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(C++) QGraphicsRectItemExample1

 

QtQt CreatorLubuntu

 

QGraphicsRectItem example 1: Basics is a QGraphicsRectItem example that displays multiple QGraphicsRectItems. These items are movable and selectable.

 

Technical facts

 

Operating system(s) or programming environment(s)

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C++ standard:

Compiler(s):

Libraries used:

 

 

 

 

 

Qt project file: ./CppQGraphicsRectItemExample1/CppQGraphicsRectItemExample1.pro

 

include(../../DesktopApplication.pri)

SOURCES += \
    qtmain.cpp \
    qtwidget.cpp \
    qtrectitem.cpp

HEADERS += \
    qtwidget.h \
    qtrectitem.h

 

 

 

 

 

./CppQGraphicsRectItemExample1/qtmain.cpp

 

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#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();
}

 

 

 

 

 

./CppQGraphicsRectItemExample1/qtrectitem.h

 

#ifndef QTRECTITEM_H
#define QTRECTITEM_H

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#include <QGraphicsRectItem>
#pragma GCC diagnostic pop

struct QtRectItem : public QGraphicsRectItem
{
  QtRectItem(QGraphicsItem *parent = 0);
};

#endif // QTRECTITEM_H

 

 

 

 

 

./CppQGraphicsRectItemExample1/qtrectitem.cpp

 

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#include "qtrectitem.h"

#include <cassert>
#include <sstream>
#include <QGraphicsScene>
#include <QPainter>
#pragma GCC diagnostic pop

QtRectItem::QtRectItem(QGraphicsItem *parent)
: QGraphicsRectItem(parent)
{
  this->setFlags(
      QGraphicsItem::ItemIsFocusable
    | QGraphicsItem::ItemIsMovable
    | QGraphicsItem::ItemIsSelectable);
  const double width  = 64.0; //pixels
  const double height = 32.0; //pixels
  this->setRect(-0.5 * width, -0.5 * height, width, height);
}

 

 

 

 

 

./CppQGraphicsRectItemExample1/qtwidget.h

 

#ifndef QTWIDGET_H
#define QTWIDGET_H

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#include <QGraphicsView>
#pragma GCC diagnostic pop

///The widget holding the items
struct QtWidget : public QGraphicsView
{
  QtWidget(QWidget *parent = 0);
};

#endif // QTWIDGET_H

 

 

 

 

 

./CppQGraphicsRectItemExample1/qtwidget.cpp

 

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Weffc++"
#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
#pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
#include "qtwidget.h"

#include <cassert>
#include <cmath>
#include <iostream>
#include <QGraphicsScene>
#include <QKeyEvent>
#include <QGraphicsSimpleTextItem>
#include "qtrectitem.h"
#pragma GCC diagnostic pop

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 ray = 150.0;
    const double x =  std::sin(angle) * ray;
    const double y = -std::cos(angle) * ray;

    QtRectItem * const item = new QtRectItem;
    item->setPos(x,y);
    scene()->addItem(item);
  }
}

 

 

 

 

 

./CppQGraphicsRectItemExample1/crosscompiletowindows.sh

 

#!/bin/sh
#From http://richelbilderbeek.nl/CppQtCrosscompileToWindowsExample15.htm

echo "Cross compiling to Windows"

echo "1/2: Creating Windows makefile"
i686-pc-mingw32-qmake CppQGraphicsRectItemExample1.pro

echo "2/2: making makefile"

make

echo "Done"

 

 

 

 

 

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