simple-application.html

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        printIcon = QPixmap( fileprint );
        QToolButton * filePrint
            = new <a href="qtoolbutton.html">QToolButton</a>( printIcon, "Print File", QString::null,
                               this, SLOT(print()), fileTools, "print file" );
</pre>
<p> Likewise we create two more tool buttons in this toolbar, each with 
appropriate icons and tool-tip text.  All three buttons are connected
to appropriate slots in this object; for example, the "Print File" button 
to <A HREF="#printer"><em>ApplicationWindow::print()</A></em>.
<p> <pre>        (void)QWhatsThis::whatsThisButton( fileTools );
</pre>
<p> The fourth button in the toolbar is somewhat peculiar: it's the one that
provides "What's This?" help.  This must be set up using a special
function, as its mouse interface is different from usual.
<p> <pre>        const char * fileOpenText = "&lt;p&gt;&lt;img source=\"fileopen\"&gt; "
                     "Click this button to open a &lt;em&gt;new file&lt;/em&gt;. &lt;br&gt;"
                     "You can also select the &lt;b&gt;Open&lt;/b&gt; command "
                     "from the &lt;b&gt;File&lt;/b&gt; menu.&lt;/p&gt;";

        QWhatsThis::<a href="qwhatsthis.html#add">add</a>( fileOpen, fileOpenText );
</pre>
<p> With the above line we add the "What's This?" help-text to the 
<em>fileOpen</em> button...
<p> <pre>        QMimeSourceFactory::<a href="qmimesourcefactory.html#defaultFactory">defaultFactory</a>()-&gt;setPixmap( "fileopen", openIcon );
</pre>
<p> ... and tell the rich-text engine that when a help-text (like the one
saved in <em>fileOpenText</em>) requests an image named "fileopen", the <em>openIcon</em> pixmap is used.
<p> <pre>        const char * fileSaveText = "&lt;p&gt;Click this button to save the file you "
                     "are editing. You will be prompted for a file name.\n"
                     "You can also select the &lt;b&gt;Save&lt;/b&gt; command "
                     "from the &lt;b&gt;File&lt;/b&gt; menu.&lt;/p&gt;";

        QWhatsThis::<a href="qwhatsthis.html#add">add</a>( fileSave, fileSaveText );
        const char * filePrintText = "Click this button to print the file you "
                     "are editing.\n You can also select the Print "
                     "command from the File menu.";

        QWhatsThis::<a href="qwhatsthis.html#add">add</a>( filePrint, filePrintText );
</pre>
<p> The "What's This?" help of the remaining two buttons doesn't make use
of pixmaps, therefore all we have to do is to add the help-text to the button.
Be however careful: To invoke the rich-text elements in <em>fileSaveText</em>,
the entire string must be surrounded by &lt;p&gt; and &lt;/p&gt;. In <em>filePrintText</em>,
we don't have rich-text elements, so this is not necessary.
<p> <pre>        <a href="qpopupmenu.html">QPopupMenu</a> * file = new <a href="qpopupmenu.html">QPopupMenu</a>( this );
        <a href="qmainwindow.html#menuBar">menuBar</a>()-&gt;insertItem( "&amp;File", file );
</pre>
<p> Next we create a <a href="qpopupmenu.html">QPopupMenu</a> for the <em>File</em> menu and 
add it to the menu bar. With the ampersand previous to the letter F,
we allow the user to use the shortcut <em>Alt+F</em> to open this menu.
<p> <pre>        file-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( "&amp;New", this, SLOT(newDoc()), CTRL+Key_N );
</pre>
<p> Its first entry is connected to the (yet to be implementled) slot <em>newDoc()</em>. When the user chooses this <em>New</em> entry (e.g. via typing the
letter N as marked by the ampersand) or uses the
<em>Ctrl+N</em> accelerator, a new editor-window will pop up.  
<p> <pre>        int id;
        id = file-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( openIcon, "&amp;Open...",
                               this, SLOT(choose()), CTRL+Key_O );
        file-&gt;<a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, fileOpenText );

