pathdeform.cpp Example File
^{demos/deform/pathdeform.cpp}

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    **
    ** 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
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    ** and appearing in the file LICENSE.GPL included in the packaging of
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    #include "pathdeform.h"

    #include <QApplication>
    #include <QtDebug>
    #include <QMouseEvent>
    #include <QTimerEvent>
    #include <QLayout>
    #include <QLineEdit>
    #include <QPainter>
    #include <QSlider>

    #include <math.h>

    PathDeformWidget::PathDeformWidget(QWidget *parent)
        : QWidget(parent)
    {
        setWindowTitle("Vector Deformation");

        m_renderer = new PathDeformRenderer(this);
        m_renderer->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);

        QGroupBox *mainGroup = new QGroupBox(this);
        mainGroup->setTitle("Vector Deformation");

        QGroupBox *radiusGroup = new QGroupBox(mainGroup);
        radiusGroup->setAttribute(Qt::WA_ContentsPropagated);
        radiusGroup->setTitle("Lens Radius");
        QSlider *radiusSlider = new QSlider(Qt::Horizontal, radiusGroup);
        radiusSlider->setRange(50, 150);
        radiusSlider->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);

        QGroupBox *deformGroup = new QGroupBox(mainGroup);
        deformGroup->setAttribute(Qt::WA_ContentsPropagated);
        deformGroup->setTitle("Deformation");
        QSlider *deformSlider = new QSlider(Qt::Horizontal, deformGroup);
        deformSlider->setRange(-100, 100);
        deformSlider->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);

        QGroupBox *fontSizeGroup = new QGroupBox(mainGroup);
        fontSizeGroup->setAttribute(Qt::WA_ContentsPropagated);
        fontSizeGroup->setTitle("Font Size");
        QSlider *fontSizeSlider = new QSlider(Qt::Horizontal, fontSizeGroup);
        fontSizeSlider->setRange(16, 200);
        fontSizeSlider->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);

        QGroupBox *textGroup = new QGroupBox(mainGroup);
        textGroup->setAttribute(Qt::WA_ContentsPropagated);
        textGroup->setTitle("Text");
        QLineEdit *textInput = new QLineEdit(textGroup);

        QPushButton *animateButton = new QPushButton(mainGroup);
        animateButton->setText("Animated");
        animateButton->setCheckable(true);

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

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

        // Layouts
        QHBoxLayout *mainLayout = new QHBoxLayout(this);
        mainLayout->addWidget(m_renderer);
        mainLayout->addWidget(mainGroup);
        mainGroup->setFixedWidth(180);

        QVBoxLayout *mainGroupLayout = new QVBoxLayout(mainGroup);
        mainGroupLayout->addWidget(radiusGroup);
        mainGroupLayout->addWidget(deformGroup);
        mainGroupLayout->addWidget(fontSizeGroup);
        mainGroupLayout->addWidget(textGroup);
        mainGroupLayout->addWidget(animateButton);
        mainGroupLayout->addStretch(1);
        mainGroupLayout->addWidget(showSourceButton);
        mainGroupLayout->addWidget(whatsThisButton);

        QVBoxLayout *radiusGroupLayout = new QVBoxLayout(radiusGroup);
        radiusGroupLayout->addWidget(radiusSlider);

        QVBoxLayout *deformGroupLayout = new QVBoxLayout(deformGroup);
        deformGroupLayout->addWidget(deformSlider);

        QVBoxLayout *fontSizeGroupLayout = new QVBoxLayout(fontSizeGroup);
        fontSizeGroupLayout->addWidget(fontSizeSlider);

        QVBoxLayout *textGroupLayout = new QVBoxLayout(textGroup);
        textGroupLayout->addWidget(textInput);

        connect(textInput, SIGNAL(textChanged(QString)), m_renderer, SLOT(setText(QString)));
        connect(radiusSlider, SIGNAL(valueChanged(int)), m_renderer, SLOT(setRadius(int)));
        connect(deformSlider, SIGNAL(valueChanged(int)), m_renderer, SLOT(setIntensity(int)));
        connect(fontSizeSlider, SIGNAL(valueChanged(int)), m_renderer, SLOT(setFontSize(int)));
        connect(animateButton, SIGNAL(clicked(bool)), m_renderer, SLOT(setAnimated(bool)));
        connect(whatsThisButton, SIGNAL(clicked(bool)), m_renderer, SLOT(setDescriptionEnabled(bool)));
        connect(showSourceButton, SIGNAL(clicked()), m_renderer, SLOT(showSource()));
        connect(m_renderer, SIGNAL(descriptionEnabledChanged(bool)),
                whatsThisButton, SLOT(setChecked(bool)));

        animateButton->animateClick();
        deformSlider->setValue(80);
        radiusSlider->setValue(100);
        fontSizeSlider->setValue(120);
        textInput->setText("Qt");

