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#include "qtriangulatingstroker_p.h"

#include <qmath.h>

QT_BEGIN_NAMESPACE

#define CURVE_FLATNESS Q_PI / 8

void QTriangulatingStroker::endCapOrJoinClosed(const qreal *start, const qreal *cur,

                                               bool implicitClose, bool endsAtStart)

{

    if (endsAtStart) {

        join(start + 2);

    } else if (implicitClose) {

        join(start);

        lineTo(start);

        join(start+2);

    } else {

        endCap(cur);

    }

    int count = m_vertices.size();

    // Copy the (x, y) values because QDataBuffer::add(const float& t)

    // may resize the buffer, which will leave t pointing at the

    // previous buffer's memory region if we don't copy first.

    float x = m_vertices.at(count-2);

    float y = m_vertices.at(count-1);

    m_vertices.add(x);

    m_vertices.add(y);

}

void QTriangulatingStroker::process(const QVectorPath &path, const QPen &pen)

{

    const qreal *pts = path.points();

    const QPainterPath::ElementType *types = path.elements();

    int count = path.elementCount();

    if (count < 2)

        return;

    float realWidth = qpen_widthf(pen);

    if (realWidth == 0)

        realWidth = 1;

    m_width = realWidth / 2;

    bool cosmetic = pen.isCosmetic();

    if (cosmetic) {

        m_width = m_width * m_inv_scale;

    }

    m_join_style = qpen_joinStyle(pen);

    m_cap_style = qpen_capStyle(pen);

    m_vertices.reset();

    m_miter_limit = pen.miterLimit() * qpen_widthf(pen);

    // The curvyness is based on the notion that I originally wanted

    // roughly one line segment pr 4 pixels. This may seem little, but

    // because we sample at constantly incrementing B(t) E [0<t<1], we

    // will get longer segments where the curvature is small and smaller

    // segments when the curvature is high.

    //

    // To get a rough idea of the length of each curve, I pretend that

    // the curve is a 90 degree arc, whose radius is

    // qMax(curveBounds.width, curveBounds.height). Based on this

    // logic we can estimate the length of the outline edges based on

    // the radius + a pen width and adjusting for scale factors

    // depending on if the pen is cosmetic or not.

    //

    // The curvyness value of PI/14 was based on,

    // arcLength=2*PI*r/4=PI/2 and splitting length into somewhere

    // between 3 and 8 where 5 seemed to be give pretty good results

    // hence: Q_PI/14. Lower divisors will give more detail at the

    // direct cost of performance.

    // simplfy pens that are thin in device size (2px wide or less)

    if (realWidth < 2.5 && (cosmetic || m_inv_scale == 1)) {

        if (m_cap_style == Qt::RoundCap)

            m_cap_style = Qt::SquareCap;

        if (m_join_style == Qt::RoundJoin)

            m_join_style = Qt::MiterJoin;

        m_curvyness_add = 0.5;

        m_curvyness_mul = CURVE_FLATNESS / m_inv_scale;

        m_roundness = 1;

    } else if (cosmetic) {

        m_curvyness_add = realWidth / 2;

        m_curvyness_mul = CURVE_FLATNESS;

        m_roundness = qMax<int>(4, realWidth * CURVE_FLATNESS);

    } else {

        m_curvyness_add = m_width;

        m_curvyness_mul = CURVE_FLATNESS / m_inv_scale;

        m_roundness = qMax<int>(4, realWidth * m_curvyness_mul);

    }

    // Over this level of segmentation, there doesn't seem to be any

    // benefit, even for huge penWidth

    if (m_roundness > 24)

        m_roundness = 24;

    m_sin_theta = qFastSin(Q_PI / m_roundness);

    m_cos_theta = qFastCos(Q_PI / m_roundness);

    const qreal *endPts = pts + (count<<1);

