update final valid region %s buffer changed %d\n", &mPaintedLayer, Stringify(aValidRegion).c_str(), isBufferChanged);
+  TILING_LOG("TILING %p: Progressive update final valid region %s buffer changed %d\n", &mPaintedLayer, Stringify(updatedValidRegion).c_str(), isBufferChanged);
   TILING_LOG("TILING %p: Progressive update final invalid region %s\n", &mPaintedLayer, Stringify(remainingInvalidRegion).c_str());
 
   // Return false if nothing has been drawn, or give what has been drawn

gfx/layers/client/TiledContentClient.h

@@ -296,9 +296,10 @@ public:
                    bool aIsProgressive = false) = 0;
 
   virtual bool SupportsProgressiveUpdate() = 0;
-  virtual bool ProgressiveUpdate(nsIntRegion& aValidRegion,
+  virtual bool ProgressiveUpdate(const nsIntRegion& aValidRegion,
                          const nsIntRegion& aInvalidRegion,
                          const nsIntRegion& aOldValidRegion,
+                         nsIntRegion& aOutDrawnRegion,
                          BasicTiledLayerPaintData* aPaintData,
                          LayerManager::DrawPaintedLayerCallback aCallback,
                          void* aCallbackData) = 0;
@@ -354,10 +355,13 @@ public:
   /**
    * Performs a progressive update of a given tiled buffer.
    * See ComputeProgressiveUpdateRegion below for parameter documentation.
+   * aOutDrawnRegion is an outparameter that contains the region that was
+   * drawn, and which can now be added to the layer's valid region.
    */
-  bool ProgressiveUpdate(nsIntRegion& aValidRegion,
+  bool ProgressiveUpdate(const nsIntRegion& aValidRegion,
                          const nsIntRegion& aInvalidRegion,
                          const nsIntRegion& aOldValidRegion,
+                         nsIntRegion& aOutDrawnRegion,
                          BasicTiledLayerPaintData* aPaintData,
                          LayerManager::DrawPaintedLayerCallback aCallback,
                          void* aCallbackData) override;