diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/core/SkPath.cpp | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp index 2308ec67ad..9c0b8afa98 100644 --- a/src/core/SkPath.cpp +++ b/src/core/SkPath.cpp @@ -587,7 +587,29 @@ static int build_arc_points(const SkRect& oval, SkScalar startAngle, start.fY = SkScalarSinCos(SkDegreesToRadians(startAngle), &start.fX); stop.fY = SkScalarSinCos(SkDegreesToRadians(startAngle + sweepAngle), &stop.fX); - + + /* If the sweep angle is nearly (but less than) 360, then due to precision + loss in radians-conversion and/or sin/cos, we may end up with coincident + vectors, which will fool SkBuildQuadArc into doing nothing (bad) instead + of drawing a nearly complete circle (good). + e.g. canvas.drawArc(0, 359.99, ...) + -vs- canvas.drawArc(0, 359.9, ...) + We try to detect this edge case, and tweak the stop vector + */ + if (start == stop) { + SkScalar sw = SkScalarAbs(sweepAngle); + if (sw < SkIntToScalar(360) && sw > SkIntToScalar(359)) { + SkScalar stopRad = SkDegreesToRadians(startAngle + sweepAngle); + // make a guess at a tiny angle (in radians) to tweak by + SkScalar deltaRad = SkScalarCopySign(SK_Scalar1/512, sweepAngle); + // not sure how much will be enough, so we use a loop + do { + stopRad -= deltaRad; + stop.fY = SkScalarSinCos(stopRad, &stop.fX); + } while (start == stop); + } + } + SkMatrix matrix; matrix.setScale(SkScalarHalf(oval.width()), SkScalarHalf(oval.height())); |