commit d3d1a988b1ed144b0123dbe594c3a47a63d6451d
author caryclark <caryclark@google.com> Mon Dec 08 04:57:38 2014 -0800
committer Commit bot <commit-bot@chromium.org> Mon Dec 08 04:57:38 2014 -0800
tree a0bbc8154e4f42af3341db8d06d5798d898b09e8
parent f4e0d9eb2d72fe92c30237de978936113143dc16

add convexity logic and tests for scalar max, Inf, and NaN

PathOps relies on isConvex() only returning true for trivially
convex paths. The old logic also returns true if the paths that
contain NaNs and Infinities. Return kUnknown_Convexity instead
in those cases and in cases where the convexity logic computes
intermediaries that overflow.

Review URL: https://codereview.chromium.org/784593002

src/core/SkPath.cpp

diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 25fd058..a08abbd 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -2215,7 +2215,8 @@
     Convexicator()
     : fPtCount(0)
     , fConvexity(SkPath::kConvex_Convexity)
-    , fDirection(SkPath::kUnknown_Direction) {
+    , fDirection(SkPath::kUnknown_Direction)
+    , fIsFinite(true) {
         fExpectedDir = kInvalid_DirChange;
         // warnings
         fLastPt.set(0, 0);
@@ -2233,7 +2234,7 @@
     SkPath::Direction getDirection() const { return fDirection; }
 
     void addPt(const SkPoint& pt) {
-        if (SkPath::kConcave_Convexity == fConvexity) {
+        if (SkPath::kConcave_Convexity == fConvexity || !fIsFinite) {
             return;
         }
 
@@ -2242,7 +2243,10 @@
             ++fPtCount;
         } else {
             SkVector vec = pt - fCurrPt;
-            if (!SkScalarNearlyZero(vec.lengthSqd(), SK_ScalarNearlyZero*SK_ScalarNearlyZero)) {
+            SkScalar lengthSqd = vec.lengthSqd();
+            if (!SkScalarIsFinite(lengthSqd)) {
+                fIsFinite = false;
+            } else if (!SkScalarNearlyZero(lengthSqd, SK_ScalarNearlyZero*SK_ScalarNearlyZero)) {
                 fLastPt = fCurrPt;
                 fCurrPt = pt;
                 if (++fPtCount == 2) {
@@ -2272,6 +2276,10 @@
         }
     }
 
+    bool isFinite() const {
+        return fIsFinite;
+    }
+
 private:
     void addVec(const SkVector& vec) {
         SkASSERT(vec.fX || vec.fY);
@@ -2310,6 +2318,7 @@
     SkPath::Convexity   fConvexity;
     SkPath::Direction   fDirection;
     int                 fDx, fDy, fSx, fSy;
+    bool                fIsFinite;
 };
 
 SkPath::Convexity SkPath::internalGetConvexity() const {
@@ -2322,6 +2331,9 @@
     int             count;
     Convexicator    state;
 
+    if (!isFinite()) {
+        return kUnknown_Convexity;
+    }
     while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {
         switch (verb) {
             case kMove_Verb:
@@ -2350,6 +2362,9 @@
             state.addPt(pts[i]);
         }
         // early exit
+        if (!state.isFinite()) {
+            return kUnknown_Convexity;
+        }
         if (kConcave_Convexity == state.getConvexity()) {
             fConvexity = kConcave_Convexity;
             return kConcave_Convexity;