mainwindow.cpp Example File | Qt Widgets 5.12.9

- Qt 5.12
- Qt Widgets
- Plug & Paint Example
- mainwindow.cpp Example File
- Qt 5.12.9 Reference Documentation

# mainwindow.cpp Example File

tools/plugandpaint/app/mainwindow.cpp

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     #include "interfaces.h"
     #include "mainwindow.h"
     #include "paintarea.h"
     #include "plugindialog.h"

     #include <QAction>
     #include <QActionGroup>
     #include <QApplication>
     #include <QColorDialog>
     #include <QFileDialog>
     #include <QInputDialog>
     #include <QMenu>
     #include <QMenuBar>
     #include <QMessageBox>
     #include <QPluginLoader>
     #include <QScrollArea>
     #include <QTimer>

     MainWindow::MainWindow() :
         paintArea(new PaintArea),
         scrollArea(new QScrollArea)
     {
         scrollArea->setBackgroundRole(QPalette::Dark);
         scrollArea->setWidget(paintArea);
         setCentralWidget(scrollArea);

         createActions();
         createMenus();
         loadPlugins();

         setWindowTitle(tr("Plug & Paint"));

         if (!brushActionGroup->actions().isEmpty())
             brushActionGroup->actions().first()->trigger();

         QTimer::singleShot(500, this, &MainWindow::aboutPlugins);
     }

     void MainWindow::open()
     {
         const QString fileName = QFileDialog::getOpenFileName(this,
                                                               tr("Open File"),
                                                               QDir::currentPath());
         if (!fileName.isEmpty()) {
             if (!paintArea->openImage(fileName)) {
                 QMessageBox::information(this, tr("Plug & Paint"),
                                          tr("Cannot load %1.").arg(fileName));
                 return;
             }
             paintArea->adjustSize();
         }
     }

     bool MainWindow::saveAs()
     {
         const QString initialPath = QDir::currentPath() + "/untitled.png";

         const QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
                                                               initialPath);
         if (fileName.isEmpty())
             return false;

         return paintArea->saveImage(fileName, "png");
     }

     void MainWindow::brushColor()
     {
         const QColor newColor = QColorDialog::getColor(paintArea->brushColor());
         if (newColor.isValid())
             paintArea->setBrushColor(newColor);
     }

     void MainWindow::brushWidth()
     {
         bool ok;
         const int newWidth = QInputDialog::getInt(this, tr("Plug & Paint"),
                                                   tr("Select brush width:"),
                                                   paintArea->brushWidth(),
                                                   1, 50, 1, &ok);
         if (ok)
             paintArea->setBrushWidth(newWidth);
     }

     void MainWindow::changeBrush()
     {
         auto action = qobject_cast<QAction *>(sender());
         auto iBrush = qobject_cast<BrushInterface *>(action->parent());
         const QString brush = action->text();

         paintArea->setBrush(iBrush, brush);
     }

     void MainWindow::insertShape()
     {
         auto action = qobject_cast<QAction *>(sender());
         auto iShape = qobject_cast<ShapeInterface *>(action->parent());

         const QPainterPath path = iShape->generateShape(action->text(), this);
         if (!path.isEmpty())
             paintArea->insertShape(path);
     }

     void MainWindow::applyFilter()
     {
         auto action = qobject_cast<QAction *>(sender());
         auto iFilter = qobject_cast<FilterInterface *>(action->parent());

         const QImage image = iFilter->filterImage(action->text(), paintArea->image(),
                                                   this);
         paintArea->setImage(image);
     }

     void MainWindow::about()
     {
        QMessageBox::about(this, tr("About Plug & Paint"),
                 tr("The <b>Plug & Paint</b> example demonstrates how to write Qt "
                    "applications that can be extended through plugins."));
     }

     void MainWindow::aboutPlugins()
     {
         PluginDialog dialog(pluginsDir.path(), pluginFileNames, this);
         dialog.exec();
     }

     void MainWindow::createActions()
     {
         openAct = new QAction(tr("&Open..."), this);
         openAct->setShortcuts(QKeySequence::Open);
         connect(openAct, &QAction::triggered, this, &MainWindow::open);

         saveAsAct = new QAction(tr("&Save As..."), this);
         saveAsAct->setShortcuts(QKeySequence::SaveAs);
         connect(saveAsAct, &QAction::triggered, this, &MainWindow::saveAs);

