diff options
| -rw-r--r-- | src/core/SkPath.cpp | 43 | ||||
| -rw-r--r-- | tests/PathTest.cpp | 6 |
2 files changed, 41 insertions, 8 deletions
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp index fc2ba42346..c99db4c560 100644 --- a/src/core/SkPath.cpp +++ b/src/core/SkPath.cpp @@ -1926,6 +1926,20 @@ static int find_max_y(const SkPoint pts[], int count) { return maxIndex; } +static int find_diff_pt(const SkPoint pts[], int index, int n, int inc) { + int i = index; + for (;;) { + i = (i + inc) % n; + if (i == index) { // we wrapped around, so abort + break; + } + if (pts[index] != pts[i]) { // found a different point, success! + break; + } + } + return i; +} + bool SkPath::cheapComputeDirection(Direction* dir) const { // don't want to pay the cost for computing this if it // is unknown, so we don't call isConvex() @@ -1935,10 +1949,15 @@ bool SkPath::cheapComputeDirection(Direction* dir) const { for (; !iter.done(); iter.next()) { int n = iter.count(); - const SkPoint* pts = iter.pts(); + if (n < 3) { + continue; + } + const SkPoint* pts = iter.pts(); SkScalar cross = 0; if (kConvex_Convexity == conv) { + // we loop, skipping over degenerate or flat segments that will + // return 0 for the cross-product for (int i = 0; i < n - 2; ++i) { cross = cross_prod(pts[i], pts[i + 1], pts[i + 2]); if (cross) { @@ -1946,10 +1965,24 @@ bool SkPath::cheapComputeDirection(Direction* dir) const { } } } else { - int i = find_max_y(pts, n); - // can't always say (i-1) % n, in case i-1 goes negative, so we - // use (i+n-1) % n instead - cross = cross_prod(pts[(i + n - 1) % n], pts[i], pts[(i + 1) % n]); + int index = find_max_y(pts, n); + // Find a next and prev index to use for the cross-product test, + // but we try to find pts that form non-zero vectors from pts[index] + // + // Its possible that we can't find two non-degenerate vectors, so + // we have to guard our search (e.g. all the pts could be in the + // same place). + + // we pass n - 1 instead of -1 so we don't foul up % operator by + // passing it a negative LH argument. + int prev = find_diff_pt(pts, index, n, n - 1); + if (prev == index) { + // completely degenerate, skip to next contour + continue; + } + int next = find_diff_pt(pts, index, n, 1); + SkASSERT(next != index); + cross = cross_prod(pts[prev], pts[index], pts[next]); } if (cross) { if (dir) { diff --git a/tests/PathTest.cpp b/tests/PathTest.cpp index 038ee0ca72..fadb0d93ca 100644 --- a/tests/PathTest.cpp +++ b/tests/PathTest.cpp @@ -38,7 +38,7 @@ static void test_direction(skiatest::Reporter* reporter) { } static const char* gCW[] = { - "M 10 10 L 10 10 L 20 10 Q 20 20 30 30", + "M 10 10 L 10 10 Q 20 10 20 20", "M 10 10 C 20 10 20 20 20 20", }; for (i = 0; i < SK_ARRAY_COUNT(gCW); ++i) { @@ -49,7 +49,7 @@ static void test_direction(skiatest::Reporter* reporter) { } static const char* gCCW[] = { - "M 10 10 L 10 10 L 20 10 Q 20 -20 30 -30", + "M 10 10 L 10 10 Q 20 10 20 -20", "M 10 10 C 20 10 20 -20 20 -20", }; for (i = 0; i < SK_ARRAY_COUNT(gCCW); ++i) { @@ -1087,7 +1087,7 @@ void TestPath(skiatest::Reporter* reporter) { test_isRect(reporter); test_zero_length_paths(reporter); -// for now test_direction(reporter); + test_direction(reporter); test_convexity(reporter); test_convexity2(reporter); test_close(reporter); |