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

src/core/SkColorSpaceXform.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkColorPriv.h"
 #include "SkColorSpace_Base.h"
 #include "SkColorSpacePriv.h"
@@ skipping 428 matching lines @@
                                            params.fF);
                     outGammaTables[i] = &gammaTableStorage[i * gammaTableSize];
                 }
             }
         }
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
-static inline bool compute_gamut_xform(SkMatrix44* srcToDst, const SkMatrix44& srcToXYZ,
-                                       const SkMatrix44& dstToXYZ) {
-    if (!dstToXYZ.invert(srcToDst)) {
-        return false;
-    }
-
-    srcToDst->postConcat(srcToXYZ);
-    return true;
+static inline void compute_gamut_xform(SkMatrix44* srcToDst, const SkColorSpace* src,
+                                       const SkColorSpace* dst) {
+    *srcToDst = as_CSB(dst)->fromXYZD50();
+    srcToDst->postConcat(src->toXYZD50());
 }
 
 static inline bool is_almost_identity(const SkMatrix44& srcToDst) {
     for (int i = 0; i < 4; i++) {
         for (int j = 0; j < 4; j++) {
             float expected = (i == j) ? 1.0f : 0.0f;
             if (!color_space_almost_equal(srcToDst.getFloat(i,j), expected)) {
                 return false;
             }
         }
     }
     return true;
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 std::unique_ptr<SkColorSpaceXform> SkColorSpaceXform::New(const sk_sp<SkColorSpace>& srcSpace,
                                                           const sk_sp<SkColorSpace>& dstSpace) {
     if (!srcSpace || !dstSpace) {
         // Invalid input
         return nullptr;
     }
 
     ColorSpaceMatch csm = kNone_ColorSpaceMatch;
     SkMatrix44 srcToDst(SkMatrix44::kUninitialized_Constructor);
     if (SkColorSpace::Equals(srcSpace.get(), dstSpace.get())) {
         srcToDst.setIdentity();
         csm = kFull_ColorSpaceMatch;
-    } else if (!compute_gamut_xform(&srcToDst, srcSpace->xyz(), dstSpace->xyz())) {
-        return nullptr;
-    } else if (is_almost_identity(srcToDst)) {
-        srcToDst.setIdentity();
-        csm = kGamut_ColorSpaceMatch;
+    } else {
+        compute_gamut_xform(&srcToDst, srcSpace.get(), dstSpace.get());
+
+        if (is_almost_identity(srcToDst)) {
+            srcToDst.setIdentity();
+            csm = kGamut_ColorSpaceMatch;
+        }
     }
 
     switch (csm) {
         case kNone_ColorSpaceMatch:
             switch (as_CSB(dstSpace)->gammaNamed()) {
                 case kSRGB_SkGammaNamed:
                     return std::unique_ptr<SkColorSpaceXform>(new SkColorSpaceXform_Base
                             <kSRGB_SkGammaNamed, kNone_ColorSpaceMatch>
                             (srcSpace, srcToDst, dstSpace));
                 case k2Dot2Curve_SkGammaNamed:
@@ skipping 704 matching lines @@
             SkASSERT(false);
             return;
     }
 }
 
 std::unique_ptr<SkColorSpaceXform> SlowIdentityXform(const sk_sp<SkColorSpace>& space) {
         return std::unique_ptr<SkColorSpaceXform>(new SkColorSpaceXform_Base
                 <kNonStandard_SkGammaNamed, kNone_ColorSpaceMatch>
                 (space, SkMatrix::I(), space));
 }