Popup.java

package com.drawbridge.vl;

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Polygon;
import java.awt.RenderingHints;

import javax.swing.JComponent;

/***
 * Fixed-size transparent popup shape 
 * @author Alistair Stead
 *
 */
abstract class Popup extends JComponent
{

	/**
	 * 
	 */
	private static final long	serialVersionUID	= 250827727489092754L;
	public static final int		mSliderHeight		= 30;
	private Dimension			mPreferredSize		= new Dimension(250, 50);
	
	private final boolean downwardTriangleVisible;
	private float transparency;
	
	public Popup(boolean downwardTriangleVisible, float transparency){
		this.downwardTriangleVisible = downwardTriangleVisible;
		this.transparency = transparency;
	}
	
	public void setTransparency(float f){
		transparency = f;
	}
	
	
	@Override
	public void paintComponent(Graphics g)
	{
		Graphics2D g2 = (Graphics2D) g;
		g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		int round = (mSliderHeight / 3 * 2);
		g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, transparency));
		g2.setColor(Color.white);
		g2.fillRoundRect(0, 0, getWidth() - 1, mSliderHeight, round, round);
		g2.setColor(Color.decode("#AAAAAA"));
		g2.drawRoundRect(0, 0, getWidth() - 1, mSliderHeight, round, round);

		if(downwardTriangleVisible){
			// Draw downward triangle
			int triangleLength = 10;
			g2.setColor(Color.white);
			int centerX = (getWidth() / 2);
			Point left = new Point(centerX - triangleLength - 5, mSliderHeight);
			Point middle = new Point(centerX, mSliderHeight + triangleLength);
			Point right = new Point(centerX + triangleLength + 5, mSliderHeight);
			g2.drawLine(left.x, left.y, right.x, right.y);
			Polygon p = new Polygon();
			p.addPoint(left.x, left.y);
			p.addPoint(middle.x, middle.y);
			p.addPoint(right.x, right.y);
			g2.fillPolygon(p);
	
			g2.setColor(Color.decode("#AAAAAA"));
			g2.drawLine(left.x, left.y, middle.x, middle.y);
			g2.drawLine(middle.x, middle.y, right.x, right.y);
		}
	}
	
	
	public void setPreferredSize(Dimension size){
		mPreferredSize = size;
		this.setSize(mPreferredSize);
	}
	
	@Override
	public Dimension getMinimumSize()
	{
		return mPreferredSize;
	}

	@Override
	public Dimension getMaximumSize()
	{
		return mPreferredSize;
	}

	@Override
	public Dimension getPreferredSize()
	{
		return mPreferredSize;
	}
}