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));
         }
     }
 }