update (non-sprite) image shader color management

Just another little step...  diffs down to ~450 from ~500.

The A8 handling has changed a little, keeping the paint
color in sRGB just to make the append_misc() logic a bit
more streamlined.

I may want to refactor things a little later so that I can
get an easy signal to use to_srgb and from_srgb stages instead
of sending them through the generic parametric stages.

Change-Id: Iefff3206b06a3aa7d81f85fd169272b6ac9c20e0
Reviewed-on: https://skia-review.googlesource.com/140250
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

5 files changed, 63 insertions, 20 deletions

diff --git a/src/core/SkColorSpaceXformSteps.cpp b/src/core/SkColorSpaceXformSteps.cpp
index ae230ee0fc..4dfe56383a 100644
--- a/src/core/SkColorSpaceXformSteps.cpp
+++ b/src/core/SkColorSpaceXformSteps.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "SkColorSpaceXformSteps.h"
+#include "SkRasterPipeline.h"
 
 // TODO: explain
 
@@ -66,7 +67,10 @@ SkColorSpaceXformSteps::SkColorSpaceXformSteps(SkColorSpace* src, SkAlphaType sr
 
 void SkColorSpaceXformSteps::apply(float* rgba) const {
     if (flags.unpremul) {
-        float invA = isfinite(1.0f / rgba[3]) ? 1.0f / rgba[3] : 0;
+        // I don't know why isfinite(x) stopped working on the Chromecast bots...
+        auto is_finite = [](float x) { return x*0 == 0; };
+
+        float invA = is_finite(1.0f / rgba[3]) ? 1.0f / rgba[3] : 0;
         rgba[0] *= invA;
         rgba[1] *= invA;
         rgba[2] *= invA;
@@ -95,3 +99,23 @@ void SkColorSpaceXformSteps::apply(float* rgba) const {
         rgba[2] *= rgba[3];
     }
 }
+
+void SkColorSpaceXformSteps::apply(SkRasterPipeline* p) const {
+    if (flags.unpremul) { p->append(SkRasterPipeline::unpremul); }
+    if (flags.linearize) {
+        // TODO: missing an opportunity to use from_srgb here.
+        p->append(SkRasterPipeline::parametric_r, &srcTF);
+        p->append(SkRasterPipeline::parametric_g, &srcTF);
+        p->append(SkRasterPipeline::parametric_b, &srcTF);
+    }
+    if (flags.gamut_transform) {
+        p->append(SkRasterPipeline::matrix_3x3, &src_to_dst_matrix);
+    }
+    if (flags.encode) {
+        // TODO: missing an opportunity to use to_srgb here.
+        p->append(SkRasterPipeline::parametric_r, &dstTFInv);
+        p->append(SkRasterPipeline::parametric_g, &dstTFInv);
+        p->append(SkRasterPipeline::parametric_b, &dstTFInv);
+    }
+    if (flags.premul) { p->append(SkRasterPipeline::premul); }
+}
diff --git a/src/core/SkColorSpaceXformSteps.h b/src/core/SkColorSpaceXformSteps.h
index 3b2a88cddc..c052ff6d99 100644
--- a/src/core/SkColorSpaceXformSteps.h
+++ b/src/core/SkColorSpaceXformSteps.h
@@ -11,6 +11,8 @@
 #include "SkColorSpace.h"
 #include "SkImageInfo.h"
 
+class SkRasterPipeline;
+
 struct SkColorSpaceXformSteps {
     struct Flags {
         bool unpremul;
@@ -39,6 +41,7 @@ struct SkColorSpaceXformSteps {
     }
 
     void apply(float rgba[4]) const;
+    void apply(SkRasterPipeline*) const;
 
     Flags flags;
 
