- Qt 5.5
- Qt Widgets
- Echo Plugin Example
- echowindow.cpp Example File
- Qt 5.5.1 Reference Documentation

# echowindow.cpp Example File

tools/echoplugin/echowindow/echowindow.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
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    #include <QtWidgets>

    #include "echowindow.h"

    EchoWindow::EchoWindow()
    {
        createGUI();
        setLayout(layout);
        setWindowTitle("Echo Plugin Example");

        if (!loadPlugin()) {
            QMessageBox::information(this, "Error", "Could not load the plugin");
            lineEdit->setEnabled(false);
            button->setEnabled(false);
        }
    }

    void EchoWindow::sendEcho()
    {
        QString text = echoInterface->echo(lineEdit->text());
        label->setText(text);
    }

    void EchoWindow::createGUI()
    {
        lineEdit = new QLineEdit;
        label = new QLabel;
        label->setFrameStyle(QFrame::Box | QFrame::Plain);
        button = new QPushButton(tr("Send Message"));

        connect(lineEdit, SIGNAL(editingFinished()),
                this, SLOT(sendEcho()));
        connect(button, SIGNAL(clicked()),
                this, SLOT(sendEcho()));

        layout = new QGridLayout;
        layout->addWidget(new QLabel(tr("Message:")), 0, 0);
        layout->addWidget(lineEdit, 0, 1);
        layout->addWidget(new QLabel(tr("Answer:")), 1, 0);
        layout->addWidget(label, 1, 1);
        layout->addWidget(button, 2, 1, Qt::AlignRight);
        layout->setSizeConstraint(QLayout::SetFixedSize);
    }

    bool EchoWindow::loadPlugin()
    {
        QDir pluginsDir(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 pluginLoader(pluginsDir.absoluteFilePath(fileName));
            QObject *plugin = pluginLoader.instance();
            if (plugin) {
                echoInterface = qobject_cast<EchoInterface *>(plugin);
                if (echoInterface)
                    return true;
            }
        }

        return false;
    }