package cytoscape.visual.strokes;

import java.awt.Shape;
import java.awt.geom.GeneralPath;
import static cytoscape.visual.LineStyle.SEPARATE_ARROW;

public class SeparateArrowStroke extends ShapeStroke {

	public SeparateArrowStroke(float width) {
		super( new Shape[] { getArrowStroke(width) }, 5f*width, SEPARATE_ARROW, width );
	}

	public WidthStroke newInstanceForWidth(float w) {
		return new SeparateArrowStroke(w);
	}

	private static Shape getArrowStroke(final float width) {
		GeneralPath shape = new GeneralPath();

		// change these to change the arrow proportions 

		// length of shape
		float length = 4f*width;

		// width of center line
		float lineWidth = width;

		// width of arrow, from one arm to its opposite 
		float arrowWidth = 3f*width;

		// fraction of the length of the total shape 
		// where the arrow head should begin
		float arrowHeadStart = length/2f; 

		// ====================================================================
		// don't change these - they should always stay
		// the same for this shape!
		float begin = 0f;
		float halfLineWidth = 0.5f * lineWidth;
		float halfArrowWidth = 0.5f * arrowWidth;

		// make the actual shape
		//             X                  Y
		shape.moveTo( begin,            halfLineWidth);
		shape.lineTo( arrowHeadStart,   halfLineWidth);
		shape.lineTo( arrowHeadStart,   halfArrowWidth);
		shape.lineTo( length,           0f);
		shape.lineTo( arrowHeadStart,   -halfArrowWidth);
		shape.lineTo( arrowHeadStart,   -halfLineWidth);
		shape.lineTo( begin,            -halfLineWidth);
		shape.lineTo( begin,            halfLineWidth);

		return shape;
	}
}