qstroker.cpp

奇趣公司比较新的qt/emd版本

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#include "private/qstroker_p.h"
#include "private/qbezier_p.h"
#include "private/qmath_p.h"
#include "qline.h"
#include "qtransform.h"

// #define QPP_STROKE_DEBUG

class QSubpathForwardIterator
{
public:
    QSubpathForwardIterator(const QDataBuffer<QStrokerOps::Element> *path)
        : m_path(path), m_pos(0) { }
    inline int position() const { return m_pos; }
    inline bool hasNext() const { return m_pos < m_path->size(); }
    inline QStrokerOps::Element next() { Q_ASSERT(hasNext()); return m_path->at(m_pos++); }

private:
    const QDataBuffer<QStrokerOps::Element> *m_path;
    int m_pos;
};

class QSubpathBackwardIterator
{
public:
    QSubpathBackwardIterator(const QDataBuffer<QStrokerOps::Element> *path)
        : m_path(path), m_pos(path->size() - 1) { }

    inline int position() const { return m_pos; }

    inline bool hasNext() const { return m_pos >= 0; }

    inline QStrokerOps::Element next()
    {
        Q_ASSERT(hasNext());

        QStrokerOps::Element ce = m_path->at(m_pos);   // current element

        if (m_pos == m_path->size() - 1) {
            --m_pos;
            ce.type = QPainterPath::MoveToElement;
            return ce;
        }

        const QStrokerOps::Element &pe = m_path->at(m_pos + 1); // previous element

        switch (pe.type) {
        case QPainterPath::LineToElement:
            ce.type = QPainterPath::LineToElement;
            break;
        case QPainterPath::CurveToDataElement:
            // First control point?
            if (ce.type == QPainterPath::CurveToElement) {
                ce.type = QPainterPath::CurveToDataElement;
            } else { // Second control point then
                ce.type = QPainterPath::CurveToElement;
            }
            break;
        case QPainterPath::CurveToElement:
            ce.type = QPainterPath::CurveToDataElement;
            break;
        default:
            qWarning("QSubpathReverseIterator::next: Case %d unhandled", ce.type);
            break;
        }
        --m_pos;

        return ce;
    }

private:
    const QDataBuffer<QStrokerOps::Element> *m_path;
    int m_pos;
};

class QSubpathFlatIterator
{
public:
    QSubpathFlatIterator(const QDataBuffer<QStrokerOps::Element> *path)
        : m_path(path), m_pos(0), m_curve_index(-1) { }

    inline bool hasNext() const { return m_curve_index >= 0 || m_pos < m_path->size(); }

    QStrokerOps::Element next()
    {
        Q_ASSERT(hasNext());

        if (m_curve_index >= 0) {
            QStrokerOps::Element e = { QPainterPath::LineToElement,
                                       qt_real_to_fixed(m_curve.at(m_curve_index).x()),
                                       qt_real_to_fixed(m_curve.at(m_curve_index).y())
                                       };
            ++m_curve_index;
            if (m_curve_index >= m_curve.size())
                m_curve_index = -1;
            return e;
        }

        QStrokerOps::Element e = m_path->at(m_pos);
        if (e.isCurveTo()) {
            Q_ASSERT(m_pos > 0);
            Q_ASSERT(m_pos < m_path->size());

            m_curve = QBezier::fromPoints(QPointF(qt_fixed_to_real(m_path->at(m_pos-1).x),
                                                  qt_fixed_to_real(m_path->at(m_pos-1).y)),
                                          QPointF(qt_fixed_to_real(e.x),
                                                  qt_fixed_to_real(e.y)),
                                          QPointF(qt_fixed_to_real(m_path->at(m_pos+1).x),
                                                  qt_fixed_to_real(m_path->at(m_pos+1).y)),
                                          QPointF(qt_fixed_to_real(m_path->at(m_pos+2).x),
                                                  qt_fixed_to_real(m_path->at(m_pos+2).y))).toPolygon();
            m_curve_index = 1;
            e.type = QPainterPath::LineToElement;
            e.x = m_curve.at(0).x();
            e.y = m_curve.at(0).y();
            m_pos += 2;
        }
        Q_ASSERT(e.isLineTo() || e.isMoveTo());
        ++m_pos;
        return e;
    }

private:
    const QDataBuffer<QStrokerOps::Element> *m_path;
    int m_pos;
    QPolygonF m_curve;
    int m_curve_index;
};

template <class Iterator> bool qt_stroke_side(Iterator *it, QStroker *stroker,
                                              bool capFirst, QLineF *startTangent);

/*******************************************************************************
 * QLineF::angle gives us the smalles angle between two lines. Here we
 * want to identify the line's angle direction on the unit circle.
 */
static inline qreal adapted_angle_on_x(const QLineF &line)
{
    qreal angle = line.angle(QLineF(0, 0, 1, 0));
    if (line.dy() > 0)
        angle = 360 - angle;
    return angle;
}

QStrokerOps::QStrokerOps()
    : m_customData(0), m_moveTo(0), m_lineTo(0), m_cubicTo(0)
{
}

QStrokerOps::~QStrokerOps()
{
}


/*!
    Prepares the stroker. Call this function once before starting a
    stroke by calling moveTo, lineTo or cubicTo.

