PDFlib Cookbook

cookbook

color/color_gradient

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/* $Id: color_gradient.java,v 1.16 2016/12/09 13:21:16 stm Exp $
 * Color gradient:
 * Fill some area or text with a smooth transition from one color to another

 * Required software: PDFlib/PDFlib+PDI/PPS 9
 * Required data: none
 */
package com.pdflib.cookbook.pdflib.color;

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

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

        pdflib p = null;
        int font, sh, pattern;
        int fontsize = 36;
	int exitcode = 0;

        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, "destination={type=fitwindow}") == -1)
                throw new Exception("Error: " + p.get_errmsg());

            p.set_info("Creator", "PDFlib Cookbook");
            p.set_info("Title", title + " $Revision: 1.16 $");

            /* Start Page */
            p.begin_page_ext(595, 842, "");

            /*
             * Fill the page completely with a gradient from green to black:
             * 
             * Set the first color for the gradient to green with option
             * 'startcolor'.
             * 
             * The second color for the gradient is set to black using the
             * parameters c1/c2/c3.
             * 
             * Note that starting with PDFlib 9.1 the final color of the
             * gradient can also set via the new option 'endcolor'.
             * The call would then look like this:
             * 
             * sh = p.shading("axial", 0, 0, 595, 842, 0.0, 0.0, 0.0, 0.0,
             *     "startcolor={rgb 0.0 0.5 0.5} endcolor={rgb 0 0 0}");
             *     
             * The parameters c1/c2/c3/c4 are ignored in this case.
             */
            sh = p.shading("axial", 0, 0, 595, 842, 0.0, 0.0, 0.0, 0.0,
        		    "startcolor={rgb 0.0 0.5 0.5}");

            /* Draw the gradient over the whole page */
            p.shfill(sh);

            /*
             * Fill a rectangle with a gradient:
             * 
             * Set the first color for the gradient to orange.
             * Set the second color for the gradient to a light orange.
             * Define an axial gradient with a size similar to the size of the
             * rectangle to be filled.
             * Create a shading pattern.
             */
            sh = p.shading("axial", 200, 200, 450, 450, 0.9, 0.8, 0.8, 0.0,
        		    "startcolor={rgb 1.0 0.5 0.1}");
            pattern = p.shading_pattern(sh, "");

            /*
             * Draw a rectangle using the shading pattern as fill color.
             */
            p.set_graphics_option("fillcolor={pattern " + pattern + "}");
            p.rect(200, 200, 250, 250);
            p.fill();

            /*
             * Fill a circle with a gradient:
             * 
             * Set the first color for the gradient to white.
             * Set the second color for the gradient to orange.
             * Define a radial gradient with a size similar to the size
             * of the circle to be filled.
             * Create a shading pattern.
             */
            sh = p.shading("radial", 400, 600, 400, 600, 1.0, 0.5, 0.1, 0.0,
                "r0=0 r1=60 startcolor={rgb 1.0 1.0 1.0}");
            pattern = p.shading_pattern(sh, "");
            
            /*
             * Draw a circle using the shading pattern as fill color.
             */
            p.set_graphics_option("fillcolor={pattern " + pattern + "}");
            p.circle(400, 600, 50);
            p.fill();

            /*
             * Fill a text with a gradient: Load the font.
             */
            font = p.load_font("Helvetica-Bold", "unicode", "");

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

            /*
             * Set the first color for the gradient to white.
             * Set the second color for the gradient to orange.
             * Define an axial gradient with a size similar to the size of
             * the text to be filled.
             * Create a shading pattern.
             */
            sh = p.shading("axial", 50, 50, 50, 200, 1.0, 0.5, 0.1, 0.0,
        		    "startcolor={rgb 1.0 1.0 1.0}");
            pattern = p.shading_pattern(sh, "");

            /*
             * Option list to use the shading pattern as the fill color
             * for the text. Also specify font and font size.
             */
            String optlist = "fillcolor={pattern " + pattern + "} "
            		+ "font=" + font + " fontsize=" + fontsize;

            /*
             * Output the text with the shading pattern as current fill color.
             */
            p.fit_textline("Hello World!", 50, 100, optlist);
            p.fit_textline("(says PDFlib GmbH)", 50, 100 - fontsize, optlist);

            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);
        }
    }
}