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# pathdeform.cpp Example File
demos/deform/pathdeform.cpp

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        **
        ** 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
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        **
        ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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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));
        }