PDFlib Cookbook

cookbook

graphics/arrows

Create an arrow using different methods.

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/*
 * Arrows:
 * Create an arrow using different methods
 *
 * Method I: Draw a simple horizontal arrow.
 * Method II: Draw an arrow with the aid of its unit vector respresentation.
 * Method III: Draw an arrow using coordinate system translation and rotation.
 *
 * 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 arrows
{
    public static void main (String argv[])
    {
	/* This is where the data files are. Adjust if necessary. */
	String searchpath = "../input";
	String outfile = "arrows.pdf";
	String title = "Arrows";

	int startx, starty, stopx, stopy, ahl, ahw, sw;
	double l, angle;
	double x, y, dx, dy;
	double ux, uy, pux, puy;    /* unit vector and its perpendicular */
	int exitcode = 0;

	pdflib p = null;

	int 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);
	    
	    /* Load the font. */
	    font = p.load_font("Helvetica", "unicode", "");
	    if (font == -1)
		throw new Exception("Error: " + p.get_errmsg());

	    p.begin_page_ext(0, 0, "width=500 height=500");

	    /* Method I:
	     * Draw a horizontal green arrow from left to right. Start at the given
	     * start point located in the middle of the arrow shaft.
	     * The following values are given:
	     */
	    startx = 100;       /* x coordinate of the starting point */
	    starty = 100;       /* y coordinate of the starting point */
	    stopx = 400;        /* x coordinate of the end point */
	    stopy = 100;        /* y coordinate of the end point */
	    ahl = 40;           /* arrow head length */
	    ahw = 10;           /* arrow head width */
	    sw = 20;            /* shaft width */
	    l = stopx - startx; /* length of the arrow */

	    /* Set the drawing properties */
	    p.setlinewidth(5.0);
	    p.setcolor("stroke", "rgb", 0.0, 0.5, 0.5, 0.0);
	    p.setcolor("fill", "rgb", 1, 1, 1, 0.0);
	    p.set_graphics_option("linejoin=1 linecap=1");

	    /* Start drawing the arrow */
	    p.moveto(startx, starty);

	    x = startx;
	    y = starty + sw/2;
	    p.lineto(x, y);

	    x = x + (l - ahl);
	    p.lineto(x, y);

	    y = y + ahw;
	    p.lineto(x, y);

	    p.lineto(stopx, stopy);

	    y = y - (2*ahw + sw);
	    p.lineto(x, y);

	    y = y + ahw;
	    p.lineto(x, y);

	    x = x - (l - ahl);
	    p.lineto(x, y);

	    y = starty + sw/2;
	    p.lineto(x, y);
	    p.fill_stroke();

	    /* Method II:
	     * Draw a non-horizontal pink arrow from left to right. Start at the
	     * given start point located in the middle of the arrow shaft.
	     * The following values are given:
	     */
	    startx = 100;       /* x coordinate of the starting point */
	    starty = 200;       /* y coordinate of the starting point */
	    stopx = 400;        /* x coodingate of the end point */
	    stopy = 300;        /* y coordinate of the end point */
	    ahl = 40;           /* arrow head length */
	    ahw = 20;           /* arrow head width */
	    sw = 20;            /* shaft width */

	    /* Calculate the unit vector (ux, uy) and its perpendicular
	     * (pux, puy)
	     */
	    dx = stopx - startx;
	    dy = stopy - starty;
	    l = Math.sqrt(dx*dx + dy*dy);
	    ux = dx/l;
	    uy = dy/l;
	    pux = uy;
	    puy = -ux;

	    /* Set the drawing properties */
	    p.setlinewidth(5.0);
	    p.setcolor("stroke", "rgb", 1.0, 0.5, 1.0, 0.0);
	    p.setcolor("fill", "rgb", 0.9, 0.8, 0.8, 0.0);
	    p.set_graphics_option("linejoin=1 linecap=1");

	    /* Start at the given start point located in the middle of the arrow
	     * shaft
	     */
	    p.moveto(startx, starty);

	    x = startx + sw/2 * pux;
	    y = starty + sw/2 * puy;
	    p.lineto(x, y);

	    x = x + (l - ahl) * ux;
	    y = y + (l - ahl) * uy;
	    p.lineto(x, y);

	    x = x + ahw * pux;
	    y = y + ahw * puy;
	    p.lineto(x, y);

	    p.lineto(stopx, stopy);

	    x = x - (2*ahw + sw) * pux;
	    y = y - (2*ahw + sw) * puy;
	    p.lineto(x, y);

	    x = x + ahw * pux;
	    y = y + ahw * puy;
	    p.lineto(x, y);

	    x = x - (l - ahl) * ux;
	    y = y - (l - ahl) * uy;
	    p.lineto(x, y);

	    x = startx + sw/2 * pux;
	    y = starty + sw/2 * puy;
	    p.lineto(x, y);

	    p.fill_stroke();

	    /* Method III:
	     * Draw a non-horizontal black arrow from left to right. Start at the
	     * given start point located in the middle of the arrow shaft.
	     * The following values are given:
	     */
	    startx = 100;       /* x coordinate of the starting point */
	    starty = 300;       /* y coordinate of the starting point */
	    angle = 40;         /* Rotation angle in degrees */
	    l = 200;            /* length of the arrow */
	    ahl = 30;           /* arrow head length */
	    ahw = 10;           /* arrow head width */
	    sw = 4;             /* shaft width */

	    /* Set the drawing properties */
	    p.setlinewidth(3.0);
	    p.setcolor("stroke", "rgb", 0.0, 0.0, 0.0, 0.0);
	    p.setcolor("fill", "rgb", 0.0, 0.0, 0.0, 0.0);
	    p.set_graphics_option("linejoin=1 linecap=1");

	    /* Rotate and translate the coordinate system */
	    p.translate(startx, starty);
	    p.rotate(angle);

	    /* Start drawing the arrow */
	    p.moveto(0, 0);

	    x = 0;
	    y = sw/2;
	    p.lineto(x, y);

	    x = x + (l - ahl);
	    p.lineto(x, y);

	    y = y + ahw;
	    p.lineto(x, y);

	    x = x + ahl;
	    y = y - (ahw + sw/2);
	    p.lineto(x, y);

	    x = x - ahl;
	    y = y - (ahw + sw/2);
	    p.lineto(x, y);

	    y = y + ahw;
	    p.lineto(x, y);

	    x = x - (l - ahl);
	    p.lineto(x, y);

	    y = y + sw/2;
	    p.lineto(x, y);
	    p.fill_stroke();

	    p.end_page_ext("");

	    p.end_document("");

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