    The \a customData is passed back through that callback functions
    and can be used by the user to for instance maintain state
    information.
*/
void QStrokerOps::begin(void *customData)
{
    m_customData = customData;
    m_elements.reset();
}


/*!
    Finishes the stroke. Call this function once when an entire
    primitive has been stroked.
*/
void QStrokerOps::end()
{
    if (m_elements.size() > 1)
        processCurrentSubpath();
    m_customData = 0;
}

/*!
    Convenience function that decomposes \a path into begin(),
    moveTo(), lineTo(), curevTo() and end() calls.

    The \a customData parameter is used in the callback functions

    The \a matrix is used to transform the points before input to the
    stroker.

    \sa begin()
*/
void QStrokerOps::strokePath(const QPainterPath &path, void *customData, const QTransform &matrix)
{
    if (path.isEmpty())
        return;

    begin(customData);
    int count = path.elementCount();
    if (matrix.isIdentity()) {
        for (int i=0; i<count; ++i) {
            const QPainterPath::Element &e = path.elementAt(i);
            switch (e.type) {
            case QPainterPath::MoveToElement:
                moveTo(qt_real_to_fixed(e.x), qt_real_to_fixed(e.y));
                break;
            case QPainterPath::LineToElement:
                lineTo(qt_real_to_fixed(e.x), qt_real_to_fixed(e.y));
                break;
            case QPainterPath::CurveToElement:
                {
                    const QPainterPath::Element &cp2 = path.elementAt(++i);
                    const QPainterPath::Element &ep = path.elementAt(++i);
                    cubicTo(qt_real_to_fixed(e.x), qt_real_to_fixed(e.y),
                            qt_real_to_fixed(cp2.x), qt_real_to_fixed(cp2.y),
                            qt_real_to_fixed(ep.x), qt_real_to_fixed(ep.y));
                }
                break;
            default:
                break;
            }
        }
    } else {
        for (int i=0; i<count; ++i) {
            const QPainterPath::Element &e = path.elementAt(i);
            QPointF pt = QPointF(e.x, e.y) * matrix;
            switch (e.type) {
            case QPainterPath::MoveToElement:
                moveTo(qt_real_to_fixed(pt.x()), qt_real_to_fixed(pt.y()));
                break;
            case QPainterPath::LineToElement:
                lineTo(qt_real_to_fixed(pt.x()), qt_real_to_fixed(pt.y()));
                break;
            case QPainterPath::CurveToElement:
                {
                    QPointF cp2 = ((QPointF) path.elementAt(++i)) * matrix;
                    QPointF ep = ((QPointF) path.elementAt(++i)) * matrix;
                    cubicTo(qt_real_to_fixed(pt.x()), qt_real_to_fixed(pt.y()),
                            qt_real_to_fixed(cp2.x()), qt_real_to_fixed(cp2.y()),
                            qt_real_to_fixed(ep.x()), qt_real_to_fixed(ep.y()));
                }
                break;
            default:
                break;
            }
        }
    }
    end();
}

/*!
    Convenience function for stroking a polygon of the \a pointCount
    first points in \a points. If \a implicit_close is set to true a
    line is implictly drawn between the first and last point in the
    polygon. Typically true for polygons and false for polylines.

    The \a matrix is used to transform the points before they enter the
    stroker.

    \sa begin()
*/

void QStrokerOps::strokePolygon(const QPointF *points, int pointCount, bool implicit_close,
                                void *data, const QTransform &matrix)
{
    if (!pointCount)
        return;
    begin(data);
    if (matrix.isIdentity()) {
        moveTo(qt_real_to_fixed(points[0].x()), qt_real_to_fixed(points[0].y()));
        for (int i=1; i<pointCount; ++i)
            lineTo(qt_real_to_fixed(points[i].x()),
                   qt_real_to_fixed(points[i].y()));
        if (implicit_close)
            lineTo(qt_real_to_fixed(points[0].x()), qt_real_to_fixed(points[0].y()));
    } else {
        QPointF start = points[0] * matrix;
        moveTo(qt_real_to_fixed(start.x()), qt_real_to_fixed(start.y()));
        for (int i=1; i<pointCount; ++i) {
            QPointF pt = points[i] * matrix;
            lineTo(qt_real_to_fixed(pt.x()), qt_real_to_fixed(pt.y()));
        }
        if (implicit_close)
            lineTo(qt_real_to_fixed(start.x()), qt_real_to_fixed(start.y()));
    }
    end();
}

/*!
    Convenience function for stroking an ellipse with bounding rect \a
    rect. The \a matrix is used to transform the coordinates before
    they enter the stroker.
*/
void QStrokerOps::strokeEllipse(const QRectF &rect, void *data, const QTransform &matrix)
{
    int count = 0;
    QPointF pts[12];
    QPointF start = qt_curves_for_arc(rect, 0, 360, pts, &count);
    Q_ASSERT(count == 12); // a perfect circle..

    if (!matrix.isIdentity()) {
        start = start * matrix;
        for (int i=0; i<12; ++i) {
            pts[i] = pts[i] * matrix;