Fix convexicator bug
BUG=crbug.com/412640
R=caryclark@google.com, bsalomon@google.com
Author: robertphillips@google.com
Review URL: https://codereview.chromium.org/573763002
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 33a0617..06f8b7e 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -2142,6 +2142,16 @@
static int sign(SkScalar x) { return x < 0; }
#define kValueNeverReturnedBySign 2
+enum DirChange {
+ kLeft_DirChange,
+ kRight_DirChange,
+ kStraight_DirChange,
+ kBackwards_DirChange,
+
+ kInvalid_DirChange
+};
+
+
static bool almost_equal(SkScalar compA, SkScalar compB) {
// The error epsilon was empirically derived; worse case round rects
// with a mid point outset by 2x float epsilon in tests had an error
@@ -2156,13 +2166,37 @@
return aBits < bBits + epsilon && bBits < aBits + epsilon;
}
+static DirChange direction_change(const SkPoint& lastPt, const SkVector& curPt,
+ const SkVector& lastVec, const SkVector& curVec) {
+ SkScalar cross = SkPoint::CrossProduct(lastVec, curVec);
+
+ SkScalar smallest = SkTMin(curPt.fX, SkTMin(curPt.fY, SkTMin(lastPt.fX, lastPt.fY)));
+ SkScalar largest = SkTMax(curPt.fX, SkTMax(curPt.fY, SkTMax(lastPt.fX, lastPt.fY)));
+ largest = SkTMax(largest, -smallest);
+
+ if (!almost_equal(largest, largest + cross)) {
+ int sign = SkScalarSignAsInt(cross);
+ if (sign) {
+ return (1 == sign) ? kRight_DirChange : kLeft_DirChange;
+ }
+ }
+
+ if (!SkScalarNearlyZero(lastVec.lengthSqd(), SK_ScalarNearlyZero*SK_ScalarNearlyZero) &&
+ !SkScalarNearlyZero(curVec.lengthSqd(), SK_ScalarNearlyZero*SK_ScalarNearlyZero) &&
+ lastVec.dot(curVec) < 0.0f) {
+ return kBackwards_DirChange;
+ }
+
+ return kStraight_DirChange;
+}
+
// only valid for a single contour
struct Convexicator {
Convexicator()
: fPtCount(0)
, fConvexity(SkPath::kConvex_Convexity)
, fDirection(SkPath::kUnknown_Direction) {
- fSign = 0;
+ fExpectedDir = kInvalid_DirChange;
// warnings
fLastPt.set(0, 0);
fCurrPt.set(0, 0);
@@ -2221,20 +2255,28 @@
private:
void addVec(const SkVector& vec) {
SkASSERT(vec.fX || vec.fY);
- SkScalar cross = SkPoint::CrossProduct(fLastVec, vec);
- SkScalar smallest = SkTMin(fCurrPt.fX, SkTMin(fCurrPt.fY, SkTMin(fLastPt.fX, fLastPt.fY)));
- SkScalar largest = SkTMax(fCurrPt.fX, SkTMax(fCurrPt.fY, SkTMax(fLastPt.fX, fLastPt.fY)));
- largest = SkTMax(largest, -smallest);
- if (!almost_equal(largest, largest + cross)) {
- int sign = SkScalarSignAsInt(cross);
- if (0 == fSign) {
- fSign = sign;
- fDirection = (1 == sign) ? SkPath::kCW_Direction : SkPath::kCCW_Direction;
- } else if (sign && fSign != sign) {
- fConvexity = SkPath::kConcave_Convexity;
- fDirection = SkPath::kUnknown_Direction;
- }
- fLastVec = vec;
+ DirChange dir = direction_change(fLastPt, fCurrPt, fLastVec, vec);
+ switch (dir) {
+ case kLeft_DirChange: // fall through
+ case kRight_DirChange:
+ if (kInvalid_DirChange == fExpectedDir) {
+ fExpectedDir = dir;
+ fDirection = (kRight_DirChange == dir) ? SkPath::kCW_Direction
+ : SkPath::kCCW_Direction;
+ } else if (dir != fExpectedDir) {
+ fConvexity = SkPath::kConcave_Convexity;
+ fDirection = SkPath::kUnknown_Direction;
+ }
+ fLastVec = vec;
+ break;
+ case kStraight_DirChange:
+ break;
+ case kBackwards_DirChange:
+ fLastVec = vec;
+ break;
+ case kInvalid_DirChange:
+ SkFAIL("Use of invalid direction change flag");
+ break;
}
}
@@ -2244,7 +2286,7 @@
// value with the current vec is deemed to be of a significant value.
SkVector fLastVec, fFirstVec;
int fPtCount; // non-degenerate points
- int fSign;
+ DirChange fExpectedDir;
SkPath::Convexity fConvexity;
SkPath::Direction fDirection;
int fDx, fDy, fSx, fSy;
diff --git a/tests/PathTest.cpp b/tests/PathTest.cpp
index 121bce9..1f0422d 100644
--- a/tests/PathTest.cpp
+++ b/tests/PathTest.cpp
@@ -1195,6 +1195,17 @@
stroke.applyToPath(&strokedSin, strokedSin);
check_convexity(reporter, strokedSin, SkPath::kConcave_Convexity);
check_direction(reporter, strokedSin, kDontCheckDir);
+
+ // http://crbug.com/412640
+ SkPath degenerateConcave;
+ degenerateConcave.moveTo(148.67912f, 191.875f);
+ degenerateConcave.lineTo(470.37695f, 7.5f);
+ degenerateConcave.lineTo(148.67912f, 191.875f);
+ degenerateConcave.lineTo(41.446522f, 376.25f);
+ degenerateConcave.lineTo(-55.971577f, 460.0f);
+ degenerateConcave.lineTo(41.446522f, 376.25f);
+ check_convexity(reporter, degenerateConcave, SkPath::kConcave_Convexity);
+ check_direction(reporter, degenerateConcave, SkPath::kUnknown_Direction);
}
static void check_convex_bounds(skiatest::Reporter* reporter, const SkPath& p,