qjpeghandler.cpp

M8手机图片查看器

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#include "qjpeghandler.h"

#include <qimage.h>
#include <qvariant.h>
#include <qvector.h>

#include <stdio.h>      // jpeglib needs this to be pre-included
#include <setjmp.h>

#ifdef FAR
#undef FAR
#endif

// including jpeglib.h seems to be a little messy
extern "C" {
// mingw includes rpcndr.h but does not define boolean
#if defined(Q_OS_WIN) && defined(Q_CC_GNU)
#   if defined(__RPCNDR_H__) && !defined(boolean)
        typedef unsigned char boolean;
#       define HAVE_BOOLEAN
#   endif
#endif

#define XMD_H           // shut JPEGlib up
#if defined(Q_OS_UNIXWARE)
#  define HAVE_BOOLEAN  // libjpeg under Unixware seems to need this
#endif
#include <jpeglib.h>
#ifdef const
#  undef const          // remove crazy C hackery in jconfig.h
#endif
}

QT_BEGIN_NAMESPACE

//#define QT_NO_IMAGE_SMOOTHSCALE
#ifndef QT_NO_IMAGE_SMOOTHSCALE
class QImageSmoothScalerPrivate;
class QImageSmoothScaler
{
public:
    QImageSmoothScaler(const int w, const int h, const QImage &src);
    QImageSmoothScaler(const int srcWidth, const int srcHeight,
                       const char *parameters);

    virtual ~QImageSmoothScaler(void);

    QImage  scale();

protected:
    int scaledWidth(void) const;

private:
    QImageSmoothScalerPrivate	*d;
    virtual QRgb *scanLine(const int line = 0, const QImage *src = 0);
};

class QImageSmoothScalerPrivate
{
public:
    int	    cols;
    int	    newcols;
    int	    rows;
    int	    newrows;
    bool    hasAlpha;

    const QImage  *src;

    void setup(const int srcWidth, const int srcHeight, const int dstWidth,
               const int dstHeight, bool hasAlphaChannel);
};

QImageSmoothScaler::QImageSmoothScaler(const int w, const int h,
                                       const QImage &src)
{
    d = new QImageSmoothScalerPrivate;
    
    d->setup(src.width(), src.height(), w, h, src.hasAlphaChannel() );
    this->d->src = &src;
}

QImageSmoothScaler::QImageSmoothScaler(const int srcWidth, const int srcHeight,
                                       const char *parameters)
{
    char    sModeStr[1024];
    int	    t1;
    int	    t2;
    int	    dstWidth;
    int	    dstHeight;

    sModeStr[0] = '\0';

    d = new QImageSmoothScalerPrivate;
#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE) && defined(_MSC_VER) && _MSC_VER >= 1400
    sscanf_s(parameters, "Scale( %i, %i, %1023s )", &dstWidth, &dstHeight, sModeStr, sizeof(sModeStr));
#else
    sscanf(parameters, "Scale( %i, %i, %s )", &dstWidth, &dstHeight, sModeStr);
#endif
    QString sModeQStr = QString::fromLatin1(sModeStr);

    t1 = srcWidth * dstHeight;
    t2 = srcHeight * dstWidth;

    if (((sModeQStr == QLatin1String("ScaleMin")) && (t1 > t2)) || ((sModeQStr == QLatin1String("ScaleMax")) && (t2 < t2))) {
	dstHeight = t2 / srcWidth;
    } else if (sModeQStr != QLatin1String("ScaleFree")) {
	dstWidth = t1 / srcHeight;
    }

    d->setup(srcWidth, srcHeight, dstWidth, dstHeight, 0);
}

void QImageSmoothScalerPrivate::setup(const int srcWidth, const int srcHeight,
                                      const int dstWidth, const int dstHeight,
                                      bool hasAlphaChannel)
{
    cols = srcWidth;
    rows = srcHeight;
    newcols = dstWidth;
    newrows = dstHeight;
    hasAlpha = hasAlphaChannel;
}

int QImageSmoothScaler::scaledWidth() const
{
    return d->cols;
}

QImageSmoothScaler::~QImageSmoothScaler()
{
    delete d;
}

inline QRgb *QImageSmoothScaler::scanLine(const int line, const QImage *src)
{
    return (QRgb*)src->scanLine(line);
}

/*
  This function uses code based on pnmscale.c by Jef Poskanzer.

  pnmscale.c - read a portable anymap and scale it
  
  Copyright (C) 1989, 1991 by Jef Poskanzer.

