add explicit accessor for sRGB singleton colorspaces

SkColorSpace::MakeSRGB().get() is scary, and causes more ref/unref
pairs than strictly necessary for these singletons.

This time the implementation is still in SkColorSpace.cpp,
so these should really work as singletons.

Change-Id: I40f2942c8dcde3040663a04c4f5330aca90868ae
Reviewed-on: https://skia-review.googlesource.com/143305
Auto-Submit: Mike Klein <mtklein@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

11 files changed, 43 insertions, 29 deletions

diff --git a/src/core/SkBlitter_Sprite.cpp b/src/core/SkBlitter_Sprite.cpp
index b26b712d93..e0998d9608 100644
--- a/src/core/SkBlitter_Sprite.cpp
+++ b/src/core/SkBlitter_Sprite.cpp
@@ -7,6 +7,7 @@
 
 #include "SkArenaAlloc.h"
 #include "SkColorSpace.h"
+#include "SkColorSpacePriv.h"
 #include "SkColorSpaceXformSteps.h"
 #include "SkCoreBlitters.h"
 #include "SkOpts.h"
@@ -143,7 +144,7 @@ public:
             if (!srcCS || fSource.colorType() == kAlpha_8_SkColorType) {
                 // We treat untagged images as sRGB.
                 // A8 images get their r,g,b from the paint color, so they're also sRGB.
-                srcCS = SkColorSpace::MakeSRGB().get();
+                srcCS = sk_srgb_singleton();
             }
             fAlloc->make<SkColorSpaceXformSteps>(srcCS, kPremul_SkAlphaType, dstCS)
                 ->apply(&p);
diff --git a/src/core/SkColorSpace.cpp b/src/core/SkColorSpace.cpp
index 3b08e29a89..239f98aac8 100644
--- a/src/core/SkColorSpace.cpp
+++ b/src/core/SkColorSpace.cpp
@@ -192,21 +192,21 @@ static SkColorSpace* singleton_colorspace(SkGammaNamed gamma, const float to_xyz
     return new SkColorSpace_XYZ(gamma, m44);
 }
 
-static SkColorSpace* srgb() {
+SkColorSpace* sk_srgb_singleton() {
     static SkColorSpace* cs = singleton_colorspace(kSRGB_SkGammaNamed, gSRGB_toXYZD50);
     return cs;
 }
-static SkColorSpace* srgb_linear() {
+SkColorSpace* sk_srgb_linear_singleton() {
     static SkColorSpace* cs = singleton_colorspace(kLinear_SkGammaNamed, gSRGB_toXYZD50);
     return cs;
 }
 
 sk_sp<SkColorSpace> SkColorSpace::MakeSRGB() {
-    return sk_ref_sp(srgb());
+    return sk_ref_sp(sk_srgb_singleton());
 }
 
 sk_sp<SkColorSpace> SkColorSpace::MakeSRGBLinear() {
-    return sk_ref_sp(srgb_linear());
+    return sk_ref_sp(sk_srgb_linear_singleton());
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
@@ -258,7 +258,7 @@ uint32_t SkColorSpace::toXYZD50Hash() const {
 }
 
