C++ SkAutoConicToQuads类代码示例

int GrPathUtils::worstCasePointCount(const SkPath& path, int* subpaths,
                                     SkScalar tol) {
    if (tol < gMinCurveTol) {
        tol = gMinCurveTol;
    }
    SkASSERT(tol > 0);

    int pointCount = 0;
    *subpaths = 1;

    bool first = true;

    SkPath::Iter iter(path, false);
    SkPath::Verb verb;

    SkPoint pts[4];
    while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {

        switch (verb) {
            case SkPath::kLine_Verb:
                pointCount += 1;
                break;
            case SkPath::kConic_Verb: {
                SkScalar weight = iter.conicWeight();
                SkAutoConicToQuads converter;
                const SkPoint* quadPts = converter.computeQuads(pts, weight, 0.25f);
                for (int i = 0; i < converter.countQuads(); ++i) {
                    pointCount += quadraticPointCount(quadPts + 2*i, tol);
                }
            }
            case SkPath::kQuad_Verb:
                pointCount += quadraticPointCount(pts, tol);
                break;
            case SkPath::kCubic_Verb:
                pointCount += cubicPointCount(pts, tol);
                break;
            case SkPath::kMove_Verb:
                pointCount += 1;
                if (!first) {
                    ++(*subpaths);
                }
                break;
            default:
                break;
        }
        first = false;
    }
    return pointCount;
}

void SkParsePath::ToSVGString(const SkPath& path, SkString* str) {
    SkDynamicMemoryWStream  stream;

    SkPath::Iter    iter(path, false);
    SkPoint         pts[4];

    for (;;) {
        switch (iter.next(pts, false)) {
            case SkPath::kConic_Verb: {
                const SkScalar tol = SK_Scalar1 / 1024; // how close to a quad
                SkAutoConicToQuads quadder;
                const SkPoint* quadPts = quadder.computeQuads(pts, iter.conicWeight(), tol);
                for (int i = 0; i < quadder.countQuads(); ++i) {
                    append_scalars(&stream, 'Q', &quadPts[i*2 + 1].fX, 4);
                }
            } break;
           case SkPath::kMove_Verb:
                append_scalars(&stream, 'M', &pts[0].fX, 2);
                break;
            case SkPath::kLine_Verb:
                append_scalars(&stream, 'L', &pts[1].fX, 2);
                break;
            case SkPath::kQuad_Verb:
                append_scalars(&stream, 'Q', &pts[1].fX, 4);
                break;
            case SkPath::kCubic_Verb:
                append_scalars(&stream, 'C', &pts[1].fX, 6);
                break;
            case SkPath::kClose_Verb:
                stream.write("Z", 1);
                break;
            case SkPath::kDone_Verb:
                str->resize(stream.getOffset());
                stream.copyTo(str->writable_str());
            return;
        }
    }
}

