tqt3/doc/html/grapher-nsplugin-example.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/extensions/nsplugin/examples/grapher/grapher.doc:1 -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Grapher Plugin</title>
<style type="text/css"><!--
fn { margin-left: 1cm; text-indent: -1cm; }
a:link { color: #004faf; text-decoration: none }
a:visited { color: #672967; text-decoration: none }
body { background: #ffffff; color: black; }
--></style>
</head>
<body>

<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr bgcolor="#E5E5E5">
<td valign=center>
 <a href="index.html">
<font color="#004faf">Home</font></a>
 | <a href="classes.html">
<font color="#004faf">All&nbsp;Classes</font></a>
 | <a href="mainclasses.html">
<font color="#004faf">Main&nbsp;Classes</font></a>
 | <a href="annotated.html">
<font color="#004faf">Annotated</font></a>
 | <a href="groups.html">
<font color="#004faf">Grouped&nbsp;Classes</font></a>
 | <a href="functions.html">
<font color="#004faf">Functions</font></a>
</td>
<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Grapher Plugin</h1>

 
<p> This example graphs data from a simple text file.  It
demonstrates the use of the <a href="qnpinstance.html#writeReady">TQNPInstance::writeReady</a>()
and <a href="qnpinstance.html#write">TQNPInstance::write</a>() functions.
<p> To build the example, you must first build the
<a href=nsplugin.html>TQt Netscape Plugin Extension</a> library.
Then type <tt>make</tt> in <tt>extensions/nsplugin/examples/grapher/</tt>
and copy the resulting <tt>grapher.so</tt> or <tt>npgrapher.dll</tt>
to the Plugins directory of your WWW browser.
<p> <EMBED ALIGN=LEFT WIDTH=49% HEIGHT=300 SRC=graph.g1n
graphstyle=pie fontfamily=times fontsize=18>
<p> The text file it accepts as input has a title line, then
a sequence of lines with a number, then a string.  The
plugin displays a pie chart of the numbers, each segment
labelled by the associated string.  The user can select
a bar chart view of the same data by selecting from the
menu that appears when they point at the plugin.
<p> The HTML tag used to embed the graph is:
<small>
<pre>
  &lt;EMBED
    SRC=graph.g1n
    ALIGN=LEFT
    WIDTH=49% HEIGHT=300
    graphstyle=pie fontfamily=times
    fontsize=18&gt;
</pre><p> </small>
Note that some HTML arguments (which we have capitalized here)
are interpreted by the browser, while others are used by the
plugin.
<p> <br clear>
With the simplicity and cross-platform nature of TQt-based plugins,
pages like <a href="http://www.netcraft.com/survey/">Netcraft's
Server Graphs</a> can be provided much more efficiently for both
the service provider and consumer.  Data need not be converted
to an image at the server.
<p> <br clear>
<hr>
Implementation:
<p> <pre>// Include TQt Netscape Plugin classes.
#include "ntqnp.h"

// Include other TQt classes.
#include &lt;<a href="qpainter-h.html">ntqpainter.h</a>&gt;
#include &lt;<a href="qtextstream-h.html">ntqtextstream.h</a>&gt;
#include &lt;<a href="qbuffer-h.html">ntqbuffer.h</a>&gt;
#include &lt;<a href="qpixmap-h.html">ntqpixmap.h</a>&gt;
#include &lt;<a href="qmenubar-h.html">ntqmenubar.h</a>&gt;
#include &lt;<a href="qpushbutton-h.html">ntqpushbutton.h</a>&gt;
#include &lt;<a href="qptrlist-h.html">ntqptrlist.h</a>&gt;
#include &lt;<a href="qmessagebox-h.html">ntqmessagebox.h</a>&gt;

// Include some C library functions.
#include &lt;math.h&gt;
#include &lt;stdlib.h&gt;

#ifndef M_PI // Some math.h don't include this.
#define M_PI 3.14159265358979323846264338327950288
#endif


