(C++) QtExample35

February 24, 2017 · View on GitHub

(C++) QtExample35

Qt
Creator Lubuntu

Qt example 35: arrows with an angle is a Qt example elaborates on Qt example 34: moveable, selectable and editable arrows, but has arrows with an angle in them instead.

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: ./CppQtExample35/CppQtExample35.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 \ qtarrowswidget.cpp \ qtarrowitem.cpp HEADERS += \ qtarrowswidget.h \ qtarrowitem.h

./CppQtExample35/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 QGraphicsItem { QtArrowItem( const double tail_x, const double tail_y, const bool tail, const double mid_x, const double mid_y, const bool head, const double head_x, const double head_y, QGraphicsItem parent = 0); ///Respond to key presses void keyPressEvent(QKeyEvent event); protected: ///The rectangle that containg the item, used for rough calculations like ///collision detection QRectF boundingRect() const; ///Respond to mouse press void mousePressEvent(QGraphicsSceneMouseEvent event); ///Paint a QtTextPositionItem void paint(QPainter painter, const QStyleOptionGraphicsItem , QWidget ); ///More precise shape compared to boundingRect ///In this example, it is redefined to ease selecting those thin lines QPainterPath shape() const; private: ///The extra width given to the line for easier clicking static const double m_click_easy_width; ///Show arrow at head bool m_head; double m_head_x; double m_head_y; double m_mid_x; double m_mid_y; ///Show arrow at tail bool m_tail; double m_tail_x; double m_tail_y; ///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

./CppQtExample35/qtarrowitem.cpp

./CppQtExample35/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(); protected: ///Respond to a key press void keyPressEvent(QKeyEvent event); private: ///The QGraphicsScene working on QGraphicsScene const m_scene; }; #endif // QTARROWSWIDGET_H

./CppQtExample35/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() : m_scene(new QGraphicsScene(this)) { this->setScene(m_scene); const int n_arrows = 16; for (int i=0; i!=n_arrows; ++i) { const double angle = 2.0 * boost::math::constants::pi<double>() * (static_cast<double>(i) / static_cast<double>(n_arrows)); const double d_angle = (2.0 * boost::math::constants::pi<double>()) / 32.0; const double tail_x = std::sin(angle) * 100.0; const double tail_y = -std::cos(angle) * 100.0; const bool tail = (std::rand() >> 4) % 2; const double mid_x = std::sin(angle + d_angle) * 150.0; const double mid_y = -std::cos(angle + d_angle) * 150.0; const double head_x = std::sin(angle) * 200.0; const double head_y = -std::cos(angle) * 200.0; const bool head = (std::rand() >> 4) % 2; QtArrowItem * item = new QtArrowItem(tail_x,tail_y,tail,mid_x,mid_y,head,head_x,head_y); m_scene->addItem(item); } } void QtArrowsWidget::keyPressEvent(QKeyEvent event) { const QList<QGraphicsItem > v = m_scene->selectedItems(); std::for_each(v.begin(),v.end(), [event](QGraphicsItem * item) { if (QtArrowItem * const arrow = dynamic_cast<QtArrowItem*>(item)) { arrow->keyPressEvent(event); } } ); }

./CppQtExample35/qtmain.cpp

#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <QApplication> #include <QDesktopWidget> #include "qtarrowswidget.h" #pragma GCC diagnostic pop int main(int argc, char *argv[]) { QApplication a(argc, argv); QtArrowsWidget 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(); }