int SkOpEdgeBuilder::preFetch() {
    if (!fPath->isFinite()) {
        fUnparseable = true;
        return 0;
    }
    SkAutoConicToQuads quadder;
    const SkScalar quadderTol = SK_Scalar1 / 16;
    SkPath::RawIter iter(*fPath);
    SkPoint curveStart;
    SkPoint curve[4];
    SkPoint pts[4];
    SkPath::Verb verb;
    bool lastCurve = false;
    do {
        verb = iter.next(pts);
        switch (verb) {
            case SkPath::kMove_Verb:
                if (!fAllowOpenContours && lastCurve) {
                    closeContour(curve[0], curveStart);
                }
                fPathVerbs.push_back(verb);
                force_small_to_zero(&pts[0]);
                fPathPts.push_back(pts[0]);
                curveStart = curve[0] = pts[0];
                lastCurve = false;
                continue;
            case SkPath::kLine_Verb:
                force_small_to_zero(&pts[1]);
                if (SkDPoint::ApproximatelyEqual(curve[0], pts[1])) {
                    uint8_t lastVerb = fPathVerbs.back();
                    if (lastVerb != SkPath::kLine_Verb && lastVerb != SkPath::kMove_Verb) {
                        fPathPts.back() = pts[1];
                    }
                    continue;  // skip degenerate points
                }
                break;
            case SkPath::kQuad_Verb:
                force_small_to_zero(&pts[1]);
                force_small_to_zero(&pts[2]);
                curve[1] = pts[1];
                curve[2] = pts[2];
                verb = SkReduceOrder::Quad(curve, pts);
                if (verb == SkPath::kMove_Verb) {
                    continue;  // skip degenerate points
                }
                break;
            case SkPath::kConic_Verb: {
                    const SkPoint* quadPts = quadder.computeQuads(pts, iter.conicWeight(),
                            quadderTol);
                    const int nQuads = quadder.countQuads();
                    for (int i = 0; i < nQuads; ++i) {
                       fPathVerbs.push_back(SkPath::kQuad_Verb);
                    }
                    fPathPts.push_back_n(nQuads * 2, &quadPts[1]);
                    curve[0] = pts[2];
                    lastCurve = true;
                }
                continue;
            case SkPath::kCubic_Verb:
                force_small_to_zero(&pts[1]);
                force_small_to_zero(&pts[2]);
                force_small_to_zero(&pts[3]);
                curve[1] = pts[1];
                curve[2] = pts[2];
                curve[3] = pts[3];
                verb = SkReduceOrder::Cubic(curve, pts);
                if (verb == SkPath::kMove_Verb) {
                    continue;  // skip degenerate points
                }
                break;
            case SkPath::kClose_Verb:
                closeContour(curve[0], curveStart);
                lastCurve = false;
                continue;
            case SkPath::kDone_Verb:
                continue;
        }
        fPathVerbs.push_back(verb);
        int ptCount = SkPathOpsVerbToPoints(verb);
        fPathPts.push_back_n(ptCount, &pts[1]);
        curve[0] = pts[ptCount];
        lastCurve = true;
    } while (verb != SkPath::kDone_Verb);
    if (!fAllowOpenContours && lastCurve) {
        closeContour(curve[0], curveStart);
    }
    fPathVerbs.push_back(SkPath::kDone_Verb);
    return fPathVerbs.count() - 1;
}

void SkStroke::strokePath(const SkPath& src, SkPath* dst) const {
    SkASSERT(&src != NULL && dst != NULL);

    SkScalar radius = SkScalarHalf(fWidth);

    AutoTmpPath tmp(src, &dst);

    if (radius <= 0) {
        return;
    }

    // If src is really a rect, call our specialty strokeRect() method
    {
        bool isClosed;
        SkPath::Direction dir;
        if (src.isRect(&isClosed, &dir) && isClosed) {
            this->strokeRect(src.getBounds(), dst, dir);
            // our answer should preserve the inverseness of the src
            if (src.isInverseFillType()) {
                SkASSERT(!dst->isInverseFillType());
                dst->toggleInverseFillType();
            }
            return;
        }
    }

    SkAutoConicToQuads converter;
    const SkScalar conicTol = SK_Scalar1 / 4;

    SkPathStroker   stroker(src, radius, fMiterLimit, this->getCap(),
                            this->getJoin());
    SkPath::Iter    iter(src, false);
    SkPath::Verb    lastSegment = SkPath::kMove_Verb;

    for (;;) {
        SkPoint  pts[4];
        switch (iter.next(pts, false)) {
            case SkPath::kMove_Verb:
                stroker.moveTo(pts[0]);
                break;
            case SkPath::kLine_Verb:
                stroker.lineTo(pts[1]);
                lastSegment = SkPath::kLine_Verb;
                break;
            case SkPath::kQuad_Verb:
                stroker.quadTo(pts[1], pts[2]);
                lastSegment = SkPath::kQuad_Verb;
                break;
            case SkPath::kConic_Verb: {
                // todo: if we had maxcurvature for conics, perhaps we should
                // natively extrude the conic instead of converting to quads.
                const SkPoint* quadPts =
                    converter.computeQuads(pts, iter.conicWeight(), conicTol);
                for (int i = 0; i < converter.countQuads(); ++i) {
                    stroker.quadTo(quadPts[1], quadPts[2]);
                    quadPts += 2;
                }
                lastSegment = SkPath::kQuad_Verb;
            } break;
            case SkPath::kCubic_Verb:
                stroker.cubicTo(pts[1], pts[2], pts[3]);
                lastSegment = SkPath::kCubic_Verb;
                break;
            case SkPath::kClose_Verb:
                stroker.close(lastSegment == SkPath::kLine_Verb);
                break;
            case SkPath::kDone_Verb:
                goto DONE;
        }
    }
DONE:
    stroker.done(dst, lastSegment == SkPath::kLine_Verb);