//
// GraphModel is a simple abstract class that describes
// a table of numeric and text data.
//

class GraphModel {
public:
    enum ColType { Numeric, Label };

    union Datum {
        double dbl;
        <a href="ntqstring.html">TQString</a>* str;
    };

    virtual TQPtrList&lt;Datum&gt;&amp; graphData()=0;
    virtual ColType colType(int col) const=0;
    virtual int nCols() const=0;
};


//
// Graph is a widget subclass that displays a GraphModel.
// Since the widget is a TQNPWidget, it can be used as a plugin window,
// returned by Grapher::newWindow() below.
//

class Graph : public <a href="qnpwidget.html">TQNPWidget</a> {
    <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
public:
    // Constructs a Graph to display a GraphModel
    //
    Graph(GraphModel&amp;);
    ~Graph();

    // Two styles are available - Pie and Bar graph
    //
    enum Style { Pie, Bar };
    static const char* styleName[];
    void setStyle(Style);
    void setStyle(const char*);

    // Timer event processing rotates the pie graph
    //
    void timerEvent(TQTimerEvent*);

    // These functions are provided by TQNPWidget - we override
    // them to hide and show the plugin menubar.
    //
    void enterInstance();
    void leaveInstance();

    // Paint the graph...
    //
    void paintEvent(TQPaintEvent*);
    //
    // ... as either a "Loading" message, a Bar graph, a Pie graph,
    // or an error message.
    //
    void paintWait(TQPaintEvent*);
    void paintBar(TQPaintEvent*);
    void paintPie(TQPaintEvent*);
    void paintError(const char*);

signals:
    // Signals emitted when the Help menus are selected.
    void aboutPlugin();
    void aboutData();

private:
    GraphModel&amp; model;
    <a href="ntqmenubar.html">TQMenuBar</a> *menubar;
    Style style;
    <a href="ntqpopupmenu.html">TQPopupMenu</a>* stylemenu;
    int pieRotationTimer;
    int pieRotation;
    <a href="ntqpixmap.html">TQPixmap</a> pm;

private slots:
    void setStyleFromMenu(int id);
};


<a name="f564"></a>Graph::Graph( GraphModel&amp; mdl ) :
    model(mdl),
    <a href="ntqwidget.html#style">style</a>(Bar),
    pieRotationTimer(0),
    pieRotation(0)
{
    // Create a menubar for the widget
    //
    menubar = new <a href="ntqmenubar.html">TQMenuBar</a>( this );
    stylemenu = new <a href="ntqpopupmenu.html">TQPopupMenu</a>;
<a name="x2768"></a>    stylemenu-&gt;<a href="ntqpopupmenu.html#setCheckable">setCheckable</a>(TRUE);
    for ( Style s = Pie; styleName[s]; s = Style(s+1)) {
        stylemenu-&gt;<a href="ntqmenudata.html#insertItem">insertItem</a>(styleName[s], s+100);
    }
<a name="x2767"></a>    <a href="ntqobject.html#connect">connect</a>(stylemenu, SIGNAL(<a href="ntqpopupmenu.html#activated">activated</a>(int)),
        this, SLOT(setStyleFromMenu(int)));
    <a href="ntqwidget.html#setStyle">setStyle</a>(Pie);

    menubar-&gt;<a href="ntqmenudata.html#insertItem">insertItem</a>("Style", stylemenu);
    menubar-&gt;<a href="ntqmenudata.html#insertSeparator">insertSeparator</a>();

    <a href="ntqpopupmenu.html">TQPopupMenu</a>* help = new <a href="ntqpopupmenu.html">TQPopupMenu</a>;
    help-&gt;<a href="ntqmenudata.html#insertItem">insertItem</a>( "About plugin...", this, SIGNAL(aboutPlugin()) );
    help-&gt;<a href="ntqmenudata.html#insertItem">insertItem</a>( "About data...", this, SIGNAL(aboutData()) );
    menubar-&gt;<a href="ntqmenudata.html#insertItem">insertItem</a>("Help", help);
<a name="x2745"></a>    menubar-&gt;<a href="ntqmenubar.html#hide">hide</a>();
}

