/usr/share/qt3/doc/html/drawdemo-example.html

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<title>Draw Demo</title>
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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>Draw Demo</h1>

   
<p> 
This example demonstrates several drawing functions and printer output.
You can easily add you own drawing functions.
<p> <hr>
<p> Implementation:
<p> <pre>/****************************************************************************
** $Id: qt/drawdemo.cpp   3.3.8   edited Jan 11 14:37 $
**
** Copyright (C) 1992-2007 Trolltech ASA.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include &lt;<a href="qwidget-h.html">qwidget.h</a>&gt;
#include &lt;<a href="qpainter-h.html">qpainter.h</a>&gt;
#include &lt;<a href="qprinter-h.html">qprinter.h</a>&gt;
#include &lt;<a href="qpushbutton-h.html">qpushbutton.h</a>&gt;
#include &lt;<a href="qradiobutton-h.html">qradiobutton.h</a>&gt;
#include &lt;<a href="qbuttongroup-h.html">qbuttongroup.h</a>&gt;
#include &lt;<a href="qapplication-h.html">qapplication.h</a>&gt;
#include &lt;math.h&gt;

//
// First we define the functionality our demo should present
// to the user. You might add different demo-modes if you wish so.
//

//
// This function draws a color wheel.
// The coordinate system x=(0..500), y=(0..500) spans the paint device.
//

void drawColorWheel( <a href="qpainter.html">QPainter</a> *p )
{
    <a href="qfont.html">QFont</a> f( "times", 18, QFont::Bold );
<a name="x1075"></a>    p-&gt;<a href="qpainter.html#setFont">setFont</a>( f );
<a name="x1076"></a>    p-&gt;<a href="qpainter.html#setPen">setPen</a>( Qt::black );
<a name="x1077"></a>    p-&gt;<a href="qpainter.html#setWindow">setWindow</a>( 0, 0, 500, 500 );             // defines coordinate system

    for ( int i=0; i&lt;36; i++ ) {                // draws 36 rotated rectangles

        <a href="qwmatrix.html">QWMatrix</a> matrix;
<a name="x1097"></a>        matrix.<a href="qwmatrix.html#translate">translate</a>( 250.0F, 250.0F );     // move to center
<a name="x1096"></a>        matrix.<a href="qwmatrix.html#shear">shear</a>( 0.0F, 0.3F );             // twist it
<a name="x1095"></a>        matrix.<a href="qwmatrix.html#rotate">rotate</a>( (float)i*10 );           // rotate 0,10,20,.. degrees
<a name="x1078"></a>        p-&gt;<a href="qpainter.html#setWorldMatrix">setWorldMatrix</a>( matrix );            // use this world matrix

        <a href="qcolor.html">QColor</a> c;
<a name="x1063"></a>        c.<a href="qcolor.html#setHsv">setHsv</a>( i*10, 255, 255 );             // rainbow effect
<a name="x1074"></a>        p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( c );                       // solid fill with color c
<a name="x1070"></a>        p-&gt;<a href="qpainter.html#drawRect">drawRect</a>( 70, -10, 80, 10 );         // draw the rectangle

        <a href="qstring.html">QString</a> n;
        n.<a href="qstring.html#sprintf">sprintf</a>( "H=%d", i*10 );
<a name="x1072"></a>        p-&gt;<a href="qpainter.html#drawText">drawText</a>( 80+70+5, 0, n );           // draw the hue number
    }
}


//
// This function draws a few lines of text using different fonts.
//

void drawFonts( <a href="qpainter.html">QPainter</a> *p )
{
    static const char *fonts[] = { "Helvetica", "Courier", "Times", 0 };
    static int   sizes[] = { 10, 12, 18, 24, 36, 0 };
    int f = 0;
    int y = 0;
    while ( fonts[f] ) {
        int s = 0;
        while ( sizes[s] ) {
            <a href="qfont.html">QFont</a> font( fonts[f], sizes[s] );
            p-&gt;<a href="qpainter.html#setFont">setFont</a>( font );
<a name="x1073"></a>            <a href="qfontmetrics.html">QFontMetrics</a> fm = p-&gt;<a href="qpainter.html#fontMetrics">fontMetrics</a>();
<a name="x1064"></a>            y += fm.<a href="qfontmetrics.html#ascent">ascent</a>();
            p-&gt;<a href="qpainter.html#drawText">drawText</a>( 10, y, "Quartz Glyph Job Vex'd Cwm Finks" );
<a name="x1065"></a>            y += fm.<a href="qfontmetrics.html#descent">descent</a>();
            s++;
        }
        f++;
    }
}