 bool SkColorSpace::isSRGB() const {
-    return srgb() == this;
+    return sk_srgb_singleton() == this;
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
@@ -331,13 +331,13 @@ size_t SkColorSpace::writeToMemory(void* memory) const {
         SkASSERT(this->toXYZD50());
         // If we have a named profile, only write the enum.
         const SkGammaNamed gammaNamed = this->gammaNamed();
-        if (this == srgb()) {
+        if (this == sk_srgb_singleton()) {
             if (memory) {
                 *((ColorSpaceHeader*) memory) = ColorSpaceHeader::Pack(
                         k0_Version, kSRGB_NamedColorSpace, gammaNamed, 0);
             }
             return sizeof(ColorSpaceHeader);
-        } else if (this == srgb_linear()) {
+        } else if (this == sk_srgb_linear_singleton()) {
             if (memory) {
                 *((ColorSpaceHeader*) memory) = ColorSpaceHeader::Pack(
                         k0_Version, kSRGBLinear_NamedColorSpace, gammaNamed, 0);
diff --git a/src/core/SkColorSpacePriv.h b/src/core/SkColorSpacePriv.h
index 7742a8770a..278a6a47d2 100644
--- a/src/core/SkColorSpacePriv.h
+++ b/src/core/SkColorSpacePriv.h
@@ -216,4 +216,10 @@ static inline bool named_to_parametric(SkColorSpaceTransferFn* coeffs,
             return false;
     }
 }
+
+// Return raw pointers to commonly used SkColorSpaces.
+// No need to ref/unref these, but if you do, do it in pairs.
+SkColorSpace* sk_srgb_singleton();
+SkColorSpace* sk_srgb_linear_singleton();
+
 #endif  // SkColorSpacePriv_DEFINED
diff --git a/src/core/SkColorSpaceXformer.cpp b/src/core/SkColorSpaceXformer.cpp
index 5329294982..1e56d4da93 100644
--- a/src/core/SkColorSpaceXformer.cpp
+++ b/src/core/SkColorSpaceXformer.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "SkColorFilter.h"
+#include "SkColorSpacePriv.h"
 #include "SkColorSpaceXformer.h"
 #include "SkColorSpaceXformPriv.h"
 #include "SkDrawLooper.h"
@@ -26,7 +27,7 @@ SkColorSpaceXformer::~SkColorSpaceXformer() {}
 
 std::unique_ptr<SkColorSpaceXformer> SkColorSpaceXformer::Make(sk_sp<SkColorSpace> dst) {
     std::unique_ptr<SkColorSpaceXform> fromSRGB = SkMakeColorSpaceXform(
-            SkColorSpace::MakeSRGB().get(), dst.get());
+            sk_srgb_singleton(), dst.get());
 
     return fromSRGB
         ? std::unique_ptr<SkColorSpaceXformer>(new SkColorSpaceXformer(std::move(dst),
diff --git a/src/core/SkPM4fPriv.h b/src/core/SkPM4fPriv.h
index f5e9aa02e6..f7daabf7dc 100644
--- a/src/core/SkPM4fPriv.h
+++ b/src/core/SkPM4fPriv.h
@@ -10,6 +10,7 @@
 
 #include "SkColorData.h"
 #include "SkColorSpace.h"
+#include "SkColorSpacePriv.h"
 #include "SkColorSpaceXformSteps.h"
 #include "SkArenaAlloc.h"
 #include "SkPM4f.h"
@@ -40,7 +41,7 @@ static inline uint32_t Sk4f_toL32(const Sk4f& px) {
 static inline SkPM4f premul_in_dst_colorspace(SkColor4f color4f,
                                               SkColorSpace* srcCS, SkColorSpace* dstCS) {
     // We treat untagged sources as sRGB.
-    if (!srcCS) { srcCS = SkColorSpace::MakeSRGB().get(); }
+    if (!srcCS) { srcCS = sk_srgb_singleton(); }
 
     // If dstCS is null, no color space transformation is needed (and apply() will just premul).
     if (!dstCS) { dstCS = srcCS; }
@@ -58,7 +59,7 @@ static inline SkPM4f premul_in_dst_colorspace(SkColor c, SkColorSpace* dstCS) {
     swizzle_rb(Sk4f_fromL32(c)).store(color4f.vec());
 
     // SkColors are always sRGB.
-    return premul_in_dst_colorspace(color4f, SkColorSpace::MakeSRGB().get(), dstCS);
+    return premul_in_dst_colorspace(color4f, sk_srgb_singleton(), dstCS);
 }
 
 // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
diff --git a/src/core/SkRasterPipelineBlitter.cpp b/src/core/SkRasterPipelineBlitter.cpp
index ab6990ad1a..58497e07c6 100644
--- a/src/core/SkRasterPipelineBlitter.cpp
+++ b/src/core/SkRasterPipelineBlitter.cpp
@@ -11,6 +11,7 @@
 #include "SkBlitter.h"
 #include "SkColor.h"
 #include "SkColorFilter.h"
+#include "SkColorSpacePriv.h"
 #include "SkColorSpaceXformer.h"
 #include "SkColorSpaceXformSteps.h"
 #include "SkOpts.h"
@@ -94,7 +95,7 @@ SkBlitter* SkCreateRasterPipelineBlitter(const SkPixmap& dst,
     // we need to sometimes still need to distinguish null dstCS from sRGB.
 #if 0
     SkColorSpace* dstCS = dst.colorSpace() ? dst.colorSpace()
-                                           : SkColorSpace::MakeSRGB().get();
+                                           : sk_srgb_singleton();
 #else
     SkColorSpace* dstCS = dst.colorSpace();
 #endif
diff --git a/src/effects/SkToSRGBColorFilter.cpp b/src/effects/SkToSRGBColorFilter.cpp
index 0bfa40b1d3..9942b02f37 100644
--- a/src/effects/SkToSRGBColorFilter.cpp
+++ b/src/effects/SkToSRGBColorFilter.cpp
@@ -5,6 +5,7 @@
  * found in the LICENSE file.
  */
 