Graph::~Graph()
{
}

<a name="x2778"></a>void Graph::<a href="ntqwidget.html#setStyle">setStyle</a>(Style s)
{
    if (style != s) {
        if (pieRotationTimer)
            <a href="ntqobject.html#killTimer">killTimer</a>(pieRotationTimer);
<a name="x2749"></a>        stylemenu-&gt;<a href="ntqmenudata.html#setItemChecked">setItemChecked</a>(100+style, FALSE);
        style = s;
        if ( style == Pie )
            pieRotationTimer = <a href="ntqobject.html#startTimer">startTimer</a>( 80 );
        else
            pieRotationTimer = 0;
        stylemenu-&gt;<a href="ntqmenudata.html#setItemChecked">setItemChecked</a>(100+style, TRUE);
        <a href="ntqwidget.html#update">update</a>();
    }
}

<a name="x2755"></a>void Graph::<a href="ntqobject.html#timerEvent">timerEvent</a>(TQTimerEvent*)
{
    pieRotation = ( pieRotation + 6 ) % 360; repaint(FALSE);
}

void Graph::<a href="ntqwidget.html#setStyle">setStyle</a>(const char* stext)
{
    for ( Style s = Pie; styleName[s]; s = Style(s+1) ) {
        if ( <a href="ntqcstring.html#qstricmp">qstricmp</a>(stext,styleName[s])==0 ) {
            <a href="ntqwidget.html#setStyle">setStyle</a>(s);
            return;
        }
    }
}

<a name="x2753"></a>void Graph::<a href="qnpwidget.html#enterInstance">enterInstance</a>()
{
<a name="x2746"></a>    menubar-&gt;<a href="ntqmenubar.html#show">show</a>();
}

<a name="x2754"></a>void Graph::<a href="qnpwidget.html#leaveInstance">leaveInstance</a>()
{
    menubar-&gt;<a href="ntqmenubar.html#hide">hide</a>();
}

void <a name="f565"></a>Graph::paintError(const char* e)
{
    <a href="ntqpainter.html">TQPainter</a> p(this);
    int w = <a href="ntqwidget.html#width">width</a>();
<a name="x2760"></a>    p.<a href="ntqpainter.html#drawText">drawText</a>(w/8, 0, w-w/4, height(), AlignCenter|WordBreak, e);
}

void <a name="f566"></a>Graph::paintBar(TQPaintEvent* event)
{
    if ( model.colType(0) != GraphModel::Numeric ) {
        paintError("First column not numeric, cannot draw bar graph\n");
        return;
    }

    <a href="ntqptrlist.html">TQPtrList</a>&lt;GraphModel::Datum&gt;&amp; data = model.graphData();

    double max = 0.0;

<a name="x2772"></a>    for (GraphModel::Datum* rowdata = data.<a href="ntqptrlist.html#first">first</a>();
<a name="x2773"></a>        rowdata; rowdata = data.<a href="ntqptrlist.html#next">next</a>())
    {
        if (rowdata[0].dbl &gt; max) max = rowdata[0].dbl;
    }

    const uint w = <a href="ntqwidget.html#width">width</a>();
    const uint h = <a href="ntqwidget.html#height">height</a>();

    <a href="ntqpainter.html">TQPainter</a> p(this);

<a name="x2762"></a>    p.<a href="ntqpainter.html#setClipRect">setClipRect</a>(event-&gt;rect());

