Add BGRA as input format to SkColorSpaceXform

src/core/SkColorSpaceXform.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkColorSpaceXform_DEFINED
 #define SkColorSpaceXform_DEFINED
 
@@ skipping 16 matching lines @@
     enum ColorFormat : uint8_t {
         kRGBA_8888_ColorFormat,
         kBGRA_8888_ColorFormat,
         kRGBA_F16_ColorFormat,
         kRGBA_F32_ColorFormat,
     };
 
     /**
      *  Apply the color conversion to a |src| buffer, storing the output in the |dst| buffer.
      *
-     *  @param dst            Stored in the format described by |dstColorType| and |dstAlphaType|
-     *  @param src            Stored as RGBA_8888, kUnpremul (note kOpaque is a form of kUnpremul)
+     *  @param dst            Stored in the format described by |dstColorFormat|
+     *  @param src            Stored in the format described by |srcColorFormat|
      *  @param len            Number of pixels in the buffers
      *  @param dstColorFormat Describes color format of |dst|
-     *  @param dstAlphaType   Describes alpha type of |dst|
+     *  @param srcColorFormat Describes color format of |src|
+     *                        Must be kRGBA_8888 or kBGRA_8888
+     *  @param alphaType      Describes alpha properties of the |dst| (and |src|)
      *                        kUnpremul preserves input alpha values
      *                        kPremul   performs a premultiplication and also preserves alpha values
      *                        kOpaque   optimization hint, |dst| alphas set to 1
      *
      */
     virtual void apply(void* dst, const uint32_t* src, int len, ColorFormat dstColorFormat,
-                       SkAlphaType dstAlphaType) const = 0;
+                       ColorFormat srcColorFormat, SkAlphaType alphaType) const = 0;
 
     virtual ~SkColorSpaceXform() {}
 };
 
 enum SrcGamma {
     kLinear_SrcGamma,
     kTable_SrcGamma,
 };
 
 enum DstGamma {
     kLinear_DstGamma,
     kSRGB_DstGamma,
     k2Dot2_DstGamma,
     kTable_DstGamma,
 };
 
 enum ColorSpaceMatch {
     kNone_ColorSpaceMatch,
     kGamut_ColorSpaceMatch,
     kFull_ColorSpaceMatch,
 };
 
 template <SrcGamma kSrc, DstGamma kDst, ColorSpaceMatch kCSM>
 class SkColorSpaceXform_Base : public SkColorSpaceXform {
 public:
 
     void apply(void* dst, const uint32_t* src, int len, ColorFormat dstColorFormat,
-               SkAlphaType dstAlphaType) const override;
+               ColorFormat srcColorFormat, SkAlphaType alphaType) const override;
 
     static constexpr int      kDstGammaTableSize = 1024;
 
 private:
     SkColorSpaceXform_Base(SkColorSpace* srcSpace, const SkMatrix44& srcToDst,
                            SkColorSpace* dstSpace);
 
     sk_sp<SkColorLookUpTable> fColorLUT;
 
     // Contain pointers into storage or pointers into precomputed tables.
     const float*              fSrcGammaTables[3];
     const uint8_t*            fDstGammaTables[3];
     SkAutoMalloc              fStorage;
 
     float                     fSrcToDst[16];
 
     friend class SkColorSpaceXform;
     friend std::unique_ptr<SkColorSpaceXform> SlowIdentityXform(SkColorSpace* space);
 };
 
 // For testing.  Bypasses opts for when src and dst color spaces are equal.
 std::unique_ptr<SkColorSpaceXform> SlowIdentityXform(SkColorSpace* space);
 
 #endif