SkBitmap::ComputeIsOpaque -> SkPixmap::computeIsOpaque

Motivation:  Twice internal Skia clients have to do something awkward like this:

    bool ComputeIsOpaque(const SkPixmap& pixmap) {
      SkBitmap bm;
      return bm.installPixels(pixmap) && SkBitmap::ComputeIsOpaque(bm);
    }

Change-Id: I7263c06f754c1305ecb07c4c005d9cfb9d1f523d
Reviewed-on: https://skia-review.googlesource.com/5684
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>

2 files changed, 10 insertions, 1 deletions

diff --git a/include/core/SkBitmap.h b/include/core/SkBitmap.h
index 061f0e5c95..7c3cd7f9b7 100644
--- a/include/core/SkBitmap.h
+++ b/include/core/SkBitmap.h
@@ -215,7 +215,10 @@ public:
      *  this (isOpaque). Only call this if you need to compute this value from
      *  "unknown" pixels.
      */
-    static bool ComputeIsOpaque(const SkBitmap&);
+    static bool ComputeIsOpaque(const SkBitmap& bm) {
+        SkAutoPixmapUnlock result;
+        return bm.requestLock(&result) && result.pixmap().computeIsOpaque();
+    }
 
     /**
      *  Return the bitmap's bounds [0, 0, width, height] as an SkRect
diff --git a/include/core/SkPixmap.h b/include/core/SkPixmap.h
index ce13297fb9..6cf948e601 100644
--- a/include/core/SkPixmap.h
+++ b/include/core/SkPixmap.h
@@ -91,6 +91,12 @@ public:
     size_t getSafeSize() const { return fInfo.getSafeSize(fRowBytes); }
 
     /**
+     *  This will brute-force return true if all of the pixels in the pixmap
+     *  are opaque. If there are no pixels, or encounters an error, returns false.
+     */
+    bool computeIsOpaque() const;
+
+    /**
      *  Converts the pixel at the specified coordinate to an unpremultiplied
      *  SkColor. Note: this ignores any SkColorSpace information, and may return
      *  lower precision data than is actually in the pixel. Alpha only