pathstroke.cpp Example File
^{demos/pathstroke/pathstroke.cpp}

    /****************************************************************************
    **
    ** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
    **
    ** This file is part of the documentation of the Qt Toolkit.
    **
    ** This file may be used under the terms of the GNU General Public
    ** License version 2.0 as published by the Free Software Foundation
    ** and appearing in the file LICENSE.GPL included in the packaging of
    ** this file.  Please review the following information to ensure GNU
    ** General Public Licensing requirements will be met:
    ** http://www.trolltech.com/products/qt/opensource.html
    **
    ** If you are unsure which license is appropriate for your use, please
    ** review the following information:
    ** http://www.trolltech.com/products/qt/licensing.html or contact the
    ** sales department at sales@trolltech.com.
    **
    ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
    **
    ****************************************************************************/

    #include "pathstroke.h"
    #include "arthurstyle.h"
    #include "arthurwidgets.h"

    extern void draw_round_rect(QPainter *p, const QRect &bounds, int radius);

    PathStrokeWidget::PathStrokeWidget()
    {
        setWindowTitle(tr("Path Stroking"));

        // Setting up palette.
        QPalette pal = palette();
    //     pal.setBrush(QPalette::Background, Qt::white);
    //     pal.setBrush(QPalette::Foreground, QColor("aquamarine"));
    //     pal.setBrush(QPalette::Background, QPixmap("background.png"));
        setPalette(pal);

        // Widget construction and property setting
        m_renderer = new PathStrokeRenderer(this);

        QGroupBox *mainGroup = new QGroupBox(this);
    //     QWidget *mainGroup = new QWidget(this);
        mainGroup->setFixedWidth(180);
        mainGroup->setTitle("Path Stroking");

        QGroupBox *capGroup = new QGroupBox(mainGroup);
        capGroup->setAttribute(Qt::WA_ContentsPropagated);
        QRadioButton *flatCap = new QRadioButton(capGroup);
        QRadioButton *squareCap = new QRadioButton(capGroup);
        QRadioButton *roundCap = new QRadioButton(capGroup);
        capGroup->setTitle("Cap Style");
        flatCap->setText("Flat Cap");
        squareCap->setText("Square Cap");
        roundCap->setText("Round Cap");

        QGroupBox *joinGroup = new QGroupBox(mainGroup);
        joinGroup->setAttribute(Qt::WA_ContentsPropagated);
        QRadioButton *bevelJoin = new QRadioButton(joinGroup);
        QRadioButton *miterJoin = new QRadioButton(joinGroup);
        QRadioButton *roundJoin = new QRadioButton(joinGroup);
        joinGroup->setTitle("Join Style");
        bevelJoin->setText("Bevel Join");
        miterJoin->setText("Miter Join");
        roundJoin->setText("Round Join");

        QGroupBox *styleGroup = new QGroupBox(mainGroup);
        styleGroup->setAttribute(Qt::WA_ContentsPropagated);
        QRadioButton *solidLine = new QRadioButton(styleGroup);
        QRadioButton *dashLine = new QRadioButton(styleGroup);
        QRadioButton *dotLine = new QRadioButton(styleGroup);
        QRadioButton *dashDotLine = new QRadioButton(styleGroup);
        QRadioButton *dashDotDotLine = new QRadioButton(styleGroup);
        QRadioButton *customDashLine = new QRadioButton(styleGroup);
        styleGroup->setTitle("Pen Style");
    #if 0
        solidLine->setText("Solid Line");
        dashLine->setText("Dash Line");
        dotLine->setText("Dot Line");
        dashDotLine->setText("Dash Dot Line");
        dashDotDotLine->setText("Dash Dot Dot Line");
    #else
        solidLine->setIcon(QPixmap(":res/images/line_solid.png"));
        dashLine->setIcon(QPixmap(":res/images/line_dashed.png"));
        dotLine->setIcon(QPixmap(":res/images/line_dotted.png"));
        dashDotLine->setIcon(QPixmap(":res/images/line_dash_dot.png"));
        dashDotDotLine->setIcon(QPixmap(":res/images/line_dash_dot_dot.png"));
        customDashLine->setText("Custom Style");

        int fixedHeight = bevelJoin->sizeHint().height();
        solidLine->setFixedHeight(fixedHeight);
        dashLine->setFixedHeight(fixedHeight);
        dotLine->setFixedHeight(fixedHeight);
        dashDotLine->setFixedHeight(fixedHeight);
        dashDotDotLine->setFixedHeight(fixedHeight);
    #endif

