(C++) QtExample29

 

 

Qt example 29: bouncing balls widget is a Qt Example that uses QGraphicsView to create a simple widget in which the items (ellipses) respond to collision with others.

 

 

 

 

 

Downloads

 

• Download the source code for Qt example 29 (zip)
• View a screenshot of Qt example 29 (png)

Technical facts

 

Application type(s)

• Desktop application

Operating system(s) or programming environment(s)

• Lubuntu 15.04 (vivid)

IDE(s):

• Qt Creator 3.1.1

Project type:

• GUI application

C++ standard:

• C++11

Compiler(s):

• G++ 4.9.2

Libraries used:

• Qt: version 5.4.1 (32 bit)
• STL: GNU ISO C++ Library, version 4.9.2

 

 

 

 

 

Qt project file: ./CppQtExample29/CppQtExample29.pro

 

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exists(../../DesktopApplication.pri) {   include(../../DesktopApplication.pri) } !exists(../../DesktopApplication.pri) {   QT += core gui   greaterThan(QT_MAJOR_VERSION, 4): QT += widgets   TEMPLATE = app   CONFIG(debug, debug|release) {     message(Debug mode)   }   CONFIG(release, debug|release) {     message(Release mode)     DEFINES += NDEBUG NTRACE_BILDERBIKKEL   }   QMAKE_CXXFLAGS += -std=c++11 -Wall -Wextra   unix {     QMAKE_CXXFLAGS += -Werror   } } exists(../../Libraries/Boost.pri) {   include(../../Libraries/Boost.pri) } !exists(../../Libraries/Boost.pri) {   win32 {     INCLUDEPATH += \       ../../../Projects/Libraries/boost_1_55_0   } } SOURCES += \     qttooltestbouncingballswidgetmaindialog.cpp \     qtmain.cpp \     qtbouncingballswidget.cpp \     qtbouncingball.cpp HEADERS  += \     qttooltestbouncingballswidgetmaindialog.h \     qtbouncingballswidget.h \     qtbouncingball.h FORMS    += qttooltestbouncingballswidgetmaindialog.ui

 

 

 

 

 

./CppQtExample29/qtbouncingball.h

 

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#ifndef QTBOUNCINGBALL_H #define QTBOUNCINGBALL_H #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <QGraphicsItem> #pragma GCC diagnostic pop struct QGraphicsScene; struct QtBouncingRect : public QGraphicsItem {   QtBouncingRect(QGraphicsItem *parent, QGraphicsScene *scene);   ///Make the balls move   void advance(int phase);   ///Thanks compiler for reminding me to add this member function!   QRectF boundingRect() const;   ///The real collision shape   QPainterPath shape() const;   ///Thanks compiler for reminding me to add this member function!   void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);   private:   ///Use simplified physics in this example   ///Horizontal speed (delta x)   double m_dx;   ///Use simplified physics in this example   ///Vertical speed (delta y)   double m_dy;   ///The scene this class is in   QGraphicsScene * const m_scene; }; #endif // QTBOUNCINGBALL_H

 

 

 

 

 

./CppQtExample29/qtbouncingball.cpp

 

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#include <cassert> #include <cmath> #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <QGraphicsItem> #include <QGraphicsScene> #include <QList> #include <QPainter> #include "qtbouncingball.h" #pragma GCC diagnostic pop QtBouncingRect::QtBouncingRect(QGraphicsItem *parent, QGraphicsScene *scene) : QGraphicsItem(parent),    m_dx(1.0), m_dy(1.0), m_scene(scene) {   assert(m_scene && "An initialized QGraphicsScene must be supplied");   m_scene->addItem(this); } void QtBouncingRect::advance(int /* phase */) {   if (x() + m_dx + (boundingRect().width() * 0.5) > m_scene->width()) m_dx = -std::abs(m_dx);   else if (x() + m_dx - (boundingRect().width() * 0.5) < 0.0) m_dx = std::abs(m_dx);   if (y() + m_dy + (boundingRect().height() * 0.5) > m_scene->height()) m_dy = -std::abs(m_dy);   else if (y() + m_dy - (boundingRect().width() * 0.5) < 0.0) m_dy = std::abs(m_dy);   this->setPos(x() + m_dx, y() + m_dy);   //Respond to collision with other item   const QList<QGraphicsItem *> others = collidingItems();   if (others.isEmpty()) return;   const QGraphicsItem * const other = others[0];   if (this->x() < other->x()) m_dx = -std::abs(m_dx);   else if (this->x() > other->x()) m_dx =  std::abs(m_dx);   if (this->y() < other->y()) m_dy = -std::abs(m_dy);   else if (this->y() > other->y()) m_dy =  std::abs(m_dy);   this->setPos(x() + m_dx, y() + m_dy);   this->setPos(x() + m_dx, y() + m_dy); } QRectF QtBouncingRect::boundingRect() const {   return QRectF(-16.0,-16.0,32.0,32.0); } void QtBouncingRect::paint(   QPainter *painter,   const QStyleOptionGraphicsItem * /* option */,   QWidget * /* widget */) {   painter->drawEllipse(this->boundingRect()); } QPainterPath QtBouncingRect::shape() const {   QPainterPath p;   p.addEllipse(boundingRect());   return p; }

