aggressively refactor pipeline building in SkColorSpaceXform

This rewrites things into 5 distinct phases:
  1) load src
  2) linearize src
  3) gamut transform
  4) apply dst transfer function and premul
  5) store dst

In the existing code, steps 1+2 were really intertwined,
and we had all sorts of arbitrary restrictions on input
formats and output formats.  I've removed most of those.

This is guarded by SK_COLOR_SPACE_XFORM_LEGACY_PIPELINE
for Blink layout tests.  (The 35 diffs all look fine.)

Bug: skia:7114

Change-Id: Ib5f15d1ac3240a6ef202ba30acef660152beee82
Reviewed-on: https://skia-review.googlesource.com/55320
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/src/core/SkColorSpaceXform.cpp b/src/core/SkColorSpaceXform.cpp
index 7f55c6f82d..887b0a0361 100644
--- a/src/core/SkColorSpaceXform.cpp
+++ b/src/core/SkColorSpaceXform.cpp
@@ -439,6 +439,7 @@ bool SkColorSpaceXform_XYZ::onApply(ColorFormat dstColorFormat, void* dst,
     SkJumper_MemoryCtx src_ctx = { (void*)src, 0 },
                        dst_ctx = { (void*)dst, 0 };
 
+#if defined(SK_COLOR_SPACE_XFORM_LEGACY_PIPELINE)
     LoadTablesContext loadTables;
     switch (srcColorFormat) {
         case kRGBA_8888_ColorFormat:
@@ -589,6 +590,77 @@ bool SkColorSpaceXform_XYZ::onApply(ColorFormat dstColorFormat, void* dst,
         default:
             return false;
     }
+#else
+    // 1) Load src pixels.
+    SkRasterPipeline::StockStage load_src;
+    switch (srcColorFormat) {
+        case   kRGBA_8888_ColorFormat: load_src = SkRasterPipeline::load_8888      ; break;
+        case   kBGRA_8888_ColorFormat: load_src = SkRasterPipeline::load_bgra      ; break;
+        case  kRGB_U16_BE_ColorFormat: load_src = SkRasterPipeline::load_rgb_u16_be; break;
+        case kRGBA_U16_BE_ColorFormat: load_src = SkRasterPipeline::load_u16_be    ; break;
+        case    kRGBA_F16_ColorFormat: load_src = SkRasterPipeline::load_f16       ; break;
+        case    kRGBA_F32_ColorFormat: load_src = SkRasterPipeline::load_f32       ; break;
+        case     kBGR_565_ColorFormat: load_src = SkRasterPipeline::load_565       ; break;
+    }
+    pipeline.append(load_src, &src_ctx);
+
+    // 2) Linearize.
+    SkJumper_TableCtx table_r{fSrcGammaTables[0], 256},
+                      table_g{fSrcGammaTables[1], 256},
+                      table_b{fSrcGammaTables[2], 256};
+    switch (fSrcGamma) {
+        case kLinear_SrcGamma:                                                       break;
+        case   kSRGB_SrcGamma: pipeline.append_from_srgb(kUnpremul_SkAlphaType);     break;
+        case  kTable_SrcGamma: pipeline.append(SkRasterPipeline::table_r, &table_r);
+                               pipeline.append(SkRasterPipeline::table_g, &table_g);
+                               pipeline.append(SkRasterPipeline::table_b, &table_b); break;
+    }
+
+    // 3) Gamut transform.
+    if (!fSrcToDstIsIdentity) {
+        pipeline.append(SkRasterPipeline::matrix_3x4, fSrcToDst);
+        if (kRGBA_F16_ColorFormat != dstColorFormat && kRGBA_F32_ColorFormat != dstColorFormat) {
+            pipeline.append(SkRasterPipeline::clamp_0);
+            pipeline.append(SkRasterPipeline::clamp_1);
+        }
+    }
+
+    // 4) Apply transfer function and any premultiplication if necessary.
+    float to_2dot2 = 1/2.2f;
+    TablesContext tables = {
+        fDstGammaTables[0],
+        fDstGammaTables[1],
+        fDstGammaTables[2],
+        SkColorSpaceXform_Base::kDstGammaTableSize,
+    };
+
+    if (kPremul_SkAlphaType == alphaType && SkTransferFunctionBehavior::kRespect == fPremulBehavior)
+    {
+        pipeline.append(SkRasterPipeline::premul);
+    }
+    switch (fDstGamma) {
+        case kLinear_DstGamma:                                                              break;
+        case kSRGB_DstGamma:   pipeline.append(SkRasterPipeline::to_srgb);                  break;
+        case k2Dot2_DstGamma:  pipeline.append(SkRasterPipeline::gamma, &to_2dot2);         break;
+        case kTable_DstGamma:  pipeline.append(SkRasterPipeline::byte_tables_rgb, &tables); break;
+    }
+    if (kPremul_SkAlphaType == alphaType && SkTransferFunctionBehavior::kIgnore == fPremulBehavior)
+    {
+        pipeline.append(SkRasterPipeline::premul);
+    }
+
+    // 5) Store to dst.
+    SkRasterPipeline::StockStage store_dst;
+    switch (dstColorFormat) {
+        case kRGBA_8888_ColorFormat: store_dst = SkRasterPipeline::store_8888; break;
+        case kBGRA_8888_ColorFormat: store_dst = SkRasterPipeline::store_bgra; break;
+        case  kRGBA_F16_ColorFormat: store_dst = SkRasterPipeline::store_f16 ; break;
+        case  kRGBA_F32_ColorFormat: store_dst = SkRasterPipeline::store_f32 ; break;
+        case   kBGR_565_ColorFormat: store_dst = SkRasterPipeline::store_565 ; break;
+        default: return false;
+    }
+    pipeline.append(store_dst, &dst_ctx);
+#endif
 
     pipeline.run(0,0, len,1);
     return true;