fix conic path fuzz

The test conic has a very large weight, so it reduces to a pair
of lines. Detect this case rather than subdividing the conic
so much that the answers are meaningless.

R=herb@google.com, reed@google.com
BUG=638223
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2268073004

Review-Url: https://codereview.chromium.org/2268073004

1 files changed, 16 insertions, 2 deletions

diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp
index 7dd5359b7d..03a63b2bda 100644
--- a/src/core/SkGeometry.cpp
+++ b/src/core/SkGeometry.cpp
@@ -1170,10 +1170,24 @@ static SkPoint* subdivide(const SkConic& src, SkPoint pts[], int level) {
 
 int SkConic::chopIntoQuadsPOW2(SkPoint pts[], int pow2) const {
     SkASSERT(pow2 >= 0);
+    *pts = fPts[0];
+    SkDEBUGCODE(SkPoint* endPts);
+    if (pow2 == kMaxConicToQuadPOW2) {  // If an extreme weight generates many quads ...
+        SkConic dst[2];
+        this->chop(dst);
+        // check to see if the first chop generates a pair of lines
+        if (dst[0].fPts[1] == dst[0].fPts[2] && dst[1].fPts[0] == dst[1].fPts[1]) {
+            pts[1] = pts[2] = pts[3] = dst[0].fPts[1];  // set ctrl == end to make lines
+            pts[4] = dst[1].fPts[2];
+            pow2 = 1;
+            SkDEBUGCODE(endPts = &pts[5]);
+            goto commonFinitePtCheck;
+        }
+    }
+    SkDEBUGCODE(endPts = ) subdivide(*this, pts + 1, pow2);
+commonFinitePtCheck:
     const int quadCount = 1 << pow2;
     const int ptCount = 2 * quadCount + 1;
-    *pts = fPts[0];
-    SkDEBUGCODE(SkPoint* endPts =) subdivide(*this, pts + 1, pow2);
     SkASSERT(endPts - pts == ptCount);
     if (!SkPointsAreFinite(pts, ptCount)) {
         // if we generated a non-finite, pin ourselves to the middle of the hull,