        QGroupBox *pathModeGroup = new QGroupBox(mainGroup);
        pathModeGroup->setAttribute(Qt::WA_ContentsPropagated);
        QRadioButton *curveMode = new QRadioButton(pathModeGroup);
        QRadioButton *lineMode = new QRadioButton(pathModeGroup);
        pathModeGroup->setTitle("Path composed of");
        curveMode->setText("Curves");
        lineMode->setText("Lines");

        QGroupBox *penWidthGroup = new QGroupBox(mainGroup);
        penWidthGroup->setAttribute(Qt::WA_ContentsPropagated);
        QSlider *penWidth = new QSlider(Qt::Horizontal, penWidthGroup);
        penWidth->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
        penWidthGroup->setTitle("Pen Width");
        penWidth->setRange(0, 500);

    #if 0
        QCheckBox *animated = new QCheckBox(mainGroup);
        animated->setText("Animated");
    #else
        QPushButton *animated = new QPushButton(mainGroup);
        animated->setText("Animate");
        animated->setCheckable(true);
    #endif

        QPushButton *showSourceButton = new QPushButton(mainGroup);
        showSourceButton->setText("Show Source");

        QPushButton *whatsThisButton = new QPushButton(mainGroup);
        whatsThisButton->setText("What's This?");
        whatsThisButton->setCheckable(true);

        // Layouting
        QHBoxLayout *viewLayout = new QHBoxLayout(this);
        viewLayout->addWidget(m_renderer);
        viewLayout->addWidget(mainGroup);

        QVBoxLayout *mainGroupLayout = new QVBoxLayout(mainGroup);
        mainGroupLayout->setMargin(3);
        mainGroupLayout->addWidget(capGroup);
        mainGroupLayout->addWidget(joinGroup);
        mainGroupLayout->addWidget(styleGroup);
        mainGroupLayout->addWidget(penWidthGroup);
        mainGroupLayout->addWidget(pathModeGroup);
        mainGroupLayout->addWidget(animated);
        mainGroupLayout->addStretch(1);
        mainGroupLayout->addWidget(showSourceButton);
        mainGroupLayout->addWidget(whatsThisButton);

        QVBoxLayout *capGroupLayout = new QVBoxLayout(capGroup);
        capGroupLayout->addWidget(flatCap);
        capGroupLayout->addWidget(squareCap);
        capGroupLayout->addWidget(roundCap);

        QVBoxLayout *joinGroupLayout = new QVBoxLayout(joinGroup);
        joinGroupLayout->addWidget(bevelJoin);
        joinGroupLayout->addWidget(miterJoin);
        joinGroupLayout->addWidget(roundJoin);

        QVBoxLayout *styleGroupLayout = new QVBoxLayout(styleGroup);
        styleGroupLayout->addWidget(solidLine);
        styleGroupLayout->addWidget(dashLine);
        styleGroupLayout->addWidget(dotLine);
        styleGroupLayout->addWidget(dashDotLine);
        styleGroupLayout->addWidget(dashDotDotLine);
        styleGroupLayout->addWidget(customDashLine);

        QVBoxLayout *pathModeGroupLayout = new QVBoxLayout(pathModeGroup);
        pathModeGroupLayout->addWidget(curveMode);
        pathModeGroupLayout->addWidget(lineMode);

        QVBoxLayout *penWidthLayout = new QVBoxLayout(penWidthGroup);
        penWidthLayout->addWidget(penWidth);