    if (fDoFill) {
        if (src.cheapIsDirection(SkPath::kCCW_Direction)) {
            dst->reverseAddPath(src);
        } else {
            dst->addPath(src);
        }
    } else {
        //  Seems like we can assume that a 2-point src would always result in
        //  a convex stroke, but testing has proved otherwise.
        //  TODO: fix the stroker to make this assumption true (without making
        //  it slower that the work that will be done in computeConvexity())
#if 0
        // this test results in a non-convex stroke :(
        static void test(SkCanvas* canvas) {
            SkPoint pts[] = { 146.333328,  192.333328, 300.333344, 293.333344 };
            SkPaint paint;
            paint.setStrokeWidth(7);
            paint.setStrokeCap(SkPaint::kRound_Cap);
            canvas->drawLine(pts[0].fX, pts[0].fY, pts[1].fX, pts[1].fY, paint);
        }
#endif
#if 0
        if (2 == src.countPoints()) {
            dst->setIsConvex(true);
        }
#endif
    }

    bool createGeom(void* vertices,
                    size_t vertexOffset,
                    void* indices,
                    size_t indexOffset,
                    int* vertexCnt,
                    int* indexCnt,
                    const SkPath& path,
                    SkScalar srcSpaceTol,
                    bool isIndexed) const {
        {
            SkScalar srcSpaceTolSqd = SkScalarMul(srcSpaceTol, srcSpaceTol);

            uint16_t indexOffsetU16 = (uint16_t)indexOffset;
            uint16_t vertexOffsetU16 = (uint16_t)vertexOffset;

            uint16_t* idxBase = reinterpret_cast<uint16_t*>(indices) + indexOffsetU16;
            uint16_t* idx = idxBase;
            uint16_t subpathIdxStart = vertexOffsetU16;

            SkPoint* base = reinterpret_cast<SkPoint*>(vertices) + vertexOffset;
            SkPoint* vert = base;

            SkPoint pts[4];

            bool first = true;
            int subpath = 0;

            SkPath::Iter iter(path, false);

            bool done = false;
            while (!done) {
                SkPath::Verb verb = iter.next(pts);
                switch (verb) {
                    case SkPath::kMove_Verb:
                        if (!first) {
                            uint16_t currIdx = (uint16_t) (vert - base) + vertexOffsetU16;
                            subpathIdxStart = currIdx;
                            ++subpath;
                        }
                        *vert = pts[0];
                        vert++;
                        break;
                    case SkPath::kLine_Verb:
                        if (isIndexed) {
                            uint16_t prevIdx = (uint16_t)(vert - base) - 1 + vertexOffsetU16;
                            append_countour_edge_indices(this->isHairline(), subpathIdxStart,
                                                         prevIdx, &idx);
                        }
                        *(vert++) = pts[1];
                        break;
                    case SkPath::kConic_Verb: {
                        SkScalar weight = iter.conicWeight();
                        SkAutoConicToQuads converter;
                        // Converting in src-space, hance the finer tolerance (0.25)
                        // TODO: find a way to do this in dev-space so the tolerance means something
                        const SkPoint* quadPts = converter.computeQuads(pts, weight, 0.25f);
                        for (int i = 0; i < converter.countQuads(); ++i) {
                            add_quad(&vert, base, quadPts + i*2, srcSpaceTolSqd, srcSpaceTol,
                                     isIndexed, this->isHairline(), subpathIdxStart,
                                     (int)vertexOffset, &idx);
                        }
                        break;
                    }
                    case SkPath::kQuad_Verb:
                        add_quad(&vert, base, pts, srcSpaceTolSqd, srcSpaceTol, isIndexed,
                                 this->isHairline(), subpathIdxStart, (int)vertexOffset, &idx);
                        break;
                    case SkPath::kCubic_Verb: {
                        // first pt of cubic is the pt we ended on in previous step
                        uint16_t firstCPtIdx = (uint16_t)(vert - base) - 1 + vertexOffsetU16;
                        uint16_t numPts = (uint16_t) GrPathUtils::generateCubicPoints(
                                        pts[0], pts[1], pts[2], pts[3],
                                        srcSpaceTolSqd, &vert,
                                        GrPathUtils::cubicPointCount(pts, srcSpaceTol));
                        if (isIndexed) {
                            for (uint16_t i = 0; i < numPts; ++i) {
                                append_countour_edge_indices(this->isHairline(), subpathIdxStart,
                                                             firstCPtIdx + i, &idx);
                            }
                        }
                        break;
                    }
                    case SkPath::kClose_Verb:
                        break;
                    case SkPath::kDone_Verb:
                        done = true;
                }
                first = false;
            }

