Make AALinearizingConvexPathRenderer able to handle stroke and fill

src/gpu/batches/GrAAConvexTessellator.cpp

Index: src/gpu/batches/GrAAConvexTessellator.cpp
diff --git a/src/gpu/batches/GrAAConvexTessellator.cpp b/src/gpu/batches/GrAAConvexTessellator.cpp
index af3ce89257d890132db64b5767bf120fd3b5540c..528114a2753e28db8ceea52da2320c1c0bd5f7f8 100644
--- a/src/gpu/batches/GrAAConvexTessellator.cpp
+++ b/src/gpu/batches/GrAAConvexTessellator.cpp
@@ -32,11 +32,17 @@ static const SkScalar kRoundCapThreshold = 0.8f;
 // dot product above which we consider two adjacent curves to be part of the "same" curve
 static const SkScalar kCurveConnectionThreshold = 0.8f;
 
-static SkScalar intersect(const SkPoint& p0, const SkPoint& n0,
-                          const SkPoint& p1, const SkPoint& n1) {
+static bool intersect(const SkPoint& p0, const SkPoint& n0,
+                      const SkPoint& p1, const SkPoint& n1,
+                      SkScalar* t) {
     const SkPoint v = p1 - p0;
     SkScalar perpDot = n0.fX * n1.fY - n0.fY * n1.fX;
-    return (v.fX * n1.fY - v.fY * n1.fX) / perpDot;
+    if (SkScalarNearlyZero(perpDot)) {
+        return true;

[ethannicholas, 2016/09/06 20:34:05]

The return value of this function seems backward to me -- intersect() returns
true if the function fails because the lines don't intersect?

[robertphillips, 2016/09/06 20:47:06]

Haha - good point. Fixed.

+    }
+    *t = (v.fX * n1.fY - v.fY * n1.fX) / perpDot;
+    SkASSERT(SkScalarIsFinite(*t));
+    return false;
 }
 
 // This is a special case version of intersect where we have the vector
@@ -218,7 +224,44 @@ bool GrAAConvexTessellator::tessellate(const SkMatrix& m, const SkPath& path) {
 
     SkScalar coverage = 1.0f;
     SkScalar scaleFactor = 0.0f;
-    if (fStrokeWidth >= 0.0f) {
+
+    if (SkStrokeRec::kStrokeAndFill_Style == fStyle) {
+        SkASSERT(m.isSimilarity());
+        scaleFactor = m.getMaxScale(); // x and y scale are the same
+        SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
+        Ring outerStrokeAndAARing;
+        this->createOuterRing(fInitialRing,
+                              effectiveStrokeWidth / 2 + kAntialiasingRadius, 0.0,
+                              &outerStrokeAndAARing);
+
+        // discard all the triangles added between the originating ring and the new outer ring
+        fIndices.rewind();
+
+        outerStrokeAndAARing.init(*this);
+
+        outerStrokeAndAARing.makeOriginalRing();
+
+        // Add the outer stroke ring's normals to the originating ring's normals
+        // so it can also act as an originating ring
+        fNorms.setReserve(fNorms.count() + outerStrokeAndAARing.numPts());
+        for (int i = 0; i < outerStrokeAndAARing.numPts(); ++i) {
+            fNorms.push(outerStrokeAndAARing.norm(i));
+        }
+
+        // the bisectors are only needed for the computation of the outer ring
+        fBisectors.rewind();
+
+        Ring* insetAARing;
+        this->createInsetRings(outerStrokeAndAARing,
+                               0.0f, 0.0f, 2*kAntialiasingRadius, 1.0f,
+                               &insetAARing);
+
+        SkDEBUGCODE(this->validate();)
+        return true;
+    }
+
+    if (SkStrokeRec::kStroke_Style == fStyle) {
+        SkASSERT(fStrokeWidth >= 0.0f);
         SkASSERT(m.isSimilarity());
         scaleFactor = m.getMaxScale(); // x and y scale are the same
         SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
@@ -235,15 +278,16 @@ bool GrAAConvexTessellator::tessellate(const SkMatrix& m, const SkPath& path) {
 
