update mode color filter color management

Change-Id: I2f371e279f45086ae8885c7206fefff3fbc8c941
Reviewed-on: https://skia-review.googlesource.com/140985
Auto-Submit: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

src/core/SkModeColorFilter.cpp

@@ -67,7 +67,7 @@ void SkModeColorFilter::onAppendStages(SkRasterPipeline* p,
                                        SkArenaAlloc* scratch,
                                        bool shaderIsOpaque) const {
     p->append(SkRasterPipeline::move_src_dst);
-    p->append_constant_color(scratch, SkPM4f_from_SkColor(fColor, dst));
+    p->append_constant_color(scratch, premul_in_dst_colorspace(fColor, dst));
     SkBlendMode_AppendStages(fMode, p);
 }
 

src/core/SkPM4fPriv.h

@@ -10,29 +10,61 @@
 
 #include "SkColorData.h"
 #include "SkColorSpace.h"
+#include "SkColorSpaceXformSteps.h"
 #include "SkArenaAlloc.h"
 #include "SkPM4f.h"
 #include "SkRasterPipeline.h"
 #include "SkSRGB.h"
 #include "../jumper/SkJumper.h"
 
+// This file is mostly helper routines for doing color space management.
+// It probably wants a new name, and they likely don't need to be inline.
+//
+// There are two generations of routines in here, the old ones that assumed linear blending,
+// and the new ones assuming as-encoded blending.  We're trying to move to the new as-encoded
+// ones and will hopefully eventually remove all the linear routines.
+//
+// We'll start with the new as-encoded routines first,
+// and shove all the old broken routines towards the bottom.
+
 static inline Sk4f Sk4f_fromL32(uint32_t px) {
     return SkNx_cast<float>(Sk4b::Load(&px)) * (1/255.0f);
 }
 
-static inline Sk4f Sk4f_fromS32(uint32_t px) {
-    return { sk_linear_from_srgb[(px >>  0) & 0xff],
-             sk_linear_from_srgb[(px >>  8) & 0xff],
-             sk_linear_from_srgb[(px >> 16) & 0xff],
-                    (1/255.0f) * (px >> 24)          };
-}
-
 static inline uint32_t Sk4f_toL32(const Sk4f& px) {
     uint32_t l32;
     SkNx_cast<uint8_t>(Sk4f_round(px * 255.0f)).store(&l32);
     return l32;
 }
 
+static inline SkPM4f premul_in_dst_colorspace(SkColor color, SkColorSpace* dstCS) {
+    float rgba[4];
+    swizzle_rb(Sk4f_fromL32(color)).store(rgba);
+
+    // SkColors are always sRGB.
+    auto srcCS = SkColorSpace::MakeSRGB().get();
+
+    // If dstCS is null, no color space transformation is needed (and apply() will just premul).
+    if (!dstCS) { dstCS = srcCS; }
+
+    // TODO: Can we use a precomputed sRGB -> dstCS SkColorSpaceXformSteps for each device?
+    SkColorSpaceXformSteps(srcCS, kUnpremul_SkAlphaType, dstCS)
+        .apply(rgba);
+
+    return {{rgba[0], rgba[1], rgba[2], rgba[3]}};
+}
+
+// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+// Functions below this line are probably totally broken as far as color space management goes.
+// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+static inline Sk4f Sk4f_fromS32(uint32_t px) {
+    return { sk_linear_from_srgb[(px >>  0) & 0xff],
+             sk_linear_from_srgb[(px >>  8) & 0xff],
+             sk_linear_from_srgb[(px >> 16) & 0xff],
+                    (1/255.0f) * (px >> 24)          };
+}
+
 static inline uint32_t Sk4f_toS32(const Sk4f& px) {
     Sk4i  rgb = sk_linear_to_srgb(px),
          srgb = { rgb[0], rgb[1], rgb[2], (int)(255.0f * px[3] + 0.5f) };
@@ -106,4 +138,5 @@ static inline SkPM4f SkPM4f_from_SkColor(SkColor color, SkColorSpace* dst) {
     return SkColor4f_from_SkColor(color, dst).premul();
 }
 
+
 #endif

src/core/SkRasterPipelineBlitter.cpp

@@ -86,22 +86,6 @@ private:
     typedef SkBlitter INHERITED;
 };
 
-static SkPM4f premul_in_dst_colorspace(SkColor color, SkColorSpace* dstCS) {
-    float rgba[4];
-    swizzle_rb(SkNx_cast<float>(Sk4b::Load(&color)) * (1/255.0f)).store(rgba);
-
-    // SkColors are always sRGB.
-    auto srcCS = SkColorSpace::MakeSRGB().get();
-
-    // If dstCS is null, no color space transformation is needed (and apply() will just premul).
-    if (!dstCS) { dstCS = srcCS; }
-
-    SkColorSpaceXformSteps(srcCS, kUnpremul_SkAlphaType, dstCS)
-        .apply(rgba);
-
-    return {{rgba[0], rgba[1], rgba[2], rgba[3]}};
-}
-
 SkBlitter* SkCreateRasterPipelineBlitter(const SkPixmap& dst,
                                          const SkPaint& paint,
                                          const SkMatrix& ctm,