/*
 * @(#)ArrowTip.java 5.1
 *
 */

package CH.ifa.draw.figures;

import java.io.*;
import java.awt.*;

import CH.ifa.draw.framework.*;
import CH.ifa.draw.standard.*;
import CH.ifa.draw.util.*;

/**
 * An arrow tip line decoration.
 * @see PolyLineFigure
 */
public  class ArrowTip implements LineDecoration {

    private double  fAngle;         // pointiness of arrow
    private double  fOuterRadius;
    private double  fInnerRadius;

    /*
     * Serialization support.
     */
    private static final long serialVersionUID = -3459171428373823638L;
    private int arrowTipSerializedDataVersion = 1;

	public ArrowTip() {
	    fAngle = 0.40;//0.35;
	    fOuterRadius = 8;//15;
	    fInnerRadius = 8;//12;
	}

   /**
    * Constructs an arrow tip with the given angle and radius.
    */
	public ArrowTip(double angle, double outerRadius, double innerRadius) {
	    fAngle = angle;
	    fOuterRadius = outerRadius;
	    fInnerRadius = innerRadius;
	}

   /**
    * Draws the arrow tip in the direction specified by the given two
    * points..
    */
    public void draw(Graphics g, int x1, int y1, int x2, int y2) {
        // TBD: reuse the Polygon object
        Polygon p = outline(x1, y1, x2, y2);
        g.fillPolygon(p.xpoints, p.ypoints, p.npoints);
    }

   /**
    * Calculates the outline of an arrow tip.
    */
    public Polygon outline(int x1, int y1, int x2, int y2) {
        double dir = Math.PI/2 - Math.atan2(x2-x1, y1-y2);
        return outline(x1, y1, dir);
    }

    private Polygon outline(int x, int y, double direction) {
        Polygon shape = new Polygon();

        shape.addPoint(x, y);
        addPointRelative(shape, x, y, fOuterRadius, direction - fAngle);
        addPointRelative(shape, x, y, fInnerRadius, direction);
        addPointRelative(shape, x, y, fOuterRadius, direction + fAngle);
        shape.addPoint(x,y); // Closing the polygon (TEG 97-04-23)
        return shape;
    }

    private void addPointRelative(Polygon shape, int x, int y, double radius, double angle) {
        shape.addPoint(
            x + (int) (radius * Math.cos(angle)),
            y - (int) (radius * Math.sin(angle)));
    }

    /**
     * Stores the arrow tip to a StorableOutput.
     */
    public void write(StorableOutput dw) {
    }

    /**
     * Reads the arrow tip from a StorableInput.
     */
    public void read(StorableInput dr) throws IOException {
    }

}