            *vertexCnt = static_cast<int>(vert - base);
            *indexCnt = static_cast<int>(idx - idxBase);

        }
        return true;
    }

static bool get_geometry(const SkPath& path, const SkMatrix& m, PLSVertices& triVertices, 
                         PLSVertices& quadVertices, GrResourceProvider* resourceProvider,
                         SkRect bounds) {
    SkScalar screenSpaceTol = GrPathUtils::kDefaultTolerance;
    SkScalar tol = GrPathUtils::scaleToleranceToSrc(screenSpaceTol, m, bounds);
    int contourCnt;
    int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tol);
    if (maxPts <= 0) {
        return 0;
    }
    SkPath linesOnlyPath;
    linesOnlyPath.setFillType(path.getFillType());
    SkSTArray<15, SkPoint, true> quadPoints;
    SkPath::Iter iter(path, true);
    bool done = false;
    while (!done) {
        SkPoint pts[4];
        SkPath::Verb verb = iter.next(pts);
        switch (verb) {
            case SkPath::kMove_Verb:
                SkASSERT(quadPoints.count() % 3 == 0);
                for (int i = 0; i < quadPoints.count(); i += 3) {
                    add_quad(&quadPoints[i], quadVertices);
                }
                quadPoints.reset();
                m.mapPoints(&pts[0], 1);
                linesOnlyPath.moveTo(pts[0]);
                break;
            case SkPath::kLine_Verb:
                m.mapPoints(&pts[1], 1);
                linesOnlyPath.lineTo(pts[1]);
                break;
            case SkPath::kQuad_Verb:
                m.mapPoints(pts, 3);
                linesOnlyPath.lineTo(pts[2]);
                quadPoints.push_back(pts[0]);
                quadPoints.push_back(pts[1]);
                quadPoints.push_back(pts[2]);
                break;
            case SkPath::kCubic_Verb: {
                m.mapPoints(pts, 4);
                SkSTArray<15, SkPoint, true> quads;
                GrPathUtils::convertCubicToQuads(pts, kCubicTolerance, &quads);
                int count = quads.count();
                for (int q = 0; q < count; q += 3) {
                    linesOnlyPath.lineTo(quads[q + 2]);
                    quadPoints.push_back(quads[q]);
                    quadPoints.push_back(quads[q + 1]);
                    quadPoints.push_back(quads[q + 2]);
                }
                break;
            }
            case SkPath::kConic_Verb: {
                m.mapPoints(pts, 3);
                SkScalar weight = iter.conicWeight();
                SkAutoConicToQuads converter;
                const SkPoint* quads = converter.computeQuads(pts, weight, kConicTolerance);
                int count = converter.countQuads();
                for (int i = 0; i < count; ++i) {
                    linesOnlyPath.lineTo(quads[2 * i + 2]);
                    quadPoints.push_back(quads[2 * i]);
                    quadPoints.push_back(quads[2 * i + 1]);
                    quadPoints.push_back(quads[2 * i + 2]);
                }
                break;
            }
            case SkPath::kClose_Verb:
                linesOnlyPath.close();
                break;
            case SkPath::kDone_Verb:
                done = true;
                break;
            default: SkASSERT(false);
        }
    }
    SkASSERT(quadPoints.count() % 3 == 0);
    for (int i = 0; i < quadPoints.count(); i += 3) {
        add_quad(&quadPoints[i], quadVertices);
    }

