transform paint color to dst colorspace

Hopefully I can start to knock off effects that need
to be converted to dst colorspace one at a time now.

My rough list is,
   - paint color               <----
   - image shader
   - sprite blitter
   - gradients?
   - mode color filter
   - lighting color filter
   - high contrast filter
   - toSRGB color filter

This change cuts the diffs between 8888 and srgb from
~540 to ~500.

I left myself a note about not being able to interpret null
to sRGB at a high level yet.  That'd cause a ton of 8888 diffs,
and I think SkColorSpaceXformCanvas diffs too.

Change-Id: Id66a63e0e92130927f267719aeccb8bbcd92973a
Reviewed-on: https://skia-review.googlesource.com/140244
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/src/core/SkRasterPipeline.cpp b/src/core/SkRasterPipeline.cpp
index 46658969cd..5125476dde 100644
--- a/src/core/SkRasterPipeline.cpp
+++ b/src/core/SkRasterPipeline.cpp
@@ -90,9 +90,7 @@ void SkRasterPipeline::dump() const {
 #endif
 
 void SkRasterPipeline::append_constant_color(SkArenaAlloc* alloc, const float rgba[4]) {
-    SkASSERT(0 <= rgba[0] && rgba[0] <= 1);
-    SkASSERT(0 <= rgba[1] && rgba[1] <= 1);
-    SkASSERT(0 <= rgba[2] && rgba[2] <= 1);
+    // r,g,b might be outside [0,1], but alpha should probably always be in [0,1].
     SkASSERT(0 <= rgba[3] && rgba[3] <= 1);
 
     if (rgba[0] == 0 && rgba[1] == 0 && rgba[2] == 0 && rgba[3] == 1) {
@@ -106,6 +104,10 @@ void SkRasterPipeline::append_constant_color(SkArenaAlloc* alloc, const float rg
         Sk4f color = Sk4f::Load(rgba);
         color.store(&ctx->r);
 
+        // TODO: if any channel is out of [0,1], append a float-only stage
+        // that can handle that, instead of this uniform_color that assumes
+        // in-range values so it can work in lowp.
+
         // To make loads more direct, we store 8-bit values in 16-bit slots.
         color = color * 255.0f + 0.5f;
         ctx->rgba[0] = (uint16_t)color[0];