diff --git a/src/core/SkRasterPipeline.h b/src/core/SkRasterPipeline.h
index 36f7ce3eeb..3c14480132 100644
--- a/src/core/SkRasterPipeline.h
+++ b/src/core/SkRasterPipeline.h
@@ -67,7 +67,7 @@
     M(srcover_rgba_8888) M(srcover_bgra_8888)                      \
     M(luminance_to_alpha)                                          \
     M(matrix_translate) M(matrix_scale_translate)                  \
-    M(matrix_2x3) M(matrix_3x4) M(matrix_4x5) M(matrix_4x3)        \
+    M(matrix_2x3) M(matrix_3x3) M(matrix_3x4) M(matrix_4x5) M(matrix_4x3) \
     M(matrix_perspective)                                          \
     M(parametric_r) M(parametric_g) M(parametric_b)                \
     M(parametric_a) M(gamma) M(gamma_dst)                          \
diff --git a/src/opts/SkRasterPipeline_opts.h b/src/opts/SkRasterPipeline_opts.h
index 2431ad78f9..23b5e22829 100644
--- a/src/opts/SkRasterPipeline_opts.h
+++ b/src/opts/SkRasterPipeline_opts.h
@@ -1803,6 +1803,14 @@ STAGE(matrix_2x3, const float* m) {
     r = R;
     g = G;
 }
+STAGE(matrix_3x3, const float* m) {
+    auto R = mad(r,m[0], mad(g,m[3], b*m[6])),
+         G = mad(r,m[1], mad(g,m[4], b*m[7])),
+         B = mad(r,m[2], mad(g,m[5], b*m[8]));
+    r = R;
+    g = G;
+    b = B;
+}
 STAGE(matrix_3x4, const float* m) {
     auto R = mad(r,m[0], mad(g,m[3], mad(b,m[6], m[ 9]))),
          G = mad(r,m[1], mad(g,m[4], mad(b,m[7], m[10]))),
@@ -3204,7 +3212,7 @@ static NotImplemented
         store_u16_be,
         byte_tables,
         colorburn, colordodge, softlight, hue, saturation, color, luminosity,
-        matrix_3x4, matrix_4x5, matrix_4x3,
+        matrix_3x3, matrix_3x4, matrix_4x5, matrix_4x3,
         parametric_r, parametric_g, parametric_b, parametric_a,
         gamma, gamma_dst,
         rgb_to_hsl, hsl_to_rgb,
diff --git a/src/shaders/SkImageShader.cpp b/src/shaders/SkImageShader.cpp
index aa5ecba1ac..22c3f95c04 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 "SkColorSpaceXformSteps.h"
 #include "SkEmptyShader.h"
 #include "SkImage_Base.h"
 #include "SkImageShader.h"
@@ -314,8 +315,8 @@ bool SkImageShader::onAppendStages(const StageRec& rec) const {
         SkColor4f paint_color;
     };
     auto misc = alloc->make<MiscCtx>();
-    misc->state       = std::move(state);  // Extend lifetime to match the pipeline's.
-    misc->paint_color = SkColor4f_from_SkColor(rec.fPaint.getColor(), rec.fDstCS);
+    misc->state = std::move(state);  // Extend lifetime to match the pipeline's.
+    swizzle_rb(Sk4f_fromL32(rec.fPaint.getColor())).store(misc->paint_color.vec());  // sRGBA floats
     p->append_matrix(alloc, matrix);
 
     auto gather = alloc->make<SkJumper_GatherCtx>();
@@ -331,8 +332,6 @@ bool SkImageShader::onAppendStages(const StageRec& rec) const {
     limit_y->scale = pm.height();
     limit_y->invScale = 1.0f / pm.height();
 
-    bool is_srgb = rec.fDstCS && (!info.colorSpace() || info.gammaCloseToSRGB());
-
     SkJumper_DecalTileCtx* decal_ctx = nullptr;
     bool decal_x_and_y = fTileModeX == kDecal_TileMode && fTileModeY == kDecal_TileMode;
     if (fTileModeX == kDecal_TileMode || fTileModeY == kDecal_TileMode) {
@@ -381,40 +380,49 @@ bool SkImageShader::onAppendStages(const StageRec& rec) const {
         if (decal_ctx) {
             p->append(SkRasterPipeline::check_decal_mask, decal_ctx);
         }
-        if (is_srgb) {
-            p->append(SkRasterPipeline::from_srgb);
-        }
     };
 
     auto append_misc = [&] {
+        // TODO: if ref.fDstCS isn't null, we'll premul here then immediately unpremul
+        // to do the color space transformation.  Might be possible to streamline.
         if (info.colorType() == kAlpha_8_SkColorType) {
+            // The color for A8 images comes from the (sRGB) paint color.
             p->append(SkRasterPipeline::set_rgb, &misc->paint_color);
-        }
-        if (info.colorType() == kAlpha_8_SkColorType ||
-            info.alphaType() == kUnpremul_SkAlphaType) {
+            p->append(SkRasterPipeline::premul);
+        } else if (info.alphaType() == kUnpremul_SkAlphaType) {
+            // Convert unpremul images to premul before we carry on with the rest of the pipeline.
             p->append(SkRasterPipeline::premul);
         }
+
         if (quality > kLow_SkFilterQuality) {
             // Bicubic filtering naturally produces out of range values on both sides.
             p->append(SkRasterPipeline::clamp_0);
             p->append(fClampAsIfUnpremul ? SkRasterPipeline::clamp_1
                                          : SkRasterPipeline::clamp_a);
         }
-        append_gamut_transform(p, alloc,
-                               info.colorSpace(),
-                               rec.fDstCS,
-                               fClampAsIfUnpremul ? kUnpremul_SkAlphaType : kPremul_SkAlphaType);
+
+        if (rec.fDstCS) {
+            // If color managed, convert from premul source all the way to premul dst color space.
+            auto srcCS = info.colorSpace();
+            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();
+            }
+            alloc->make<SkColorSpaceXformSteps>(srcCS, kPremul_SkAlphaType, rec.fDstCS)
+                ->apply(p);
+        }
+
         return true;
     };
 
-    // We've got a fast path for 8888 bilinear clamp/clamp non-color-managed sampling.
+    // We've got a fast path for 8888 bilinear clamp/clamp sampling.
     auto ct = info.colorType();
     if (true
         && (ct == kRGBA_8888_SkColorType || ct == kBGRA_8888_SkColorType)
         && quality == kLow_SkFilterQuality
         && fTileModeX == SkShader::kClamp_TileMode
-        && fTileModeY == SkShader::kClamp_TileMode
-        && !is_srgb) {
+        && fTileModeY == SkShader::kClamp_TileMode) {
 
         p->append(SkRasterPipeline::bilerp_clamp_8888, gather);
         if (ct == kBGRA_8888_SkColorType) {