 

 

 

 

 

./CppQtExample29/qtbouncingballswidget.h

 

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#ifndef QTBOUNCINGBALLSWIDGET_H #define QTBOUNCINGBALLSWIDGET_H #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <QGraphicsView> #pragma GCC diagnostic pop struct QGraphicsScene; struct QtBouncingRectsWidget : public QGraphicsView {   QtBouncingRectsWidget(QWidget *parent = 0);   protected:   void resizeEvent(QResizeEvent *event);   private:   QGraphicsScene * const m_scene; }; #endif // QTBOUNCINGBALLSWIDGET_H

 

 

 

 

 

./CppQtExample29/qtbouncingballswidget.cpp

 

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#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <QTimer> #include <QGraphicsScene> #include "qtbouncingball.h" #include "qtbouncingballswidget.h" #pragma GCC diagnostic pop QtBouncingRectsWidget::QtBouncingRectsWidget(QWidget *parent)   : QGraphicsView(parent),     m_scene(new QGraphicsScene(this->rect(),this)) {   this->setScene(m_scene);   for (int i=0; i!=3; ++i)   {     QtBouncingRect * const ball = new QtBouncingRect(0,m_scene);     ball->setPos(       static_cast<double>((i - 1) * 32) + (0.5 * static_cast<double>(width())),       static_cast<double>((i - 1) * 32) + (0.5 * static_cast<double>(height())));   }   {     QTimer * const timer = new QTimer(this);     QObject::connect(timer,SIGNAL(timeout()),m_scene,SLOT(advance()));     timer->setInterval(20);     timer->start();   }   //Turn off the scrollbars, as they look ugly   this->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);   this->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff); } void QtBouncingRectsWidget::resizeEvent(QResizeEvent *) {   m_scene->setSceneRect(this->rect()); }

 

 

 

 

 

./CppQtExample29/qtmain.cpp

 

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#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <QApplication> #include "qttooltestbouncingballswidgetmaindialog.h" #pragma GCC diagnostic pop int main(int argc, char *argv[]) {   QApplication a(argc, argv);   QtToolTestBouncingBallsWidgetMainDialog w;   w.show();   return a.exec(); }

 

 

 

 

 

./CppQtExample29/qttooltestbouncingballswidgetmaindialog.h

 

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#ifndef QTTOOLTESTBOUNCINGBALLSWIDGETMAINDIALOG_H #define QTTOOLTESTBOUNCINGBALLSWIDGETMAINDIALOG_H #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <QDialog> #pragma GCC diagnostic pop namespace Ui { class QtToolTestBouncingBallsWidgetMainDialog; } class QtToolTestBouncingBallsWidgetMainDialog : public QDialog {     Q_OBJECT      public:   explicit QtToolTestBouncingBallsWidgetMainDialog(QWidget *parent = 0);   QtToolTestBouncingBallsWidgetMainDialog(const QtToolTestBouncingBallsWidgetMainDialog&) = delete;   QtToolTestBouncingBallsWidgetMainDialog& operator=(const QtToolTestBouncingBallsWidgetMainDialog&) = delete;   ~QtToolTestBouncingBallsWidgetMainDialog();      private:   Ui::QtToolTestBouncingBallsWidgetMainDialog *ui; }; #endif // QTTOOLTESTBOUNCINGBALLSWIDGETMAINDIALOG_H

 

 

 

 

 

./CppQtExample29/qttooltestbouncingballswidgetmaindialog.cpp

 

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#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include "qtbouncingballswidget.h" #include "qttooltestbouncingballswidgetmaindialog.h" #include "ui_qttooltestbouncingballswidgetmaindialog.h" #pragma GCC diagnostic pop QtToolTestBouncingBallsWidgetMainDialog::QtToolTestBouncingBallsWidgetMainDialog(QWidget *parent) :     QDialog(parent),     ui(new Ui::QtToolTestBouncingBallsWidgetMainDialog) {   ui->setupUi(this);   ui->layout->addWidget(new QtBouncingRectsWidget(this)); } QtToolTestBouncingBallsWidgetMainDialog::~QtToolTestBouncingBallsWidgetMainDialog() {   delete ui; }