rubberbandwidget.cpp

来自「Trolltech公司发布的基于C++图形开发环境」· C++ 代码 · 共 61 行

/****************************************************************************
** $Id: qt/rubberbandwidget.cpp   3.3.4   edited May 27 2003 $
**
** Implementation of a widget that draws a rubberband. Designed to be used 
** in an X11 overlay visual
**
** Copyright (C) 1999 by 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 "rubberbandwidget.h"
#include <qpainter.h>


RubberbandWidget::RubberbandWidget( QColor transparentColor, QWidget *parent, 
				    const char *name, WFlags f )
    : QWidget( parent, name, f )
{
    setBackgroundColor( transparentColor );
    on = FALSE;
}


void RubberbandWidget::mousePressEvent( QMouseEvent* e )
{
    p1 = e->pos();
    p2 = p1;
    p3 = p1;
    on = TRUE;
    setMouseTracking( TRUE );
}


void RubberbandWidget::mouseMoveEvent( QMouseEvent* e )
{
    if ( on ) {
	p2 = e->pos();
	QPainter p( this );
	// Erase last drawn rubberband:
	p.setPen( QPen( backgroundColor(), 3 ) );
	p.drawRect( QRect( p1, p3 ) );
	// Draw the new one:
	p.setPen( QPen( white, 3 ) );
	p.drawRect( QRect(p1, p2) );
	p3 = p2;
    }
}

void RubberbandWidget::mouseReleaseEvent( QMouseEvent* )
{
    if ( on ) {
	QPainter p ( this );
	p.eraseRect( rect() );
    }
    on = FALSE;
    setMouseTracking( FALSE );
}