/*
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* Copyright 2018 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 "SkPathMeasure.h"
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#include "SkTrimPathEffect.h"
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#include "SkTrimPE.h"
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#include "SkReadBuffer.h"
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#include "SkWriteBuffer.h"
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namespace {
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class Segmentator : public SkNoncopyable {
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public:
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Segmentator(const SkPath& src, SkPath* dst)
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: fMeasure(src, false)
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, fDst(dst) {}
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void add(SkScalar start, SkScalar stop) {
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SkASSERT(start < stop);
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// TODO: we appear to skip zero-length contours.
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do {
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const auto nextOffset = fCurrentSegmentOffset + fMeasure.getLength();
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if (start < nextOffset) {
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fMeasure.getSegment(start - fCurrentSegmentOffset,
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stop - fCurrentSegmentOffset,
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fDst, true);
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if (stop < nextOffset)
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break;
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}
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fCurrentSegmentOffset = nextOffset;
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} while (fMeasure.nextContour());
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}
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private:
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SkPathMeasure fMeasure;
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SkPath* fDst;
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SkScalar fCurrentSegmentOffset = 0;
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using INHERITED = SkNoncopyable;
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};
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} // namespace
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SkTrimPE::SkTrimPE(SkScalar startT, SkScalar stopT, SkTrimPathEffect::Mode mode)
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: fStartT(startT), fStopT(stopT), fMode(mode) {}
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bool SkTrimPE::onFilterPath(SkPath* dst, const SkPath& src, SkStrokeRec* rec,
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const SkRect* cullRect) const {
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if (fStartT >= fStopT) {
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SkASSERT(fMode == SkTrimPathEffect::Mode::kNormal);
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return true;
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}
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// First pass: compute the total len.
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SkScalar len = 0;
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SkPathMeasure meas(src, false);
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do {
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len += meas.getLength();
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} while (meas.nextContour());
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const auto arcStart = len * fStartT,
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arcStop = len * fStopT;
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// Second pass: actually add segments.
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Segmentator segmentator(src, dst);
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if (fMode == SkTrimPathEffect::Mode::kNormal) {
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if (arcStart < arcStop) segmentator.add(arcStart, arcStop);
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} else {
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if (0 < arcStart) segmentator.add(0, arcStart);
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if (arcStop < len) segmentator.add(arcStop, len);
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}
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return true;
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}
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void SkTrimPE::flatten(SkWriteBuffer& buffer) const {
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buffer.writeScalar(fStartT);
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buffer.writeScalar(fStopT);
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buffer.writeUInt(static_cast<uint32_t>(fMode));
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}
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sk_sp<SkFlattenable> SkTrimPE::CreateProc(SkReadBuffer& buffer) {
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const auto start = buffer.readScalar(),
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stop = buffer.readScalar();
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const auto mode = buffer.readUInt();
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return SkTrimPathEffect::Make(start, stop,
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(mode & 1) ? SkTrimPathEffect::Mode::kInverted : SkTrimPathEffect::Mode::kNormal);
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}
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//////////////////////////////////////////////////////////////////////////////////////////////////
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sk_sp<SkPathEffect> SkTrimPathEffect::Make(SkScalar startT, SkScalar stopT, Mode mode) {
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if (!SkScalarsAreFinite(startT, stopT)) {
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return nullptr;
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}
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if (startT <= 0 && stopT >= 1 && mode == Mode::kNormal) {
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return nullptr;
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}
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startT = SkTPin(startT, 0.f, 1.f);
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stopT = SkTPin(stopT, 0.f, 1.f);
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if (startT >= stopT && mode == Mode::kInverted) {
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return nullptr;
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}
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return sk_sp<SkPathEffect>(new SkTrimPE(startT, stopT, mode));
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}
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