<a name="x2771"></a>    if ( w &gt; data.<a href="ntqptrlist.html#count">count</a>() ) {
        // More pixels than data
        int x = 0;
        int i = 0;
        <a href="ntqfontmetrics.html">TQFontMetrics</a> fm=<a href="ntqwidget.html#fontMetrics">fontMetrics</a>();
<a name="x2741"></a>        int fh = fm.<a href="ntqfontmetrics.html#height">height</a>();

        for (GraphModel::Datum* rowdata = data.<a href="ntqptrlist.html#first">first</a>();
            rowdata; rowdata = data.<a href="ntqptrlist.html#next">next</a>())
        {
            <a href="ntqcolor.html">TQColor</a> c;
<a name="x2740"></a>            c.<a href="ntqcolor.html#setHsv">setHsv</a>( (i * 255)/data.<a href="ntqptrlist.html#count">count</a>(), 255, 255 );// rainbow effect
            p.<a href="ntqpainter.html#setBrush">setBrush</a>(c);
            int bw = (w-w/4-x)/(data.<a href="ntqptrlist.html#count">count</a>()-i);
            int bh = int((h-h/4-1)*rowdata[0].dbl/max);
            p.<a href="ntqpainter.html#drawRect">drawRect</a>( w/8+x, h-h/8-1-bh, bw, bh );

            i++;
            x+=bw;
        }
    } else {
        // More data than pixels
        int x = 0;
        int i = 0;
        double av = 0.0;
        int n = 0;
        for (GraphModel::Datum* rowdata = data.<a href="ntqptrlist.html#first">first</a>(); rowdata;
            rowdata = data.<a href="ntqptrlist.html#next">next</a>())
        {
            int bx = i*w/data.<a href="ntqptrlist.html#count">count</a>();

            if (bx &gt; x) {
                <a href="ntqcolor.html">TQColor</a> c;
                c.<a href="ntqcolor.html#setHsv">setHsv</a>( (x * 255)/w, 255, 255 );// rainbow effect
                p.<a href="ntqpainter.html#setPen">setPen</a>(c);
                int bh = int(h*av/n/max);

                p.<a href="ntqpainter.html#drawLine">drawLine</a>(x,h-1,x,h-bh);

                av = 0.0;
                n = 0;
                x = bx;
            }

            av += rowdata[0].dbl;
            n++;

            i++;
        }
    }
}

void <a name="f567"></a>Graph::paintPie(TQPaintEvent* event)
{
    if ( model.colType(0) != GraphModel::Numeric ) {
        paintError("First column not numeric, cannot draw pie graph\n");
        return;
    }

    <a href="ntqptrlist.html">TQPtrList</a>&lt;GraphModel::Datum&gt;&amp; data = model.graphData();

    double total = 0.0;

    GraphModel::Datum* rowdata;

    for (rowdata = data.<a href="ntqptrlist.html#first">first</a>();
        rowdata; rowdata = data.<a href="ntqptrlist.html#next">next</a>())
    {
        total += rowdata[0].dbl;
    }

    // Only use first column for pie chart
    if ( !total ) return;

    int apos = (pieRotation-90)*16;

    const int w = <a href="ntqwidget.html#width">width</a>();
    const int h = <a href="ntqwidget.html#height">height</a>();

    const int xd = w - w/5;
    const int yd = h - h/5;

<a name="x2766"></a>    pm.<a href="ntqpixmap.html#resize">resize</a>(<a href="ntqwidget.html#width">width</a>(),height());
<a name="x2765"></a>    pm.<a href="ntqpixmap.html#fill">fill</a>(<a href="ntqwidget.html#backgroundColor">backgroundColor</a>());
    <a href="ntqpainter.html">TQPainter</a> p(&amp;pm);
<a name="x2763"></a>    p.<a href="ntqpainter.html#setFont">setFont</a>(<a href="ntqwidget.html#font">font</a>());

    p.<a href="ntqpainter.html#setClipRect">setClipRect</a>(event-&gt;rect());

    int i = 0;

    for (rowdata = data.<a href="ntqptrlist.html#first">first</a>();
        rowdata; rowdata = data.<a href="ntqptrlist.html#next">next</a>())
    {
        <a href="ntqcolor.html">TQColor</a> c;

