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<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">QNPInstance::writeReady</a>()
and <a href="qnpinstance.html#write">QNPInstance::write</a>() functions.
<p> To build the example, you must first build the
<a href=nsplugin.html>Qt 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>
<EMBED
SRC=graph.g1n
ALIGN=LEFT
WIDTH=49% HEIGHT=300
graphstyle=pie fontfamily=times
fontsize=18>
</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 Qt-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 Qt Netscape Plugin classes.
#include "qnp.h"
// Include other Qt classes.
#include <<a href="qpainter-h.html">qpainter.h</a>>
#include <<a href="qtextstream-h.html">qtextstream.h</a>>
#include <<a href="qbuffer-h.html">qbuffer.h</a>>
#include <<a href="qpixmap-h.html">qpixmap.h</a>>
#include <<a href="qmenubar-h.html">qmenubar.h</a>>
#include <<a href="qpushbutton-h.html">qpushbutton.h</a>>
#include <<a href="qptrlist-h.html">qptrlist.h</a>>
#include <<a href="qmessagebox-h.html">qmessagebox.h</a>>
// Include some C library functions.
#include <math.h>
#include <stdlib.h>
#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="qstring.html">QString</a>* str;
};
virtual QPtrList<Datum>& 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 QNPWidget, it can be used as a plugin window,
// returned by Grapher::newWindow() below.
//
class Graph : public <a href="qnpwidget.html">QNPWidget</a> {
<a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
public:
// Constructs a Graph to display a GraphModel
//
Graph(GraphModel&);
~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(QTimerEvent*);
// These functions are provided by QNPWidget - we override
// them to hide and show the plugin menubar.
//
void enterInstance();
void leaveInstance();
// Paint the graph...
//
void paintEvent(QPaintEvent*);
//
// ... as either a "Loading" message, a Bar graph, a Pie graph,
// or an error message.
//
void paintWait(QPaintEvent*);
void paintBar(QPaintEvent*);
void paintPie(QPaintEvent*);
void paintError(const char*);
signals:
// Signals emitted when the Help menus are selected.
void aboutPlugin();
void aboutData();
private:
GraphModel& model;
<a href="qmenubar.html">QMenuBar</a> *menubar;
Style style;
<a href="qpopupmenu.html">QPopupMenu</a>* stylemenu;
int pieRotationTimer;
int pieRotation;
<a href="qpixmap.html">QPixmap</a> pm;
private slots:
void setStyleFromMenu(int id);
};
<a name="f564"></a>Graph::Graph( GraphModel& mdl ) :
model(mdl),
<a href="qwidget.html#style">style</a>(Bar),
pieRotationTimer(0),
pieRotation(0)
{
// Create a menubar for the widget
//
menubar = new <a href="qmenubar.html">QMenuBar</a>( this );
stylemenu = new <a href="qpopupmenu.html">QPopupMenu</a>;
<a name="x2768"></a> stylemenu-><a href="qpopupmenu.html#setCheckable">setCheckable</a>(TRUE);
for ( Style s = Pie; styleName[s]; s = Style(s+1)) {
stylemenu-><a href="qmenudata.html#insertItem">insertItem</a>(styleName[s], s+100);
}
<a name="x2767"></a> <a href="qobject.html#connect">connect</a>(stylemenu, SIGNAL(<a href="qpopupmenu.html#activated">activated</a>(int)),
this, SLOT(setStyleFromMenu(int)));
<a href="qwidget.html#setStyle">setStyle</a>(Pie);
menubar-><a href="qmenudata.html#insertItem">insertItem</a>("Style", stylemenu);
menubar-><a href="qmenudata.html#insertSeparator">insertSeparator</a>();
<a href="qpopupmenu.html">QPopupMenu</a>* help = new <a href="qpopupmenu.html">QPopupMenu</a>;
