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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 3.0.2 edited Oct 12 12:18 $
**
** Copyright (C) 1992-2000 Trolltech AS. 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 <<a href="qwidget-h.html">qwidget.h</a>>
#include <<a href="qpainter-h.html">qpainter.h</a>>
#include <<a href="qprinter-h.html">qprinter.h</a>>
#include <<a href="qpushbutton-h.html">qpushbutton.h</a>>
#include <<a href="qradiobutton-h.html">qradiobutton.h</a>>
#include <<a href="qbuttongroup-h.html">qbuttongroup.h</a>>
#include <<a href="qapplication-h.html">qapplication.h</a>>
#include <math.h>
//
// 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="x1642"></a> p-><a href="qpainter.html#setFont">setFont</a>( f );
<a name="x1643"></a> p-><a href="qpainter.html#setPen">setPen</a>( Qt::black );
<a name="x1644"></a> p-><a href="qpainter.html#setWindow">setWindow</a>( 0, 0, 500, 500 ); // defines coordinate system
for ( int i=0; i<36; i++ ) { // draws 36 rotated rectangles
<a href="qwmatrix.html">QWMatrix</a> matrix;
<a name="x1662"></a> matrix.<a href="qwmatrix.html#translate">translate</a>( 250.0F, 250.0F ); // move to center
<a name="x1661"></a> matrix.<a href="qwmatrix.html#shear">shear</a>( 0.0F, 0.3F ); // twist it
<a name="x1660"></a> matrix.<a href="qwmatrix.html#rotate">rotate</a>( (float)i*10 ); // rotate 0,10,20,.. degrees
<a name="x1645"></a> p-><a href="qpainter.html#setWorldMatrix">setWorldMatrix</a>( matrix ); // use this world matrix
<a href="qcolor.html">QColor</a> c;
<a name="x1631"></a> c.<a href="qcolor.html#setHsv">setHsv</a>( i*10, 255, 255 ); // rainbow effect
<a name="x1641"></a> p-><a href="qpainter.html#setBrush">setBrush</a>( c ); // solid fill with color c
<a name="x1637"></a> p-><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="x1639"></a> p-><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-><a href="qpainter.html#setFont">setFont</a>( font );
<a name="x1640"></a> <a href="qfontmetrics.html">QFontMetrics</a> fm = p-><a href="qpainter.html#fontMetrics">fontMetrics</a>();
<a name="x1632"></a> y += fm.<a href="qfontmetrics.html#ascent">ascent</a>();
p-><a href="qpainter.html#drawText">drawText</a>( 10, y, "Quartz Glyph Job Vex'd Cwm Finks" );
<a name="x1633"></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-><a href="qpainter.html#setPen">setPen</a>( Qt::red );
p-><a href="qpainter.html#setBrush">setBrush</a>( b1 );
p-><a href="qpainter.html#drawRect">drawRect</a>( 10, 10, 200, 100 );
p-><a href="qpainter.html#setBrush">setBrush</a>( b2 );
<a name="x1638"></a> p-><a href="qpainter.html#drawRoundRect">drawRoundRect</a>( 10, 150, 200, 100, 20, 20 );
p-><a href="qpainter.html#setBrush">setBrush</a>( b3 );
<a name="x1635"></a> p-><a href="qpainter.html#drawEllipse">drawEllipse</a>( 250, 10, 200, 100 );
p-><a href="qpainter.html#setBrush">setBrush</a>( b4 );
<a name="x1636"></a> p-><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="f471"></a>DrawView::DrawView()
{
<a href="qwidget.html#setCaption">setCaption</a>( "Qt Draw Demo Application" );
<a href="qwidget.html#setBackgroundColor">setBackgroundColor</a>( white );
// Create a button group to contain all buttons
bgroup = new <a href="qbuttongroup.html">QButtonGroup</a>( this );
<a name="x1653"></a> bgroup-><a href="qwidget.html#resize">resize</a>( 200, 200 );
<a name="x1630"></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="x1649"></a> <a href="qfontmetrics.html">QFontMetrics</a> fm = bgroup-><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="x1634"></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="x1656"></a> rb-><a href="qwidget.html#setGeometry">setGeometry</a>( 10, i*30+10, maxwidth, 30 );
maxheight += 30;
if ( i == 0 )
<a name="x1647"></a> rb-><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-><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 );
print-><a href="qwidget.html#resize">resize</a>( 80, 30 );
<a name="x1658"></a><a name="x1651"></a> print-><a href="qwidget.html#move">move</a>( maxwidth/2 - print-><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="x1659"></a><a name="x1650"></a> bgroup-><a href="qwidget.html#resize">resize</a>( maxwidth, print-><a href="qwidget.html#y">y</a>()+print-><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="f472"></a>DrawView::updateIt( int index )
{
if ( index < maxindex ) {
drawindex = index;
<a href="qwidget.html#update">update</a>();
}
}
//
// Calls the drawing function as specified by the radio buttons.
//
void <a name="f473"></a>DrawView::drawIt( <a href="qpainter.html">QPainter</a> *p )
{
(*ourDrawFunctions[drawindex].f)(p);
}
//
// Called when the print button is clicked.
//
void <a name="f474"></a>DrawView::printIt()
{
<a name="x1646"></a> if ( printer-><a href="qprinter.html#setup">setup</a>( this ) ) {
<a href="qpainter.html">QPainter</a> paint( printer );
drawIt( &paint );
}
}
//
// Called when the widget needs to be updated.
//
<a name="x1652"></a>void DrawView::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> * )
{
<a href="qpainter.html">QPainter</a> paint( this );
drawIt( &paint );
}
//
// Called when the widget has been resized.
// Moves the button group to the upper right corner
// of the widget.
<a name="x1654"></a>void DrawView::<a href="qwidget.html#resizeEvent">resizeEvent</a>( <a href="qresizeevent.html">QResizeEvent</a> * )
{
bgroup-><a href="qwidget.html#move">move</a>( <a href="qwidget.html#width">width</a>()-bgroup-><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>( &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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<a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a>
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