PNGLoader.cpp

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// Copyright (C) 2005 Dave Griffiths
//
// 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include <png.h>
#include "PNGLoader.h"
#include "Trace.h"

using namespace Fluxus;

unsigned char *PNGLoader::Load(const string &Filename, unsigned int &w, unsigned int &h, PixelFormat &pf)
{
    unsigned char *ImageData = NULL;
    FILE *fp=fopen(Filename.c_str(),"rb");
    if (!fp || Filename=="") 
    {
        Trace::Stream<<"Couldn't open image ["<<Filename<<"]"<<endl;
    }
    else
    {
        png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
        png_infop info_ptr = png_create_info_struct(png_ptr);
            
        if (setjmp(png_jmpbuf(png_ptr))) 
        {
            png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
            Trace::Stream<<"Error reading image ["<<Filename<<"]"<<endl;
            return NULL;
        }
        
        png_init_io(png_ptr, fp);
        png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);      
        fclose(fp);
        
        ImageData = new unsigned char[png_ptr->rowbytes*png_ptr->height];
        int p=0;
        for (unsigned int row = 0; row < png_ptr->height; row++)
        {
            for (unsigned int i=0; i<png_ptr->rowbytes; i++)
            {
                ImageData[p]=(unsigned char)info_ptr->row_pointers[row][i];
                p++;
            }
        }
        
        w=png_ptr->width;
        h=png_ptr->height;
        
        switch (png_ptr->color_type)
        {
            case PNG_COLOR_TYPE_RGB : pf=RGB; break;
            case PNG_COLOR_TYPE_RGB_ALPHA : pf=RGBA; break;
            default : Trace::Stream<<"PNG pixel format not supported : "<<png_ptr->color_type<<endl;
        }

        png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL); 
    }
    
    return ImageData;
}

void PNGLoader::Save(const string &Filename, unsigned int w, unsigned int h, PixelFormat pf, unsigned char *data)
{
    FILE *f;
    png_structp ppng;
    png_infop pinfo;
    png_text atext[3];
    unsigned int i;

    unsigned int numchannels = 3;
    if (pf==RGBA) numchannels = 4;

    if (!(f = fopen (Filename.c_str(), "wb")))
    {
        Trace::Stream<<"Error writing png file"<<endl;
        return;
    }

    if (!(ppng = png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)))
    {
        Trace::Stream<<"Error writing png file"<<endl;
        fclose (f);
        return;
    }

    if (!(pinfo = png_create_info_struct (ppng)))
    {
        Trace::Stream<<"Error writing png file"<<endl;
        fclose (f);
        png_destroy_write_struct (&ppng, NULL);
        return;
    }

    if (setjmp (png_jmpbuf (ppng)))
    {
        Trace::Stream<<"Error writing png file"<<endl;
        fclose (f);
        png_destroy_write_struct (&ppng, &pinfo);
        return;
    }

    png_init_io (ppng, f);

    if (pf==RGB)
    {
        png_set_IHDR (ppng, pinfo, w, h, 8, PNG_COLOR_TYPE_RGB,
        PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
        PNG_FILTER_TYPE_BASE);
    }
    else if (pf==RGBA)
    {
        png_set_IHDR (ppng, pinfo, w, h, 8, PNG_COLOR_TYPE_RGBA,
        PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
        PNG_FILTER_TYPE_BASE);
    }
    else
    {
        Trace::Stream<<"Error, unknown pixel format"<<endl;
        fclose (f);
        png_destroy_write_struct (&ppng, NULL);
        return;     
    }

    atext[0].key = "title";
    atext[0].text = "made with fluxus";
    atext[0].compression = PNG_TEXT_COMPRESSION_NONE;
    #ifdef PNG_iTXt_SUPPORTED
    text_ptr[0].lang = NULL;
    text_ptr[1].lang = NULL;
    #endif
    png_set_text (ppng, pinfo, atext, 2);
    png_write_info (ppng, pinfo);
    unsigned int stride=w*numchannels;
    {
        png_bytep *aprow = (png_bytep*) malloc(h * sizeof(png_bytep));
        for (i = 0; i < h; ++i) aprow[i] = data + stride * i;
        png_write_image (ppng, aprow);
        free(aprow);
    }

    png_write_end (ppng, pinfo);
    png_destroy_write_struct (&ppng, &pinfo);
    fclose (f);
}

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