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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkSGTrimEffect.h"
#include "SkCanvas.h"
#include "SkDashPathEffect.h"
#include "SkPathMeasure.h"
#include "SkStrokeRec.h"
namespace sksg {
TrimEffect::TrimEffect(sk_sp<GeometryNode> child)
: fChild(std::move(child)) {
this->observeInval(fChild);
}
TrimEffect::~TrimEffect() {
this->unobserveInval(fChild);
}
void TrimEffect::onClip(SkCanvas* canvas, bool antiAlias) const {
canvas->clipPath(fTrimmedPath, SkClipOp::kIntersect, antiAlias);
}
void TrimEffect::onDraw(SkCanvas* canvas, const SkPaint& paint) const {
SkASSERT(!paint.getPathEffect());
canvas->drawPath(fTrimmedPath, paint);
}
SkPath TrimEffect::onAsPath() const {
return fTrimmedPath;
}
SkRect TrimEffect::onRevalidate(InvalidationController* ic, const SkMatrix& ctm) {
SkASSERT(this->hasInval());
const auto childbounds = fChild->revalidate(ic, ctm);
const auto path = fChild->asPath();
SkScalar pathLen = 0;
SkPathMeasure measure(path, false);
do {
pathLen += measure.getLength();
} while (measure.nextContour());
const auto start = pathLen * fStart,
end = pathLen * fEnd,
offset = pathLen * fOffset,
len = end - start;
fTrimmedPath.reset();
if (len > 0) {
// If the trim is positioned exactly at the beginning of the path, we don't expect any
// visible wrap-around. But due to limited precision / accumulated error, the dash effect
// may sometimes start one extra dash at the very end (a flickering dot during animation).
// To avoid this, we bump the dash len by |epsilon|.
const SkScalar dashes[] = { len, pathLen + SK_ScalarNearlyZero - len };
auto dashEffect = SkDashPathEffect::Make(dashes,
SK_ARRAY_COUNT(dashes),
-start - offset);
if (dashEffect) {
SkStrokeRec rec(SkStrokeRec::kHairline_InitStyle);
SkAssertResult(dashEffect->filterPath(&fTrimmedPath, path, &rec, &childbounds));
}
}
return fTrimmedPath.computeTightBounds();
}
} // namespace sksg
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