setPaint
public abstract void setPaint(Paint paint)

Paintインターフェース

public void paintComponent(Graphics g){
  Graphics2D g2 = (Graphics2D)g;

  g2.setPaint(Color.RED);
}

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;

  g2.setPaint(Color.RED);
  g2.draw(new Ellipse2D.Double(30, 40, 50, 50));
        
  g2.setPaint(new Color(210, 30, 50));
  g2.fill(new RoundRectangle2D.Double(30, 130, 110, 50, 10, 20));
}

サンプルプログラム

/**
 * Colorクラスによる色の指定
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Color;
import java.awt.BasicStroke;

public class PaintTest1 extends JPanel {

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

    PaintTest1 app = new PaintTest1();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D)g;

    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
                        RenderingHints.VALUE_ANTIALIAS_ON);

    BasicStroke wideStroke = new BasicStroke(4.0f);
    g2.setStroke(wideStroke);

    g2.setPaint(Color.BLUE);
    g2.draw(new Ellipse2D.Double(70, 20, 50, 50));

    g2.setPaint(Color.RED);
    g2.draw(new Ellipse2D.Double(110, 20, 50, 50));

    g2.setPaint(Color.GREEN);
    g2.draw(new Ellipse2D.Double(150, 20, 50, 50));

    g2.setPaint(Color.PINK);
    g2.draw(new Ellipse2D.Double(190, 20, 50, 50));

    g2.setPaint(Color.YELLOW);
    g2.fill(new RoundRectangle2D.Double(30, 100, 110, 50, 10, 20));
  }
}

java.lang.Object
   ⇒ java.awt.GradientPaint
public class GradientPaint extends Object implements Paint

循環式と非循環式の違い

GradientPaint
public GradientPaint(float x1,
                     float y1,
                     Color color1,
                     float x2,
                     float y2,
                     Color color2)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;

  GradientPaint gradient = new GradientPaint(
      50.0f, 50.0f, Color.ORANGE, 
      190.0f, 110.0f, Color.YELLOW
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

Point2Dクラスによる座標指定

GradientPaint
public GradientPaint(Point2D pt1,
                     Color color1,
                     Point2D pt2,
                     Color color2)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;

  GradientPaint gradient = new GradientPaint(
      new Point2D.Double(50.0d, 50.0d), Color.ORANGE, 
      new Point2D.Double(190.0f, 110.0f), Color.YELLOW
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

サンプルプログラム

/**
 * 非循環式によるグラデーション表示
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Color;
import java.awt.GradientPaint;

public class PaintTest2 extends JPanel{

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

    PaintTest2 app = new PaintTest2();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g){
    Graphics2D g2 = (Graphics2D)g;

    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
                        RenderingHints.VALUE_ANTIALIAS_ON);

    GradientPaint gradient = new GradientPaint(
        50.0f, 50.0f, Color.ORANGE, 
        190.0f, 110.0f, Color.YELLOW
    );
    g2.setPaint(gradient);

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));

/*
    g2.setPaint(Color.black);
    g2.draw(new Ellipse2D.Double(45, 45, 10, 10));
    g2.draw(new Ellipse2D.Double(185, 105, 10, 10));
*/
  }
}

GradientPaint
public GradientPaint(float x1,
                     float y1,
                     Color color1,
                     float x2,
                     float y2,
                     Color color2,
                     boolean cyclic)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;

  GradientPaint gradient = new GradientPaint(
      50.0f, 50.0f, Color.ORANGE, 
      190.0f, 110.0f, Color.YELLOW,
      true
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

Point2Dクラスによる座標指定

GradientPaint
public GradientPaint(Point2D pt1,
                     Color color1,
                     Point2D pt2,
                     Color color2,
                     boolean cyclic)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;

  GradientPaint gradient = new GradientPaint(
      new Point2D.Double(50.0d, 50.0d), Color.ORANGE, 
      new Point2D.Double(190.0f, 110.0f), Color.YELLOW, 
      true
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

サンプルプログラム

/**
 * 循環式によるグラデーション表示
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Color;
import java.awt.GradientPaint;

public class PaintTest3 extends JPanel {

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

    PaintTest3 app = new PaintTest3();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D)g;

    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
                        RenderingHints.VALUE_ANTIALIAS_ON);

    GradientPaint gradient = new GradientPaint(
        90.0f, 70.0f, Color.RED, 
        150.0f, 90.0f, Color.BLUE,
        true
    );
    g2.setPaint(gradient);

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));