     // the bisectors are only needed for the computation of the outer ring
     fBisectors.rewind();
-    if (fStrokeWidth >= 0.0f && fInitialRing.numPts() > 2) {
+    if (SkStrokeRec::kStroke_Style == fStyle && fInitialRing.numPts() > 2) {
+        SkASSERT(fStrokeWidth >= 0.0f);
         SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
         Ring* insetStrokeRing;
         SkScalar strokeDepth = effectiveStrokeWidth / 2 - kAntialiasingRadius;
         if (this->createInsetRings(fInitialRing, 0.0f, coverage, strokeDepth, coverage,
-                             &insetStrokeRing)) {
+                                   &insetStrokeRing)) {
             Ring* insetAARing;
             this->createInsetRings(*insetStrokeRing, strokeDepth, coverage, strokeDepth +
-                             kAntialiasingRadius * 2, 0.0f, &insetAARing);
+                                   kAntialiasingRadius * 2, 0.0f, &insetAARing);
         }
     } else {
         Ring* insetAARing;
@@ -390,7 +434,7 @@ bool GrAAConvexTessellator::extractFromPath(const SkMatrix& m, const SkPath& pat
         this->computeBisectors();
     } else if (this->numPts() == 2) {
         // We've got two points, so we're degenerate.
-        if (fStrokeWidth < 0.0f) {
+        if (fStyle == SkStrokeRec::kFill_Style) {
             // it's a fill, so we don't need to worry about degenerate paths
             return false;
         }
@@ -586,7 +630,7 @@ void GrAAConvexTessellator::createOuterRing(const Ring& previousRing, SkScalar o
 // Something went wrong in the creation of the next ring. If we're filling the shape, just go ahead
 // and fan it.
 void GrAAConvexTessellator::terminate(const Ring& ring) {
-    if (fStrokeWidth < 0.0f) {
+    if (fStyle != SkStrokeRec::kStroke_Style) {
         this->fanRing(ring);
     }
 }
@@ -616,8 +660,14 @@ bool GrAAConvexTessellator::createInsetRing(const Ring& lastRing, Ring* nextRing
 
     for (int cur = 0; cur < lastRing.numPts(); ++cur) {
         int next = (cur + 1) % lastRing.numPts();
-        SkScalar t = intersect(this->point(lastRing.index(cur)),  lastRing.bisector(cur),
-                               this->point(lastRing.index(next)), lastRing.bisector(next));
+
+        SkScalar t;
+        bool parallel = intersect(this->point(lastRing.index(cur)),  lastRing.bisector(cur),
+                                  this->point(lastRing.index(next)), lastRing.bisector(next),
+                                  &t);
+        if (parallel) {
+            continue;
+        }
         SkScalar dist = -t * lastRing.norm(cur).dot(lastRing.bisector(cur));
 
         if (minDist > dist) {
@@ -745,8 +795,8 @@ bool GrAAConvexTessellator::createInsetRing(const Ring& lastRing, Ring* nextRing
         this->addTri(lastRing.index(i), dst[next], dst[i]);
     }
 
-    if (done && fStrokeWidth < 0.0f) {
-        // fill
+    if (done && fStyle != SkStrokeRec::kStroke_Style) {
+        // fill or stroke-and-fill
         this->fanRing(*nextRing);
     }
 
@@ -860,7 +910,7 @@ void GrAAConvexTessellator::lineTo(SkPoint p, CurveState curve) {
             return;
         }
     }
-    SkScalar initialRingCoverage = fStrokeWidth < 0.0f ? 0.5f : 1.0f;
+    SkScalar initialRingCoverage = (SkStrokeRec::kFill_Style == fStyle) ? 0.5f : 1.0f;
     this->addPt(p, 0.0f, initialRingCoverage, false, curve);
     if (this->numPts() > 1) {
         *fNorms.push() = fPts.top() - fPts[fPts.count()-2];