From 4948e5578a863e6f480d377084937ffb508ca38f Mon Sep 17 00:00:00 2001
From: Brian Osman <brianosman@google.com>
Date: Thu, 27 Dec 2018 11:48:22 -0500
Subject: [PATCH] Wide color support in the AA linearizing convex path renderer

Bug: skia:
Change-Id: I6df042eb79af56b763cda1c58130dc40f6f4bbea
Reviewed-on: https://skia-review.googlesource.com/c/179993
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
---
 .../ops/GrAALinearizingConvexPathRenderer.cpp | 51 +++++++++----------
 1 file changed, 25 insertions(+), 26 deletions(-)

diff --git a/src/gpu/ops/GrAALinearizingConvexPathRenderer.cpp b/src/gpu/ops/GrAALinearizingConvexPathRenderer.cpp
index 52785eb1f7..41cfa1a0d4 100644
--- a/src/gpu/ops/GrAALinearizingConvexPathRenderer.cpp
+++ b/src/gpu/ops/GrAALinearizingConvexPathRenderer.cpp
@@ -83,20 +83,20 @@ GrAALinearizingConvexPathRenderer::onCanDrawPath(const CanDrawPathArgs& args) co
 static void extract_verts(const GrAAConvexTessellator& tess,
                           void* vertData,
                           size_t vertexStride,
-                          GrColor color,
+                          const SkPMColor4f& origColor,
+                          bool wideColor,
                           uint16_t firstIndex,
                           uint16_t* idxs,
                           bool tweakAlphaForCoverage) {
     GrVertexWriter verts{vertData};
-    for (int i = 0; i < tess.numPts(); ++i) {
-        verts.write(tess.point(i));
-        if (tweakAlphaForCoverage) {
-            SkASSERT(SkScalarRoundToInt(255.0f * tess.coverage(i)) <= 255);
-            unsigned scale = SkScalarRoundToInt(255.0f * tess.coverage(i));
-            GrColor scaledColor = (0xff == scale) ? color : SkAlphaMulQ(color, scale);
-            verts.write(scaledColor);
-        } else {
-            verts.write(color, tess.coverage(i));
+    if (tweakAlphaForCoverage) {
+        for (int i = 0; i < tess.numPts(); ++i) {
+            verts.write(tess.point(i), GrVertexColor(origColor * tess.coverage(i), wideColor));
+        }
+    } else {
+        GrVertexColor color(origColor, wideColor);
+        for (int i = 0; i < tess.numPts(); ++i) {
+            verts.write(tess.point(i), color, tess.coverage(i));
         }
     }
 
@@ -108,22 +108,18 @@ static void extract_verts(const GrAAConvexTessellator& tess,
 static sk_sp<GrGeometryProcessor> create_lines_only_gp(const GrShaderCaps* shaderCaps,
                                                        bool tweakAlphaForCoverage,
                                                        const SkMatrix& viewMatrix,
-                                                       bool usesLocalCoords) {
+                                                       bool usesLocalCoords,
+                                                       bool wideColor) {
     using namespace GrDefaultGeoProcFactory;
 
-    Coverage::Type coverageType;
-    if (tweakAlphaForCoverage) {
-        coverageType = Coverage::kSolid_Type;
-    } else {
-        coverageType = Coverage::kAttribute_Type;
-    }
+    Coverage::Type coverageType =
+        tweakAlphaForCoverage ? Coverage::kSolid_Type : Coverage::kAttribute_Type;
     LocalCoords::Type localCoordsType =
-            usesLocalCoords ? LocalCoords::kUsePosition_Type : LocalCoords::kUnused_Type;
-    return MakeForDeviceSpace(shaderCaps,
-                              Color::kPremulGrColorAttribute_Type,
-                              coverageType,
-                              localCoordsType,
-                              viewMatrix);
+        usesLocalCoords ? LocalCoords::kUsePosition_Type : LocalCoords::kUnused_Type;
+    Color::Type colorType =
+        wideColor ? Color::kPremulWideColorAttribute_Type : Color::kPremulGrColorAttribute_Type;
+
+    return MakeForDeviceSpace(shaderCaps, colorType, coverageType, localCoordsType, viewMatrix);
 }
 
 namespace {
@@ -174,6 +170,7 @@ public:
             bounds.outset(w, w);
         }
         this->setTransformedBounds(bounds, viewMatrix, HasAABloat::kYes, IsZeroArea::kNo);
+        fWideColor = !SkPMColor4fFitsInBytes(color);
     }
 
     const char* name() const override { return "AAFlatteningConvexPathOp"; }
@@ -243,7 +240,8 @@ private:
         sk_sp<GrGeometryProcessor> gp(create_lines_only_gp(target->caps().shaderCaps(),
                                                            fHelper.compatibleWithAlphaAsCoverage(),
                                                            this->viewMatrix(),
-                                                           fHelper.usesLocalCoords()));
+                                                           fHelper.usesLocalCoords(),
+                                                           fWideColor));
         if (!gp) {
             SkDebugf("Couldn't create a GrGeometryProcessor\n");
             return;
@@ -296,9 +294,8 @@ private:
                 indices = (uint16_t*) sk_realloc_throw(indices, maxIndices * sizeof(uint16_t));
             }
 
-            // TODO4F: Preserve float colors
             extract_verts(tess, vertices + vertexStride * vertexCount, vertexStride,
-                          args.fColor.toBytes_RGBA(), vertexCount, indices + indexCount,
+                          args.fColor, fWideColor, vertexCount, indices + indexCount,
                           fHelper.compatibleWithAlphaAsCoverage());
             vertexCount += currentVertices;
             indexCount += currentIndices;
@@ -318,6 +315,7 @@ private:
         }
 
         fPaths.push_back_n(that->fPaths.count(), that->fPaths.begin());
+        fWideColor |= that->fWideColor;
         return CombineResult::kMerged;
     }
 
@@ -335,6 +333,7 @@ private:
 
     SkSTArray<1, PathData, true> fPaths;
     Helper fHelper;
+    bool fWideColor;
 
     typedef GrMeshDrawOp INHERITED;
 };