New helpers for converting SkColor to GrColor4f

These versions will eliminate lots of copy-pasting in various fragment
processor creation code.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3787

Change-Id: I3ada2d4866e92cfc0507beeea11e05790d73757d
Reviewed-on: https://skia-review.googlesource.com/3787
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

2 files changed, 23 insertions, 0 deletions

diff --git a/include/gpu/SkGr.h b/include/gpu/SkGr.h
index 43d61e250b..fc13c3864b 100644
--- a/include/gpu/SkGr.h
+++ b/include/gpu/SkGr.h
@@ -42,6 +42,14 @@ static inline GrColor SkColorToUnpremulGrColor(SkColor c) {
     return GrColorPackRGBA(r, g, b, a);
 }
 
+/** Transform an SkColor (sRGB bytes) to GrColor4f for the specified color space. */
+GrColor4f SkColorToPremulGrColor4f(SkColor c, SkColorSpace* dstColorSpace);
+GrColor4f SkColorToUnpremulGrColor4f(SkColor c, SkColorSpace* dstColorSpace);
+
+/**
+ * As above, but with explicit control over the linearization and gamut xform steps.
+ * Typically used when you have easy access to a pre-computed xform.
+ */
 GrColor4f SkColorToPremulGrColor4f(SkColor c, bool gammaCorrect, GrColorSpaceXform* gamutXform);
 GrColor4f SkColorToUnpremulGrColor4f(SkColor c, bool gammaCorrect, GrColorSpaceXform* gamutXform);
 
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 7c008bea17..7d4d67805c 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -438,6 +438,21 @@ sk_sp<GrTexture> GrMakeCachedBitmapTexture(GrContext* ctx, const SkBitmap& bitma
 
 ///////////////////////////////////////////////////////////////////////////////
 
+GrColor4f SkColorToPremulGrColor4f(SkColor c, SkColorSpace* dstColorSpace) {
+    // We want to premultiply after linearizing, so this is easy:
+    return SkColorToUnpremulGrColor4f(c, dstColorSpace).premul();
+}
+
+GrColor4f SkColorToUnpremulGrColor4f(SkColor c, SkColorSpace* dstColorSpace) {
+    if (dstColorSpace) {
+        auto srgbColorSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
+        auto gamutXform = GrColorSpaceXform::Make(srgbColorSpace.get(), dstColorSpace);
+        return SkColorToUnpremulGrColor4f(c, true, gamutXform.get());
+    } else {
+        return SkColorToUnpremulGrColor4f(c, false, nullptr);
+    }
+}
+
 GrColor4f SkColorToPremulGrColor4f(SkColor c, bool gammaCorrect, GrColorSpaceXform* gamutXform) {
     // We want to premultiply after linearizing, so this is easy:
     return SkColorToUnpremulGrColor4f(c, gammaCorrect, gamutXform).premul();