        c.<a href="ntqcolor.html#setHsv">setHsv</a>( ( i * 255)/data.<a href="ntqptrlist.html#count">count</a>(), 255, 255 );// rainbow effect
        p.<a href="ntqpainter.html#setBrush">setBrush</a>( c );                        // solid fill with color c

        int a = int(( rowdata[0].dbl * 360.0 ) / total * 16.0 + 0.5);
<a name="x2757"></a>        p.<a href="ntqpainter.html#drawPie">drawPie</a>( w/10, h/10, xd, yd, -apos, -a );
        apos += a;
        i++;
    }

    if (model.colType(1) == GraphModel::Label) {
        double apos = (pieRotation-90)*M_PI/180;

        for (rowdata = data.<a href="ntqptrlist.html#first">first</a>();
            rowdata; rowdata = data.<a href="ntqptrlist.html#next">next</a>())
        {
            double a = rowdata[0].dbl * 360 / total * M_PI / 180;
            int x = int(cos(apos+a/2)*w*5/16 + w/2 + 0.5);
            int y = int(sin(apos+a/2)*h*5/16 + h/2 + 0.5);

            // ### This causes a crash, so comment out for now
            /*p.<a href="ntqpainter.html#drawText">drawText</a>(x-w/8, y-h/8, w/4, h/4,
                WordBreak|AlignCenter,
                *rowdata[1].str);*/
            apos += a;
        }
    }

    <a href="ntqpainter.html">TQPainter</a> p2(this);
    p2.<a href="ntqpainter.html#setClipRect">setClipRect</a>(event-&gt;rect());
<a name="x2758"></a>    p2.<a href="ntqpainter.html#drawPixmap">drawPixmap</a>(0,0,pm);
}

void <a name="f568"></a>Graph::paintWait(TQPaintEvent*)
{
    <a href="ntqpainter.html">TQPainter</a> p(this);
    p.<a href="ntqpainter.html#drawText">drawText</a>(rect(), AlignCenter, "Loading...");
}

void Graph::<a href="ntqwidget.html#paintEvent">paintEvent</a>(TQPaintEvent* event)
{
    if (!model.nCols()) {
        paintWait(event);
    } else {
        switch (style) {
          case Pie:
            paintPie(event);
            break;
          case Bar:
            paintBar(event);
            break;
        }
    }
}

void <a name="f569"></a>Graph::setStyleFromMenu(int id)
{
    setStyle(Style(id-100));
}

const char* Graph::styleName[] = { "Pie", "Bar", 0 };


//
// Grapher is a subclass of TQNPInstance, and so it can be returned
// by GrapherPlugin::newInstance().  A TQNPInstance represents the
// plugin, distinctly from the plugin window.
//
// Grapher is also a GraphModel, because it loads graph data from
// the net.  When Grapher creates a window in newWindow(), it creates
// a Graph widget to display the GraphModel that is the Grapher itself.
//

class Grapher : public <a href="qnpinstance.html">TQNPInstance</a>, GraphModel {
    Q_OBJECT
public:
    // Create a Grapher - all Grapher plugins are created
    // by one GrapherPlugin object.
    //
    Grapher();
    ~Grapher();

    // We override this TQNPInstance function to create our
    // own subclass of TQNPWidget, a Graph widget.
    //
    <a href="qnpwidget.html">TQNPWidget</a>* newWindow();

    // We override this TQNPInstance function to process the
    // incoming graph data.
    //
    int write(TQNPStream* /*str*/, int /*offset*/, int len, void* buffer);

private:
    // Grapher is a GraphModel, so it implements the pure virtual
    // functions of that class.
    //
    <a href="ntqptrlist.html">TQPtrList</a>&lt;Datum&gt;&amp; graphData();
    ColType colType(int col) const;
    int nCols() const;

    void consumeLine();
    <a href="ntqptrlist.html">TQPtrList</a>&lt;Datum&gt; data;
    <a href="ntqbuffer.html">TQBuffer</a> line;
    int ncols;
    ColType *coltype;

private slots:
    // Slots that are connected to the Graph menu items.
    //
    void aboutPlugin();
    void aboutData();
};

