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      1 /*
      2  * Copyright 2017 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkPngPriv_DEFINED
      9 #define SkPngPriv_DEFINED
     10 
     11 #include "SkTypes.h"
     12 
     13 // We store kAlpha_8 images as GrayAlpha in png. Our private signal is significant bits for gray.
     14 // If that is set to 1, we assume the gray channel can be ignored, and we output just alpha.
     15 // We tried 0 at first, but png doesn't like a 0 sigbit for a channel it expects, hence we chose 1.
     16 
     17 static constexpr int kGraySigBit_GrayAlphaIsJustAlpha = 1;
     18 
     19 #endif
     20