mainwindow.cpp Example File
^{tools/plugandpaint/mainwindow.cpp}

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    **
    ** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
    **
    ** This file is part of the documentation of the Qt Toolkit.
    **
    ** This file may be used under the terms of the GNU General Public
    ** License version 2.0 as published by the Free Software Foundation
    ** and appearing in the file LICENSE.GPL included in the packaging of
    ** this file.  Please review the following information to ensure GNU
    ** General Public Licensing requirements will be met:
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    ** review the following information:
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    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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    ****************************************************************************/

    #include <QtGui>

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

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

        QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
                                                        initialPath);
        if (fileName.isEmpty()) {
            return false;
        } else {
            return paintArea->saveImage(fileName, "png");
        }
    }

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

    void MainWindow::brushWidth()
    {
        bool ok;
        int newWidth = QInputDialog::getInteger(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());
        QString brush = action->text();

        paintArea->setBrush(iBrush, brush);
    }

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

        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());

        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->setShortcut(tr("Ctrl+O"));
        connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

        saveAsAct = new QAction(tr("&Save As..."), this);
        saveAsAct->setShortcut(tr("Ctrl+S"));
        connect(saveAsAct, SIGNAL(triggered()), this, SLOT(saveAs()));

        exitAct = new QAction(tr("E&xit"), this);
        exitAct->setShortcut(tr("Ctrl+Q"));
        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()
    {
        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) {
                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()));

                pluginFileNames += fileName;
            }
        }

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

    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);
            }
        }
    }