package Widget;

import java.awt.AlphaComposite;

import java.awt.Color;

import java.awt.Graphics;

import java.awt.Graphics2D;

import javax.swing.JScrollPane;

import javax.swing.JTextArea;

import javax.swing.JTextField;

public class AlphaScrollPane extends JScrollPane{

private float alpha = 0.8f;

public AlphaScrollPane(){

this.setBorder(null);//去边框

this.setOpaque(false);//将输入域设置成透明

this.getViewport().setOpaque(false);

}

public void setAlpha(float alpha){

this.alpha = alpha;

this.invalidate();

}

@Override

protected void paintComponent(Graphics g) {

// TODO Auto-generated method stub

super.paintComponent(g);

Graphics2D g2 = (Graphics2D)g;

//设置透明度为0.4f

AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha);

g2.setComposite(ac);

g2.setColor(Color.black);

//绘制一个与输入域等大小的填充矩形框来形成其半透明效果

g2.fillRect(0, 0, getWidth(), getHeight());

}

}