Cache the inverse matrix on SkColorSpace. Rename xyz() to toXYZ().

src/core/SkColorSpace_Base.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 SkColorSpace_Base_DEFINED
 #define SkColorSpace_Base_DEFINED
 
 #include "SkColorSpace.h"
 #include "SkData.h"
+#include "SkOnce.h"
 #include "SkTemplates.h"
 
 enum SkGammaNamed : uint8_t {
     kLinear_SkGammaNamed,
     kSRGB_SkGammaNamed,
     k2Dot2Curve_SkGammaNamed,
     kNonStandard_SkGammaNamed,
 };
 
 struct SkGammas : SkRefCnt {
@@ skipping 158 matching lines @@
 class SkColorSpace_Base : public SkColorSpace {
 public:
 
     static sk_sp<SkColorSpace> NewRGB(const float gammas[3], const SkMatrix44& toXYZD50);
 
     SkGammaNamed gammaNamed() const { return fGammaNamed; }
     const SkGammas* gammas() const { return fGammas.get(); }
 
     const SkColorLookUpTable* colorLUT() const { return fColorLUT.get(); }
 
+    const SkMatrix44& fromXYZD50() const;
+
 private:
 
     /**
      *  FIXME (msarett):
      *  Hiding this function until we can determine if we need it.  Known issues include:
      *  Only writes 3x3 matrices
      *  Only writes float gammas
      *  Rejected by some parsers because the "profile description" is empty
      */
     sk_sp<SkData> writeToICC() const;
 
     static sk_sp<SkColorSpace> NewRGB(SkGammaNamed gammaNamed, const SkMatrix44& toXYZD50);
 
     SkColorSpace_Base(SkGammaNamed gammaNamed, const SkMatrix44& toXYZ);
 
     SkColorSpace_Base(sk_sp<SkColorLookUpTable> colorLUT, SkGammaNamed gammaNamed,
                       sk_sp<SkGammas> gammas, const SkMatrix44& toXYZ, sk_sp<SkData> profileData);
 
     sk_sp<SkColorLookUpTable> fColorLUT;
     const SkGammaNamed        fGammaNamed;
     sk_sp<SkGammas>           fGammas;
     sk_sp<SkData>             fProfileData;
 
+    mutable SkMatrix44        fFromXYZD50;
+    mutable SkOnce            fFromXYZOnce;
+
     friend class SkColorSpace;
     friend class ColorSpaceXformTest;
     friend class ColorSpaceTest;
     typedef SkColorSpace INHERITED;
 };
 
 static inline SkColorSpace_Base* as_CSB(SkColorSpace* colorSpace) {
     return static_cast<SkColorSpace_Base*>(colorSpace);
 }
 
 static inline const SkColorSpace_Base* as_CSB(const SkColorSpace* colorSpace) {
     return static_cast<const SkColorSpace_Base*>(colorSpace);
 }
 
 static inline SkColorSpace_Base* as_CSB(const sk_sp<SkColorSpace>& colorSpace) {
     return static_cast<SkColorSpace_Base*>(colorSpace.get());
 }
 
 #endif