Classes - Annotated - Tree - Functions - Home - Structure

Connect the Points

/****************************************************************************
** $Id: qt/examples/drawlines/connect.cpp   2.2.1   edited 2000-08-31 $
**
** 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 <qwidget.h>
#include <qpainter.h>
#include <qapplication.h>
#include <stdlib.h>

const int MAXPOINTS = 2000;                     // maximum number of points
const int MAXCOLORS = 40;

//
// ConnectWidget - draws connected lines
//

class ConnectWidget : public QWidget
{
public:
    ConnectWidget( QWidget *parent=0, const char *name=0 );
   ~ConnectWidget();
protected:
    void        paintEvent( QPaintEvent * );
    void        mousePressEvent( QMouseEvent *);
    void        mouseReleaseEvent( QMouseEvent *);
    void        mouseMoveEvent( QMouseEvent *);
private:
    QPoint     *points;                         // point array
    QColor     *colors;                         // color array
    int         count;                          // count = number of points
    bool        down;                           // TRUE if mouse down
};

//
// Constructs a ConnectWidget.
//

ConnectWidget::ConnectWidget( QWidget *parent, const char *name )
    : QWidget( parent, name, WNorthWestGravity )
{
    setBackgroundColor( white );                // white background
    count = 0;
    down = FALSE;
    points = new QPoint[MAXPOINTS];
    colors = new QColor[MAXCOLORS];
    for ( int i=0; i<MAXCOLORS; i++ )           // init color array
        colors[i] = QColor( rand()&255, rand()&255, rand()&255 );
}

ConnectWidget::~ConnectWidget()
{
    delete[] points;                            // cleanup
    delete[] colors;
}

//
// Handles paint events for the connect widget.
//

void ConnectWidget::paintEvent( QPaintEvent * )
{
    QPainter paint( this );
    for ( int i=0; i<count-1; i++ ) {           // connect all points
        for ( int j=i+1; j<count; j++ ) {
            paint.setPen( colors[rand()%MAXCOLORS] ); // set random pen color
            paint.drawLine( points[i], points[j] ); // draw line
        }
    }
}

//
// Handles mouse press events for the connect widget.
//

void ConnectWidget::mousePressEvent( QMouseEvent * )
{
    down = TRUE;
    count = 0;                                  // start recording points
    erase();                                    // erase widget contents
}

//
// Handles mouse release events for the connect widget.
//

void ConnectWidget::mouseReleaseEvent( QMouseEvent * )
{
    down = FALSE;                               // done recording points
    update();                                   // draw the lines
}

//
// Handles mouse move events for the connect widget.
//

void ConnectWidget::mouseMoveEvent( QMouseEvent *e )
{
    if ( down && count < MAXPOINTS ) {
        QPainter paint( this );
        points[count++] = e->pos();             // add point
        paint.drawPoint( e->pos() );            // plot point
    }
}

//
// Create and display a ConnectWidget.
//

int main( int argc, char **argv )
{
    QApplication a( argc, argv );
    ConnectWidget connect;
    a.setMainWidget( &connect );
    connect.show();
    return a.exec();
}