/*
    g2.setPaint(Color.black);
    g2.draw(new Ellipse2D.Double(85, 65, 10, 10));
    g2.draw(new Ellipse2D.Double(145, 85, 10, 10));
*/
  }
}

java.lang.Object
  ⇒ java.awt.TexturePaint
public class TexturePaint extends Object implements Paint

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;

  BufferedImage img = 
    new BufferedImage(45, 59, BufferedImage.TYPE_INT_RGB);

  File f = new File("./img/sample.png");
  try {
    img = ImageIO.read(f);
  }catch (IOException ex) {
    ex.printStackTrace();
  }

  Rectangle2D.Double rec = 
    new Rectangle2D.Double(0, 0, img.getWidth(), img.getHeight());

  g2.setPaint(new TexturePaint(img, rec));

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

サンプルプログラム

/**
 * TexturePaintクラスによるテクスチャーによる塗りつぶし
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.TexturePaint;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import java.io.IOException;

public class PaintTest4 extends JPanel {

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

    PaintTest4 app = new PaintTest4();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D)g;

    BufferedImage img = 
      new BufferedImage(45, 59, BufferedImage.TYPE_INT_RGB);

    File f = new File("./img/uma_b1.gif");
    try {
      img = ImageIO.read(f);
    }catch (IOException ex){
      ex.printStackTrace();
    }

    Rectangle2D.Double rec = 
      new Rectangle2D.Double(0, 0, img.getWidth(), img.getHeight());

    g2.setPaint(new TexturePaint(img, rec));

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
  }
}

/**
 * TexturePaintクラスによるテクスチャーによる塗りつぶし(2)
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.TexturePaint;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import java.io.IOException;

public class PaintTest5 extends JPanel {

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

    PaintTest5 app = new PaintTest5();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D)g;

    BufferedImage img = 
      new BufferedImage(45, 59, BufferedImage.TYPE_INT_RGB);

    File f = new File("./img/uma_b1.gif");
    try {
      img = ImageIO.read(f);
    }catch (IOException ex){
      ex.printStackTrace();
    }

    Rectangle2D.Double rec = 
      new Rectangle2D.Double(0, 0, img.getWidth() / 2, img.getHeight() / 2);

    g2.setPaint(new TexturePaint(img, rec));

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
  }
}

java.lang.Object
  ⇒ java.awt.MultipleGradientPaint
       ⇒ java.awt.LinearGradientPaint
public final class LinearGradientPaint extends MultipleGradientPaint

LinearGradientPaint
public LinearGradientPaint(float startX,
                           float startY,
                           float endX,
                           float endY,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

float[] dist = {0.2f, 0.4f, 1.0f};
Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

float[] dist = {0.2f, 0.4f, 1.0f};
Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

float[] dist = {0.0f, 0.2f, 0.4f, 1.0f};
Color[] colors = {Color.RED, Color.RED, Color.WHITE, Color.BLUE};

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;
    
  float[] dist = {0.0f, 0.4f, 1.0f};
  Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

  LinearGradientPaint gradient = new LinearGradientPaint(
      50.0f, 50.0f, 
      190.0f, 110.0f,
      dist,
      colors,
      MultipleGradientPaint.CycleMethod.NO_CYCLE
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

Point2Dクラスによる座標指定

LinearGradientPaint
public LinearGradientPaint(Point2D start,
                           Point2D end,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;
    
  float[] dist = {0.0f, 0.4f, 1.0f};
  Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
  
  LinearGradientPaint gradient = new LinearGradientPaint(
      new Point2D.Double(50.0d, 50.0d), 
      new Point2D.Double(190.0f, 110.0f),
      dist,
      colors,
      MultipleGradientPaint.CycleMethod.NO_CYCLE
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

サンプルプログラム

/**
 * LinearGradientPaintクラスによるグラデーションの指定
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Color;
import java.awt.LinearGradientPaint;
import java.awt.MultipleGradientPaint;

public class PaintTest6 extends JPanel {

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

    PaintTest6 app = new PaintTest6();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D)g;

    float[] dist = {0.0f, 0.4f, 1.0f};
    Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

    LinearGradientPaint gradient = new LinearGradientPaint(
        50.0f, 50.0f, 
        100.0f, 110.0f,
        dist,
        colors,
        MultipleGradientPaint.CycleMethod.NO_CYCLE
        // MultipleGradientPaint.CycleMethod.REFLECT
        // MultipleGradientPaint.CycleMethod.REPEAT
    );
    g2.setPaint(gradient);