        // Set up connections
        connect(penWidth, SIGNAL(valueChanged(int)),
                m_renderer, SLOT(setPenWidth(int)));
        connect(animated, SIGNAL(toggled(bool)),
                m_renderer, SLOT(setAnimation(bool)));

        connect(flatCap, SIGNAL(clicked()), m_renderer, SLOT(setFlatCap()));
        connect(squareCap, SIGNAL(clicked()), m_renderer, SLOT(setSquareCap()));
        connect(roundCap, SIGNAL(clicked()), m_renderer, SLOT(setRoundCap()));

        connect(bevelJoin, SIGNAL(clicked()), m_renderer, SLOT(setBevelJoin()));
        connect(miterJoin, SIGNAL(clicked()), m_renderer, SLOT(setMiterJoin()));
        connect(roundJoin, SIGNAL(clicked()), m_renderer, SLOT(setRoundJoin()));

        connect(curveMode, SIGNAL(clicked()), m_renderer, SLOT(setCurveMode()));
        connect(lineMode, SIGNAL(clicked()), m_renderer, SLOT(setLineMode()));

        connect(solidLine, SIGNAL(clicked()), m_renderer, SLOT(setSolidLine()));
        connect(dashLine, SIGNAL(clicked()), m_renderer, SLOT(setDashLine()));
        connect(dotLine, SIGNAL(clicked()), m_renderer, SLOT(setDotLine()));
        connect(dashDotLine, SIGNAL(clicked()), m_renderer, SLOT(setDashDotLine()));
        connect(dashDotDotLine, SIGNAL(clicked()), m_renderer, SLOT(setDashDotDotLine()));
        connect(customDashLine, SIGNAL(clicked()), m_renderer, SLOT(setCustomDashLine()));

        connect(showSourceButton, SIGNAL(clicked()), m_renderer, SLOT(showSource()));

        connect(whatsThisButton, SIGNAL(clicked(bool)), m_renderer, SLOT(setDescriptionEnabled(bool)));
        connect(m_renderer, SIGNAL(descriptionEnabledChanged(bool)),
                whatsThisButton, SLOT(setChecked(bool)));

        // Set the defaults
        animated->setChecked(true);
        flatCap->setChecked(true);
        bevelJoin->setChecked(true);
        penWidth->setValue(50);
        curveMode->setChecked(true);
        solidLine->setChecked(true);

        m_renderer->loadSourceFile(":res/pathstroke.cpp");
        m_renderer->loadDescription(":res/pathstroke.html");
    }

    PathStrokeRenderer::PathStrokeRenderer(QWidget *parent)
        : ArthurFrame(parent)
    {
        m_pointSize = 10;
        m_activePoint = -1;
        m_capStyle = Qt::FlatCap;
        m_joinStyle = Qt::BevelJoin;
        m_pathMode = CurveMode;
        m_penWidth = 1;
        m_penStyle = Qt::SolidLine;
        m_wasAnimated = true;
        setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    }

    void PathStrokeRenderer::paint(QPainter *painter)
    {
        if (m_points.isEmpty())
            initializePoints();

        painter->setRenderHint(QPainter::Antialiasing);

        QPalette pal = palette();
        painter->setPen(Qt::NoPen);

        // Construct the path
        QPainterPath path;
        path.moveTo(m_points.at(0));

        if (m_pathMode == LineMode) {
            for (int i=1; i<m_points.size(); ++i) {
                path.lineTo(m_points.at(i));
            }
        } else {
            int i=1;
            while (i + 2 < m_points.size()) {
                path.cubicTo(m_points.at(i), m_points.at(i+1), m_points.at(i+2));
                i += 3;
            }
            while (i < m_points.size()) {
                path.lineTo(m_points.at(i));
                ++i;
            }
        }

        // Draw the path
        {
            QColor lg = Qt::red;

            // The "custom" pen
            if (m_penStyle == Qt::NoPen) {
                QPainterPathStroker stroker;
                stroker.setWidth(m_penWidth);
                stroker.setJoinStyle(m_joinStyle);
                stroker.setCapStyle(m_capStyle);

