Image Viewer Tutorial: Part 1

Initial Setup

First the project file has to be created (qbuild.pro) for the Qt Extended build system.

File: qbuild.pro

    TEMPLATE=app
    CONFIG+=qtopia
    TARGET=iviewer

    CONFIG+=quicklaunch

    HEADERS += iviewer.h
    SOURCES += main.cpp iviewer.cpp

Here a Qt Extended application is declared (iviewer). The start code will be in main and the application in iviewer{.h,.cpp}.

File: main.cpp

    #include "iviewer.h"
    #include <qtopiaapplication.h>

    QTOPIA_ADD_APPLICATION(QTOPIA_TARGET, IViewer)
    QTOPIA_MAIN

"IViewer" is the class name and "iviewer" is the executable name. The syntax is described here.

Classes: QtopiaApplication

File: iviewer.h

    #ifndef IVIEWER_H
    #define IVIEWER_H

    #include <QStackedWidget>
    #include <QWidget>

    class IViewer : public QStackedWidget
    {
        Q_OBJECT
    public:
        IViewer(QWidget *parent=0, Qt::WFlags f=0);
    };

    #endif

Classes: QStackedWidget, QWidget

The IViewer should be a QStackedWidget derived class. The widget stack will be used later to manage our screens. The constructor needs to have the QWidget and Qt::WindowFlags as parameters, due to the QTOPIA macros in main.cpp.

File: iviewer.cpp

    #include "iviewer.h"
    IViewer::IViewer(QWidget *parent, Qt::WFlags /*f*/)
    : QStackedWidget(parent)
    {
        _listScreen  = 0;
        _imageScreen = 0;
        setCurrentWidget(listScreen());
        setWindowTitle("Image Viewer");
    }

Namespace: Qt

It is now time for the first run. qbuild must be called. When the QVFB emulator is running, the application can be started with ./iviewer. This should display an empty application in the emulator. Great!

    #ifndef LISTSCREEN_H
    #define LISTSCREEN_H

    #include <QListWidget>
    class IViewer;
    class QContentSet;
    class QContentSetModel;
    class QAction;
    class QKeyEvent;
    class ImageScreen;
    class InfoScreen;

    class ListScreen : public QListWidget
    {
        Q_OBJECT
    public:
        ListScreen(IViewer *viewer);
    private:
        IViewer          *_viewer;
    };

    #endif

    #include "listscreen.h"
    #include "iviewer.h"
    ListScreen::ListScreen(IViewer *viewer)
    : QListWidget(viewer), _viewer(viewer)
    {
    }

    SOURCES += listscreen.cpp
    HEADERS += listscreen.h