<a name="f570"></a>Grapher::Grapher()
{
<a name="x2769"></a>    data.<a href="ntqptrcollection.html#setAutoDelete">setAutoDelete</a>(TRUE);
    ncols = 0;
<a name="x2743"></a>    line.<a href="ntqiodevice.html#open">open</a>(IO_WriteOnly|IO_Truncate);
}

Grapher::~Grapher()
{
}

TQPtrList&lt;GraphModel::Datum&gt;&amp; <a name="f571"></a>Grapher::graphData()
{
    return data;
}

GraphModel::ColType <a name="f572"></a>Grapher::colType(int col) const
{
    return coltype[col];
}

int <a name="f573"></a>Grapher::nCols() const
{
    return ncols;
}


<a name="x2751"></a>TQNPWidget* Grapher::<a href="qnpinstance.html#newWindow">newWindow</a>()
{
    // Create a Graph - our subclass of TQNPWidget.
    Graph *graph = new Graph(*this);

    // Look at the arguments from the EMBED tag.
    //   GRAPHSTYLE chooses pie or bar
    //   FONTFAMILY and FONTSIZE choose the font
    //
    const char* style = <a href="qnpinstance.html#arg">arg</a>("GRAPHSTYLE");
    if ( style ) graph-&gt;<a href="ntqwidget.html#setStyle">setStyle</a>(style);

    const char* fontfamily = <a href="qnpinstance.html#arg">arg</a>("FONTFAMILY");
    const char* fontsize = <a href="qnpinstance.html#arg">arg</a>("FONTSIZE");
<a name="x2775"></a>    int ptsize = fontsize ? atoi(fontsize) : graph-&gt;<a href="ntqwidget.html#font">font</a>().pointSize();
    if (fontfamily) graph-&gt;<a href="ntqwidget.html#setFont">setFont</a>(TQFont(fontfamily, ptsize));

    <a href="ntqobject.html#connect">connect</a>(graph, SIGNAL(aboutPlugin()), this, SLOT(aboutPlugin()));
    <a href="ntqobject.html#connect">connect</a>(graph, SIGNAL(aboutData()), this, SLOT(aboutData()));

    return graph;
}

void <a name="f574"></a>Grapher::consumeLine()
{
<a name="x2742"></a>    line.<a href="ntqiodevice.html#close">close</a>();
    line.<a href="ntqiodevice.html#open">open</a>(IO_ReadOnly);

    <a href="ntqtextstream.html">TQTextStream</a> ts( &amp;line );

    if (ncols == 0 ) {
        ncols=0;
        <a href="ntqptrlist.html">TQPtrList</a>&lt;ColType&gt; typelist;
        typelist.<a href="ntqptrcollection.html#setAutoDelete">setAutoDelete</a>(TRUE);
        do {
            <a href="ntqstring.html">TQString</a> typestr;
            ts &gt;&gt; typestr &gt;&gt; ws;
            ColType* t = 0;
            if ( typestr == "num" ) {
                t = new ColType(Numeric);
            } else if ( typestr == "label" ) {
                t = new ColType(Label);
            }
<a name="x2770"></a>            if (t) typelist.<a href="ntqptrlist.html#append">append</a>(t);
<a name="x2774"></a>        } while (!ts.<a href="ntqtextstream.html#atEnd">atEnd</a>());
        coltype = new ColType[ncols];
        for (ColType* t = typelist.<a href="ntqptrlist.html#first">first</a>(); t; t = typelist.<a href="ntqptrlist.html#next">next</a>()) {
            coltype[ncols++] = *t;
        }
    } else {
        int col=0;
        Datum *rowdata = new Datum[ncols];
        while ( col &lt; ncols &amp;&amp; !ts.<a href="ntqtextstream.html#atEnd">atEnd</a>() ) {
            switch (coltype[col]) {
              case Numeric: {
                double value;
                ts &gt;&gt; value &gt;&gt; ws;
                rowdata[col].dbl = value;
                break;
              }
              case Label: {
                <a href="ntqstring.html">TQString</a>* value = new <a href="ntqstring.html">TQString</a>;
                ts &gt;&gt; *value &gt;&gt; ws;
                rowdata[col].str = value;
                break;
              }
            }
            col++;
        }

        data.<a href="ntqptrlist.html#append">append</a>(rowdata);
    }

    line.<a href="ntqiodevice.html#close">close</a>();
    line.<a href="ntqiodevice.html#open">open</a>(IO_WriteOnly|IO_Truncate);
}