+#include "SkColorSpacePriv.h"
 #include "SkColorSpaceXformSteps.h"
 #include "SkPM4fPriv.h"
 #include "SkRasterPipeline.h"
@@ -22,7 +23,7 @@ void SkToSRGBColorFilter::onAppendStages(SkRasterPipeline* p,
                                          SkArenaAlloc* alloc,
                                          bool shaderIsOpaque) const {
     alloc->make<SkColorSpaceXformSteps>(fSrcColorSpace.get(), kPremul_SkAlphaType,
-                                        SkColorSpace::MakeSRGB().get())
+                                        sk_srgb_singleton())
         ->apply(p);
 }
 
@@ -51,6 +52,6 @@ void SkToSRGBColorFilter::flatten(SkWriteBuffer& buffer) const {
 #if SK_SUPPORT_GPU
 std::unique_ptr<GrFragmentProcessor> SkToSRGBColorFilter::asFragmentProcessor(
         GrContext*, const GrColorSpaceInfo&) const {
-    return GrColorSpaceXformEffect::Make(fSrcColorSpace.get(), SkColorSpace::MakeSRGB().get());
+    return GrColorSpaceXformEffect::Make(fSrcColorSpace.get(), sk_srgb_singleton());
 }
 #endif
diff --git a/src/gpu/GrColorSpaceXform.cpp b/src/gpu/GrColorSpaceXform.cpp
index 4ccca52185..af822a882d 100644
--- a/src/gpu/GrColorSpaceXform.cpp
+++ b/src/gpu/GrColorSpaceXform.cpp
@@ -19,9 +19,9 @@ sk_sp<GrColorSpaceXform> GrColorSpaceXform::Make(SkColorSpace* src, SkColorSpace
         return nullptr;
     }
 
-    // Treat null sources as sRGB (safe because sRGB is a global singleton)
+    // Treat null sources as sRGB.
     if (!src) {
-        src = SkColorSpace::MakeSRGB().get();
+        src = sk_srgb_singleton();
     }
 
     // TODO: Plumb source alpha type
@@ -38,9 +38,9 @@ sk_sp<GrColorSpaceXform> GrColorSpaceXform::MakeUnpremulToUnpremul(SkColorSpace*
         return nullptr;
     }
 
-    // Treat null sources as sRGB (safe because sRGB is a global singleton)
+    // Treat null sources as sRGB.
     if (!src) {
-        src = SkColorSpace::MakeSRGB().get();
+        src = sk_srgb_singleton();
     }
 
     SkColorSpaceXformSteps steps = SkColorSpaceXformSteps::UnpremulToUnpremul(src, dst);
diff --git a/src/shaders/SkImageShader.cpp b/src/shaders/SkImageShader.cpp
index 938b7d6da8..9ccd5cd4cf 100644
--- a/src/shaders/SkImageShader.cpp
+++ b/src/shaders/SkImageShader.cpp
@@ -9,6 +9,7 @@
 #include "SkBitmapController.h"
 #include "SkBitmapProcShader.h"
 #include "SkBitmapProvider.h"
+#include "SkColorSpacePriv.h"
 #include "SkColorSpaceXformSteps.h"
 #include "SkEmptyShader.h"
 #include "SkImage_Base.h"
@@ -402,7 +403,7 @@ bool SkImageShader::onAppendStages(const StageRec& rec) const {
             if (!srcCS || info.colorType() == kAlpha_8_SkColorType) {
                 // We treat untagged images as sRGB.
                 // A8 images get their r,g,b from the paint color, so they're also sRGB.
-                srcCS = SkColorSpace::MakeSRGB().get();
+                srcCS = sk_srgb_singleton();
             }
             alloc->make<SkColorSpaceXformSteps>(srcCS, kPremul_SkAlphaType, rec.fDstCS)
                 ->apply(p);
diff --git a/src/shaders/gradients/SkGradientShader.cpp b/src/shaders/gradients/SkGradientShader.cpp
index ff22cc598a..8536dd82eb 100644
--- a/src/shaders/gradients/SkGradientShader.cpp
+++ b/src/shaders/gradients/SkGradientShader.cpp
@@ -8,6 +8,7 @@
 #include <algorithm>
 #include "Sk4fLinearGradient.h"
 #include "SkColorSpace_XYZ.h"
+#include "SkColorSpacePriv.h"
 #include "SkColorSpaceXformer.h"
 #include "SkFlattenablePriv.h"
 #include "SkFloatBits.h"
@@ -462,14 +463,14 @@ SkColor4fXformer::SkColor4fXformer(const SkColor4f* colors, int colorCount,
     // Transform all of the colors to destination color space
     fColors = colors;
 