        id = file-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( saveIcon, "&amp;Save",
                               this, SLOT(save()), CTRL+Key_S );
        file-&gt;<a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, fileSaveText );

        id = file-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( "Save &amp;As...", this, SLOT(saveAs()) );
        file-&gt;<a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, fileSaveText );
</pre>
<p> We populate the <em>File</em> menu with three more commands (<em>Open</em>, <em>Save</em> and
<em>Save</em> As), and set "What's This?" help for them.  Note in particular
that "What's This?" help and pixmaps are used in both the toolbar (above)
and the menu bar (here).
<p> <pre>        file-&gt;<a href="qmenudata.html#insertSeparator">insertSeparator</a>();
</pre>
<p> Then we insert a separator, ... 
<p> <pre>        id = file-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( printIcon, "&amp;Print...",
                               this, SLOT(print()), CTRL+Key_P );
        file-&gt;<a href="qmenudata.html#setWhatsThis">setWhatsThis</a>( id, filePrintText );

        file-&gt;<a href="qmenudata.html#insertSeparator">insertSeparator</a>();

        file-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( "&amp;Close", this, SLOT(<a href="qwidget.html#close">close</a>()), CTRL+Key_W );
        file-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( "&amp;Quit", qApp, SLOT( <a href="qapplication.html#closeAllWindows">closeAllWindows</a>() ), CTRL+Key_Q );
</pre>
<p> ... the <em>Print</em> command with "What's This?" help, another separator and
two more commands (<em>Close</em> and <em>Quit</em>) without "What's This?" and pixmaps.
In case of the <em>Close</em> command, the signal is connected 
to the <em>close()</em> slot of the respective <em>ApplicationWindow</em> object whilst
the <em>Quit</em> command affects the entire application.
<p> Because <em>ApplicationWindow</em> is a <a href="qwidget.html">QWidget</a>, the <em>close()</em> function
triggers a call to <A HREF="#closeEvent"><em>closeEvent()</A></em> which we will
implement later.
<p> <A NAME="common_constructor"></A>
<pre>        <a href="qmainwindow.html#menuBar">menuBar</a>()-&gt;insertSeparator();
</pre>
<p> Now that we are done with the File menu we shift our focus back to the
menu bar and insert a separator. From now on 
further menu bar entries will be aligned to the right if the windows system style 
suggests so.
<p> <pre>        <a href="qpopupmenu.html">QPopupMenu</a> * help = new <a href="qpopupmenu.html">QPopupMenu</a>( this );
        <a href="qmainwindow.html#menuBar">menuBar</a>()-&gt;insertItem( "&amp;Help", help );

