시소당

Color gradient

import  java.awt.Color;
import  java.awt.Dimension;
import  java.awt.Graphics;
import  java.awt.Graphics2D;
import  java.awt.geom.Rectangle2D;

import  javax.swing.JFrame;
import  javax.swing.JPanel;

public  class  ColorBlocks  extends  JPanel{
        public  void  paint(Graphics  g)  {
                Graphics2D  g2  =  (Graphics2D)g;

                Dimension  d  =  getSize();
                g2.translate(d.width  /  2,  d.height  /  2);
                        
                Color[]  colors  =  {
                        Color.white,  Color.lightGray,  Color.gray,  Color.darkGray,
                        Color.black,  Color.red,  Color.pink,  Color.orange,
                        Color.yellow,  Color.green,  Color.magenta,  Color.cyan,  Color.blue
                };
                        
                float  size  =  25;
                float  x  =  -size  *  colors.length  /  2;
                float  y  =  -size  *  3  /  2;
                        
                //  Show  all  the  predefined  colors.
                for  (int  i  =  0;  i  <  colors.length;  i++)  {
                    Rectangle2D  r  =  new  Rectangle2D.Float(
                            x  +  size  *  (float)i,  y,  size,  size);
                    g2.setPaint(colors[i]);
                    g2.fill(r);
                }
                        
                //a  linear  gradient.
                y  +=  size;
                Color  c1  =  Color.yellow;
                Color  c2  =  Color.blue;
                for  (int  i  =  0;  i  <  colors.length;  i++)  {
                    float  ratio  =  (float)i  /  (float)colors.length;
                    int  red  =  (int)(c2.getRed()  *  ratio  +  c1.getRed()  *  (1  -  ratio));
                    int  green  =  (int)(c2.getGreen()  *  ratio  +
                                                        c1.getGreen()  *  (1  -  ratio));
                    int  blue  =  (int)(c2.getBlue()  *  ratio  +
                                                      c1.getBlue()  *  (1  -  ratio));
                    Color  c  =  new  Color(red,  green,  blue);
                    Rectangle2D  r  =  new  Rectangle2D.Float(
                            x  +  size  *  (float)i,  y,  size,  size);
                    g2.setPaint(c);
                    g2.fill(r);
                }
                        
                //  Show  an  alpha  gradient.
                y  +=  size;
                c1  =  Color.red;
                for  (int  i  =  0;  i  <  colors.length;  i++)  {
                    int  alpha  =  (int)(255  *  (float)i  /  (float)colors.length);
                    Color  c  =  new  Color(c1.getRed(),  c1.getGreen(),
                                                            c1.getBlue(),  alpha);
                    Rectangle2D  r  =  new  Rectangle2D.Float(
                            x  +  size  *  (float)i,  y,  size,  size);
                    g2.setPaint(c);
                    g2.fill(r);
                }
                        
                //  Draw  a  frame  around  the  whole  thing.
                y  -=  size  *  2;
                Rectangle2D  frame  =  new  Rectangle2D.Float(x,  y,  size  *  colors.length,  size  *  3);
                g2.setPaint(Color.black);
                g2.draw(frame);
            }

    public  static  void  main(String[]  args)  {
        JFrame  f  =  new  JFrame();
        f.getContentPane().add(new  ColorBlocks());
        f.setSize(350,  250);
        f.show();
    }
}