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# Picture

This example shows how to make a picture, store it to a file, and read it as a set of drawing commands.

Implementation:

    /****************************************************************************
    ** $Id: qt/picture.cpp   3.3.7   edited Aug 31 2005 $
    **
    ** Copyright (C) 1992-2005 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 <qapplication.h>
    #include <qpainter.h>
    #include <qpicture.h>
    #include <qpixmap.h>
    #include <qwidget.h>
    #include <qmessagebox.h>
    #include <qfile.h>
    #include <ctype.h>

    void paintCar( QPainter *p )                    // paint a car
    {
        QPointArray a;
        QBrush brush( Qt::yellow, Qt::SolidPattern );
        p->setBrush( brush );                       // use solid, yellow brush

        a.setPoints( 5, 50,50, 350,50, 450,120, 450,250, 50,250 );
        p->drawPolygon( a );                        // draw car body

        QFont f( "courier", 12, QFont::Bold );
        p->setFont( f );

        QColor windowColor( 120, 120, 255 );        // a light blue color
        brush.setColor( windowColor );              // set this brush color
        p->setBrush( brush );                       // set brush
        p->drawRect( 80, 80, 250, 70 );             // car window
        p->drawText( 180, 80, 150, 70, Qt::AlignCenter, "--  Qt  --\nTrolltech AS" );

        QPixmap pixmap;
        if ( pixmap.load("flag.bmp") )              // load and draw image
            p->drawPixmap( 100, 85, pixmap );

        p->setBackgroundMode( Qt::OpaqueMode );     // set opaque mode
        p->setBrush( Qt::DiagCrossPattern );        // black diagonal cross pattern
        p->drawEllipse( 90, 210, 80, 80 );          // back wheel
        p->setBrush( Qt::CrossPattern );            // black cross fill pattern
        p->drawEllipse( 310, 210, 80, 80 );         // front wheel
    }

    class PictureDisplay : public QWidget           // picture display widget
    {
    public:
        PictureDisplay( const char *fileName );
       ~PictureDisplay();
    protected:
        void        paintEvent( QPaintEvent * );
        void        keyPressEvent( QKeyEvent * );
    private:
        QPicture   *pict;
        QString     name;
    };

    PictureDisplay::PictureDisplay( const char *fileName )
    {
        pict = new QPicture;
        name = fileName;
        if ( !pict->load(fileName) ) {              // cannot load picture
            delete pict;
            pict = 0;
            name.sprintf( "Not able to load picture: %s", fileName );
        }
    }

    PictureDisplay::~PictureDisplay()
    {
        delete pict;
    }

    void PictureDisplay::paintEvent( QPaintEvent * )
    {
        QPainter paint( this );                     // paint widget
        if ( pict )
            paint.drawPicture( *pict );             // draw picture
        else
            paint.drawText( rect(), AlignCenter, name );
    }

    void PictureDisplay::keyPressEvent( QKeyEvent *k )
    {
        switch ( tolower(k->ascii()) ) {
            case 'r':                               // reload
                pict->load( name );
                update();
                break;
            case 'q':                               // quit
                QApplication::exit();
                break;
        }
    }

    int main( int argc, char **argv )
    {
        QApplication a( argc, argv );               // QApplication required!

        const char *fileName = "car.pic";           // default picture file name

        if ( argc == 2 )                            // use argument as file name
            fileName = argv[1];

        if ( !QFile::exists(fileName) ) {
            QPicture pict;                          // our picture
            QPainter paint;                         // our painter

            paint.begin( &pict );                   // begin painting onto picture
            paintCar( &paint );                     // paint!
            paint.end();                            // painting done

            pict.save( fileName );                  // save picture
            QMessageBox::information(0, "Qt Example - Picture", "Saved.  Run me again!");
            return 0;
        } else {
            PictureDisplay test( fileName );        // create picture display
            a.setMainWidget( &test);                // set main widget
            test.setCaption("Qt Example - Picture");
            test.show();                            // show it

            return a.exec();                        // start event loop
        }
    }

See also Examples.