    static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
    GrUniqueKey key;
    GrUniqueKey::Builder builder(&key, kDomain, 2);
    builder[0] = path.getGenerationID();
    builder[1] = path.getFillType();
    builder.finish();
    GrTessellator::WindingVertex* windingVertices;
    int triVertexCount = GrTessellator::PathToVertices(linesOnlyPath, 0, bounds, &windingVertices);
    if (triVertexCount > 0) {
        for (int i = 0; i < triVertexCount; i += 3) {
            SkPoint p1 = windingVertices[i].fPos;
            SkPoint p2 = windingVertices[i + 1].fPos;
            SkPoint p3 = windingVertices[i + 2].fPos;
            int winding = windingVertices[i].fWinding;
            SkASSERT(windingVertices[i + 1].fWinding == winding);
            SkASSERT(windingVertices[i + 2].fWinding == winding);
            SkScalar cross = (p2 - p1).cross(p3 - p1);
            SkPoint bloated[3] = { p1, p2, p3 };
            if (cross < 0.0f) {
                SkTSwap(p1, p3);
//.........这里部分代码省略.........

static bool get_segments(const SkPath& path,
                         const SkMatrix& m,
                         SegmentArray* segments,
                         SkPoint* fanPt,
                         int* vCount,
                         int* iCount) {
    SkPath::Iter iter(path, true);
    // This renderer over-emphasizes very thin path regions. We use the distance
    // to the path from the sample to compute coverage. Every pixel intersected
    // by the path will be hit and the maximum distance is sqrt(2)/2. We don't
    // notice that the sample may be close to a very thin area of the path and
    // thus should be very light. This is particularly egregious for degenerate
    // line paths. We detect paths that are very close to a line (zero area) and
    // draw nothing.
    DegenerateTestData degenerateData;
    SkPath::Direction dir;
    // get_direction can fail for some degenerate paths.
    if (!get_direction(path, m, &dir)) {
        return false;
    }

    for (;;) {
        SkPoint pts[4];
        SkPath::Verb verb = iter.next(pts);
        switch (verb) {
            case SkPath::kMove_Verb:
                m.mapPoints(pts, 1);
                update_degenerate_test(&degenerateData, pts[0]);
                break;
            case SkPath::kLine_Verb: {
                m.mapPoints(&pts[1], 1);
                update_degenerate_test(&degenerateData, pts[1]);
                add_line_to_segment(pts[1], segments);
                break;
            }
            case SkPath::kQuad_Verb:
                m.mapPoints(pts, 3);
                update_degenerate_test(&degenerateData, pts[1]);
                update_degenerate_test(&degenerateData, pts[2]);
                add_quad_segment(pts, segments);
                break;
            case SkPath::kConic_Verb: {
                m.mapPoints(pts, 3);
                SkScalar weight = iter.conicWeight();
                SkAutoConicToQuads converter;
                const SkPoint* quadPts = converter.computeQuads(pts, weight, 0.5f);
                for (int i = 0; i < converter.countQuads(); ++i) {
                    update_degenerate_test(&degenerateData, quadPts[2*i + 1]);
                    update_degenerate_test(&degenerateData, quadPts[2*i + 2]);
                    add_quad_segment(quadPts + 2*i, segments);
                }
                break;
            }
            case SkPath::kCubic_Verb: {
                m.mapPoints(pts, 4);
                update_degenerate_test(&degenerateData, pts[1]);
                update_degenerate_test(&degenerateData, pts[2]);
                update_degenerate_test(&degenerateData, pts[3]);
                add_cubic_segments(pts, dir, segments);
                break;
            };
            case SkPath::kDone_Verb:
                if (degenerateData.isDegenerate()) {
                    return false;
                } else {
                    compute_vectors(segments, fanPt, dir, vCount, iCount);
                    return true;
                }
            default:
                break;
        }
    }
}