                QVector<qreal> dashes;
                qreal space = 4;
                dashes << 1 << space
                       << 3 << space
                       << 9 << space
                       << 27 << space
                       << 9 << space
                       << 3 << space;
                stroker.setDashPattern(dashes);
                QPainterPath stroke = stroker.createStroke(path);
                painter->fillPath(stroke, lg);

            } else {
                QPen pen(lg, m_penWidth, m_penStyle, m_capStyle, m_joinStyle);
                painter->strokePath(path, pen);
            }
        }

        if (1) {
            // Draw the control points
            painter->setPen(QColor(50, 100, 120, 200));
            painter->setBrush(QColor(200, 200, 210, 120));
            for (int i=0; i<m_points.size(); ++i) {
                QPointF pos = m_points.at(i);
                painter->drawEllipse(QRectF(pos.x() - m_pointSize,
                                           pos.y() - m_pointSize,
                                           m_pointSize*2, m_pointSize*2));
            }
            painter->setPen(QPen(Qt::lightGray, 0, Qt::SolidLine));
            painter->setBrush(Qt::NoBrush);
            painter->drawPolyline(m_points);
        }

    }

    void PathStrokeRenderer::initializePoints()
    {
        const int count = 7;
        m_points.clear();
        m_vectors.clear();

        QMatrix m;
        double rot = 360 / count;
        QPointF center(width() / 2, height() / 2);
        QMatrix vm;
        vm.shear(2, -1);
        vm.scale(3, 3);

        for (int i=0; i<count; ++i) {
            m_vectors << QPointF(.1f, .25f) * (m * vm);
            m_points << QPointF(0, 100) * m + center;
            m.rotate(rot);
        }
    }

    void PathStrokeRenderer::updatePoints()
    {
        double pad = 10;
        double left = pad;
        double right = width() - pad;
        double top = pad;
        double bottom = height() - pad;

        Q_ASSERT(m_points.size() == m_vectors.size());
        for (int i=0; i<m_points.size(); ++i) {

            if (i == m_activePoint)
                continue;

            QPointF pos = m_points.at(i);
            QPointF vec = m_vectors.at(i);
            pos += vec;
            if (pos.x() < left || pos.x() > right) {
                vec.setX(-vec.x());
                pos.setX(pos.x() < left ? left : right);
            } if (pos.y() < top || pos.y() > bottom) {
                vec.setY(-vec.y());
                pos.setY(pos.y() < top ? top : bottom);
            }
            m_points[i] = pos;
            m_vectors[i] = vec;
        }
        update();
    }

    void PathStrokeRenderer::mousePressEvent(QMouseEvent *e)
    {
        setDescriptionEnabled(false);
        m_activePoint = -1;
        qreal distance = -1;
        for (int i=0; i<m_points.size(); ++i) {
            qreal d = QLineF(e->pos(), m_points.at(i)).length();
            if ((distance < 0 && d < 8 * m_pointSize) || d < distance) {
                distance = d;
                m_activePoint = i;
            }
        }

        if (m_activePoint != -1) {
            m_wasAnimated = m_timer.isActive();
            setAnimation(false);
            mouseMoveEvent(e);
        }
    }

    void PathStrokeRenderer::mouseMoveEvent(QMouseEvent *e)
    {
        if (m_activePoint >= 0 && m_activePoint < m_points.size()) {
            m_points[m_activePoint] = e->pos();
            update();
        }
    }

    void PathStrokeRenderer::mouseReleaseEvent(QMouseEvent *)
    {
        m_activePoint = -1;
        setAnimation(m_wasAnimated);
    }

    void PathStrokeRenderer::timerEvent(QTimerEvent *e)
    {
        if (e->timerId() == m_timer.timerId()) {
            updatePoints();
            QApplication::syncX();
        } // else if (e->timerId() == m_fpsTimer.timerId()) {
    //         emit frameRate(m_frameCount);
    //         m_frameCount = 0;
    //     }
    }

    void PathStrokeRenderer::setAnimation(bool animation)
    {
        m_timer.stop();
    //     m_fpsTimer.stop();

        if (animation) {
            m_timer.start(25, this);
    //         m_fpsTimer.start(1000, this);
    //         m_frameCount = 0;
        }
    }