help-><a href="qmenudata.html#insertItem">insertItem</a>( "About plugin...", this, SIGNAL(aboutPlugin()) );
help-><a href="qmenudata.html#insertItem">insertItem</a>( "About data...", this, SIGNAL(aboutData()) );
menubar-><a href="qmenudata.html#insertItem">insertItem</a>("Help", help);
<a name="x2745"></a> menubar-><a href="qmenubar.html#hide">hide</a>();
}
Graph::~Graph()
{
}
<a name="x2778"></a>void Graph::<a href="qwidget.html#setStyle">setStyle</a>(Style s)
{
if (style != s) {
if (pieRotationTimer)
<a href="qobject.html#killTimer">killTimer</a>(pieRotationTimer);
<a name="x2749"></a> stylemenu-><a href="qmenudata.html#setItemChecked">setItemChecked</a>(100+style, FALSE);
style = s;
if ( style == Pie )
pieRotationTimer = <a href="qobject.html#startTimer">startTimer</a>( 80 );
else
pieRotationTimer = 0;
stylemenu-><a href="qmenudata.html#setItemChecked">setItemChecked</a>(100+style, TRUE);
<a href="qwidget.html#update">update</a>();
}
}
<a name="x2755"></a>void Graph::<a href="qobject.html#timerEvent">timerEvent</a>(QTimerEvent*)
{
pieRotation = ( pieRotation + 6 ) % 360; repaint(FALSE);
}
void Graph::<a href="qwidget.html#setStyle">setStyle</a>(const char* stext)
{
for ( Style s = Pie; styleName[s]; s = Style(s+1) ) {
if ( <a href="qcstring.html#qstricmp">qstricmp</a>(stext,styleName[s])==0 ) {
<a href="qwidget.html#setStyle">setStyle</a>(s);
return;
}
}
}
<a name="x2753"></a>void Graph::<a href="qnpwidget.html#enterInstance">enterInstance</a>()
{
<a name="x2746"></a> menubar-><a href="qmenubar.html#show">show</a>();
}
<a name="x2754"></a>void Graph::<a href="qnpwidget.html#leaveInstance">leaveInstance</a>()
{
menubar-><a href="qmenubar.html#hide">hide</a>();
}
void <a name="f565"></a>Graph::paintError(const char* e)
{
<a href="qpainter.html">QPainter</a> p(this);
int w = <a href="qwidget.html#width">width</a>();
<a name="x2760"></a> p.<a href="qpainter.html#drawText">drawText</a>(w/8, 0, w-w/4, height(), AlignCenter|WordBreak, e);
}
void <a name="f566"></a>Graph::paintBar(QPaintEvent* event)
{
if ( model.colType(0) != GraphModel::Numeric ) {
paintError("First column not numeric, cannot draw bar graph\n");
return;
}
<a href="qptrlist.html">QPtrList</a><GraphModel::Datum>& data = model.graphData();
double max = 0.0;
<a name="x2772"></a> for (GraphModel::Datum* rowdata = data.<a href="qptrlist.html#first">first</a>();
<a name="x2773"></a> rowdata; rowdata = data.<a href="qptrlist.html#next">next</a>())
{
if (rowdata[0].dbl > max) max = rowdata[0].dbl;
}
const uint w = <a href="qwidget.html#width">width</a>();
const uint h = <a href="qwidget.html#height">height</a>();
<a href="qpainter.html">QPainter</a> p(this);
<a name="x2762"></a> p.<a href="qpainter.html#setClipRect">setClipRect</a>(event->rect());
<a name="x2771"></a> if ( w > data.<a href="qptrlist.html#count">count</a>() ) {
// More pixels than data
int x = 0;
int i = 0;
<a href="qfontmetrics.html">QFontMetrics</a> fm=<a href="qwidget.html#fontMetrics">fontMetrics</a>();
<a name="x2741"></a> int fh = fm.<a href="qfontmetrics.html#height">height</a>();
for (GraphModel::Datum* rowdata = data.<a href="qptrlist.html#first">first</a>();
rowdata; rowdata = data.<a href="qptrlist.html#next">next</a>())
{
<a href="qcolor.html">QColor</a> c;
<a name="x2740"></a> c.<a href="qcolor.html#setHsv">setHsv</a>( (i * 255)/data.<a href="qptrlist.html#count">count</a>(), 255, 255 );// rainbow effect
p.<a href="qpainter.html#setBrush">setBrush</a>(c);
int bw = (w-w/4-x)/(data.<a href="qptrlist.html#count">count</a>()-i);
int bh = int((h-h/4-1)*rowdata[0].dbl/max);
