PDFlib Cookbook

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geospatial_pdf/georeferenced_image

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package com.pdflib.cookbook.pdflib.geospatial;

import com.pdflib.pdflib;
import com.pdflib.PDFlibException;

/**
 * This topic attaches geospatial reference data to an image. This works fine
 * in Acrobat, but is not currently supported in the Avenza PDF Maps app which
 * supports only geospatial reference data attached to the whole page.
 * In order to create georeferenced PDF for use with Avenza use the method
 * demonstrated in the georeferenced_image Cookbook topic.
 *
 * Sample map and coordinates:
 * We use a map from www.openstreetmap.com; the geospatial coordinates of the
 * image edges were also provided by that Web site.
 * The coordinate system is WGS84 which is also used for GPS.
 *
 * Required software: PDFlib/PDFlib+PDI/PPS 9
 * Required data: image file and associated geospatial reference information
 * 
 * @version $Id: georeferenced_image.java,v 1.1 2016/06/28 13:36:35 stm Exp $
 */
class georeferenced_image {
    public static void main(String argv[]) {
        /* This is where the data files are. Adjust if necessary. */
        final String searchpath = "../input";
        final String outfile = "georeferenced_image.pdf";

        String georefoptlist;
        pdflib p = null;
        int image;
        final String imagefile = "munich.png";
        int exitcode = 0;

        /* WKT for plain latitude/longitude values in WGS84 */
        final String georef = "worldsystem={type=geographic wkt={"
            + "GEOGCS[\"WGS 84\","
            + "  DATUM[\"WGS_1984\", SPHEROID[\"WGS 84\", 6378137,298.257223563]],"
            + "  PRIMEM[\"Greenwich\", 0.0],"
            + "  UNIT[\"Degree\", 0.01745329251994328]]"
            + "}} linearunit=M areaunit=SQM angularunit=degree";

        /* world coordinates of the image (in degrees) */
        double worldpoints[] = {
            48.145, /* latitude of top edge */
            11.565, /* longitude of left edge */
            11.59, /* longitude of right edge */
            48.13 /* latitude of bottom edge */
        };

        try {
            p = new pdflib();

            p.set_option("searchpath={" + searchpath + "}");

            /* This means we must check return values of load_font() etc. */
            p.set_option("errorpolicy=return");

            /* Start the document */
            if (p.begin_document(outfile, "compatibility=1.7ext3") == -1) {
                throw new Exception("Error: " + p.get_errmsg());
            }

            p.set_info("Creator", "PDFlib starter sample");
            p.set_info("Title", "georeferenced_image $Revision: 1.1 $");

            /* Generate georeference option list */
            /*
             * Use the four corners as reference points; (0,0)=lower left etc.
             */
            georefoptlist = "georeference={" + georef
                + " mappoints={0 0  1 0  1 1  0 1} ";

            georefoptlist += "worldpoints={";

            /* lower left corner */
            georefoptlist += worldpoints[3] + " " + worldpoints[1] + " ";
            /* lower right corner */
            georefoptlist += worldpoints[3] + " " + worldpoints[2] + " ";
            /* upper right corner */
            georefoptlist += worldpoints[0] + " " + worldpoints[2] + " ";
            /* upper left corner */
            georefoptlist += worldpoints[0] + " " + worldpoints[1] + " ";

            georefoptlist += "} }";

            /* Load the image with geospatial reference attached */
            image = p.load_image("auto", imagefile, georefoptlist);
            if (image == -1) {
                throw new Exception("Error: " + p.get_errmsg());
            }

            p.begin_page_ext(0, 0, "width=a4.width height=a4.height");

            /* Create caption */
            p.fit_textline("Map with geospatial reference information", 50, 700,
                "fontname=LuciduxSans-Oblique encoding=winansi fontsize=18");

            /* Place the map on the page */
            p.fit_image(image, 50, 50, "boxsize={500 600} fitmethod=meet");

            p.end_page_ext("");

            p.end_document("");
        }
        catch (PDFlibException e) {
            System.err.print("PDFlib exception occurred:\n");
            System.err.print("[" + e.get_errnum() + "] " + e.get_apiname()
                + ": " + e.get_errmsg() + "\n");
            exitcode = 1;
        }
        catch (Exception e) {
            System.err.println(e.getMessage());
            exitcode = 1;
        }
        finally {
            if (p != null) {
                p.delete();
            }
            System.exit(exitcode);
        }
    }
}