使用Java awt的4 Color Gradient

Question

I´m trying to create a 4 color gradient to fill a rectangle. Each corner will have a diferent color.

The result image I´m trying to achieve is something like this:

https://www.dropbox.com/s/vu3yxbaenu2cnwg/Screenshot%202014-08-29%2012.53.43.png?dl=0

There is a lot of helpful resources on how to make a 2 color gradient, but none for more than 3.

Answer 1

Something like this?

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;

public class ThreeWayGradient {

    public static void main(String[] args) {
        final BufferedImage image = new BufferedImage(
                200, 200, BufferedImage.TYPE_INT_RGB);
        Runnable r = new Runnable() {
            @Override
            public void run() {
                Graphics2D g = image.createGraphics();
                GradientPaint primary = new GradientPaint(
                        0f, 0f, Color.WHITE, 200f, 0f, Color.ORANGE);
                GradientPaint shade = new GradientPaint(
                        0f, 0f, new Color(0, 0, 0, 0),
                        0f, 200f, new Color(0, 0, 0, 255));
                g.setPaint(primary);
                g.fillRect(0, 0, 200, 200);
                g.setPaint(shade);
                g.fillRect(0, 0, 200, 200);

                JLabel l = new JLabel(new ImageIcon(image));
                JOptionPane.showMessageDialog(null, l);
                File f = new File(System.getProperty("user.home"),
                        "ThreeWayGradient.png");
                try {
                    ImageIO.write(image, "png", f);
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        };
        SwingUtilities.invokeLater(r);
    }
}

Making it into a factory method

..because it is prettier.

import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;

public class ThreeWayGradient {

    public static BufferedImage getThreeWayGradient(
            int size,
            Color primaryLeft,
            Color primaryRight,
            Color shadeColor) {
        BufferedImage image = new BufferedImage(
                size, size, BufferedImage.TYPE_INT_RGB);

        Graphics2D g = image.createGraphics();
        GradientPaint primary = new GradientPaint(
                0f, 0f, primaryLeft, size, 0f, primaryRight);
        int rC = shadeColor.getRed();
        int gC = shadeColor.getGreen();
        int bC = shadeColor.getBlue();
        GradientPaint shade = new GradientPaint(
                0f, 0f, new Color(rC, gC, bC, 0),
                0f, size, shadeColor);
        g.setPaint(primary);
        g.fillRect(0, 0, size, size);
        g.setPaint(shade);
        g.fillRect(0, 0, size, size);

        g.dispose();
        return image;
    }

    /**
     * Presumed to have a layout that shows multiple components.
     */
    public static void addGradient(
            JPanel p, int s, Color pL, Color pR, Color sh) {

        JLabel l = new JLabel(new ImageIcon(getThreeWayGradient(s, pL, pR, sh)));
        p.add(l);
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {

            @Override
            public void run() {
                JPanel gui = new JPanel(new GridLayout(2,4,1,1));
                addGradient(gui,100,Color.YELLOW,Color.RED,Color.GREEN);
                addGradient(gui,100,Color.GREEN,Color.YELLOW,Color.RED);
                addGradient(gui,100,Color.RED,Color.GREEN,Color.YELLOW);
                addGradient(gui,100,Color.BLUE,Color.MAGENTA,Color.PINK);
                addGradient(gui,100,Color.WHITE,Color.RED,Color.BLACK);
                addGradient(gui,100,Color.RED,Color.GREEN,Color.BLACK);
                addGradient(gui,100,Color.BLUE,Color.PINK,Color.BLACK);
                addGradient(gui,100,Color.BLUE,Color.CYAN,Color.BLACK);
                JOptionPane.showMessageDialog(null, gui);
            }
        };
        SwingUtilities.invokeLater(r);
    }
}

Answer 2

Here is one solution

package foursidesgradient;

import java.awt.*;
import java.awt.geom.Point2D;
import java.awt.image.BufferedImage;
import javax.swing.*;
import static javax.swing.JFrame.EXIT_ON_CLOSE;

public class FourSidesGradient{

public static void main(String[] args) {
    JFrame frame = new JFrame("My frame");
    frame.add(new MyLabel(200, Color.RED, Color.YELLOW, Color.BLUE, Color.CYAN));
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
}

private static class MyLabel extends JLabel{
    private BufferedImage image0;
    private BufferedImage image1;
    private BufferedImage image2;
    private Color noColor = new Color(255, 255, 255, 0);
    private int size;
    public MyLabel(int size, Color leftTop, Color rightTop, Color leftBottom, Color rightBottom){
        super();
        image0 = getTwoWayGradient(size, rightTop,leftBottom);
        image1 = getLeftGradient(size, leftTop);
        image2 = getRightGradient(size, rightBottom);
        this.size = size;
        this.setPreferredSize(new Dimension(size, size));
    }

    private BufferedImage getTwoWayGradient(int size,Color rightTop,Color leftBottom) {
        image0 = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = image0.createGraphics();
        GradientPaint twoColorGradient = new GradientPaint(size, 0f, rightTop, 0, size, leftBottom);
        g2d.setPaint(twoColorGradient);
        g2d.fillRect(0, 0, size, size);
        return image0;
    }