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

    static inline QRect circle_bounds(const QPointF &center, double radius, double compensation)
    {
        return QRect(qRound(center.x() - radius - compensation),
                     qRound(center.y() - radius - compensation),
                     qRound((radius + compensation) * 2),
                     qRound((radius + compensation) * 2));

    }

    const int LENS_EXTENT = 10;

    PathDeformRenderer::PathDeformRenderer(QWidget *widget)
        : ArthurFrame(widget)
    {
        m_radius = 100;
        m_pos = QPointF(m_radius, m_radius);
        m_direction = QPointF(1, 1);
        m_fontSize = 24;
        m_animated = true;
        m_repaintTimer.start(25, this);
        m_repaintTracker.start();
        m_intensity = 100;

    //     m_fpsTimer.start(1000, this);
    //     m_fpsCounter = 0;

        generateLensPixmap();
    }

    void PathDeformRenderer::setText(const QString &text)
    {
        m_text = text;

        QFont f("times new roman,utopia");
        f.setStyleStrategy(QFont::ForceOutline);
        f.setPointSize(m_fontSize);
        f.setStyleHint(QFont::Times);

        QFontMetrics fm(f);

        m_paths.clear();
        m_pathBounds = QRect();

        QPointF advance(0, 0);

        bool do_quick = true;
        for (int i=0; i<text.size(); ++i) {
            if (text.at(i).unicode() >= 0x4ff && text.at(i).unicode() <= 0x1e00) {
                do_quick = false;
                break;
            }
        }

        if (do_quick) {
            for (int i=0; i<text.size(); ++i) {
                QPainterPath path;
                path.addText(advance, f, text.mid(i, 1));
                m_pathBounds |= path.boundingRect();
                m_paths << path;
                advance += QPointF(fm.width(text.mid(i, 1)), 0);
            }
        } else {
            QPainterPath path;
            path.addText(advance, f, text);
            m_pathBounds |= path.boundingRect();
            m_paths << path;
        }

        for (int i=0; i<m_paths.size(); ++i)
            m_paths[i] = m_paths[i] * QMatrix(1, 0, 0, 1, -m_pathBounds.x(), -m_pathBounds.y());

        update();
    }

    void PathDeformRenderer::generateLensPixmap()
    {
        double rad = m_radius + LENS_EXTENT;

        QRect bounds = circle_bounds(QPointF(), rad, 0);

        QPainter painter;

        if (preferImage()) {
            m_lens_image = QImage(bounds.size(), QImage::Format_ARGB32_Premultiplied);
            m_lens_image.fill(0);
            painter.begin(&m_lens_image);
        } else {
            m_lens_pixmap = QPixmap(bounds.size());
            m_lens_pixmap.fill(QColor(0, 0, 0, 0));
            painter.begin(&m_lens_pixmap);
        }

        QRadialGradient gr(rad, rad, rad, 3 * rad / 5, 3 * rad / 5);
        gr.setColorAt(0.0, QColor(255, 255, 255, 191));
        gr.setColorAt(0.2, QColor(255, 255, 127, 191));
        gr.setColorAt(0.9, QColor(150, 150, 200, 63));
        gr.setColorAt(0.95, QColor(0, 0, 0, 127));
        gr.setColorAt(1, QColor(0, 0, 0, 0));
        painter.setRenderHint(QPainter::Antialiasing);
        painter.setBrush(gr);
        painter.setPen(Qt::NoPen);
        painter.drawEllipse(0, 0, bounds.width(), bounds.height());
    }

    void PathDeformRenderer::setAnimated(bool animated)
    {
        m_animated = animated;

        if (m_animated) {
    //         m_fpsTimer.start(1000, this);
    //         m_fpsCounter = 0;
            m_repaintTimer.start(25, this);
            m_repaintTracker.start();
        } else {
    //         m_fpsTimer.stop();
            m_repaintTimer.stop();
        }
    }

    void PathDeformRenderer::timerEvent(QTimerEvent *e)
    {

        if (e->timerId() == m_repaintTimer.timerId()) {

            if (QLineF(QPointF(0,0), m_direction).length() > 1)
                m_direction *= 0.995;
            double time = m_repaintTracker.restart();

            QRect rectBefore = circle_bounds(m_pos, m_radius, m_fontSize);

            double dx = m_direction.x();
            double dy = m_direction.y();
            if (time > 0) {
                dx = dx * time * .1;
                dy = dy * time * .1;
            }

            m_pos += QPointF(dx, dy);

            if (m_pos.x() - m_radius < 0) {
                m_direction.setX(-m_direction.x());
                m_pos.setX(m_radius);
            } else if (m_pos.x() + m_radius > width()) {
                m_direction.setX(-m_direction.x());
                m_pos.setX(width() - m_radius);
            }

            if (m_pos.y() - m_radius < 0) {
                m_direction.setY(-m_direction.y());
                m_pos.setY(m_radius);
            } else if (m_pos.y() + m_radius > height()) {
                m_direction.setY(-m_direction.y());
                m_pos.setY(height() - m_radius);
            }

