readerwriterjpeg.cpp

最新osg包

            /* jpeg_read_scanlines expects an array of pointers to scanlines.
             * Here the array is only one element long, but you could ask for
             * more than one scanline at a time if that's more convenient.
             */
            (void) jpeg_read_scanlines(&cinfo, rowbuffer, 1);
            /* Assume put_scanline_someplace wants a pointer and sample count. */
            currPtr = copyScanline(currPtr, rowbuffer[0], row_stride);
        }
    }
    /* Step 7: Finish decompression */

    (void) jpeg_finish_decompress(&cinfo);
    /* We can ignore the return value since suspension is not possible
     * with the stdio data source.
     */

    /* Step 8: Release JPEG decompression object */

    /* This is an important step since it will release a good deal of memory. */
    jpeg_destroy_decompress(&cinfo);

    /* After finish_decompress, we can close the input file.
     * Here we postpone it until after no more JPEG errors are possible,
     * so as to simplify the setjmp error logic above.  (Actually, I don't
     * think that jpeg_destroy can do an error exit, but why assume anything...)
     */
    //fclose(infile);

    /* At this point you may want to check to see whether any corrupt-data
     * warnings occurred (test whether jerr.pub.num_warnings is nonzero).
     */

    /* And we're done! */
    if (buffer)
    {
        *width_ret = width;
        *height_ret = height;
        *numComponents_ret = format;
    }
    else
    {
        jpegerror = ERR_MEM;
    }
    return buffer;
}
} // namespace osgDBJPEG

class ReaderWriterJPEG : public osgDB::ReaderWriter
{
    
        WriteResult::WriteStatus write_JPEG_file (std::ostream &fout,int image_width,int image_height,JSAMPLE* image_buffer,int quality = 100) const
        {
            if ( (image_width == 0) || (image_height == 0) )
                return WriteResult::ERROR_IN_WRITING_FILE;

            /* This struct contains the JPEG compression parameters and pointers to
            * working space (which is allocated as needed by the JPEG library).
            * It is possible to have several such structures, representing multiple
            * compression/decompression processes, in existence at once.  We refer
            * to any one struct (and its associated working data) as a "JPEG object".
            */
            struct jpeg_compress_struct cinfo;
            /* This struct represents a JPEG error handler.  It is declared separately
            * because applications often want to supply a specialized error handler
            * (see the second half of this file for an example).  But here we just
            * take the easy way out and use the standard error handler, which will
            * print a message on stderr and call exit() if compression fails.
            * Note that this struct must live as long as the main JPEG parameter
            * struct, to avoid dangling-pointer problems.
            */
            struct jpeg_error_mgr jerr;
            /* More stuff */
            //FILE * outfile;        /* target file */
            JSAMPROW row_pointer[1];    /* pointer to JSAMPLE row[s] */
            int row_stride;        /* physical row width in image buffer */

            /* Step 1: allocate and initialize JPEG compression object */

            /* We have to set up the error handler first, in case the initialization
            * step fails.  (Unlikely, but it could happen if you are out of memory.)
            * This routine fills in the contents of struct jerr, and returns jerr's
            * address which we place into the link field in cinfo.
            */
            cinfo.err = jpeg_std_error(&jerr);
            /* Now we can initialize the JPEG compression object. */
            jpeg_create_compress(&cinfo);

            /* Step 2: specify data destination (eg, a file) */
            /* Note: steps 2 and 3 can be done in either order. */

            /* Here we use the library-supplied code to send compressed data to a
            * stdio stream.  You can also write your own code to do something else.
            * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
            * requires it in order to write binary files.
            */
            /*if (!(outfile = fopen(filename, "wb")))
            {
                return WriteResult::ERROR_IN_WRITING_FILE;
            }*/
    
            //jpeg_stdio_dest(&cinfo, outfile);
            osgDBJPEG::jpeg_stream_dest(&cinfo, &fout);

            /* Step 3: set parameters for compression */

            /* First we supply a description of the input image.
            * Four fields of the cinfo struct must be filled in:
            */
            cinfo.image_width = image_width;     /* image width and height, in pixels */
            cinfo.image_height = image_height;
            cinfo.input_components = 3;        /* # of color components per pixel */
            cinfo.in_color_space = JCS_RGB;     /* colorspace of input image */
            /* Now use the library's routine to set default compression parameters.
            * (You must set at least cinfo.in_color_space before calling this,
            * since the defaults depend on the source color space.)
            */
            jpeg_set_defaults(&cinfo);
            /* Now you can set any non-default parameters you wish to.
            * Here we just illustrate the use of quality (quantization table) scaling:
            */
            jpeg_set_quality(&cinfo, quality, TRUE /* limit to baseline-JPEG values */);

            /* Step 4: Start compressor */

            /* TRUE ensures that we will write a complete interchange-JPEG file.
            * Pass TRUE unless you are very sure of what you're doing.
            */
            jpeg_start_compress(&cinfo, TRUE);

            /* Step 5: while (scan lines remain to be written) */
            /*           jpeg_write_scanlines(...); */