-    // Treat null destinations as sRGB (safe because sRGB is a global singleton)
+    // Treat null destinations as sRGB.
     if (!dst) {
-        dst = SkColorSpace::MakeSRGB().get();
+        dst = sk_srgb_singleton();
     }
 
-    // Treat null sources as sRGB (safe because sRGB is a global singleton)
+    // Treat null sources as sRGB.
     if (!src) {
-        src = SkColorSpace::MakeSRGB().get();
+        src = sk_srgb_singleton();
     }
 
     if (!SkColorSpace::Equals(src, dst)) {
diff --git a/src/utils/SkPatchUtils.cpp b/src/utils/SkPatchUtils.cpp
index af91626b51..badd63ff15 100644
--- a/src/utils/SkPatchUtils.cpp
+++ b/src/utils/SkPatchUtils.cpp
@@ -8,6 +8,7 @@
 #include "SkPatchUtils.h"
 
 #include "SkColorData.h"
+#include "SkColorSpacePriv.h"
 #include "SkGeometry.h"
 #include "SkPM4f.h"
 #include "SkTo.h"
@@ -254,8 +255,8 @@ struct SkRGBAf {
 
 static void skcolor_to_float(SkRGBAf dst[], const SkColor src[], int count, SkColorSpace* dstCS,
                              bool doPremul) {
-    // Source is always sRGB SkColor (safe because sRGB is a global singleton)
-    auto srcCS = SkColorSpace::MakeSRGB().get();
+    // Source is always sRGB SkColor.
+    auto srcCS = sk_srgb_singleton();
 
     auto op = doPremul ? SkColorSpaceXform::kPremul_AlphaOp : SkColorSpaceXform::kPreserve_AlphaOp;
     SkAssertResult(SkColorSpaceXform::Apply(dstCS, SkColorSpaceXform::kRGBA_F32_ColorFormat,  dst,
@@ -264,8 +265,8 @@ static void skcolor_to_float(SkRGBAf dst[], const SkColor src[], int count, SkCo
 }
 
 static void float_to_skcolor(SkColor dst[], const SkRGBAf src[], int count, SkColorSpace* srcCS) {
-    // Destination is always sRGB SkColor (safe because sRGB is a global singleton)
-    auto dstCS = SkColorSpace::MakeSRGB().get();
+    // Destination is always sRGB SkColor.
+    auto dstCS = sk_srgb_singleton();
     SkAssertResult(SkColorSpaceXform::Apply(dstCS, SkColorSpaceXform::kBGRA_8888_ColorFormat, dst,
                                             srcCS, SkColorSpaceXform::kRGBA_F32_ColorFormat,  src,
                                             count, SkColorSpaceXform::kPreserve_AlphaOp));
@@ -292,9 +293,9 @@ sk_sp<SkVertices> SkPatchUtils::MakeVertices(const SkPoint cubics[12], const SkC
         return nullptr;
     }
 
-    // Treat null interpolation space as sRGB (safe because sRGB is a global singleton)
+    // Treat null interpolation space as sRGB.
     if (!colorSpace) {
-        colorSpace = SkColorSpace::MakeSRGB().get();
+        colorSpace = sk_srgb_singleton();
     }
 
     int vertexCount = SkToS32(mult64);