p.<a href="qpainter.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="qptrlist.html#first">first</a>(); rowdata;
rowdata = data.<a href="qptrlist.html#next">next</a>())
{
int bx = i*w/data.<a href="qptrlist.html#count">count</a>();
if (bx > x) {
<a href="qcolor.html">QColor</a> c;
c.<a href="qcolor.html#setHsv">setHsv</a>( (x * 255)/w, 255, 255 );// rainbow effect
p.<a href="qpainter.html#setPen">setPen</a>(c);
int bh = int(h*av/n/max);
p.<a href="qpainter.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(QPaintEvent* event)
{
if ( model.colType(0) != GraphModel::Numeric ) {
paintError("First column not numeric, cannot draw pie graph\n");
return;
}
<a href="qptrlist.html">QPtrList</a><GraphModel::Datum>& data = model.graphData();
double total = 0.0;
GraphModel::Datum* rowdata;
for (rowdata = data.<a href="qptrlist.html#first">first</a>();
rowdata; rowdata = data.<a href="qptrlist.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="qwidget.html#width">width</a>();
const int h = <a href="qwidget.html#height">height</a>();
const int xd = w - w/5;
const int yd = h - h/5;
<a name="x2766"></a> pm.<a href="qpixmap.html#resize">resize</a>(<a href="qwidget.html#width">width</a>(),height());
<a name="x2765"></a> pm.<a href="qpixmap.html#fill">fill</a>(<a href="qwidget.html#backgroundColor">backgroundColor</a>());
<a href="qpainter.html">QPainter</a> p(&pm);
<a name="x2763"></a> p.<a href="qpainter.html#setFont">setFont</a>(<a href="qwidget.html#font">font</a>());
p.<a href="qpainter.html#setClipRect">setClipRect</a>(event->rect());
int i = 0;
for (rowdata = data.<a href="qptrlist.html#first">first</a>();
rowdata; rowdata = data.<a href="qptrlist.html#next">next</a>())
{
<a href="qcolor.html">QColor</a> c;
c.<a href="qcolor.html#setHsv">setHsv</a>( ( i * 255)/data.<a href="qptrlist.html#count">count</a>(), 255, 255 );// rainbow effect
p.<a href="qpainter.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="qpainter.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="qptrlist.html#first">first</a>();
rowdata; rowdata = data.<a href="qptrlist.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="qpainter.html#drawText">drawText</a>(x-w/8, y-h/8, w/4, h/4,
WordBreak|AlignCenter,
*rowdata[1].str);*/
apos += a;
}
}
<a href="qpainter.html">QPainter</a> p2(this);
p2.<a href="qpainter.html#setClipRect">setClipRect</a>(event->rect());
<a name="x2758"></a> p2.<a href="qpainter.html#drawPixmap">drawPixmap</a>(0,0,pm);
}
void <a name="f568"></a>Graph::paintWait(QPaintEvent*)
{
<a href="qpainter.html">QPainter</a> p(this);
p.<a href="qpainter.html#drawText">drawText</a>(rect(), AlignCenter, "Loading...");
}
void Graph::<a href="qwidget.html#paintEvent">paintEvent</a>(QPaintEvent* 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 QNPInstance, and so it can be returned
// by GrapherPlugin::newInstance(). A QNPInstance 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">QNPInstance</a>, GraphModel {
Q_OBJECT
public:
// Create a Grapher - all Grapher plugins are created
// by one GrapherPlugin object.
//
Grapher();
~Grapher();
// We override this QNPInstance function to create our
// own subclass of QNPWidget, a Graph widget.
//
<a href="qnpwidget.html">QNPWidget</a>* newWindow();
// We override this QNPInstance function to process the
// incoming graph data.
//
int write(QNPStream* /*str*/, int /*offset*/, int len, void* buffer);
private:
// Grapher is a GraphModel, so it implements the pure virtual
// functions of that class.
