use conics for arcTo
guarded by SK_SUPPORT_LEGACY_ARCTO_QUADS
BUG=skia:
Review URL: https://codereview.chromium.org/892703002
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 195424e..4f5fffb 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -915,23 +915,22 @@
return false;
}
-static int build_arc_points(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle,
- SkPoint pts[kSkBuildQuadArcStorage]) {
- SkVector start, stop;
-
- start.fY = SkScalarSinCos(SkDegreesToRadians(startAngle), &start.fX);
- stop.fY = SkScalarSinCos(SkDegreesToRadians(startAngle + sweepAngle),
- &stop.fX);
+// Return the unit vectors pointing at the start/stop points for the given start/sweep angles
+//
+static void angles_to_unit_vectors(SkScalar startAngle, SkScalar sweepAngle,
+ SkVector* startV, SkVector* stopV, SkRotationDirection* dir) {
+ startV->fY = SkScalarSinCos(SkDegreesToRadians(startAngle), &startV->fX);
+ stopV->fY = SkScalarSinCos(SkDegreesToRadians(startAngle + sweepAngle), &stopV->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
+ 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) {
+ if (*startV == *stopV) {
SkScalar sw = SkScalarAbs(sweepAngle);
if (sw < SkIntToScalar(360) && sw > SkIntToScalar(359)) {
SkScalar stopRad = SkDegreesToRadians(startAngle + sweepAngle);
@@ -940,21 +939,34 @@
// not sure how much will be enough, so we use a loop
do {
stopRad -= deltaRad;
- stop.fY = SkScalarSinCos(stopRad, &stop.fX);
- } while (start == stop);
+ stopV->fY = SkScalarSinCos(stopRad, &stopV->fX);
+ } while (*startV == *stopV);
}
}
+ *dir = sweepAngle > 0 ? kCW_SkRotationDirection : kCCW_SkRotationDirection;
+}
+#ifdef SK_SUPPORT_LEGACY_ARCTO_QUADS
+static int build_arc_points(const SkRect& oval, const SkVector& start, const SkVector& stop,
+ SkRotationDirection dir, SkPoint pts[kSkBuildQuadArcStorage]) {
SkMatrix matrix;
matrix.setScale(SkScalarHalf(oval.width()), SkScalarHalf(oval.height()));
matrix.postTranslate(oval.centerX(), oval.centerY());
- return SkBuildQuadArc(start, stop,
- sweepAngle > 0 ? kCW_SkRotationDirection :
- kCCW_SkRotationDirection,
- &matrix, pts);
+ return SkBuildQuadArc(start, stop, dir, &matrix, pts);
}
+#else
+static int build_arc_conics(const SkRect& oval, const SkVector& start, const SkVector& stop,
+ SkRotationDirection dir, SkConic conics[SkConic::kMaxConicsForArc]) {
+ SkMatrix matrix;
+
+ matrix.setScale(SkScalarHalf(oval.width()), SkScalarHalf(oval.height()));
+ matrix.postTranslate(oval.centerX(), oval.centerY());
+
+ return SkConic::BuildUnitArc(start, stop, dir, &matrix, conics);
+}
+#endif
void SkPath::addRoundRect(const SkRect& rect, const SkScalar radii[],
Direction dir) {
@@ -1320,8 +1332,13 @@
return;
}
+ SkVector startV, stopV;
+ SkRotationDirection dir;
+ angles_to_unit_vectors(startAngle, sweepAngle, &startV, &stopV, &dir);
+
+#ifdef SK_SUPPORT_LEGACY_ARCTO_QUADS
SkPoint pts[kSkBuildQuadArcStorage];
- int count = build_arc_points(oval, startAngle, sweepAngle, pts);
+ int count = build_arc_points(oval, startV, stopV, dir, pts);
SkASSERT((count & 1) == 1);
this->incReserve(count);
@@ -1329,6 +1346,18 @@
for (int i = 1; i < count; i += 2) {
this->quadTo(pts[i], pts[i+1]);
}
+#else
+ SkConic conics[SkConic::kMaxConicsForArc];
+ int count = build_arc_conics(oval, startV, stopV, dir, conics);
+ if (count) {
+ this->incReserve(count * 2 + 1);
+ const SkPoint& pt = conics[0].fPts[0];
+ forceMoveTo ? this->moveTo(pt) : this->lineTo(pt);
+ for (int i = 0; i < count; ++i) {
+ this->conicTo(conics[i].fPts[1], conics[i].fPts[2], conics[i].fW);
+ }
+ }
+#endif
}
void SkPath::addArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle) {