  Permission to use, copy, modify, and distribute this software and its
  documentation for any purpose and without fee is hereby granted, provided
  that the above copyright notice appear in all copies and that both that
  copyright notice and this permission notice appear in supporting
  documentation.  This software is provided "as is" without express or
  implied warranty.
*/

QImage QImageSmoothScaler::scale()
{
    long    SCALE;
    long    HALFSCALE;
    QRgb    *xelrow = 0;
    QRgb    *tempxelrow = 0;
    QRgb    *xP;
    QRgb    *nxP;
    int	    row, rowsread;
    int	    col, needtoreadrow;
    uchar   maxval = 255;
    double  xscale, yscale;
    long    sxscale, syscale;
    long    fracrowtofill, fracrowleft;
    long    *as;
    long    *rs;
    long    *gs;
    long    *bs;
    int	    rowswritten = 0;
    QImage  dst;

    if (d->cols > 4096) {
	SCALE = 4096;
	HALFSCALE = 2048;
    } else {
	int fac = 4096;
	while (d->cols * fac > 4096) {
	    fac /= 2;
	}

	SCALE = fac * d->cols;
	HALFSCALE = fac * d->cols / 2;
    }

    xscale = (double) d->newcols / (double) d->cols;
    yscale = (double) d->newrows / (double) d->rows;
    sxscale = (long)(xscale * SCALE);
    syscale = (long)(yscale * SCALE);

    if ( d->newrows != d->rows )	/* shortcut Y scaling if possible */
	tempxelrow = new QRgb[d->cols];

    if ( d->hasAlpha ) {
	as = new long[d->cols];
	for ( col = 0; col < d->cols; ++col )
	    as[col] = HALFSCALE;
    } else {
	as = 0;
    }
    rs = new long[d->cols];
    gs = new long[d->cols];
    bs = new long[d->cols];
    rowsread = 0;
    fracrowleft = syscale;
    needtoreadrow = 1;
    for ( col = 0; col < d->cols; ++col )
	rs[col] = gs[col] = bs[col] = HALFSCALE;
    fracrowtofill = SCALE;

    dst = QImage( d->newcols, d->newrows, d->hasAlpha ? QImage::Format_ARGB32 : QImage::Format_RGB32 );

    for ( row = 0; row < d->newrows; ++row ) {
	/* First scale Y from xelrow into tempxelrow. */
	if ( d->newrows == d->rows ) {
	    /* shortcut Y scaling if possible */
	    tempxelrow = xelrow = scanLine(rowsread++, d->src);
	} else {
	    while ( fracrowleft < fracrowtofill ) {
		if ( needtoreadrow && rowsread < d->rows ) {
		    xelrow = scanLine(rowsread++, d->src);
		}
		for ( col = 0, xP = xelrow; col < d->cols; ++col, ++xP ) {
		    if (as) {
			as[col] += fracrowleft * qAlpha( *xP );
			rs[col] += fracrowleft * qRed( *xP ) * qAlpha( *xP ) / 255;
			gs[col] += fracrowleft * qGreen( *xP ) * qAlpha( *xP ) / 255;
			bs[col] += fracrowleft * qBlue( *xP ) * qAlpha( *xP ) / 255;
		    } else {
			rs[col] += fracrowleft * qRed( *xP );
			gs[col] += fracrowleft * qGreen( *xP );
			bs[col] += fracrowleft * qBlue( *xP );
		    }
		}
		fracrowtofill -= fracrowleft;
		fracrowleft = syscale;
		needtoreadrow = 1;
	    }
	    /* Now fracrowleft is >= fracrowtofill, so we can produce a row. */
	    if ( needtoreadrow && rowsread < d->rows) {
		xelrow = scanLine(rowsread++, d->src);
		needtoreadrow = 0;
	    }
	    for ( col = 0, xP = xelrow, nxP = tempxelrow;
		  col < d->cols; ++col, ++xP, ++nxP )
	    {
		register long a, r, g, b;

