// Edge for connecting nodes in trees

package ciips.animation.tree;

import java.awt.*;
import ciips.animation.*;

/** A drawable object connecting two <CODE>TreeNode</CODE>'s
**/
public class TreeEdge extends Drawable {
	
	private TreeNode start, end;
	private Color arrow_colour, value_colour;
	private Dimension offset;
	
	/** Create a new edge 
	 * joining <CODE>start</CODE> and <CODE>end</CODE>
	 * @par start - reference to start node
	 * @par end - reference to end node
	 * @par offset - offset from node reference point to
										centre - used to determine start and end	
										points of arcs
	**/
	public TreeEdge( TreeNode start, TreeNode end, Dimension offset ) {
		this.start = start;
		this.end = end;
		arrow_colour = Color.black;		
		this.offset = offset;
		}

	/**
		Constructor in which offset is set to (0,0)
	**/
	public TreeEdge( TreeNode start, TreeNode end ) {
		this( start, end, new Dimension(0,0) );
		}
	
	public void setStart( TreeNode s ) { start = s; }
	public void setEnd( TreeNode e ) { end = e; }
	public TreeNode getStart() { return start; }
	public TreeNode getEnd() { return end; }

	/** Changes the offset to the arc start and end points ..
		used if the node size shrinks or expands, eg because a tree
		became larger or the panel changed size
	**/
	public void setOffset( Dimension offset ) {
		this.offset = offset;
		}

	public void setColour( Color c ) { arrow_colour = c; }

	/** Match an edge
	**/
	public boolean equals( TreeNode s, TreeNode end ) {
		return (start == s) && (this.end == end);
		}

	/** Draw the edge
	 */
	public void draw( Graphics g ) {
		g.setColor( arrow_colour );
		// g.fillPolygon(arrow_x, arrow_y, 3);
		g.drawLine( start.getX() + offset.width, start.getY() + offset.height,
									end.getX() + offset.width, end.getY() + offset.width );
		}
	
	public String toString() {
		return "TreeEdge (" + start + "-" + end + ")";
		}	
}