(C++) QGraphicsSimpleTextItemExample6

 

 

QGraphicsSimpleTextItem example 6: remote texting is a QGraphicsSimpleTextItem example that displays multiple QGraphicsSimpleTextItems with a text that changes in time. These items, however, are not modified themselves: they are updated with a boost::signal2.

 

• View a screenshot of 'QGraphicsSimpleTextItemExample6' (png)
• Download the Qt Creator project 'QGraphicsSimpleTextItemExample6' (zip)
• Download a Windows executable of 'QGraphicsSimpleTextItemExample6' (zip)

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++98

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: ./CppQGraphicsSimpleTextItemExample6/CppQGraphicsSimpleTextItemExample6.pro

 

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exists(../../DesktopApplication.pri) {   include(../../DesktopApplication.pri) } !exists(../../DesktopApplication.pri) {   QT       += core gui   greaterThan(QT_MAJOR_VERSION, 4): QT += widgets   win32 {     greaterThan(QT_MAJOR_VERSION, 4): QT += svg   }   TEMPLATE = app   CONFIG(debug, debug|release) {     message(Debug mode)   }   CONFIG(release, debug|release) {     message(Release mode)     DEFINES += NDEBUG NTRACE_BILDERBIKKEL   }   QMAKE_CXXFLAGS += -std=c++1y -Wall -Wextra -Weffc++   unix {     QMAKE_CXXFLAGS += -Werror   } } exists(../../Libraries/Boost.pri) {   include(../../Libraries/Boost.pri) } !exists(../../Libraries/Boost.pri) {   INCLUDEPATH += \     ../../Libraries/boost_1_55_0 } SOURCES += \     qtmain.cpp \     qtwidget.cpp \     qttextitem.cpp \     text.cpp HEADERS += \     qtwidget.h \     qttextitem.h \     text.h

 

 

 

 

 

./CppQGraphicsSimpleTextItemExample6/qtmain.cpp

 

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#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-but-set-variable" #include <QApplication> #include <QDesktopWidget> #include "qtwidget.h" #pragma GCC diagnostic pop int main(int argc, char *argv[]) {   QApplication a(argc, argv);   QtWidget w;   {     //Resize the dialog and put it in the screen center     w.setGeometry(0,0,600,400);     const QRect screen = QApplication::desktop()->screenGeometry();     w.move( screen.center() - w.rect().center() );   }   w.show();   return a.exec(); }

 

 

 

 

 

./CppQGraphicsSimpleTextItemExample6/qttextitem.h

 

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#ifndef QTTEXTITEM_H #define QTTEXTITEM_H #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-but-set-variable" #include <boost/shared_ptr.hpp> #include <QGraphicsSimpleTextItem> #pragma GCC diagnostic pop struct Text; struct QtTextItem : public QGraphicsSimpleTextItem {   QtTextItem(const boost::shared_ptr<const Text> text,     QGraphicsItem *parent = 0   );   private:   ///Read-only Text   const boost::shared_ptr<const Text> m_text;   //Respond to a change of Text   void OnTextChanged(); }; #endif // QTTEXTITEM_H

 

 

 

 

 

./CppQGraphicsSimpleTextItemExample6/qttextitem.cpp

 

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#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-but-set-variable" #include "qttextitem.h" #include <cassert> #include "text.h" #pragma GCC diagnostic pop QtTextItem::QtTextItem(   const boost::shared_ptr<const Text> text,   QGraphicsItem *parent ) : QGraphicsSimpleTextItem(parent),     m_text(text) {   this->setFlags(       QGraphicsItem::ItemIsSelectable     | QGraphicsItem::ItemIsMovable);   m_text->m_signal_text_changed.connect(     boost::bind(&QtTextItem::OnTextChanged,this));   this->setText(m_text->GetText().c_str()); } void QtTextItem::OnTextChanged() {   this->setText(m_text->GetText().c_str());   //this->update(); //No need to }

 

 

 

 

 

./CppQGraphicsSimpleTextItemExample6/qtwidget.h

 

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#ifndef QTWIDGET_H #define QTWIDGET_H #include <vector> #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-but-set-variable" #include <boost/shared_ptr.hpp> #include <QGraphicsView> #pragma GCC diagnostic pop struct Text; ///The widget holding the items ///Must be a Q_OBJECT for slots to work class QtWidget : public QGraphicsView {   Q_OBJECT   public:   QtWidget(QWidget *parent = 0);   private slots:   void OnTimer();   private:   std::vector<boost::shared_ptr<Text> > m_texts; }; #endif // QTWIDGET_H

 

 

 

 

 

./CppQGraphicsSimpleTextItemExample6/qtwidget.cpp

 

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#include "qtwidget.h" #include <cassert> #include <cmath> #include <sstream> #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-but-set-variable" #include <boost/math/constants/constants.hpp> #include <QGraphicsScene> #include <QTimer> #include "qttextitem.h" #include "text.h" #pragma GCC diagnostic pop QtWidget::QtWidget(QWidget *parent)   : QGraphicsView(new QGraphicsScene,parent),     m_texts{} {   const int n_items = 16;   //Create the Texts   for (int i=0; i!=n_items; ++i)   {     boost::shared_ptr<Text> text(new Text("*"));     m_texts.push_back(text);   }   //Create the QtTextItems   for (int i=0; i!=n_items; ++i)   {     const double angle       = boost::math::constants::two_pi<double>()       * (static_cast<double>(i+0) / static_cast<double>(n_items));     const double ray = 150.0;     const double x =  std::sin(angle) * ray;     const double y = -std::cos(angle) * ray;     QtTextItem * const item = new QtTextItem(m_texts.at(i));     item->setPos(x,y);     scene()->addItem(item);   }   //Create and start a timer   {     QTimer * const timer(new QTimer(this));     QObject::connect(timer,SIGNAL(timeout()),this,SLOT(OnTimer()));     timer->setInterval(100);     timer->start();   } } void QtWidget::OnTimer() {   const boost::shared_ptr<Text>& text = m_texts[ std::rand() % m_texts.size() ];   text->SetText(text->GetText() + "*"); }

 

 

 

 

 

./CppQGraphicsSimpleTextItemExample6/text.h

 

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#ifndef TEXT_H #define TEXT_H #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-but-set-variable" #include <boost/signals2.hpp> #pragma GCC diagnostic pop struct Text {   Text(const std::string& text);   const std::string& GetText() const { return m_text; }   void SetText(const std::string& text);   ///Allow a const Text to send signals   mutable boost::signals2::signal<void()> m_signal_text_changed;   private:   std::string m_text; }; #endif // TEXT_H

 

 

 

 

 

./CppQGraphicsSimpleTextItemExample6/text.cpp

 

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#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #pragma GCC diagnostic ignored "-Wunused-but-set-variable" #include "text.h" #pragma GCC diagnostic pop Text::Text(const std::string& text)   : m_signal_text_changed{},     m_text(text) { } void Text::SetText(const std::string& text) {   m_text = text;   m_signal_text_changed(); }