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# pathstroke.cpp Example File
demos/pathstroke/pathstroke.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 versions 2.0 or 3.0 as published by the Free Software
    ** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3
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    ** granted herein.
     **
     ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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     #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
         QPixmap line_solid(":res/images/line_solid.png");
         solidLine->setIcon(line_solid);
         solidLine->setIconSize(line_solid.size());
         QPixmap line_dashed(":res/images/line_dashed.png");
         dashLine->setIcon(line_dashed);
         dashLine->setIconSize(line_dashed.size());
         QPixmap line_dotted(":res/images/line_dotted.png");
         dotLine->setIcon(line_dotted);
         dotLine->setIconSize(line_dotted.size());
         QPixmap line_dash_dot(":res/images/line_dash_dot.png");
         dashDotLine->setIcon(line_dash_dot);
         dashDotLine->setIconSize(line_dash_dot.size());
         QPixmap line_dash_dot_dot(":res/images/line_dash_dot_dot.png");
         dashDotDotLine->setIcon(line_dash_dot_dot);
         dashDotDotLine->setIconSize(line_dash_dot_dot.size());
         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");
     #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);

         // 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);
     #ifdef QT_OPENGL_SUPPORT
         mainGroupLayout->addWidget(enableOpenGLButton);
     #endif
         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()));
     #ifdef QT_OPENGL_SUPPORT
         connect(enableOpenGLButton, SIGNAL(clicked(bool)), m_renderer, SLOT(enableOpenGL(bool)));
     #endif
         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;
         }
     }