            QRect rectAfter = circle_bounds(m_pos, m_radius, m_fontSize);
            update(QRect(rectBefore | rectAfter));
            QApplication::syncX();
        }
    //     else if (e->timerId() == m_fpsTimer.timerId()) {
    //         printf("fps: %d\n", m_fpsCounter);
    //         emit frameRate(m_fpsCounter);
    //         m_fpsCounter = 0;

    //     }
    }

    void PathDeformRenderer::mousePressEvent(QMouseEvent *e)
    {
        setDescriptionEnabled(false);

        m_repaintTimer.stop();
        m_offset = QPointF();
        if (QLineF(m_pos, e->pos()).length() <= m_radius)
            m_offset = m_pos - e->pos();

        mouseMoveEvent(e);
    }

    void PathDeformRenderer::mouseReleaseEvent(QMouseEvent *e)
    {
        if (e->buttons() == Qt::NoButton && m_animated) {
            m_repaintTimer.start(10, this);
            m_repaintTracker.start();
        }
    }

    void PathDeformRenderer::mouseMoveEvent(QMouseEvent *e)
    {
        QRect rectBefore = circle_bounds(m_pos, m_radius, m_fontSize);
        if (e->type() == QEvent::MouseMove) {
            QLineF line(m_pos, e->pos() + m_offset);
            line.setLength(line.length() * .1);
            QPointF dir(line.dx(), line.dy());
            m_direction = (m_direction + dir) / 2;
        }
        m_pos = e->pos() + m_offset;
        QRect rectAfter = circle_bounds(m_pos, m_radius, m_fontSize);
        update(rectBefore | rectAfter);
    }

    QPainterPath PathDeformRenderer::lensDeform(const QPainterPath &source, const QPointF &offset)
    {
        QPainterPath path;
        path.addPath(source);

        double flip = m_intensity / 100.0;

        for (int i=0; i<path.elementCount(); ++i) {
            QPainterPath::Element &e = const_cast<QPainterPath::Element &>(path.elementAt(i));

            double x = e.x + offset.x();
            double y = e.y + offset.y();

            double dx = x - m_pos.x();
            double dy = y - m_pos.y();
            double len = m_radius - sqrt(dx * dx + dy * dy);

            if (len > 0) {
                e.x = x + flip * dx * len / m_radius;
                e.y = y + flip * dy * len / m_radius;
            } else {
                e.x = x;
                e.y = y;
            }

        }

        return path;
    }

    void PathDeformRenderer::paint(QPainter *painter)
    {
        int pad_x = 5;
        int pad_y = 5;

        int skip_x = qRound(m_pathBounds.width() + pad_x + m_fontSize/2);
        int skip_y = qRound(m_pathBounds.height() + pad_y);

        painter->setPen(Qt::NoPen);
        painter->setBrush(Qt::black);

        QRectF clip(painter->clipPath().boundingRect());

        int overlap = pad_x / 2;

        for (int start_y=0; start_y < height(); start_y += skip_y) {

            if (start_y > clip.bottom())
                break;

            int start_x = -overlap;
            for (; start_x < width(); start_x += skip_x) {

                if (start_y + skip_y >= clip.top() &&
                    start_x + skip_x >= clip.left() &&
                    start_x <= clip.right()) {
                    for (int i=0; i<m_paths.size(); ++i) {
                        QPainterPath path = lensDeform(m_paths[i], QPointF(start_x, start_y));
                        painter->drawPath(path);
                    }
                }
            }
            overlap = skip_x - (start_x - width());

        }

        if (preferImage()) {
            painter->drawImage(m_pos - QPointF(m_radius + LENS_EXTENT, m_radius + LENS_EXTENT),
                               m_lens_image);
        } else {
            painter->drawPixmap(m_pos - QPointF(m_radius + LENS_EXTENT, m_radius + LENS_EXTENT),
                                m_lens_pixmap);
        }
    }

    void PathDeformRenderer::setRadius(int radius)
    {
        double max = qMax(m_radius, (double)radius);
        m_radius = radius;
        generateLensPixmap();
        if (!m_animated || m_radius < max)
            update(circle_bounds(m_pos, max, m_fontSize));
    }

    void PathDeformRenderer::setIntensity(int intensity)
    {
        m_intensity = intensity;
        if (!m_animated)
            update(circle_bounds(m_pos, m_radius, m_fontSize));
    }