<a name="x2752"></a>int Grapher::<a href="qnpinstance.html#write">write</a>(TQNPStream* /*str*/, int /*offset*/, int len, void* buffer)
{
    // The browser calls this function when data is available on one
    // of the streams the plugin has requested.  Since we are only
    // processing one stream - the URL in the SRC argument of the EMBED
    // tag, we assume the TQNPStream is that one.  Also, since we do not
    // override TQNPInstance::writeReady(), we must accepts ALL the data
    // that is sent to this function.
    //
    char* txt = (char*)buffer;
    for (int i=0; i&lt;len; i++) {
        char ch = txt[i];
        switch ( ch ) {
          case '\n':
            consumeLine();
            break;
          case '\r': // ignore;
            break;
          default:
<a name="x2744"></a>            line.<a href="ntqiodevice.html#putch">putch</a>(ch);
        }
    }
    if ( <a href="qnpinstance.html#widget">widget</a>() )
        <a href="qnpinstance.html#widget">widget</a>()-&gt;update();

    return len;
}

void <a name="f575"></a>Grapher::aboutPlugin()
{
    <a href="qnpinstance.html#getURL">getURL</a>( "http://doc.trolltech.com/netscape-plugin.html", "_blank" );
}

void <a name="f576"></a>Grapher::aboutData()
{
    const char* page = <a href="qnpinstance.html#arg">arg</a>("DATAPAGE");
    if (page)
        <a href="qnpinstance.html#getURL">getURL</a>( page, "_blank" );
    else
<a name="x2750"></a>        TQMessageBox::<a href="ntqmessagebox.html#message">message</a>("Help", "No help for this data");
}


//
// GrapherPlugin is the start of everything.  It is a TQNPlugin subclass,
// and it is responsible for describing the plugin to the browser, and
// creating instances of the plugin when it appears in web page.
//

class GrapherPlugin : public <a href="qnplugin.html">TQNPlugin</a> {
public:
    GrapherPlugin()
    {
    }

    <a href="qnpinstance.html">TQNPInstance</a>* newInstance()
    {
        // Make a new Grapher, our subclass of TQNPInstance.
        return new Grapher;
    }

    const char* getMIMEDescription() const
    {
        // Describe the MIME types which this plugin can
        // process.  Just the concocted "application/x-graphable"
        // type, with the "g1n" filename extension.
        //
        return "application/x-graphable:g1n:Graphable ASCII numeric data";
    }

    const char * getPluginNameString() const
    {
        // The name of the plugin.  This is the title string used in
        // the "About Plugins" page of the browser.
        //
        return "TQt-based Graph Plugin";
    }

    const char * getPluginDescriptionString() const
    {
        // A longer description of the plugin.
        //
        return "A TQt-based LiveConnected plug-in that graphs numeric data";
    }

};

//
// Finally, we provide the implementation of TQNPlugin::create(), to
// provide our subclass of TQNPlugin.
//

TQNPlugin* TQNPlugin::create()
{
    return new GrapherPlugin;
}

#include "grapher.moc"
</pre>

<p>See also <a href="nsplugin-examples.html">Netscape Plugin Examples</a>.

<!-- eof -->
<p><address><hr><div align=center>
<table width=100% cellspacing=0 border=0><tr>
<td>Copyright &copy; 2007
<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
<td align=right><div align=right>TQt 3.3.8</div>
</table></div></address></body>
</html>