Qt example 3: a changing background in 2D is a Qt example that shows a changing background in 2D, like this screenshot (png).
Operating system(s) or programming environment(s)
Lubuntu 15.04 (vivid)
Qt Creator 3.1.1
- G++ 4.9.2
Libraries used:
Qt project file: ./CppQtExample3/CppQtExample3.pro
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 += main.cpp
#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <boost/shared_ptr.hpp> #include <QApplication> #include <QDesktopWidget> #include <QGraphicsPixmapItem> #include <QGraphicsScene> #include <QGraphicsView> #include <QTimer> #pragma GCC diagnostic pop struct ChangingBackground : public QGraphicsPixmapItem { ChangingBackground(const int width, const int height) : z(0) { QPixmap m(width,height); this->setPixmap(m); } void advance(int) { QImage i = this->pixmap().toImage(); const int width = i.width(); const int height = i.height(); for (int y=0;y!=height;++y) { for (int x=0;x!=width;++x) { i.setPixel( QPoint(x,y), //Position QColor( //Color (x+z+0)%256, (y+z+0)%256, (x+y+z)%256) .rgb()); } } this->setPixmap(this->pixmap().fromImage(i)); ++z; } private: int z; }; int main(int argc, char *argv[]) { QApplication a(argc, argv); //Create a scene to add the background sprite to boost::shared_ptr<QGraphicsScene> scene(new QGraphicsScene); //Create a background sprite to add to the scene boost::shared_ptr<ChangingBackground> background( new ChangingBackground(256,256)); scene->addItem(background.get()); //Create a view to display the scene boost::shared_ptr<QGraphicsView> view(new QGraphicsView); view->setScene(scene.get()); //Create a timer to call 'advance' on the scene and its sprite boost::shared_ptr<QTimer> timer(new QTimer(scene.get())); timer->connect(timer.get(), SIGNAL(timeout()), scene.get(), SLOT(advance())); timer->start(20); //Display the view view->show(); //Move the view to the screen center const QRect screen = QApplication::desktop()->screenGeometry(); view->move( screen.center() - view->rect().center() ); return a.exec(); }