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78 lines
2.8 KiB
78 lines
2.8 KiB
15 years ago
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/*
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Copyright (C) 2005 Lubos Lunak <l.lunak@kde.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "croppedqimage.h"
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namespace ImageUtils
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{
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// This class is used in ImageView::performPaint(). Just using QImage::copy( QRect )
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// takes a significant time with very large images. So instead of copying the image data
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// just create CroppedQImage which fakes a subimage by manipulating its scanline pointers.
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// That will of course break if something doesn't use scanlines but accesses the image
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// data directly, QImage::copy() being the most notable case. There are two ways
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// to handle that: 1) It is possible to manually call normalize() which will make
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// CroppedQImage copy the image data and own it, just like proper QImage. 2) CroppedQImage
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// has as a data member also QImage holding the original image. This ensures that all
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// the original image data are still available for the whole lifetime of CroppedQImage.
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CroppedQImage::CroppedQImage( const QImage& im, const QRect& rect )
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: QImage( rect.size(), im.depth(), im.numColors(), im.bitOrder())
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, orig( im )
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{
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if( im.isNull())
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return;
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memcpy( colorTable(), im.colorTable(), im.numColors() * sizeof( QRgb ));
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setAlphaBuffer( im.hasAlphaBuffer());
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setDotsPerMeterX( im.dotsPerMeterX());
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setDotsPerMeterY( im.dotsPerMeterY());
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//data->offset = im.offset();
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// make scanlines point to right places in the original QImage
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for( int i = 0;
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i < height();
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++i )
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jumpTable()[ i ] = im.scanLine( rect.y() + i ) + rect.x() * ( depth() / 8 );
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}
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CroppedQImage& CroppedQImage::operator= ( const QImage& im )
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{
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QImage::operator=( im );
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return *this;
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}
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void CroppedQImage::normalize()
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{
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// is it a normal QImage with its own data?
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uchar* firstdata = ( uchar* )( jumpTable() + height());
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if( scanLine( 0 ) == firstdata )
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return;
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// copy the image data to our own data and make scanlines point properly there
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for( int i = 0;
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i < height();
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++i )
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{
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uchar* oldline = scanLine( i );
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jumpTable()[ i ] = firstdata + i * bytesPerLine();
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memcpy( scanLine( i ), oldline, bytesPerLine());
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}
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}
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} // namespace
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