    Qt::PenCapStyle cap = m_cap_style;

    if (!types) {

        startPts = pts;

        bool endsAtStart = startPts[0] == *(endPts-2) && startPts[1] == *(endPts-1);

        if (endsAtStart || path.hasImplicitClose())

            m_cap_style = Qt::FlatCap;

        moveTo(pts);

        m_cap_style = cap;

        pts += 2;

        lineTo(pts);

        pts += 2;

        while (pts < endPts) {

            pts += 2;

        }

        endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart);

    } else {

        while (pts < endPts) {

            switch (*types) {

            case QPainterPath::MoveToElement: {

                if (pts != path.points())

                    endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart);

                startPts = pts;

                int end = (endPts - pts) / 2;

                int i = 2; // Start looking to ahead since we never have two moveto's in a row

                while (i<end && types[i] != QPainterPath::MoveToElement) {

                    ++i;

                }

                endsAtStart = startPts[0] == pts[i*2 - 2] && startPts[1] == pts[i*2 - 1];

                if (endsAtStart || path.hasImplicitClose())

                    m_cap_style = Qt::FlatCap;

                moveTo(pts);

                m_cap_style = cap;

                pts+=2;

                ++types;

                break; }

            case QPainterPath::LineToElement:

                if (*(types - 1) != QPainterPath::MoveToElement)

                    join(pts);

                lineTo(pts);

                pts+=2;

                ++types;

                break;

            case QPainterPath::CurveToElement:

                if (*(types - 1) != QPainterPath::MoveToElement)

                    join(pts);

                cubicTo(pts);

                pts+=6;

                types+=3;

                break;

            default:

                Q_ASSERT(false);

                break;

            }

        }

        endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart);

    }

}

void QTriangulatingStroker::moveTo(const qreal *pts)

{

    m_cx = pts[0];

    m_cy = pts[1];

    float x2 = pts[2];

    float y2 = pts[3];

    normalVector(m_cx, m_cy, x2, y2, &m_nvx, &m_nvy);

    // To acheive jumps we insert zero-area tringles. This is done by

    // adding two identical points in both the end of previous strip

    // and beginning of next strip

    bool invisibleJump = m_vertices.size();

    switch (m_cap_style) {

    case Qt::FlatCap:

        if (invisibleJump) {

            m_vertices.add(m_cx + m_nvx);

            m_vertices.add(m_cy + m_nvy);

        }

        break;

    case Qt::SquareCap: {

        float sx = m_cx - m_nvy;

        float sy = m_cy + m_nvx;

        if (invisibleJump) {

            m_vertices.add(sx + m_nvx);

            m_vertices.add(sy + m_nvy);

        }

        emitLineSegment(sx, sy, m_nvx, m_nvy);

        break; }

    case Qt::RoundCap: {

        QVarLengthArray<float> points;

        arcPoints(m_cx, m_cy, m_cx + m_nvx, m_cy + m_nvy, m_cx - m_nvx, m_cy - m_nvy, points);

        m_vertices.resize(m_vertices.size() + points.size() + 2 * int(invisibleJump));

        int count = m_vertices.size();

        int front = 0;

        int end = points.size() / 2;

        while (front != end) {

            m_vertices.at(--count) = points[2 * end - 1];

            m_vertices.at(--count) = points[2 * end - 2];

            --end;

            if (front == end)

                break;

            m_vertices.at(--count) = points[2 * front + 1];

            m_vertices.at(--count) = points[2 * front + 0];

            ++front;

        }

        if (invisibleJump) {

            m_vertices.at(count - 1) = m_vertices.at(count + 1);

            m_vertices.at(count - 2) = m_vertices.at(count + 0);

        }

        break; }

    default: break; // ssssh gcc...