    private BufferedImage getLeftGradient(int size, Color RED) {
        image1 = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = image1.createGraphics();
        float radius = size;
        float[] dist = {0f, 1.0f};
        Point2D center = new Point2D.Float(0, 0);
        Color[] colors2 = {RED, noColor};
        RadialGradientPaint two = new RadialGradientPaint(center, radius, dist, colors2);
        g2d.setPaint(two);
        g2d.fillRect(0, 0, size, size);
        return image1;
    }

    private BufferedImage getRightGradient(int size, Color CYAN) {
        image2 = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = image2.createGraphics();
        float radius = size;
        float[] dist = {0f, 1.0f};
        Point2D center = new Point2D.Float(size, size);
        Color[] colors2 = {CYAN, noColor};
        RadialGradientPaint three = new RadialGradientPaint(center, radius, dist, colors2);
        g2d.setPaint(three);
        g2d.fillRect(0, 0, size, size);
        return image2;
    }

    @Override
    protected void paintComponent(Graphics g){
        g.drawImage(image0, 0, 0, null);
        g.drawImage(image2, 0, 0, null);
        g.drawImage(image1, 0, 0, null);
    }
}
}

The result:

Here is another solution:

package foursidesgradient;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RadialGradientPaint;
import java.awt.geom.Point2D;
import javax.swing.JFrame;
import static javax.swing.JFrame.EXIT_ON_CLOSE;
import javax.swing.JLabel;
import javax.swing.JPanel;



public class FourSidesGradient {

    public static void main(String[] args) {
    JFrame frame = new JFrame("My frame");
    JPanel myPanel = new JPanel();
    frame.add(myPanel);

    myPanel.add(new MyLabel(200, Color.RED, Color.YELLOW, Color.BLUE, Color.CYAN));
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
}

private static class MyLabel extends JLabel{
    int size;
    Color leftTop;
    Color rightTop;
    Color leftBottom;
    Color rightBottom;

    public MyLabel(int size, Color leftTop, Color rightTop, Color leftBottom, Color rightBottom){
        super();
        this.size = size;
        this.leftTop = leftTop;
        this.rightTop = rightTop;
        this.leftBottom = leftBottom;
        this.rightBottom = rightBottom;
        this.setPreferredSize(new Dimension(size, size));
    }

    @Override
    protected void paintComponent(Graphics g){
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        GradientPaint twoColorGradient = new GradientPaint(
            size, 0f, rightTop, 0, size, leftBottom);

        float radius = size-(size/4);
        float[] dist = {0f, 1.0f};
        Point2D center = new Point2D.Float(0f, 0f);
        Color noColor = new Color(0f, 0f, 0f, 0f);
        Color[] colors = {leftTop, noColor};
        RadialGradientPaint thirdColor = new RadialGradientPaint(center, radius, dist, colors);


        center = new Point2D.Float(size, size);
        Color[] colors2 = {rightBottom, noColor};
        RadialGradientPaint fourthColor = new RadialGradientPaint(center, radius, dist, colors2);

        g2d.setPaint(twoColorGradient);
        g2d.fillRect(0, 0, size, size);

        g2d.setPaint(thirdColor);
        g2d.fillRect(0, 0, size, size);

        g2d.setPaint(fourthColor);
        g2d.fillRect(0, 0, size, size);
    }
}
}

Second result:

The pictures will be a little bit different in spite of usage the same methods.

Answer 3

I was able to solve my problem like this.

 import java.awt.Color;
 import java.awt.Graphics;
 import javax.swing.JPanel;
 import javax.swing.JFrame;
 import java.lang.Math;
public class main extends JPanel{

public void paintComponent(Graphics g){
    //super.paintComponent(g);
    int ancho = getWidth();
    int alto  = getHeight();
    int r, gg, b;
    double pitagorazo, hypotenuse;
    Color miColor;

    for(int i=0; i<800; i++){
        for(int j=0; j<600; j++){
            pitagorazo = Math.pow(i,2)+Math.pow(j,2);
            hypotenuse = Math.sqrt(pitagorazo);
            hypotenuse=hypotenuse/3;
            if(hypotenuse > 255)
                hypotenuse = 255;
            System.out.println(hypotenuse);

            r = 255-(int)hypotenuse;
            pitagorazo = Math.pow((255-i),2)+Math.pow(j,2);
            hypotenuse = Math.sqrt(pitagorazo);
            hypotenuse=hypotenuse/3;

            if(hypotenuse > 255)
                hypotenuse = 255;
            gg = 255-(int)hypotenuse;
            pitagorazo = Math.pow(i,2)+Math.pow((255-j),2);
            hypotenuse = Math.sqrt(pitagorazo);
            hypotenuse=hypotenuse/3;

            if(hypotenuse > 255)
                hypotenuse = 255;
            b = 255-(int)hypotenuse;
            miColor = new Color(r,gg,b);
            g.setColor(miColor);

            g.fillRect(i,j,1,1);
            }
        }


}

public static void main(String args[]){
    main panel = new main();

    JFrame application = new JFrame();
    application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    application.add(panel);
    application.setSize(800, 600);
    application.setVisible(true);
}
  }

Here is the result : https://www.dropbox.com/s/ptsbiz0lxehcta8/Screenshot%202014-01-30%2023.35.23.png