//
// This function draws some shapes
//

void drawShapes( <a href="qpainter.html">QPainter</a> *p )
{
    <a href="qbrush.html">QBrush</a> b1( Qt::blue );
    <a href="qbrush.html">QBrush</a> b2( Qt::green, Qt::Dense6Pattern );          // green 12% fill
    <a href="qbrush.html">QBrush</a> b3( Qt::NoBrush );                           // void brush
    <a href="qbrush.html">QBrush</a> b4( Qt::CrossPattern );                      // black cross pattern

    p-&gt;<a href="qpainter.html#setPen">setPen</a>( Qt::red );
    p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( b1 );
    p-&gt;<a href="qpainter.html#drawRect">drawRect</a>( 10, 10, 200, 100 );
    p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( b2 );
<a name="x1071"></a>    p-&gt;<a href="qpainter.html#drawRoundRect">drawRoundRect</a>( 10, 150, 200, 100, 20, 20 );
    p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( b3 );
<a name="x1068"></a>    p-&gt;<a href="qpainter.html#drawEllipse">drawEllipse</a>( 250, 10, 200, 100 );
    p-&gt;<a href="qpainter.html#setBrush">setBrush</a>( b4 );
<a name="x1069"></a>    p-&gt;<a href="qpainter.html#drawPie">drawPie</a>( 250, 150, 200, 100, 45*16, 90*16 );
}


typedef void (*draw_func)(QPainter*);

struct DrawThing {
    draw_func    f;
    const char  *name;
};

//
// All previously implemented functions are collected
// in the following "table".
// If you implement different functionality, your new draw
// function must be assigned here with a function pointer and
// description.
// Leave the zeros at the end, they will be used
// as markers referring to the end of the array.
//

DrawThing ourDrawFunctions[] = {
// name of the function, title presented to the user
    { drawColorWheel,   "Draw color wheel" },
    { drawFonts,        "Draw fonts" },
    { drawShapes,       "Draw shapes" },
    { 0,                0 } };



class DrawView : public <a href="qwidget.html">QWidget</a>
{
    <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
public:
    DrawView();
    ~DrawView();
public slots:
    void   updateIt( int );
    void   printIt();
protected:
    void   drawIt( <a href="qpainter.html">QPainter</a> * );
    void   paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * );
    void   resizeEvent( <a href="qresizeevent.html">QResizeEvent</a> * );
private:
    <a href="qprinter.html">QPrinter</a>     *printer;
    <a href="qbuttongroup.html">QButtonGroup</a> *bgroup;
    <a href="qpushbutton.html">QPushButton</a>  *print;
    int           drawindex;
    int           maxindex;
};


//
// Construct the DrawView with buttons.
//

<a name="f367"></a>DrawView::DrawView()
{
    <a href="qwidget.html#setCaption">setCaption</a>( "Qt Draw Demo Application" );
    <a href="qwidget.html#setBackgroundMode">setBackgroundMode</a>(PaletteBase);

    // Create a button group to contain all buttons
    bgroup = new <a href="qbuttongroup.html">QButtonGroup</a>( this );
<a name="x1088"></a>    bgroup-&gt;<a href="qwidget.html#resize">resize</a>( 200, 200 );
<a name="x1062"></a>    <a href="qobject.html#connect">connect</a>( bgroup, SIGNAL(<a href="qbuttongroup.html#clicked">clicked</a>(int)), SLOT(updateIt(int)) );

    // Calculate the size for the radio buttons
    int maxwidth = 80;
    int maxheight = 10;
    int i;
    const char *n;
<a name="x1084"></a>    <a href="qfontmetrics.html">QFontMetrics</a> fm = bgroup-&gt;<a href="qwidget.html#fontMetrics">fontMetrics</a>();

    // Find out the longest function description.
    // Here we make use of the last "0,0"-entry in the
    // ourDrawFunctions-array.
    for ( i=0; (n=ourDrawFunctions[i].name) != 0; i++ ) {
<a name="x1066"></a>        int w = fm.<a href="qfontmetrics.html#width">width</a>( n );
        maxwidth = QMAX(w,maxwidth); // QMAX is a macro defined in qglobal.h
                                     // and returns the biggest of to values.
        // Due to its macro nature one should use it with care and with
        // constant parameters only.
    }