    }

    emitLineSegment(m_cx, m_cy, m_nvx, m_nvy);

}

void QTriangulatingStroker::cubicTo(const qreal *pts)

{

    const QPointF *p = (const QPointF *) pts;

    QBezier bezier = QBezier::fromPoints(*(p - 1), p[0], p[1], p[2]);

    QRectF bounds = bezier.bounds();

    float rad = qMax(bounds.width(), bounds.height());

    int threshold = qMin<float>(64, (rad + m_curvyness_add) * m_curvyness_mul);

    if (threshold < 4)

        threshold = 4;

    qreal threshold_minus_1 = threshold - 1;

    float vx, vy;

    float cx = m_cx, cy = m_cy;

    float x, y;

    for (int i=1; i<threshold; ++i) {

        qreal t = qreal(i) / threshold_minus_1;

        QPointF p = bezier.pointAt(t);

        x = p.x();

        y = p.y();

        normalVector(cx, cy, x, y, &vx, &vy);

        emitLineSegment(x, y, vx, vy);

        cx = x;

        cy = y;

    }

    m_cx = cx;

    m_cy = cy;

    m_nvx = vx;

    m_nvy = vy;

}

void QTriangulatingStroker::join(const qreal *pts)

{

    // Creates a join to the next segment (m_cx, m_cy) -> (pts[0], pts[1])

    normalVector(m_cx, m_cy, pts[0], pts[1], &m_nvx, &m_nvy);

    switch (m_join_style) {

    case Qt::BevelJoin:

        break;

    case Qt::SvgMiterJoin:

    case Qt::MiterJoin: {

        // Find out on which side the join should be.

        int count = m_vertices.size();

        float prevNvx = m_vertices.at(count - 2) - m_cx;

        float prevNvy = m_vertices.at(count - 1) - m_cy;

        float xprod = prevNvx * m_nvy - prevNvy * m_nvx;

        float px, py, qx, qy;

        // If the segments are parallel, use bevel join.

        if (qFuzzyIsNull(xprod))

            break;

        // Find the corners of the previous and next segment to join.

        if (xprod < 0) {

            px = m_vertices.at(count - 2);

            py = m_vertices.at(count - 1);

            qx = m_cx - m_nvx;

            qy = m_cy - m_nvy;

        } else {

            px = m_vertices.at(count - 4);

            py = m_vertices.at(count - 3);

            qx = m_cx + m_nvx;

            qy = m_cy + m_nvy;

        }

        // Find intersection point.

        float pu = px * prevNvx + py * prevNvy;

        float qv = qx * m_nvx + qy * m_nvy;

        float ix = (m_nvy * pu - prevNvy * qv) / xprod;

        float iy = (prevNvx * qv - m_nvx * pu) / xprod;

        // Check that the distance to the intersection point is less than the miter limit.

        if ((ix - px) * (ix - px) + (iy - py) * (iy - py) <= m_miter_limit * m_miter_limit) {

            m_vertices.add(ix);

            m_vertices.add(iy);

            m_vertices.add(ix);

            m_vertices.add(iy);

        }

        // else

        // Do a plain bevel join if the miter limit is exceeded or if

        // the lines are parallel. This is not what the raster

        // engine's stroker does, but it is both faster and similar to

        // what some other graphics API's do.

        break; }

    case Qt::RoundJoin: {

        QVarLengthArray<float> points;

        int count = m_vertices.size();

        float prevNvx = m_vertices.at(count - 2) - m_cx;

        float prevNvy = m_vertices.at(count - 1) - m_cy;

        if (m_nvx * prevNvy - m_nvy * prevNvx < 0) {

            arcPoints(0, 0, m_nvx, m_nvy, -prevNvx, -prevNvy, points);

            for (int i = points.size() / 2; i > 0; --i)

                emitLineSegment(m_cx, m_cy, points[2 * i - 2], points[2 * i - 1]);

        } else {

            arcPoints(0, 0, -prevNvx, -prevNvy, m_nvx, m_nvy, points);

            for (int i = 0; i < points.size() / 2; ++i)

                emitLineSegment(m_cx, m_cy, points[2 * i + 0], points[2 * i + 1]);

        }

        break; }

    default: break; // gcc warn--

    }

    emitLineSegment(m_cx, m_cy, m_nvx, m_nvy);

}

void QTriangulatingStroker::endCap(const qreal *)

