The example program on this page may be used, distributed and modified
without limitation.
C0664 510077 qtdoc-1.2-a4-2.ps
Draw Demo
This example demontrates several drawing functions and printer output.
You can easily add you own drawing functions. See "ourDrawFunctions".
//
// Qt Example Application: drawdemo
//
// Demonstrates the painter and the printer.
//
#include <qwindow.h>
#include <qpainter.h>
#include <qprinter.h>
#include <qpushbt.h>
#include <qradiobt.h>
#include <qbttngrp.h>
#include <qapp.h>
#include <math.h>
//
// This function draws a color wheel.
// The coordinate system x=(0..500), y=(0..500) spans the paint device.
//
void drawColorWheel( QPainter *p )
{
QFont f( "times", 18, QFont::Bold );
p->setFont( f );
p->setPen( black ); // black pen outline
p->setWindow( 0, 0, 500, 500 ); // defines coordinate system
for ( int i=0; i<36; i++ ) { // draws 36 rotated rectangles
QWMatrix matrix;
matrix.translate( 250.0F, 250.0F ); // move to center
matrix.shear( 0.0F, 0.3F ); // twist it
matrix.rotate( (float)i*10 ); // rotate 0,10,20,.. degrees
p->setWorldMatrix( matrix ); // use this world matrix
QColor c;
c.setHsv( i*10, 255, 255 ); // rainbow effect
p->setBrush( c ); // solid fill with color c
p->drawRect( 70, -10, 80, 10 ); // draw the rectangle
QString n;
n.sprintf( "H=%d", i*10 );
p->drawText( 80+70+5, 0, n ); // draw the hue number
}
}
//
// This function draws a few lines of text using different fonts.
//
void drawFonts( QPainter *p )
{
static char *fonts[] = { "Helvetica", "Courier", "Times", 0 };
static int sizes[] = { 10, 12, 18, 24, 0 };
int f = 0;
int s = 0;
int y = 0;
while ( fonts[f] ) {
s = 0;
while ( sizes[s] ) {
QFont font( fonts[f], sizes[s] );
p->setFont( font );
QFontMetrics fm = p->fontMetrics();
y += fm.ascent();
p->drawText( 10, y, "Quartz Glyph Job Vex'd Cwm Finks" );
y += fm.descent();
s++;
}
f++;
}
}
//
// This function draws some shapes
//
void drawShapes( QPainter *p )
{
QBrush b1( blue ); // solid blue brush
QBrush b2( green, Dense6Pattern ); // green 12% fill
QBrush b3( NoBrush ); // void brush
QBrush b4( CrossPattern ); // black cross pattern
p->setPen( red );
p->setBrush( b1 );
p->drawRect( 10, 10, 200, 100 ); // draw some shapes
p->setBrush( b2 );
p->drawRoundRect( 10, 150, 200, 100, 20, 20 );
p->setBrush( b3 );
p->drawEllipse( 250, 10, 200, 100 );
p->setBrush( b4 );
p->drawPie( 250, 150, 200, 100, 45*16, 90*16 );
}
//
// This function draws a text that follows a (Bezier) curve.
// Notice that this function does not support the general case.
// It should be rewritten to calculate the real dx/dy.
//
void drawPathText( QPainter *p )
{
QPointArray a( 4 );
a.setPoint( 0, 100,200 );
a.setPoint( 1, 150,75 );
a.setPoint( 2, 250,75 );
a.setPoint( 3, 300,200 );
a = a.quadBezier(); // calculate Bezier curve
p->setPen( lightGray ); // set light gray pen
p->drawPolyline( a ); // draw Bezier point array
p->setFont( QFont("Times",24) ); // set fast font
p->setPen( black ); // set black pen
const char *text = "Troll Tech AS";
int len = strlen(text);
if ( len == 0 )
return;
int ipos = a.size()/len;
int cpos = ipos;
for ( int i=0; i<len; i++ ) { // for each char in text...
