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Viewing changes to imagesource/imagesource_bilinear.cpp

  • Committer: Bazaar Package Importer
  • Author(s): Milan Zamazal
  • Date: 2006-09-29 12:18:16 UTC
  • Revision ID: james.westby@ubuntu.com-20060929121816-6t2iz9zaymixd3om
Tags: upstream-0.3.3
Import upstream version 0.3.3

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imagesource/imagesource_bilinear.cpp
 
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/*
 
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 * imagesource_bilinear.cpp - Interpolated scaling filter
 
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 * Implements bilinear scaling
 
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 *
 
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 * Supports Greyscale, RGB and CMYK data
 
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 * Doesn't (yet) support random access
 
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 *
 
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 * Copyright (c) 2004 by Alastair M. Robinson
 
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 * Distributed under the terms of the GNU General Public License -
 
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 * see the file named "COPYING" for more details.
 
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 *
 
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 */
 
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#include <iostream>
 
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#include <stdlib.h>
 
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#include <string.h>
 
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#include <math.h>
 
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#include "imagesource_bilinear.h"
 
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using namespace std;
 
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ImageSource_Bilinear::~ImageSource_Bilinear()
 
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{
 
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        if(source)
 
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                delete source;
 
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        if(lastrow)
 
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                free(lastrow);
 
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}
 
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ISDataType *ImageSource_Bilinear::GetRow(int row)
 
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{
 
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        int i;
 
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        if(row==currentrow)
 
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                return(rowbuffer);
 
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        int srow1=(row*source->height)/height;
 
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        int srow2=srow1+1;
 
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        if(srow2>=source->height)
 
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                srow2=srow1;
 
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        ISDataType *src1,*src2;
 
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        if(srow1==cachedrow)
 
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        {
 
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                src1=lastrow;
 
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        }
 
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        else
 
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        {
 
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                src1=source->GetRow(srow1);
 
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                for(int i=0;i<source->width*source->samplesperpixel;++i)
 
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                        lastrow[i]=src1[i];
 
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                cachedrow=srow1;
 
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                src1=lastrow;
 
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        }
 
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        src2=source->GetRow(srow2);
 
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        double yfactor=row*source->height;
 
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        yfactor/=height;
 
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        yfactor-=srow1;
 
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        for(i=0;i<width;++i)
 
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        {
 
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                int x1=(i*source->width)/width;
 
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                int x2=x1+1;
 
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                if(x2 >= source->width)
 
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                        x2=x1;
 
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                float xfactor=(i*source->width);
 
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                xfactor/=width;
 
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                xfactor-=x1;
 
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                x1*=samplesperpixel;
 
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                x2*=samplesperpixel;
 
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                for(int s=0;s<samplesperpixel;++s)
 
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                {
 
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                        double s1=src1[x1+s];
 
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                        double s2=src1[x2+s];
 
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                        double s3=src2[x1+s];
 
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                        double s4=src2[x2+s];
 
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                        double a1=(1.0-xfactor)*s1+xfactor*s2;
 
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                        double a2=(1.0-xfactor)*s3+xfactor*s4;
 
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                        double a3=(1.0-yfactor)*a1+yfactor*a2;
 
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                        rowbuffer[i*samplesperpixel+s]=int(a3);
 
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                }
 
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        }
 
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        currentrow=row;
 
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        return(rowbuffer);
 
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}
 
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ImageSource_Bilinear::ImageSource_Bilinear(struct ImageSource *source,int width,int height)
 
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        : ImageSource(source), source(source), lastrow(NULL), cachedrow(-1)
 
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{
 
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        this->width=width; this->height=height;
 
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        xres=(source->xres*width); xres/=source->width;
 
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        yres=(source->yres*height); yres/=source->height;
 
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        lastrow=(ISDataType *)malloc(source->width*source->samplesperpixel*sizeof(ISDataType));
 
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        MakeRowBuffer();
 
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        randomaccess=false;
 
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}