image.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

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** Copyright (C) 2000-2005 Trolltech AS.  All rights reserved.
**
** This file is part of the Qtopia Environment.
** 
** This program is free software; you can redistribute it and/or modify it
** under the terms of the GNU General Public License as published by the
** Free Software Foundation; either version 2 of the License, or (at your
** option) any later version.
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** A copy of the GNU GPL license version 2 is included in this package as 
** LICENSE.GPL.
**
** This program is distributed in the hope that it will be useful, but
** WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
** See the GNU General Public License for more details.
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** the code of this program with Qtopia applications copyrighted, developed
** and distributed by Trolltech under the terms of the Qtopia Personal Use
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** in all respects for all of the code used other than the applications
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#include "image.h"

#include <qfileinfo.h>
#include <qimage.h>
#include <qstring.h>

/*!
   Returns an image created by loading the \a filename,
   and scalining it, preserving aspect ratio, to fit in
   \a width by \a height pixels.

   First availability: Qtopia 2.0
*/
QImage Image::loadScaled(const QString &filename, const int width, const int height, ScaleMode mode)
{
    QImageIO    iio;
    QString     param;
    int         w = width;
    int         h = height;

    if (width == 0 || height == 0)
	return QImage();

    iio.setFileName(filename);

    //
    // Try and load and scale the image in one hit.
    //
    param.sprintf("GetHeaderInformation");
    iio.setParameters(param);
    iio.read();

    //
    // If we don't have bits(), read() understands parameters,
    // and we can setup for fast reading.  Otherwise, take the
    // performance hit and do things slowly.
    //
    if (!iio.image().bits()) {
	if ((iio.image().width() < w) && (iio.image().height() < h)) {
	    param.sprintf("%s", "Fast"); // No Tr
	} else {
	    int shrink_factor=1;
	    QString smode;
	    switch (mode) {
		case ScaleMin:
		    smode = "ScaleMin";
		    shrink_factor = QMAX(iio.image().width() / w,
			iio.image().height() / h);
		    break;
		case ScaleMax:
		    smode = "ScaleMax";
		    shrink_factor = QMIN(iio.image().width() / w,
			iio.image().height() / h);
		    break;
		case ScaleFree:
		    smode = "ScaleFree";
		    shrink_factor = QMIN(iio.image().width() / w,
			iio.image().height() / h);
		    break;
	    }
	    param.sprintf("Scale( %i, %i, %s )%s, Shrink( %i )", // No tr
		    w, h, smode.latin1(),
		    ", Fast", shrink_factor); // No tr
	}

        iio.setParameters(param);
        iio.read();
        return iio.image();
    }

    if((iio.image().width() > w) || (iio.image().height() > h))
    {
	QSize s = aspectScaleSize(iio.image().width(), iio.image().height(), w, h, mode);
	return iio.image().smoothScale(s.width(), s.height());
    }
    
    return iio.image();
}

//
// Returns new size of image, scaled to target_width and target_height,
// whilst preserving aspect ratio.  Useful when it's not possible to
// scale an image prior to using it (eg. using RichText).  Should be in
// global image utils.
//
// NOTE
// - expensive for images whose drivers do not allow us to retrieve
//   parameters without reading the entire image.  Currently (20030930)
//   only the jpeg driver allows parameter reading.
//
QSize Image::loadScaledImageSize(const QString &filename, int target_width, int target_height, int maxscale, ScaleMode mode)
{
    QImageIO    iio;
    iio.setFileName(filename);
    iio.setParameters("GetHeaderInformation");
    iio.read();

    int w = iio.image().width();
    int h = iio.image().height();

    //
    // Scaling up small pictures can be very ugly.
    // Leave them alone if they are too small.
    //
    if (maxscale && w*maxscale < target_width && h*maxscale < target_height)
	return QSize(w*maxscale, h*maxscale);

    return aspectScaleSize(w, h, target_width, target_height, mode);
}

// Load an image to be used as a portrait. Force its height to height, 
// scale width to new height, and crop the width if it's still > width
// XXX : Should be using integer math
QImage Image::loadPortrait(const QString &filename, const int width, const int height)
{
    QImageIO    iio;
    QString     param;
    int         w = width;
    int         h = height;

    if (width == 0 || height == 0)
	return QImage();

    iio.setFileName(filename);

    //
    // Try and load and scale the image in one hit.
    //
    param.sprintf("GetHeaderInformation");
    iio.setParameters(param);
    iio.read();

    //
    // If we don't have bits(), read() understands parameters,
    // and we can setup for fast reading.  Otherwise, take the
    // performance hit and do things slowly.
    //
    if (!iio.image().bits()) 
    {

	w = (int)((double)iio.image().width() / (double)(iio.image().height()) * (double)height);
	param.sprintf("Scale( %i, %i, ScaleFree )%s", // No tr
		w, h,
		", Fast"
		); // No tr

        iio.setParameters(param);
        iio.read();

	if( w > width )
	{
	    int x = (int)((double)(w-width) / 2);
	    QRect r( x, 0, width, height );
	    return iio.image().copy( r );
	}
	else
	    return iio.image();
    } 
    else 
    {
	//scale width to the new height
	w = (int)((double)iio.image().width() / (double)(iio.image().height()) * (double)height);
	if( w > width )
	{
	    int x = (int)((double)(w-width) / 2);
	    QRect r( x, 0, width, height );
	    return iio.image().smoothScale(w, h).copy(r);
	}
	else
	    return iio.image().smoothScale(w, h);
    }
}

//
// Return (w x h) scaled to (target_width x target_height) with aspect
// ratio preserved.
//
QSize
Image::aspectScaleSize(const int w, const int h, const int target_width,
    const int target_height, ScaleMode mode)
{
    QSize s;
    if ( mode == ScaleFree ) {
	s = QSize(target_width, target_height);
    } else {
	bool useHeight = TRUE;
	int rw = target_height * w / h;

	if ( mode == ScaleMin ) {
	    useHeight = ( rw <= target_width );
	} else { // mode == ScaleMax
	    useHeight = ( rw >= target_width );
	}

	if ( useHeight ) {
	    s = QSize(rw, target_height);
	} else {
	    s = QSize(target_width, target_width * h / w);
	}
    }

    return s;
}