Adding comments based on review https://codereview.appspot.com/7300072/

git-svn-id: http://skia.googlecode.com/svn/trunk@7686 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 3 insertions, 0 deletions

diff --git a/src/core/SkTileGrid.cpp b/src/core/SkTileGrid.cpp
index 51c40cc0af..25a1fa8873 100644
--- a/src/core/SkTileGrid.cpp
+++ b/src/core/SkTileGrid.cpp
@@ -56,6 +56,9 @@ void SkTileGrid::insert(void* data, const SkIRect& bounds, bool) {
 }
 
 void SkTileGrid::search(const SkIRect& query, SkTDArray<void*>* results) {
+    // Convert the query rectangle from device coordinates to tile coordinates
+    // by rounding outwards to the nearest tile boundary so that the resulting tile
+    // region includes the query rectangle. (using truncating division to "floor")
     int tileStartX = (query.left() + fBorderPixels) / fTileWidth;
     int tileEndX = (query.right() + fTileWidth - fBorderPixels) / fTileWidth;
     int tileStartY = (query.top() + fBorderPixels) / fTileHeight;