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
  }
}

java.lang.Object
  ⇒ java.awt.MultipleGradientPaint
       ⇒ java.awt.RadialGradientPaint
public final class RadialGradientPaint extends MultipleGradientPaint

RadialGradientPaint
public RadialGradientPaint(float cx,
                           float cy,
                           float radius,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

float[] dist = {0.0f, 0.4f, 1.0f};
Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

float[] dist = {0.2f, 0.4f, 1.0f};
Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

float[] dist = {0.0f, 0.2f, 0.4f, 1.0f};
Color[] colors = {Color.RED, Color.RED, Color.WHITE, Color.BLUE};

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;
    
  float[] dist = {0.0f, 0.4f, 1.0f};
  Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
  
  RadialGradientPaint gradient = new RadialGradientPaint(
      50.0f, 50.0f, 
      60.0f,
      dist,
      colors,
      MultipleGradientPaint.CycleMethod.NO_CYCLE
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

Point2Dクラスによる座標指定

RadialGradientPaint
public RadialGradientPaint(float cx,
                           float cy,
                           float radius,
                           float fx,
                           float fy,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;
    
  float[] dist = {0.0f, 0.4f, 1.0f};
  Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
  
  RadialGradientPaint gradient = new RadialGradientPaint(
      new Point2D.Double(50.0d, 50.0d), 
      60.0f,
      dist,
      colors,
      MultipleGradientPaint.CycleMethod.NO_CYCLE
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

サンプルプログラム

/**
 * RadialGradientPaintクラスによるグラデーションの指定
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Color;
import java.awt.RadialGradientPaint;
import java.awt.MultipleGradientPaint;

public class PaintTest7 extends JPanel{

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

    PaintTest7 app = new PaintTest7();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g){
    Graphics2D g2 = (Graphics2D)g;

    float[] dist = {0.0f, 0.4f, 1.0f};
    Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

    RadialGradientPaint gradient = new RadialGradientPaint(
        100.0f, 80.0f, 
        60.0f,
        dist,
        colors,
        MultipleGradientPaint.CycleMethod.NO_CYCLE
        // MultipleGradientPaint.CycleMethod.REFLECT
        // MultipleGradientPaint.CycleMethod.REPEAT
    );
    g2.setPaint(gradient);

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
  }
}

RadialGradientPaint
public RadialGradientPaint(float cx,
                           float cy,
                           float radius,
                           float fx,
                           float fy,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;
    
  float[] dist = {0.0f, 0.4f, 1.0f};
  Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
	  
  RadialGradientPaint gradient = new RadialGradientPaint(
      50.0f, 50.0f, 
      60.0f,
      40.0f, 40.0f, 
      dist,
      colors,
      MultipleGradientPaint.CycleMethod.NO_CYCLE
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

Point2Dクラスによる座標指定

RadialGradientPaint
public RadialGradientPaint(Point2D center,
                           float radius,
                           Point2D focus,
                           float[] fractions,
                           Color[] colors,
                           MultipleGradientPaint.CycleMethod cycleMethod)

public void paintComponent(Graphics g) {
  Graphics2D g2 = (Graphics2D)g;
    
  float[] dist = {0.0f, 0.4f, 1.0f};
  Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};
  
  RadialGradientPaint gradient = new RadialGradientPaint(
      new Point2D.Double(50.0d, 50.0d), 
      60.0f,
      new Point2D.Double(40.0d, 40.0d), 
      dist,
      colors,
      MultipleGradientPaint.CycleMethod.NO_CYCLE
  );
  g2.setPaint(gradient);

  g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
}

サンプルプログラム

/**
 * 焦点を中心点と異なる位置に設定する
 */
import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Color;
import java.awt.RadialGradientPaint;
import java.awt.MultipleGradientPaint;

public class PaintTest8 extends JPanel{

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

    PaintTest8 app = new PaintTest8();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("タイトル");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g){
    Graphics2D g2 = (Graphics2D)g;

    float[] dist = {0.0f, 0.4f, 1.0f};
    Color[] colors = {Color.RED, Color.WHITE, Color.BLUE};

    RadialGradientPaint gradient = new RadialGradientPaint(
        100.0f, 80.0f, 
        60.0f,
        60.0f, 60.0f, 
        dist,
        colors,
        MultipleGradientPaint.CycleMethod.NO_CYCLE
        // MultipleGradientPaint.CycleMethod.REFLECT
        // MultipleGradientPaint.CycleMethod.REPEAT
    );
    g2.setPaint(gradient);

    g2.fill(new Rectangle2D.Double(20, 20, 200, 130));
  }
}