convert svg

        var svg_image = document.getElementsByTagName('image');
        var svg_count = 0;
        var svg_count_done = 0;

        if ( svg_image.length > 0 ) {
            svg_finish = 0;
            svg_count_done = 0;
            for(var si = 0; si < svg_image.length; si++ ) {
                var svg_image_href = svg_image[si].getAttribute('xlink:href');
                console.log( svg_image_href );
                if ( (svg_image_href == '') || (svg_image_href == null) || (svg_image_href == undefined)) {
                    svg_image_href = svg_image[si].getAttribute('href');
                }

                var new_image_href = resolvePath(svg_image_href, opf.manifest[opf.spine[ this_chapter ]].href );
                var img_ext = new_image_href.substring( new_image_href.lastIndexOf('.') + 1 );
                var this_image = svg_image[si];

                $.ajax({
                  url: new_image_href,
                  beforeSend: function ( xhr ) { xhr.overrideMimeType("text/plain; charset=x-user-defined"); }
                })
                .done(function ( data2 ) {
                    svg_count_done++;

                    var image_el = document.createElement("IMG");
                    var img_data = do_decrypt( book_key, data2, 'binary');
                    image_el.setAttribute('class','svg-image');
                    svg_count++;
                    image_el.setAttribute('id','svg'+svg_count);

                    image_el.setAttribute("src", 'data:image/'+img_ext+';base64,'+img_data );
                    console.log('svg_length:'+img_data.length);

                    var this_parent = this_image.parentNode; // the SVG
                    var parent_parent = this_parent.parentNode; // SVG's parent

                    parent_parent.insertBefore(image_el, this_parent);
                    $('img#svg'+svg_count).load(function(){
                        if ( $(this).width() > (colwidth) ) {
                            var ori_width = $(this).width();
                            var ori_height = $(this).height();
                            var resize_ratio = (colwidth) / ori_width;

                            $(this).width( colwidth );
                            $(this).height( ori_height * resize_ratio );
                        }

                        if ( $(this).height() > (colheight) ) {
                            var ori_width = $(this).width();
                            var ori_height = $(this).height();
                            var resize_ratio = (colheight) / ori_height;

                            $(this).height( colheight );
                            $(this).width( ori_width * resize_ratio );
                        }
                    });

                  delete img_data;
                  delete image_el;
                  delete this_parent;
                  delete parent_parent;
                })
                .fail(function(){
                    svg_count_done++;
                })
                .always(function(){
                    console.log('svg_count_done:'+svg_count_done +'  svg_image.length:'+svg_image.length);
                    if ( svg_count_done == svg_image.length ) {
                        svg_finish = 1;
                        $('svg').hide();
                    }
                });
            }
        }