waveform.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.7平台上编译为嵌入式图形界面操作系统。

/**********************************************************************
** Copyright (C) 2000-2002 Trolltech AS.  All rights reserved.
**
** This file is part of the Qtopia Environment.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
** See http://www.trolltech.com/gpl/ for GPL licensing information.
**
** Contact [e-mail] if any conditions of this licensing are
** not clear to you.
**
**********************************************************************/
#include "waveform.h"

#include <qlabel.h>
#include <qpainter.h>


Waveform::Waveform( QWidget *parent, const char *name, WFlags fl )
    : QWidget( parent, name, fl )
{
    pixmap = 0;
    windowSize = 100;
    samplesPerPixel = 8000 / (5 * windowSize);
    currentValue = 0;
    numSamples = 0;
    windowPosn = 0;
    window = 0;
}


void Waveform::changeSettings( int frequency, int channels )
{
    makePixmap();
    samplesPerPixel = frequency * channels / (5 * windowSize);
    if ( !samplesPerPixel )
	samplesPerPixel = 1;
    currentValue = 0;
    numSamples = 0;
    windowPosn = 0;
    draw();
}


Waveform::~Waveform()
{
    if ( window )
	delete[] window;
    if ( pixmap )
	delete pixmap;
}


void Waveform::reset()
{
    makePixmap();
    currentValue = 0;
    numSamples = 0;
    windowPosn = 0;
    draw();
}


void Waveform::newSamples( const short *buf, int len )
{
    // Cache the object values in local variables.
    int samplesPerPixel = this->samplesPerPixel;
    int currentValue = this->currentValue;
    int numSamples = this->numSamples;
    short *window = this->window;
    int windowPosn = this->windowPosn;
    int windowSize = this->windowSize;

    // Average the incoming samples to scale them to the window.
    while ( len > 0 ) {
	currentValue += *buf++;
	--len;
	if ( ++numSamples >= samplesPerPixel ) {
	    window[windowPosn++] = (short)(currentValue / numSamples);
	    if ( windowPosn >= windowSize ) {
		this->windowPosn = windowPosn;
		draw();
		windowPosn = 0;
	    }
	    numSamples = 0;
	    currentValue = 0;
	}
    }

    // Copy the final state back to the object.
    this->currentValue = currentValue;
    this->numSamples = numSamples;
    this->windowPosn = windowPosn;
}


void Waveform::makePixmap()
{
    if ( !pixmap ) {
	pixmap = new QPixmap( size() );
	windowSize = pixmap->width();
	window = new short [windowSize];
    }
}


void Waveform::draw()
{
    pixmap->fill( Qt::black );
    QPainter painter;
    painter.begin( pixmap );
    painter.setPen( Qt::green );

    int middle = pixmap->height() / 2;
    int mag;
    short *window = this->window;
    int posn;
    int size = windowPosn;
    for( posn = 0; posn < size; ++posn )
    {
	mag = (window[posn] * middle / 32768);
	painter.drawLine(posn, middle - mag, posn, middle + mag);
    }
    if ( windowPosn < windowSize )
    {
	painter.drawLine(windowPosn, middle, windowSize, middle);
    }

    painter.end();

    paintEvent( 0 );
}


void Waveform::paintEvent( QPaintEvent * )
{
    QPainter painter;
    painter.begin( this );

    if ( pixmap ) {
	painter.drawPixmap( 0, 0, *pixmap );
    } else {
	painter.setPen( Qt::green );
	QSize sz = size();
	painter.drawLine(0, sz.height() / 2, sz.width(), sz.height() / 2);
    }

    painter.end();
}