{

    switch (m_cap_style) {

    case Qt::FlatCap:

        break;

    case Qt::SquareCap:

        emitLineSegment(m_cx + m_nvy, m_cy - m_nvx, m_nvx, m_nvy);

        break;

    case Qt::RoundCap: {

        QVarLengthArray<float> points;

        int count = m_vertices.size();

        arcPoints(m_cx, m_cy, m_vertices.at(count - 2), m_vertices.at(count - 1), m_vertices.at(count - 4), m_vertices.at(count - 3), points);

        int front = 0;

        int end = points.size() / 2;

        while (front != end) {

            m_vertices.add(points[2 * end - 2]);

            m_vertices.add(points[2 * end - 1]);

            --end;

            if (front == end)

                break;

            m_vertices.add(points[2 * front + 0]);

            m_vertices.add(points[2 * front + 1]);

            ++front;

        }

        break; }

    default: break; // to shut gcc up...

    }

}

void QTriangulatingStroker::arcPoints(float cx, float cy, float fromX, float fromY, float toX, float toY, QVarLengthArray<float> &points)

{

    float dx1 = fromX - cx;

    float dy1 = fromY - cy;

    float dx2 = toX - cx;

    float dy2 = toY - cy;

    // while more than 180 degrees left:

    while (dx1 * dy2 - dx2 * dy1 < 0) {

        float tmpx = dx1 * m_cos_theta - dy1 * m_sin_theta;

        float tmpy = dx1 * m_sin_theta + dy1 * m_cos_theta;

        dx1 = tmpx;

        dy1 = tmpy;

        points.append(cx + dx1);

        points.append(cy + dy1);

    }

    // while more than 90 degrees left:

    while (dx1 * dx2 + dy1 * dy2 < 0) {

        float tmpx = dx1 * m_cos_theta - dy1 * m_sin_theta;

        float tmpy = dx1 * m_sin_theta + dy1 * m_cos_theta;

        dx1 = tmpx;

        dy1 = tmpy;

        points.append(cx + dx1);

        points.append(cy + dy1);

    }

    // while more than 0 degrees left:

    while (dx1 * dy2 - dx2 * dy1 > 0) {

        float tmpx = dx1 * m_cos_theta - dy1 * m_sin_theta;

        float tmpy = dx1 * m_sin_theta + dy1 * m_cos_theta;

        dx1 = tmpx;

        dy1 = tmpy;

        points.append(cx + dx1);

        points.append(cy + dy1);

    }

    // remove last point which was rotated beyond [toX, toY].

    if (!points.isEmpty())

        points.resize(points.size() - 2);

}

static void qdashprocessor_moveTo(qreal x, qreal y, void *data)

{

    ((QDashedStrokeProcessor *) data)->addElement(QPainterPath::MoveToElement, x, y);

}

static void qdashprocessor_lineTo(qreal x, qreal y, void *data)

{

    ((QDashedStrokeProcessor *) data)->addElement(QPainterPath::LineToElement, x, y);

}

static void qdashprocessor_cubicTo(qreal, qreal, qreal, qreal, qreal, qreal, void *)

{

    Q_ASSERT(0); // The dasher should not produce curves...

}

QDashedStrokeProcessor::QDashedStrokeProcessor()

    : m_dash_stroker(0), m_inv_scale(1)

{

    m_dash_stroker.setMoveToHook(qdashprocessor_moveTo);

    m_dash_stroker.setLineToHook(qdashprocessor_lineTo);

    m_dash_stroker.setCubicToHook(qdashprocessor_cubicTo);

}

void QDashedStrokeProcessor::process(const QVectorPath &path, const QPen &pen)

{

    const qreal *pts = path.points();

    const QPainterPath::ElementType *types = path.elements();

    int count = path.elementCount();

    m_points.reset();

    m_types.reset();

    qreal width = qpen_widthf(pen);

    if (width == 0)

        width = 1;

    m_dash_stroker.setDashPattern(pen.dashPattern());

    m_dash_stroker.setStrokeWidth(pen.isCosmetic() ? width * m_inv_scale : width);

    m_dash_stroker.setMiterLimit(pen.miterLimit());

    qreal curvyness = sqrt(width) * m_inv_scale / 8;

    if (count < 2)

        return;