60 lines
1.6 KiB
C++
60 lines
1.6 KiB
C++
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/*
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* Copyright 2017 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "SkSGTrimEffect.h"
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#include "SkCanvas.h"
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#include "SkDashPathEffect.h"
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#include "SkPathMeasure.h"
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namespace sksg {
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TrimEffect::TrimEffect(sk_sp<GeometryNode> child)
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: fChild(std::move(child)) {
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fChild->addInvalReceiver(this);
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}
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TrimEffect::~TrimEffect() {
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fChild->removeInvalReceiver(this);
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}
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// TODO
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// This is a quick hack to get something on the screen. What we really want here is to apply
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// the geometry transformation and cache the result on revalidation. Or an SkTrimPathEffect.
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void TrimEffect::onDraw(SkCanvas* canvas, const SkPaint& paint) const {
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SkASSERT(!paint.getPathEffect());
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const auto path = fChild->asPath();
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SkScalar pathLen = 0;
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SkPathMeasure measure(path, false);
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do {
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pathLen += measure.getLength();
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} while (measure.nextContour());
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const auto start = SkScalarPin(fStart , 0, 1) * pathLen,
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end = SkScalarPin(fEnd , 0, 1) * pathLen,
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offset = SkScalarPin(fOffset, 0, 1) * pathLen,
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len = SkTMax<SkScalar>(end - start, 0);
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const SkScalar dashes[4] = { 0, start, len, pathLen - end };
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SkPaint dashedPaint(paint);
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dashedPaint.setPathEffect(SkDashPathEffect::Make(dashes, 4, -offset));
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canvas->drawPath(path, dashedPaint);
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}
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SkPath TrimEffect::onAsPath() const {
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return fChild->asPath();
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}
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SkRect TrimEffect::onRevalidate(InvalidationController* ic, const SkMatrix& ctm) {
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SkASSERT(this->hasInval());
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return fChild->revalidate(ic, ctm);
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}
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} // namespace sksg
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