PDFlib Cookbook

cookbook

graphics/transparent_graphics

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/* $Id: transparent_graphics.java,v 1.6 2013/01/15 10:11:59 stm Exp $
 * Transparent graphics:
 * Create some transparent graphics objects
 *
 * Display a yellow rectangle and show some transparent graphics objects
 * overlapping with it. Create transparency by applying an extended graphics
 * state with the "opacityfill" option set to a value less than 1.
 *
 * Required software: PDFlib/PDFlib+PDI/PPS 9
 * Required data: none
 */
package com.pdflib.cookbook.pdflib.graphics;

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

public class transparent_graphics
{
    public static void main (String argv[])
    {
    /* This is where the data files are. Adjust as necessary. */
    String searchpath = "../input";
    String outfile = "transparent_graphics.pdf";
    String title = "Transparent Graphics";

    pdflib p = null;
    
    int gstate, font;
 
    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");

        if (p.begin_document(outfile, "") == -1)
            throw new Exception("Error: " + p.get_errmsg());

        p.set_info("Creator", "PDFlib Cookbook");
        p.set_info("Title", title + " $Revision: 1.6 $");
        
        /* Load the font. */
        font = p.load_font("Helvetica", "unicode", "");
        if (font == -1)
        throw new Exception("Error: " + p.get_errmsg());

        /* Start page */
        p.begin_page_ext(0, 0, "width=a4.width height=a4.height");
        
        /* Draw a yellow background rectangle */
        p.setcolor("fill", "rgb", 1, 0.9, 0.58, 0);
        p.rect(50, 50, 500, 750);
        p.fill();
        
        /* Display some descriptive red text */
        p.setcolor("fill", "rgb", 0.73, 0.12, 0.30, 0);
        p.fit_textline("Transparent vector graphics", 100, 100, "font=" + font +
            " fontsize=20");
        
        /* Save the current graphics state. The save/restore of the current
         * state is not necessarily required, but it will help you get back to
         * a graphics state without any transparency.
         */
        p.save();
        
        /* Create an extended graphics state with transparency set to 50%, using
         * create_gstate() with the "opacityfill" option set to 0.5.
         */
        gstate = p.create_gstate("opacityfill=.5");
        
        /* Apply the extended graphics state */
        p.set_gstate(gstate);
        
        /* Draw a blue rectangle which will be transparent according to the
         * graphics state set
         */
        p.setcolor("fill", "rgb", 0, 0.52, 0.64, 0);
        p.rect(100, 500, 200, 600);
        p.fill();
        
        /* Draw a red circle which will be transparent according to the
         * graphics state set
         */
        p.setcolor("fill", "rgb", 0.73, 0.12, 0.30, 0);
        p.arc(100, 100, 200, 0, 360);
        p.fill();
        
        /* Restore the current graphics state */
        p.restore();
        
        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");
        } catch (Exception e) {
            System.err.println(e.getMessage());
        } finally {
            if (p != null) {
                p.delete();
            }
        }
    }
}