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: ./CppQtExample33/CppQtExample33.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 += \

    qtmain.cpp \

    dialog.cpp \

    qtarrowswidget.cpp \

    qtarrowitem.cpp



HEADERS += \

    dialog.h \

    qtarrowswidget.h \

    qtarrowitem.h



FORMS += dialog.ui

./CppQtExample33/dialog.h


#ifndef DIALOG_H

#define DIALOG_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 Dialog;

}



class Dialog : public QDialog

{

  Q_OBJECT

    

public:

  explicit Dialog(QWidget *parent = 0);

  Dialog(const Dialog&) = delete;

  Dialog& operator=(const Dialog&) = delete;

  ~Dialog() noexcept;

    

private:

  Ui::Dialog *ui;

};



#endif // DIALOG_H

./CppQtExample33/dialog.cpp


#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include "qtarrowswidget.h"

#include "dialog.h"

#include "ui_dialog.h"

#pragma GCC diagnostic pop



Dialog::Dialog(QWidget *parent) :

    QDialog(parent),

    ui(new Ui::Dialog)

{

  ui->setupUi(this);

  ui->layout->addWidget(new QtArrowsWidget);

}



Dialog::~Dialog() noexcept

{

  delete ui;

}

./CppQtExample33/qtarrowitem.h


#ifndef QTARROWITEM_H

#define QTARROWITEM_H



#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <QGraphicsLineItem>

#pragma GCC diagnostic pop



struct QtArrowItem : public QGraphicsLineItem

{

  QtArrowItem(

    const double x1,

    const double y1,

    const bool tail,

    const double x2,

    const double y2,

    const bool head,

    QGraphicsItem *parent = 0);



  protected:

  ///Paint a QtTextPositionItem

  void paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *);



  ///The rectangle that containg the item, used for rough calculations like

  ///collision detection

  QRectF boundingRect() const;



  ///More precise shape compared to boundingRect

  ///In this example, it is redefined to ease selecting those thin lines

  QPainterPath shape() const;



  private:

  ///Show arrow at head

  const bool m_head;



  ///Show arrow at tail

  const bool m_tail;



  ///Obtain the angle in radians between two deltas

  ///12 o'clock is 0.0 * pi

  /// 3 o'clock is 0.5 * pi

  /// 6 o'clock is 1.0 * pi

  /// 9 o'clock is 1.5 * pi

  //From www.richelbilderbeek.nl/CppGetAngle.htm

  static double GetAngle(const double dx, const double dy);



};



#endif // QTARROWITEM_H

./CppQtExample33/qtarrowitem.cpp


#include <cmath>



#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <boost/math/constants/constants.hpp>

#include <QPainter>

#include "qtarrowitem.h"

#pragma GCC diagnostic pop



QtArrowItem::QtArrowItem(

  const double x1,

  const double y1,

  const bool tail,

  const double x2,

  const double y2,

  const bool head,

  QGraphicsItem *parent)

  : QGraphicsLineItem(x1,y1,x2,y2,parent),

    m_head(head),

    m_tail(tail)

{

  this->setFlag(QGraphicsItem::ItemIsMovable);

  this->setFlag(QGraphicsItem::ItemIsSelectable);

}



double QtArrowItem::GetAngle(const double dx, const double dy)

{

  return boost::math::constants::pi<double>() - (std::atan(dx/dy));

}



QPainterPath QtArrowItem::shape() const

{

  //Thanks to norobro for posting this code at 

  //http://www.qtcentre.org/threads/49201-Increase-margin-for-detecting-tooltip-events-of-QGraphicsLineItem

  QPainterPath path;

  QPainterPathStroker stroker;

  path.moveTo(line().p1());

  path.lineTo(line().p2());

  stroker.setWidth(10);

  return stroker.createStroke(path);

}



QRectF QtArrowItem::boundingRect() const

{

  return shape().boundingRect();

}



void QtArrowItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)

{

  painter->setRenderHint(QPainter::Antialiasing);

  if (this->isSelected())

  {

    const QColor color(255,0,0);

    QPen pen;

    pen.setColor(color);

    pen.setWidth(3);

    painter->setPen(pen);

    QBrush brush;

    brush.setColor(color);

    brush.setStyle(Qt::SolidPattern);

    painter->setBrush(brush);

  }

  else

  {

    const QColor color(0,0,0);

    QPen pen;

    pen.setColor(color);

    pen.setWidth(1);

    painter->setPen(pen);