		if ( as ) {
		    r = rs[col] + fracrowtofill * qRed( *xP ) * qAlpha( *xP ) / 255;
		    g = gs[col] + fracrowtofill * qGreen( *xP ) * qAlpha( *xP ) / 255;
		    b = bs[col] + fracrowtofill * qBlue( *xP ) * qAlpha( *xP ) / 255;
		    a = as[col] + fracrowtofill * qAlpha( *xP );
		    if ( a ) {
			r = r * 255 / a * SCALE;
			g = g * 255 / a * SCALE;
			b = b * 255 / a * SCALE;
		    }
		} else {
		    r = rs[col] + fracrowtofill * qRed( *xP );
		    g = gs[col] + fracrowtofill * qGreen( *xP );
		    b = bs[col] + fracrowtofill * qBlue( *xP );
		    a = 0; // unwarn
		}
		r /= SCALE;
		if ( r > maxval ) r = maxval;
		g /= SCALE;
		if ( g > maxval ) g = maxval;
		b /= SCALE;
		if ( b > maxval ) b = maxval;
		if ( as ) {
		    a /= SCALE;
		    if ( a > maxval ) a = maxval;
		    *nxP = qRgba( (int)r, (int)g, (int)b, (int)a );
		    as[col] = HALFSCALE;
		} else {
		    *nxP = qRgb( (int)r, (int)g, (int)b );
		}
		rs[col] = gs[col] = bs[col] = HALFSCALE;
	    }
	    fracrowleft -= fracrowtofill;
	    if ( fracrowleft == 0 ) {
		fracrowleft = syscale;
		needtoreadrow = 1;
	    }
	    fracrowtofill = SCALE;
	}

	/* Now scale X from tempxelrow into dst and write it out. */
	if ( d->newcols == d->cols ) {
	    /* shortcut X scaling if possible */
	    memcpy(dst.scanLine(rowswritten++), tempxelrow, d->newcols*4);
	} else {
	    register long a, r, g, b;
	    register long fraccoltofill, fraccolleft = 0;
	    register int needcol;

	    nxP = (QRgb*)dst.scanLine(rowswritten++);
	    fraccoltofill = SCALE;
	    a = r = g = b = HALFSCALE;
	    needcol = 0;
	    for ( col = 0, xP = tempxelrow; col < d->cols; ++col, ++xP ) {
		fraccolleft = sxscale;
		while ( fraccolleft >= fraccoltofill ) {
		    if ( needcol ) {
			++nxP;
			a = r = g = b = HALFSCALE;
		    }
		    if ( as ) {
			r += fraccoltofill * qRed( *xP ) * qAlpha( *xP ) / 255;
			g += fraccoltofill * qGreen( *xP ) * qAlpha( *xP ) / 255;
			b += fraccoltofill * qBlue( *xP ) * qAlpha( *xP ) / 255;
			a += fraccoltofill * qAlpha( *xP );
			if ( a ) {
			    r = r * 255 / a * SCALE;
			    g = g * 255 / a * SCALE;
			    b = b * 255 / a * SCALE;
			}
		    } else {
			r += fraccoltofill * qRed( *xP );
			g += fraccoltofill * qGreen( *xP );
			b += fraccoltofill * qBlue( *xP );
		    }
		    r /= SCALE;
		    if ( r > maxval ) r = maxval;
		    g /= SCALE;
		    if ( g > maxval ) g = maxval;
		    b /= SCALE;
		    if ( b > maxval ) b = maxval;
		    if (as) {
			a /= SCALE;
			if ( a > maxval ) a = maxval;
			*nxP = qRgba( (int)r, (int)g, (int)b, (int)a );
		    } else {
			*nxP = qRgb( (int)r, (int)g, (int)b );
		    }
		    fraccolleft -= fraccoltofill;
		    fraccoltofill = SCALE;
		    needcol = 1;
		}
		if ( fraccolleft > 0 ) {
		    if ( needcol ) {
			++nxP;
			a = r = g = b = HALFSCALE;
			needcol = 0;
		    }
		    if (as) {
			a += fraccolleft * qAlpha( *xP );
			r += fraccolleft * qRed( *xP ) * qAlpha( *xP ) / 255;
			g += fraccolleft * qGreen( *xP ) * qAlpha( *xP ) / 255;