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# displaywidget.cpp Example File
tools/qtdemo/displaywidget.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
     **
     ** This file is part of the example classes 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
     ** General Public Licensing requirements will be met:
     ** http://www.trolltech.com/products/qt/opensource.html
     **
     ** If you are unsure which license is appropriate for your use, please
     ** review the following information:
     ** http://www.trolltech.com/products/qt/licensing.html or contact the
     ** sales department at sales@trolltech.com.
     **
     ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
     ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
     **
     ****************************************************************************/

     #include <QtGui>

     #if defined(Q_WS_X11)
     #include <QTime>
     #include <private/qt_x11_p.h>
     #endif

     #include "displayshape.h"
     #include "displaywidget.h"

     DisplayWidget::DisplayWidget(QWidget *parent)
         : QWidget(parent)
     {
     #if defined(Q_WS_X11)
         frameTime = 0;
         avgRate = 0;
         numFrames = 0;
         testDrawSpeed = true;
     #endif
         empty = true;
         emptying = false;

         enableUpdates();

         setBackgroundRole(QPalette::Base);
         setMouseTracking(true);
     }

     void DisplayWidget::appendShape(DisplayShape *shape)
     {
         shapes.append(shape);
         empty = false;
         enableUpdates();
     }

     void DisplayWidget::insertShape(int position, DisplayShape *shape)
     {
         shapes.insert(position, shape);
         empty = false;
         enableUpdates();
     }

     QSize DisplayWidget::minimumSizeHint() const
     {
         return QSize(800, 600);
     }

     void DisplayWidget::mouseMoveEvent(QMouseEvent *event)
     {
         if (emptying)
             return;

         bool updated = false;

         foreach (DisplayShape *shape, shapes) {
             if (shape->rect().contains(event->pos())) {
                 if (shape->isInteractive() && !shape->contains("fade")
                     && !shape->contains("highlight")) {
                     shape->setMetaData("highlight", true);
                     updated = true;
                 }
             } else if (shape->isInteractive() && shape->contains("highlight")
                        && shape->metaData("highlight").toBool()) {
                 shape->setMetaData("highlight", false);
                 updated = true;
             }
         }

         if (updated)
             enableUpdates();
     }

     void DisplayWidget::mousePressEvent(QMouseEvent *event)
     {
         if (event->button() != Qt::LeftButton)
             return;

         if (emptying)
             return;

         foreach (DisplayShape *shape, shapes) {
             if (shape->rect().contains(event->pos()) && !shape->contains("fade")) {
                 if (shape->contains("action"))
                     emit actionRequested(shape->metaData("action").toString());
                 else if (shape->contains("category"))
                     emit categoryRequested(shape->metaData("category").toString());
                 else if (shape->contains("example"))
                     emit exampleRequested(shape->metaData("example").toString());
                 else if (shape->contains("documentation")) {
                     emit documentationRequested(
                         shape->metaData("documentation").toString());
                     shape->setMetaData("highlight", false);
                     enableUpdates();
                 } else if (shape->contains("launch")) {
                     emit launchRequested(shape->metaData("launch").toString());
                     shape->setMetaData("fade", -5);
                     enableUpdates();
                 }
             }
         }
     }

     void DisplayWidget::paintEvent(QPaintEvent *event)
     {
     #if defined(Q_WS_X11)
         QTime renderTime;
         if (testDrawSpeed)
             renderTime.restart();
     #endif

         QPainter painter;
         painter.begin(this);
         painter.fillRect(event->rect(), Qt::white);
         foreach (DisplayShape *shape, shapes) {
             if (shape->rect().intersects(event->rect()))
                 shape->paint(&painter);
         }
         painter.end();

     #if defined(Q_WS_X11)
         if (testDrawSpeed) {
             numFrames++;
             frameTime += renderTime.elapsed();
             avgRate = frameTime/numFrames;
             if (numFrames > 20) {
                 testDrawSpeed = false;
                 if (avgRate > 50 && X11->use_xrender)
                     QTimer::singleShot(0, this, SLOT(toggleXRender()));
             }
         }
     #endif
     }

     #if defined(Q_WS_X11)
     void DisplayWidget::toggleXRender()
     {
         timer.stop();
         int result = QMessageBox::question(this,
                                            QObject::tr("Disable XRender?"),
                                            QObject::tr("Your XRender implementation does not appear to be accelerated.\n"
                                                        "This may cause this demo to run very slowly.\n"
                                                        "Do you wish to turn XRender support off in this demo to improve\n"
                                                        "the frame rate?"),
                                            QMessageBox::Yes|QMessageBox::No);
         if (result == QMessageBox::Yes)
             X11->use_xrender = false;
         enableUpdates();
     }
     #endif

     void DisplayWidget::reset()
     {
         if (emptying)
             return;

         if (shapes.size() == 0) {
             empty = true;
             timer.stop();
             emit displayEmpty();    // Note: synchronous signal
         } else {
             enableUpdates();
             emptying = true;
             empty = false;
             foreach (DisplayShape *shape, shapes) {
                 shape->setMetaData("fade", -15);
                 shape->setMetaData("fade minimum", 0);
             }
         }
     }

     DisplayShape *DisplayWidget::shape(int index) const
     {
         return shapes.value(index);
     }

     int DisplayWidget::shapesCount() const
     {
         return shapes.size();
     }

     void DisplayWidget::enableUpdates()
     {
         if (!timer.isActive())
             timer.start(25, this);
     }

     void DisplayWidget::timerEvent(QTimerEvent *event)
     {
         if (event->timerId() == timer.timerId()) {
             QVector<DisplayShape*> discard;

             int updated = 0;

             foreach (DisplayShape *shape, shapes) {
                 QRect oldRect = shape->rect().toRect().adjusted(-1,-1,1,1);
                 if (shape->animate()) {

                     update(oldRect);
                     QRect newRect = shape->rect().toRect().adjusted(-1,-1,1,1);
                     ++updated;

                     if (shape->contains("destroy")) {
                         discard.append(shape);
                     } else {
                         update(newRect);
                     }
                 }
             }

             if (updated == 0)
                 timer.stop();

             foreach (DisplayShape *shape, discard) {
                 shapes.removeAll(shape);
                 delete shape;
             }

             if (shapes.size() == 0 && !empty) {
                 empty = true;
                 emptying = false;
                 timer.stop();
                 emit displayEmpty();    // Note: synchronous signal
             }
         } else {
             QWidget::timerEvent(event);
         }
     }