        help-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( "&amp;About", this, SLOT(about()), Key_F1 );
        help-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( "About &amp;Qt", this, SLOT(aboutQt()) );
        help-&gt;<a href="qmenudata.html#insertSeparator">insertSeparator</a>();
        help-&gt;<a href="qmenudata.html#insertItem">insertItem</a>( "What's &amp;This", this, SLOT(<a href="qmainwindow.html#whatsThis">whatsThis</a>()), SHIFT+Key_F1 );
</pre>
<p> We create a <em>Help</em> menu, add it to the menu bar, and insert a few
commands. Depending on the style it will appear on the right hand 
side of the menu bar or not.
<p> <pre>        e = new <a href="qtextedit.html">QTextEdit</a>( this, "editor" );
        e-&gt;<a href="qwidget.html#setFocus">setFocus</a>();
        <a href="qmainwindow.html#setCentralWidget">setCentralWidget</a>( e );
</pre>
<p> Now we create a simple text-editor, set the initial focus to it,
and make it the central widget of this window.
<p> <a href="qmainwindow.html#centralWidget">QMainWindow::centralWidget</a>() is the heart of the entire application:
It's what menu bar, statusbar and toolbars are all arranged around.  Since
the central widget is a text editing widget, we reveal at this line that
our simple application is a text editor. :)
<p> <pre>        <a href="qmainwindow.html#statusBar">statusBar</a>()-&gt;message( "Ready", 2000 );
</pre>
<p> We make the statusbar say "Ready" for two seconds at startup, just to
tell the user that this window has finished initialization and can be
used.
<p> <pre>        <a href="qwidget.html#resize">resize</a>( 450, 600 );
</pre>
<p> Finally it's time to resize the new window to a a nice default size.
<p> <pre>    }
</pre>
<p> At this stage, we are done with the constructor. Among others we have learned 
about the classic way of creating menus and toolbars. There is
however a more modern approach to deal with this: actions that
help you saving some work. You may
have a look at how the <em>ApplicationWindow</em> constructor is implemented
using 
<A HREF="simple-application-action.html">actions</A>. Here
we'll continue with the destructor. 
<p> <pre>    ApplicationWindow::~ApplicationWindow()
    {
        delete printer;
    }
</pre>
<p> The only thing an <em>ApplicationWindow</em> widget needs to do in its destructor 
is  to delete the
printer it created.  All other objects are child widgets, which Qt
will delete as appropriate.
<p> Now our task is to implement all the slots mentioned in the header file
and used in the constructor.
<p> <A NAME="newDoc()"></A>
<pre>    void ApplicationWindow::newDoc()
    {
        ApplicationWindow *ed = new ApplicationWindow;
        ed-&gt;<a href="qwidget.html#setCaption">setCaption</a>("Qt Example - Application");
        ed-&gt;<a href="qwidget.html#show">show</a>();
    }
</pre>
<p> This slot, connected to the <em>File->New</em> menu item, simply creates a 
new <em>ApplicationWindow</em> and shows it.
<p> <A NAME="choose()"></A>
<pre>    void ApplicationWindow::choose()
    {
        <a href="qstring.html">QString</a> fn = QFileDialog::<a href="qfiledialog.html#getOpenFileName">getOpenFileName</a>( QString::null, QString::null,
                                                   this);
        if ( !fn.<a href="qstring.html#isEmpty">isEmpty</a>() )
            load( fn );
        else
            <a href="qmainwindow.html#statusBar">statusBar</a>()-&gt;message( "Loading aborted", 2000 );
    }
</pre>
<p> The <em>choose()</em> slot is connected to the <em>Open</em> menu item and
tool button.  With a little help from <a href="qfiledialog.html#getOpenFileName">QFileDialog::getOpenFileName</a>(), it
asks the user for a file name and then either loads that file or gives an
error message in the statusbar.
<p> <pre>    void ApplicationWindow::load( const <a href="qstring.html">QString</a> &amp;fileName )
    {
        <a href="qfile.html">QFile</a> f( fileName );
        if ( !f.<a href="qfile.html#open">open</a>( <a href="qfile.html#open">IO_ReadOnly</a> ) )
            return;

        <a href="qtextstream.html">QTextStream</a> ts( &amp;f );
        e-&gt;<a href="qtextedit.html#setText">setText</a>( ts.<a href="qtextstream.html#read">read</a>() );
        e-&gt;<a href="qtextedit.html#setModified">setModified</a>( FALSE );
        <a href="qwidget.html#setCaption">setCaption</a>( fileName );
        <a href="qmainwindow.html#statusBar">statusBar</a>()-&gt;message( "Loaded document " + fileName, 2000 );
    }
</pre>
<p> This function loads a file into the editor. When it's done, it sets the
window system caption to the file name and displays a success message in
the statusbar for two seconds.  With files that exist but are not
readable, nothing happens.
<p> <A NAME="save()"></A>
<pre>    void ApplicationWindow::save()
    {
        if ( filename.isEmpty() ) {
            saveAs();
            return;
        }

        <a href="qstring.html">QString</a> text = e-&gt;<a href="qtextedit.html#text">text</a>();
        <a href="qfile.html">QFile</a> f( filename );
        if ( !f.<a href="qfile.html#open">open</a>( <a href="qfile.html#open">IO_WriteOnly</a> ) ) {
            <a href="qmainwindow.html#statusBar">statusBar</a>()-&gt;message( QString("Could not write to %1").arg(filename),
                                  2000 );
            return;
        }