- Qt 5.5
- Qt Widgets
- Plug & Paint Example
- mainwindow.cpp Example File
- Qt 5.5.1 Reference Documentation

# mainwindow.cpp Example File

tools/plugandpaint/mainwindow.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
    **   * Redistributions in binary form must reproduce the above copyright
    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
    **   * Neither the name of The Qt Company Ltd nor the names of its
    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
    **
    **
    ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

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

    #include <QPluginLoader>
    #include <QTimer>

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

    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, SLOT(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;
        } else {
            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()
    {
        QAction *action = qobject_cast<QAction *>(sender());
        BrushInterface *iBrush = qobject_cast<BrushInterface *>(action->parent());
        const QString brush = action->text();

        paintArea->setBrush(iBrush, brush);
    }

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

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

    void MainWindow::applyFilter()
    {
        QAction *action = qobject_cast<QAction *>(sender());
        FilterInterface *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, SIGNAL(triggered()), this, SLOT(open()));

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

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

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

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

        brushActionGroup = new QActionGroup(this);

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

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

        aboutPluginsAct = new QAction(tr("About &Plugins"), this);
        connect(aboutPluginsAct, SIGNAL(triggered()), this, SLOT(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()
    {
        foreach (QObject *plugin, QPluginLoader::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");

        foreach (QString fileName, pluginsDir.entryList(QDir::Files)) {
            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)
    {
        BrushInterface *iBrush = qobject_cast<BrushInterface *>(plugin);
        if (iBrush)
            addToMenu(plugin, iBrush->brushes(), brushMenu, SLOT(changeBrush()),
                      brushActionGroup);

        ShapeInterface *iShape = qobject_cast<ShapeInterface *>(plugin);
        if (iShape)
            addToMenu(plugin, iShape->shapes(), shapesMenu, SLOT(insertShape()));

        FilterInterface *iFilter = qobject_cast<FilterInterface *>(plugin);
        if (iFilter)
            addToMenu(plugin, iFilter->filters(), filterMenu, SLOT(applyFilter()));
    }

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

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