         exitAct = new QAction(tr("E&xit"), this);
         exitAct->setShortcuts(QKeySequence::Quit);
         connect(exitAct, &QAction::triggered, this, &MainWindow::close);

         brushColorAct = new QAction(tr("&Brush Color..."), this);
         connect(brushColorAct, &QAction::triggered, this, &MainWindow::brushColor);

         brushWidthAct = new QAction(tr("&Brush Width..."), this);
         connect(brushWidthAct, &QAction::triggered, this, &MainWindow::brushWidth);

         brushActionGroup = new QActionGroup(this);

         aboutAct = new QAction(tr("&About"), this);
         connect(aboutAct, &QAction::triggered, this, &MainWindow::about);

         aboutQtAct = new QAction(tr("About &Qt"), this);
         connect(aboutQtAct, &QAction::triggered, qApp, &QApplication::aboutQt);

         aboutPluginsAct = new QAction(tr("About &Plugins"), this);
         connect(aboutPluginsAct, &QAction::triggered, this, &MainWindow::aboutPlugins);
     }

     void MainWindow::createMenus()
     {
         fileMenu = menuBar()->addMenu(tr("&File"));
         fileMenu->addAction(openAct);
         fileMenu->addAction(saveAsAct);
         fileMenu->addSeparator();
         fileMenu->addAction(exitAct);

         brushMenu = menuBar()->addMenu(tr("&Brush"));
         brushMenu->addAction(brushColorAct);
         brushMenu->addAction(brushWidthAct);
         brushMenu->addSeparator();

         shapesMenu = menuBar()->addMenu(tr("&Shapes"));

         filterMenu = menuBar()->addMenu(tr("&Filter"));

         menuBar()->addSeparator();

         helpMenu = menuBar()->addMenu(tr("&Help"));
         helpMenu->addAction(aboutAct);
         helpMenu->addAction(aboutQtAct);
         helpMenu->addAction(aboutPluginsAct);
     }

     void MainWindow::loadPlugins()
     {
         const auto staticInstances = QPluginLoader::staticInstances();
         for (QObject *plugin : staticInstances)
             populateMenus(plugin);

         pluginsDir = QDir(qApp->applicationDirPath());

     #if defined(Q_OS_WIN)
         if (pluginsDir.dirName().toLower() == "debug" || pluginsDir.dirName().toLower() == "release")
             pluginsDir.cdUp();
     #elif defined(Q_OS_MAC)
         if (pluginsDir.dirName() == "MacOS") {
             pluginsDir.cdUp();
             pluginsDir.cdUp();
             pluginsDir.cdUp();
         }
     #endif
         pluginsDir.cd("plugins");

         const auto entryList = pluginsDir.entryList(QDir::Files);
         for (const QString &fileName : entryList) {
             QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
             QObject *plugin = loader.instance();
             if (plugin) {
                 populateMenus(plugin);
                 pluginFileNames += fileName;
             }
         }

         brushMenu->setEnabled(!brushActionGroup->actions().isEmpty());
         shapesMenu->setEnabled(!shapesMenu->actions().isEmpty());
         filterMenu->setEnabled(!filterMenu->actions().isEmpty());
     }

     void MainWindow::populateMenus(QObject *plugin)
     {
         auto iBrush = qobject_cast<BrushInterface *>(plugin);
         if (iBrush)
             addToMenu(plugin, iBrush->brushes(), brushMenu, &MainWindow::changeBrush,
                       brushActionGroup);

         auto iShape = qobject_cast<ShapeInterface *>(plugin);
         if (iShape)
             addToMenu(plugin, iShape->shapes(), shapesMenu, &MainWindow::insertShape);

         auto iFilter = qobject_cast<FilterInterface *>(plugin);
         if (iFilter)
             addToMenu(plugin, iFilter->filters(), filterMenu, &MainWindow::applyFilter);
     }

     void MainWindow::addToMenu(QObject *plugin, const QStringList &texts,
                                QMenu *menu, Member member,
                                QActionGroup *actionGroup)
     {
         for (const QString &text : texts) {
             auto action = new QAction(text, plugin);
             connect(action, &QAction::triggered, this, member);
             menu->addAction(action);

             if (actionGroup) {
                 action->setCheckable(true);
                 actionGroup->addAction(action);
             }
         }
     }