//
<a href="qptrlist.html">QPtrList</a><Datum>& graphData();
ColType colType(int col) const;
int nCols() const;
void consumeLine();
<a href="qptrlist.html">QPtrList</a><Datum> data;
<a href="qbuffer.html">QBuffer</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="qptrcollection.html#setAutoDelete">setAutoDelete</a>(TRUE);
ncols = 0;
<a name="x2743"></a> line.<a href="qiodevice.html#open">open</a>(IO_WriteOnly|IO_Truncate);
}
Grapher::~Grapher()
{
}
QPtrList<GraphModel::Datum>& <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>QNPWidget* Grapher::<a href="qnpinstance.html#newWindow">newWindow</a>()
{
// Create a Graph - our subclass of QNPWidget.
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-><a href="qwidget.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-><a href="qwidget.html#font">font</a>().pointSize();
if (fontfamily) graph-><a href="qwidget.html#setFont">setFont</a>(QFont(fontfamily, ptsize));
<a href="qobject.html#connect">connect</a>(graph, SIGNAL(aboutPlugin()), this, SLOT(aboutPlugin()));
<a href="qobject.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="qiodevice.html#close">close</a>();
line.<a href="qiodevice.html#open">open</a>(IO_ReadOnly);
<a href="qtextstream.html">QTextStream</a> ts( &line );
if (ncols == 0 ) {
ncols=0;
<a href="qptrlist.html">QPtrList</a><ColType> typelist;
typelist.<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>(TRUE);
do {
<a href="qstring.html">QString</a> typestr;
ts >> typestr >> 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="qptrlist.html#append">append</a>(t);
<a name="x2774"></a> } while (!ts.<a href="qtextstream.html#atEnd">atEnd</a>());
coltype = new ColType[ncols];
for (ColType* t = typelist.<a href="qptrlist.html#first">first</a>(); t; t = typelist.<a href="qptrlist.html#next">next</a>()) {
coltype[ncols++] = *t;
}
} else {
int col=0;
Datum *rowdata = new Datum[ncols];
while ( col < ncols && !ts.<a href="qtextstream.html#atEnd">atEnd</a>() ) {
switch (coltype[col]) {
case Numeric: {
double value;
ts >> value >> ws;
rowdata[col].dbl = value;
break;
}
case Label: {
<a href="qstring.html">QString</a>* value = new <a href="qstring.html">QString</a>;
ts >> *value >> ws;
rowdata[col].str = value;
break;
}
}
col++;
}
data.<a href="qptrlist.html#append">append</a>(rowdata);
}
line.<a href="qiodevice.html#close">close</a>();
line.<a href="qiodevice.html#open">open</a>(IO_WriteOnly|IO_Truncate);
}
<a name="x2752"></a>int Grapher::<a href="qnpinstance.html#write">write</a>(QNPStream* /*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 QNPStream is that one. Also, since we do not
// override QNPInstance::writeReady(), we must accepts ALL the data
// that is sent to this function.
//
char* txt = (char*)buffer;
for (int i=0; i<len; i++) {
char ch = txt[i];
switch ( ch ) {
case '\n':
consumeLine();
break;
case '\r': // ignore;
break;
default:
<a name="x2744"></a> line.<a href="qiodevice.html#putch">putch</a>(ch);
}
}
if ( <a href="qnpinstance.html#widget">widget</a>() )
<a href="qnpinstance.html#widget">widget</a>()->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> QMessageBox::<a href="qmessagebox.html#message">message</a>("Help", "No help for this data");
}
//
// GrapherPlugin is the start of everything. It is a QNPlugin 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">QNPlugin</a> {
public:
GrapherPlugin()
{
}
<a href="qnpinstance.html">QNPInstance</a>* newInstance()
{
// Make a new Grapher, our subclass of QNPInstance.
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 "Qt-based Graph Plugin";
}
const char * getPluginDescriptionString() const
{
// A longer description of the plugin.
//
return "A Qt-based LiveConnected plug-in that graphs numeric data";
}
};
//
// Finally, we provide the implementation of QNPlugin::create(), to
// provide our subclass of QNPlugin.
//
QNPlugin* QNPlugin::create()
{
return new GrapherPlugin;
}
#include "grapher.moc"
</pre>
<p>See also <a href="nsplugin-examples.html">Netscape Plugin Examples</a>.
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