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

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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);
     #ifdef QT_OPENGL_SUPPORT
         QPushButton *enableOpenGLButton = new QPushButton(mainGroup);
         enableOpenGLButton->setText("Use OpenGL");
         enableOpenGLButton->setCheckable(true);
         enableOpenGLButton->setChecked(m_renderer->usesOpenGL());
         if (!QGLFormat::hasOpenGL())
             enableOpenGLButton->hide();
     #endif
         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);
     #ifdef QT_OPENGL_SUPPORT
         mainGroupLayout->addWidget(enableOpenGLButton);
     #endif
         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()));
     #ifdef QT_OPENGL_SUPPORT
         connect(enableOpenGLButton, SIGNAL(clicked(bool)), m_renderer, SLOT(enableOpenGL(bool)));
     #endif
         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);
             }

     #ifdef QT_OPENGL_SUPPORT
             if (usesOpenGL()) {
                 update();
             } else
     #endif
             {
                 QRect rectAfter = circle_bounds(m_pos, m_radius, m_fontSize);
                 update(rectAfter | rectBefore);
                 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;
     #ifdef QT_OPENGL_SUPPORT
         if (usesOpenGL()) {
             update();
         } else
     #endif
         {
             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) {
             const QPainterPath::Element &e = 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) {
                 path.setElementPositionAt(i,
                                           x + flip * dx * len / m_radius,
                                           y + flip * dy * len / m_radius);
             } else {
                 path.setElementPositionAt(i, x, 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) {
     #ifdef QT_OPENGL_SUPPORT
             if (usesOpenGL()) {
                 update();
             } else
     #endif
             {
                 update(circle_bounds(m_pos, max, m_fontSize));
             }
         }
     }

     void PathDeformRenderer::setIntensity(int intensity)
     {
         m_intensity = intensity;
         if (!m_animated) {
     #ifdef QT_OPENGL_SUPPORT
             if (usesOpenGL()) {
                 update();
             } else
     #endif
             {
                 update(circle_bounds(m_pos, m_radius, m_fontSize));
             }
         }
     }