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/*
Copyright (C) 2005 Lubos Lunak <l.lunak@kde.org>
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.
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.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "croppedqimage.h"
namespace ImageUtils
{
// This class is used in ImageView::performPaint(). Just using QImage::copy( QRect )
// takes a significant time with very large images. So instead of copying the image data
// just create CroppedQImage which fakes a subimage by manipulating its scanline pointers.
// That will of course break if something doesn't use scanlines but accesses the image
// data directly, QImage::copy() being the most notable case. There are two ways
// to handle that: 1) It is possible to manually call normalize() which will make
// CroppedQImage copy the image data and own it, just like proper QImage. 2) CroppedQImage
// has as a data member also QImage holding the original image. This ensures that all
// the original image data are still available for the whole lifetime of CroppedQImage.
CroppedQImage::CroppedQImage( const QImage& im, const QRect& rect )
: QImage( rect.size(), im.depth(), im.numColors(), im.bitOrder())
, orig( im )
{
if( im.isNull())
return;
memcpy( colorTable(), im.colorTable(), im.numColors() * sizeof( QRgb ));
setAlphaBuffer( im.hasAlphaBuffer());
setDotsPerMeterX( im.dotsPerMeterX());
setDotsPerMeterY( im.dotsPerMeterY());
//data->offset = im.offset();
// make scanlines point to right places in the original QImage
for( int i = 0;
i < height();
++i )
jumpTable()[ i ] = im.scanLine( rect.y() + i ) + rect.x() * ( depth() / 8 );
}
CroppedQImage& CroppedQImage::operator= ( const QImage& im )
{
QImage::operator=( im );
return *this;
}
void CroppedQImage::normalize()
{
// is it a normal QImage with its own data?
uchar* firstdata = ( uchar* )( jumpTable() + height());
if( scanLine( 0 ) == firstdata )
return;
// copy the image data to our own data and make scanlines point properly there
for( int i = 0;
i < height();
++i )
{
uchar* oldline = scanLine( i );
jumpTable()[ i ] = firstdata + i * bytesPerLine();
memcpy( scanLine( i ), oldline, bytesPerLine());
}
}
} // namespace
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