Remove run count field from SkTextBlob.

We can flag the last run record instead.  Run iteration is always
sequential, so no penalty.

As a side effect, we can no longer allow instantiation of zero-run text
blobs - but that seems like a good idea anyway.

Change-Id: I7ca80c4780623d5a188f92dfe6d6fe152f20f666
Reviewed-on: https://skia-review.googlesource.com/9149
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>

2 files changed, 8 insertions, 6 deletions

diff --git a/include/core/SkPicture.h b/include/core/SkPicture.h
index 8047858b16..133d3c92c0 100644
--- a/include/core/SkPicture.h
+++ b/include/core/SkPicture.h
@@ -199,10 +199,11 @@ private:
     // V49: Gradients serialized as SkColor4f + SkColorSpace
     // V50: SkXfermode -> SkBlendMode
     // V51: more SkXfermode -> SkBlendMode
+    // V52: Remove SkTextBlob::fRunCount
 
     // Only SKPs within the min/current picture version range (inclusive) can be read.
     static const uint32_t     MIN_PICTURE_VERSION = 35;     // Produced by Chrome M39.
-    static const uint32_t CURRENT_PICTURE_VERSION = 51;
+    static const uint32_t CURRENT_PICTURE_VERSION = 52;
 
     static_assert(MIN_PICTURE_VERSION <= 41,
                   "Remove kFontFileName and related code from SkFontDescriptor.cpp.");
diff --git a/include/core/SkTextBlob.h b/include/core/SkTextBlob.h
index 8198f04a80..1d17f4dafe 100644
--- a/include/core/SkTextBlob.h
+++ b/include/core/SkTextBlob.h
@@ -60,7 +60,7 @@ private:
     friend class SkNVRefCnt<SkTextBlob>;
     class RunRecord;
 
-    SkTextBlob(int runCount, const SkRect& bounds);
+    explicit SkTextBlob(const SkRect& bounds);
 
     ~SkTextBlob();
 
@@ -78,8 +78,7 @@ private:
     friend class SkTextBlobBuilder;
     friend class SkTextBlobRunIterator;
 
-    const int        fRunCount;
-    const SkRect     fBounds;
+    const SkRect   fBounds;
     const uint32_t fUniqueID;
 
     SkDEBUGCODE(size_t fStorageSize;)
@@ -101,8 +100,10 @@ public:
     ~SkTextBlobBuilder();
 
     /**
-     *  Returns an immutable SkTextBlob for the current runs/glyphs. The builder is reset and
-     *  can be reused.
+     *  Returns an immutable SkTextBlob for the current runs/glyphs,
+     *  or nullptr if no runs were allocated.
+     *
+     *  The builder is reset and can be reused.
      */
     sk_sp<SkTextBlob> make();