Conservative SkTextBlob bounds.

Compute cheaper/more conservative text blob bounds based on the typeface
maximum glyph bbox.

BUG=chromium:451401
R=reed@google.com,bungeman@google.com

Review URL: https://codereview.chromium.org/886473002

1 files changed, 4 insertions, 1 deletions

diff --git a/include/core/SkTextBlob.h b/include/core/SkTextBlob.h
index 334cfb98c4..1f04d38912 100644
--- a/include/core/SkTextBlob.h
+++ b/include/core/SkTextBlob.h
@@ -23,7 +23,7 @@ class SkWriteBuffer;
 class SK_API SkTextBlob : public SkRefCnt {
 public:
     /**
-     *  Returns the blob bounding box.
+     *  Returns a conservative blob bounding box.
      */
     const SkRect& bounds() const { return fBounds; }
 
@@ -188,6 +188,9 @@ private:
                   int count, SkPoint offset);
     void updateDeferredBounds();
 
+    static SkRect ConservativeRunBounds(const SkTextBlob::RunRecord&);
+    static SkRect TightRunBounds(const SkTextBlob::RunRecord&);
+
     SkAutoTMalloc<uint8_t> fStorage;
     size_t                 fStorageSize;
     size_t                 fStorageUsed;