QPoint p1 = a.point( cpos-1 );
QPoint p2 = a.point( cpos+1 );
QPoint pt = a.point(cpos);
float dx = (float)(p2.x() - p1.x());
float dy = (float)(p2.y() - p1.y());
float angle = (float)atan(dy/dx); // way too simple
angle *= 180.0F/3.14F;
QWMatrix m; // setup world matrix
m.translate( (float)pt.x(), (float)pt.y() );
m.rotate( angle );
p->setWorldMatrix( m );
p->drawText( 0,0, &text[i], 1 );
cpos += ipos;
}
}
typedef void (*draw_func)(QPainter*);
struct DrawThing {
draw_func f;
char *name;
};
//
// You can add your draw function here.
// Leave the zeros at the end of the array!
//
DrawThing ourDrawFunctions[] = {
{ drawColorWheel, "Draw color wheel" },
{ drawFonts, "Draw fonts" },
{ drawShapes, "Draw shapes" },
{ drawPathText, "Draw path text" },
{ 0, 0 } };
//
// DrawView has installable draw routines, just add a function pointer
// and a text in the table above.
//
class DrawView : public QWindow
{
Q_OBJECT
public:
DrawView();
public slots:
void updateIt( int );
void printIt();
protected:
void drawIt( QPainter * );
void paintEvent( QPaintEvent * );
void resizeEvent( QResizeEvent * );
private:
QPrinter *printer;
QButtonGroup *bgroup;
QPushButton *print;
QRadioButton *rb_wheel;
QRadioButton *rb_fonts;
QRadioButton *rb_patht;
int drawindex;
int maxindex;
};
//
// Construct the DrawView with buttons.
//
DrawView::DrawView()
{
setCaption( "Qt Draw Demo Application" );
setBackgroundColor( white );
printer = new QPrinter;
// Create a button group to contain all buttons
bgroup = new QButtonGroup( this );
bgroup->resize( 200, 200 );
connect( bgroup, SIGNAL(clicked(int)), SLOT(updateIt(int)) );
// Calculate the size for the radio buttons
int maxwidth = 80;
int i;
char *n;
QFontMetrics fm = bgroup->fontMetrics();
for ( i=0; (n=ourDrawFunctions[i].name) != 0; i++ ) {
int w = fm.width( n );
maxwidth = QMAX(w,maxwidth);
}
maxwidth = maxwidth + 20; // add 20 pixels
for ( i=0; (n=ourDrawFunctions[i].name) != 0; i++ ) {
QRadioButton *rb = new QRadioButton( n, bgroup );
rb->setGeometry( 10, i*30+10, maxwidth, 30 );
if ( i == 0 )
rb->setChecked( TRUE );
}
drawindex = 0; // draw first thing
maxindex = i;
maxwidth += 40; // now size of bgroup
// Create and setup the print button
print = new QPushButton( "Print", bgroup );
print->resize( 80, 30 );
print->move( maxwidth/2 - print->width()/2, maxindex*30+20 );
connect( print, SIGNAL(clicked()), SLOT(printIt()) );
bgroup->resize( maxwidth, print->y()+print->height()+10 );
resize( 640,300 );
}
//
// Called when a radio button is clicked.
//
void DrawView::updateIt( int index )
{
if ( index < maxindex ) {
drawindex = index;
update();
}
}
//
// Calls the drawing function as specified by the radio buttons.
//
void DrawView::drawIt( QPainter *p )
{
(*ourDrawFunctions[drawindex].f)(p); // call draw function
}
//
// Called when the print button is clicked.
//
void DrawView::printIt()
{
if ( printer->setup(this) ) {
QPainter paint;
paint.begin( printer );
drawIt( &paint );
paint.end();
}
}
//
// Called when the widget needs to be updated.
//
void DrawView::paintEvent( QPaintEvent * )
{
QPainter paint;
paint.begin( this ); // begin painting
drawIt( &paint ); // draw color wheel
paint.end(); // painting done
}
//
// Called when the widget has been resized.
// Moves the button group to the upper right corner
// of the widget.
void DrawView::resizeEvent( QResizeEvent * )
{
bgroup->move( width()-bgroup->width(), 0 );
}
//
// Create and display our widget.
//
#include "drawdemo.moc"
int main( int argc, char **argv )
{
QApplication app( argc, argv );
DrawView draw;
app.setMainWidget( &draw );
draw.show();
return app.exec();
}
Generated at 17:29, 1997/04/07 for Qt version 1.2 by the webmaster at Troll Tech