            /* Here we use the library's state variable cinfo.next_scanline as the
            * loop counter, so that we don't have to keep track ourselves.
            * To keep things simple, we pass one scanline per call; you can pass
            * more if you wish, though.
            */
            row_stride = image_width * 3;    /* JSAMPLEs per row in image_buffer */

            while (cinfo.next_scanline < cinfo.image_height)
            {
                /* jpeg_write_scanlines expects an array of pointers to scanlines.
                * Here the array is only one element long, but you could pass
                * more than one scanline at a time if that's more convenient.
                */
                row_pointer[0] = & image_buffer[cinfo.next_scanline * row_stride];
                (void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
            }

            /* Step 6: Finish compression */

            jpeg_finish_compress(&cinfo);
            /* After finish_compress, we can close the output file. */
            //fclose(outfile);

            /* Step 7: release JPEG compression object */

            /* This is an important step since it will release a good deal of memory. */
            jpeg_destroy_compress(&cinfo);

            /* And we're done! */
            return WriteResult::FILE_SAVED;
        }
        int getQuality(const osgDB::ReaderWriter::Options *options) const {
            if(options) {
                std::istringstream iss(options->getOptionString());
                std::string opt;
                while (iss >> opt) {
                    if(opt=="JPEG_QUALITY") {
                        int quality;
                        iss >> quality;
                        return quality;
                    }
                }
            }

            return 100;
        }
    public:

        ReaderWriterJPEG()
        {
            supportsExtension("jpeg","JPEG image format");
            supportsExtension("jpg","JPEG image format");
        }

        virtual const char* className() const { return "JPEG Image Reader/Writer"; }

        ReadResult readJPGStream(std::istream& fin) const
        {
            unsigned char *imageData = NULL;
            int width_ret;
            int height_ret;
            int numComponents_ret;

            imageData = osgDBJPEG::simage_jpeg_load(fin,&width_ret,&height_ret,&numComponents_ret);

            if (imageData==NULL) return ReadResult::ERROR_IN_READING_FILE;

            int s = width_ret;
            int t = height_ret;
            int r = 1;

            //int internalFormat = numComponents_ret;
            int internalFormat = 
                numComponents_ret == 1 ? GL_LUMINANCE :
                numComponents_ret == 2 ? GL_LUMINANCE_ALPHA :
                numComponents_ret == 3 ? GL_RGB :
                numComponents_ret == 4 ? GL_RGBA : (GLenum)-1;

            unsigned int pixelFormat =
                numComponents_ret == 1 ? GL_LUMINANCE :
                numComponents_ret == 2 ? GL_LUMINANCE_ALPHA :
                numComponents_ret == 3 ? GL_RGB :
                numComponents_ret == 4 ? GL_RGBA : (GLenum)-1;

            unsigned int dataType = GL_UNSIGNED_BYTE;

            osg::Image* pOsgImage = new osg::Image;
            pOsgImage->setImage(s,t,r,
                internalFormat,
                pixelFormat,
                dataType,
                imageData,
                osg::Image::USE_NEW_DELETE);

            return pOsgImage;
        }

        virtual ReadResult readObject(std::istream& fin,const osgDB::ReaderWriter::Options* options =NULL) const
        {
            return readImage(fin, options);
        }

        virtual ReadResult readObject(const std::string& file, const osgDB::ReaderWriter::Options* options =NULL) const
        {
            return readImage(file, options);
        }

        virtual ReadResult readImage(std::istream& fin,const osgDB::ReaderWriter::Options* =NULL) const
        {
            return readJPGStream(fin);
        }

        virtual ReadResult readImage(const std::string& file, const osgDB::ReaderWriter::Options* options) const
        {
            std::string ext = osgDB::getLowerCaseFileExtension(file);
            if (!acceptsExtension(ext)) return ReadResult::FILE_NOT_HANDLED;

            std::string fileName = osgDB::findDataFile( file, options );
            if (fileName.empty()) return ReadResult::FILE_NOT_FOUND;

            std::ifstream istream(fileName.c_str(), std::ios::in | std::ios::binary);
            if(!istream) return ReadResult::ERROR_IN_READING_FILE;
            ReadResult rr = readJPGStream(istream);
            if(rr.validImage()) rr.getImage()->setFileName(file);
            return rr;
        }

        virtual WriteResult writeImage(const osg::Image& img,std::ostream& fout,const osgDB::ReaderWriter::Options *options) const
        {
            osg::ref_ptr<osg::Image> tmp_img = new osg::Image(img);
            tmp_img->flipVertical();
            WriteResult::WriteStatus ws = write_JPEG_file(fout,img.s(),img.t(),(JSAMPLE*)(tmp_img->data()),getQuality(options));
            return ws;
        }

        virtual WriteResult writeImage(const osg::Image &img,const std::string& fileName, const osgDB::ReaderWriter::Options *options) const
        {
            std::string ext = osgDB::getFileExtension(fileName);
            if (!acceptsExtension(ext)) return WriteResult::FILE_NOT_HANDLED;

            std::ofstream fout(fileName.c_str(), std::ios::out | std::ios::binary);
            if(!fout) return WriteResult::ERROR_IN_WRITING_FILE;

            return writeImage(img,fout,options);
        }
};

// now register with Registry to instantiate the above
// reader/writer.
REGISTER_OSGPLUGIN(jpeg, ReaderWriterJPEG)