special-case dashing a single line-segment. We can go much faster since we
can apply the stroke as we go, eliminating the generic stroker.
Review URL: https://codereview.appspot.com/6250070
git-svn-id: http://skia.googlecode.com/svn/trunk@4062 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkDashPathEffect.cpp b/src/effects/SkDashPathEffect.cpp
index 13c19af..e6f6afa 100644
--- a/src/effects/SkDashPathEffect.cpp
+++ b/src/effects/SkDashPathEffect.cpp
@@ -80,6 +80,73 @@
sk_free(fIntervals);
}
+class SpecialLineRec {
+public:
+ bool init(const SkPath& src, SkPath* dst, SkStrokeRec* rec,
+ SkScalar pathLength,
+ int intervalCount, SkScalar intervalLength) {
+ if (rec->isHairlineStyle() || !src.isLine(fPts)) {
+ return false;
+ }
+
+ // can relax this in the future, if we handle square and round caps
+ if (SkPaint::kButt_Cap != rec->getCap()) {
+ return false;
+ }
+
+ fTangent = fPts[1] - fPts[0];
+ if (fTangent.isZero()) {
+ return false;
+ }
+
+ fPathLength = pathLength;
+ fTangent.scale(SkScalarInvert(pathLength));
+ fTangent.rotateCCW(&fNormal);
+ fNormal.scale(SkScalarHalf(rec->getWidth()));
+
+ // now estimate how many quads will be added to the path
+ // resulting segments = pathLen * intervalCount / intervalLen
+ // resulting points = 4 * segments
+
+ SkScalar ptCount = SkScalarMulDiv(pathLength,
+ SkIntToScalar(intervalCount),
+ intervalLength);
+ int n = SkScalarCeilToInt(ptCount) << 2;
+ dst->incReserve(n);
+
+ // we will take care of the stroking
+ rec->setFillStyle();
+ return true;
+ }
+
+ void addSegment(SkScalar d0, SkScalar d1, SkPath* path) const {
+ SkASSERT(d0 < fPathLength);
+ // clamp the segment to our length
+ if (d1 > fPathLength) {
+ d1 = fPathLength;
+ }
+
+ SkScalar x0 = fPts[0].fX + SkScalarMul(fTangent.fX, d0);
+ SkScalar x1 = fPts[0].fX + SkScalarMul(fTangent.fX, d1);
+ SkScalar y0 = fPts[0].fY + SkScalarMul(fTangent.fY, d0);
+ SkScalar y1 = fPts[0].fY + SkScalarMul(fTangent.fY, d1);
+
+ SkPoint pts[4];
+ pts[0].set(x0 + fNormal.fX, y0 + fNormal.fY); // moveTo
+ pts[1].set(x1 + fNormal.fX, y1 + fNormal.fY); // lineTo
+ pts[2].set(x1 - fNormal.fX, y1 - fNormal.fY); // lineTo
+ pts[3].set(x0 - fNormal.fX, y0 - fNormal.fY); // lineTo
+
+ path->addPoly(pts, SK_ARRAY_COUNT(pts), false);
+ }
+
+private:
+ SkPoint fPts[2];
+ SkVector fTangent;
+ SkVector fNormal;
+ SkScalar fPathLength;
+};
+
bool SkDashPathEffect::filterPath(SkPath* dst, const SkPath& src,
SkStrokeRec* rec) {
// we do nothing if the src wants to be filled, or if our dashlength is 0
@@ -90,13 +157,17 @@
SkPathMeasure meas(src, false);
const SkScalar* intervals = fIntervals;
+ SpecialLineRec lineRec;
+ const bool specialLine = lineRec.init(src, dst, rec, meas.getLength(),
+ fCount >> 1, fIntervalLength);
+
do {
bool skipFirstSegment = meas.isClosed();
bool addedSegment = false;
SkScalar length = meas.getLength();
int index = fInitialDashIndex;
SkScalar scale = SK_Scalar1;
-
+
if (fScaleToFit) {
if (fIntervalLength >= length) {
scale = SkScalarDiv(length, fIntervalLength);
@@ -115,7 +186,12 @@
addedSegment = false;
if (is_even(index) && dlen > 0 && !skipFirstSegment) {
addedSegment = true;
- meas.getSegment(distance, distance + dlen, dst, true);
+
+ if (specialLine) {
+ lineRec.addSegment(distance, distance + dlen, dst);
+ } else {
+ meas.getSegment(distance, distance + dlen, dst, true);
+ }
}
distance += dlen;
@@ -139,6 +215,7 @@
meas.getSegment(0, SkScalarMul(fInitialDashLength, scale), dst, !addedSegment);
}
} while (meas.nextContour());
+
return true;
}