(C++) QGraphicsPathItem example 1: basic

 

QGraphicsPathItem example 1: basic is a QGraphicsPathItem example. This example shows how to draw some selectable and movable QGraphicsPathItem.

 

• View a screenshot of 'CppQGraphicsPathItemExample1' (png)
• Download the Qt Creator project 'CppQGraphicsPathItemExample1' (zip)

 

 

 

 

 

Technical facts

 

Application type(s)

• Desktop application

Operating system(s) or programming environment(s)

• Lubuntu 12.10 (quantal)

IDE(s):

• Qt Creator 2.5.2

Project type:

• GUI application

C++ standard:

• C++11

Compiler(s):

• G++ 4.7.2

Libraries used:

• Qt: version 4.8.3 (32 bit)
• STL: GNU ISO C++ Library, version 4.7.2

 

 

 

 

 

Qt project file: CppQGraphicsPathItemExample1.pro

 

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QT       += core gui QMAKE_CXXFLAGS += -std=c++11 -Wall -Wextra -Werror TARGET = CppQGraphicsPathItemExample1 TEMPLATE = app SOURCES += \     qtmain.cpp \     qtwidget.cpp \     qtitem.cpp HEADERS += \     qtwidget.h \     qtitem.h

 

 

 

 

 

qtitem.h

 

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#ifndef QTITEM_H #define QTITEM_H #include <QGraphicsPathItem> struct QtItem : public QGraphicsPathItem {   QtItem(QGraphicsItem *parent = 0, QGraphicsScene *scene = 0); }; #endif // QTITEM_H

 

 

 

 

 

qtitem.cpp

 

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#include <QPainter> #include "qtitem.h" QtItem::QtItem(   QGraphicsItem *parent, QGraphicsScene *scene)   : QGraphicsPathItem(parent,scene) {   this->setFlags(       QGraphicsItem::ItemIsSelectable     | QGraphicsItem::ItemIsMovable);   //Set a simple path   QPainterPath path;   path.quadTo(100,0,100,100);   this->setPath(path); }

 

 

 

 

 

qtmain.cpp

 

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#include <QApplication> #include <QDesktopWidget> #include "qtwidget.h" 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(); }

 

 

 

 

 

qtwidget.h

 

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#ifndef QTWIDGET_H #define QTWIDGET_H #include <QGraphicsView> ///The widget holding the items struct QtWidget : public QGraphicsView {   QtWidget(QWidget *parent = 0); }; #endif // QTWIDGET_H

 

 

 

 

 

qtwidget.cpp

 

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#include <cassert> #include <QGraphicsScene> #include "qtitem.h" #include "qtwidget.h" QtWidget::QtWidget(QWidget *parent)   : QGraphicsView(new QGraphicsScene,parent) {   const int n_items = 16;   for (int i=0; i!=n_items; ++i)   {     const double angle = 2.0 * M_PI * (static_cast<double>(i) / static_cast<double>(n_items));     const double x1 =  std::sin(angle) * 100.0;     const double y1 = -std::cos(angle) * 100.0;     QtItem * const item = new QtItem;     item->setPos(x1,y1);     scene()->addItem(item);   } }