    maxwidth = maxwidth + 30;                   // allow 30 pixels for radiobuttons

    for ( i=0; (n=ourDrawFunctions[i].name) != 0; i++ ) {
        <a href="qradiobutton.html">QRadioButton</a> *rb = new <a href="qradiobutton.html">QRadioButton</a>( n, bgroup );
<a name="x1091"></a>        rb-&gt;<a href="qwidget.html#setGeometry">setGeometry</a>( 10, i*30+10, maxwidth, 30 );

        maxheight += 30;

        if ( i == 0 )
<a name="x1082"></a>            rb-&gt;<a href="qradiobutton.html#setChecked">setChecked</a>( TRUE );
    }

    maxheight += 10;                            // maxheight is now 10 pixels upper margin
                                                // plus number_of_drawfunctions * 30
                                                // plus 10 pixels lower margin

    drawindex = 0;                              // draw first thing
    maxindex  = i;

    maxwidth += 20;                             // add some margin, this results in the
                                                // final width of bgroup

    bgroup-&gt;<a href="qwidget.html#resize">resize</a>( maxwidth, maxheight );      // resize bgroup to its final size
                                                // when no printersupport is provided


// If -- at compile time -- printer support will be disabled,
// we won't set up printing functionality.

#ifndef QT_NO_PRINTER

    printer = new <a href="qprinter.html">QPrinter</a>;

    // Create and setup the print button
    print = new <a href="qpushbutton.html">QPushButton</a>( "Print...", bgroup );
<a name="x1081"></a>    print-&gt;<a href="qwidget.html#resize">resize</a>( 80, 30 );
<a name="x1093"></a><a name="x1080"></a>    print-&gt;<a href="qwidget.html#move">move</a>( maxwidth/2 - print-&gt;<a href="qwidget.html#width">width</a>()/2, maxindex*30+20 );
    <a href="qobject.html#connect">connect</a>( print, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()), SLOT(printIt()) );

    // Resize bgroup to its final size when printersupport is given.
<a name="x1094"></a><a name="x1085"></a>    bgroup-&gt;<a href="qwidget.html#resize">resize</a>( maxwidth, print-&gt;<a href="qwidget.html#y">y</a>()+print-&gt;<a href="qwidget.html#height">height</a>()+10 );

#endif

    <a href="qwidget.html#resize">resize</a>( 640,300 );
}

//
// Clean up.
//
DrawView::~DrawView()
{
#ifndef QT_NO_PRINTER
    delete printer;
#endif
}

//
// Called when a radio button is clicked.
//

void <a name="f368"></a>DrawView::updateIt( int index )
{
    if ( index &lt; maxindex ) {
        drawindex = index;
        <a href="qwidget.html#update">update</a>();
    }
}

//
// Calls the drawing function as specified by the radio buttons.
//

void <a name="f369"></a>DrawView::drawIt( <a href="qpainter.html">QPainter</a> *p )
{
    (*ourDrawFunctions[drawindex].f)(p);
}

//
// Called when the print button is clicked.
//

void <a name="f370"></a>DrawView::printIt()
{
<a name="x1079"></a>    if ( printer-&gt;<a href="qprinter.html#setup">setup</a>( this ) ) {
        <a href="qpainter.html">QPainter</a> paint;
<a name="x1067"></a>        if( !paint.<a href="qpainter.html#begin">begin</a>( printer ) )
            return;
        drawIt( &amp;paint );
    }
}

//
// Called when the widget needs to be updated.
//

void DrawView::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> * )
{
    <a href="qpainter.html">QPainter</a> paint( this );
    drawIt( &amp;paint );
}

//
// Called when the widget has been resized.
// Moves the button group to the upper right corner
// of the widget.

<a name="x1089"></a>void DrawView::<a href="qwidget.html#resizeEvent">resizeEvent</a>( <a href="qresizeevent.html">QResizeEvent</a> * )
{
<a name="x1086"></a>    bgroup-&gt;<a href="qwidget.html#move">move</a>( <a href="qwidget.html#width">width</a>()-bgroup-&gt;<a href="qwidget.html#width">width</a>(), 0 );
}


//
// Create and display our widget.
//

#include "drawdemo.moc"

int main( int argc, char **argv )
{
    <a href="qapplication.html">QApplication</a> app( argc, argv );
    DrawView   draw;
    app.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &amp;draw );
    draw.<a href="qwidget.html#setCaption">setCaption</a>("Qt Example - Drawdemo");
    draw.<a href="qwidget.html#show">show</a>();
    return app.<a href="qapplication.html#exec">exec</a>();
}
</pre>

<p>See also <a href="examples.html">Examples</a>.

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