    QBrush brush;

    brush.setColor(color);

    brush.setStyle(Qt::SolidPattern);

    painter->setBrush(brush);

  }

  painter->drawLine(this->line());



  //The angle from tail to head

  double angle = GetAngle(line().dx(),line().dy());

  if (line().dy() >= 0.0) angle = (1.0 * boost::math::constants::pi<double>()) + angle;

  const double sz = 10.0; //pixels

  {

    const QPointF p0 = this->line().p1();

    const QPointF p1

      = p0 + QPointF(

         std::sin(angle + boost::math::constants::pi<double>() + (boost::math::constants::pi<double>() * 0.1)) * sz,

        -std::cos(angle + boost::math::constants::pi<double>() + (boost::math::constants::pi<double>() * 0.1)) * sz);

    const QPointF p2

      = p0 + QPointF(

         std::sin(angle + boost::math::constants::pi<double>() - (boost::math::constants::pi<double>() * 0.1)) * sz,

        -std::cos(angle + boost::math::constants::pi<double>() - (boost::math::constants::pi<double>() * 0.1)) * sz);

    painter->drawPolygon(QPolygonF() << p0 << p1 << p2);

  }

  {

    const QPointF p0 = this->line().p2();



    const QPointF p1

      = p0 + QPointF(

         std::sin(angle +  0.0 + (boost::math::constants::pi<double>() * 0.1)) * sz,

        -std::cos(angle +  0.0 + (boost::math::constants::pi<double>() * 0.1)) * sz);

    const QPointF p2

      = p0 + QPointF(

         std::sin(angle +  0.0 - (boost::math::constants::pi<double>() * 0.1)) * sz,

        -std::cos(angle +  0.0 - (boost::math::constants::pi<double>() * 0.1)) * sz);



    painter->drawPolygon(QPolygonF() << p0 << p1 << p2);

  }

}

./CppQtExample33/qtarrowswidget.h


#ifndef QTARROWSWIDGET_H

#define QTARROWSWIDGET_H



#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <QGraphicsView>

#pragma GCC diagnostic pop



struct QtArrowsWidget : public QGraphicsView

{

  QtArrowsWidget();

};



#endif // QTARROWSWIDGET_H

./CppQtExample33/qtarrowswidget.cpp


#include <cassert>



#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <boost/math/constants/constants.hpp>

#include <QGraphicsScene>

#include <QGraphicsPixmapItem>

#include "qtarrowitem.h"

#include "qtarrowswidget.h"

#pragma GCC diagnostic pop



QtArrowsWidget::QtArrowsWidget()

{

  QGraphicsScene * const scene = new QGraphicsScene(this);

  this->setScene(scene);



  const int n_arrows = 16;

  for (int i=0; i!=n_arrows; ++i)

  {

    const double angle = boost::math::constants::two_pi<double>() * (static_cast<double>(i) / static_cast<double>(n_arrows));



    const double x1 =  std::sin(angle) * 100.0;

    const double y1 = -std::cos(angle) * 100.0;

    const bool tail = (std::rand() >> 4) % 2;

    const double x2 =  std::sin(angle) * 200.0;

    const double y2 = -std::cos(angle) * 200.0;

    //const double x2 = ((static_cast<double>(std::rand()) / static_cast<double>(RAND_MAX)) * 600.0) - 300.0;

    //const double y2 = ((static_cast<double>(std::rand()) / static_cast<double>(RAND_MAX)) * 400.0) - 200.0;

    const bool head = (std::rand() >> 4) % 2;



    QtArrowItem * item = new QtArrowItem(x1,y1,tail,x2,y2,head);

    scene->addItem(item);

  }

}

./CppQtExample33/qtmain.cpp


#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <QApplication>

#include <QDesktopWidget>

#include "dialog.h"

#pragma GCC diagnostic pop



int main(int argc, char *argv[])

{

  QApplication a(argc, argv);

  Dialog 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();

}

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

This page has been created by the tool CodeToHtml

(C++) QtExample33

Technical facts

Qt project file: ./CppQtExample33/CppQtExample33.pro

./CppQtExample33/dialog.h

./CppQtExample33/dialog.cpp

./CppQtExample33/qtarrowitem.h

./CppQtExample33/qtarrowitem.cpp

./CppQtExample33/qtarrowswidget.h

./CppQtExample33/qtarrowswidget.cpp

./CppQtExample33/qtmain.cpp