(C++) QtExample33

February 24, 2017 · View on GitHub

(C++) QtExample33

Qt
Creator Lubuntu

Qt example 33: moveable and selectable arrows is a Qt example to create some arrows that are (easily) selectable and moveable.

Technical facts

Application type(s)

Desktop application

Operating system(s) or programming environment(s)

Lubuntu 15.04 (vivid)

Qt Creator 3.1.1

GUI application

C++11

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

./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(); }