Java Example

• editor

  • editor/ImageEditor.java

    package refactoring_guru.composite.example.editor;
    
    import refactoring_guru.composite.example.shapes.CompoundShape;
    import refactoring_guru.composite.example.shapes.Shape;
    
    import javax.swing.*;
    import javax.swing.border.Border;
    import java.awt.*;
    import java.awt.event.MouseAdapter;
    import java.awt.event.MouseEvent;
    
    public class ImageEditor {
        private EditorCanvas canvas;
        private CompoundShape allShapes = new CompoundShape();
    
        public ImageEditor() {
            canvas = new EditorCanvas();
        }
    
        public void loadShapes(Shape... shapes) {
            allShapes.clear();
            allShapes.add(shapes);
            canvas.refresh();
        }
    
        private class EditorCanvas extends Canvas {
            JFrame frame;
    
            private static final int PADDING = 10;
    
            EditorCanvas() {
                createFrame();
                refresh();
                addMouseListener(new MouseAdapter() {
                    @Override
                    public void mousePressed(MouseEvent e) {
                        allShapes.unSelect();
                        allShapes.selectChildAt(e.getX(), e.getY());
                        e.getComponent().repaint();
                    }
                });
            }
    
            void createFrame() {
                frame = new JFrame();
                frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
                frame.setLocationRelativeTo(null);
    
                JPanel contentPanel = new JPanel();
                Border padding = BorderFactory.createEmptyBorder(PADDING, PADDING, PADDING, PADDING);
                contentPanel.setBorder(padding);
                frame.setContentPane(contentPanel);
    
                frame.add(this);
                frame.setVisible(true);
                frame.getContentPane().setBackground(Color.LIGHT_GRAY);
            }
    
            public int getWidth() {
                return allShapes.getX() + allShapes.getWidth() + PADDING;
            }
    
            public int getHeight() {
                return allShapes.getY() + allShapes.getHeight() + PADDING;
            }
    
            void refresh() {
                this.setSize(getWidth(), getHeight());
                frame.pack();
            }
    
            public void paint(Graphics graphics) {
                allShapes.paint(graphics);
            }
        }
    }

• shapes

  • shapes/BaseShape.java

    package refactoring_guru.composite.example.shapes;
    
    import java.awt.*;
    
    abstract class BaseShape implements Shape {
        public int x;
        public int y;
        public Color color;
        private boolean selected = false;
    
        BaseShape(int x, int y, Color color) {
            this.x = x;
            this.y = y;
            this.color = color;
        }
    
        @Override
        public int getX() {
            return x;
        }
    
        @Override
        public int getY() {
            return y;
        }
    
        @Override
        public int getWidth() {
            return 0;
        }
    
        @Override
        public int getHeight() {
            return 0;
        }
    
        @Override
        public void move(int x, int y) {
            this.x += x;
            this.y += y;
        }
    
        @Override
        public boolean isInsideBounds(int x, int y) {
            return x > getX() && x < (getX() + getWidth()) &&
                    y > getY() && y < (getY() + getHeight());
        }
    
        @Override
        public void select() {
            selected = true;
        }
    
        @Override
        public void unSelect() {
            selected = false;
        }
    
        @Override
        public boolean isSelected() {
            return selected;
        }
    
        void enableSelectionStyle(Graphics graphics) {
            graphics.setColor(Color.LIGHT_GRAY);
    
            Graphics2D g2 = (Graphics2D) graphics;
            float dash1[] = {2.0f};
            g2.setStroke(new BasicStroke(1.0f,
                    BasicStroke.CAP_BUTT,
                    BasicStroke.JOIN_MITER,
                    2.0f, dash1, 0.0f));
        }
    
        void disableSelectionStyle(Graphics graphics) {
            graphics.setColor(color);
            Graphics2D g2 = (Graphics2D) graphics;
            g2.setStroke(new BasicStroke());
        }

    @Override
    public void paint(Graphics graphics) {
        if (isSelected()) {
            enableSelectionStyle(graphics);
        }
        else {
            disableSelectionStyle(graphics);
        }

        // ...
    }
}
```

• shapes/Circle.java

  package refactoring_guru.composite.example.shapes;
  
  import java.awt.*;
  
  public class Circle extends BaseShape {
      public int radius;
  
      public Circle(int x, int y, int radius, Color color) {
          super(x, y, color);
          this.radius = radius;
      }
  
      @Override
      public int getWidth() {
          return radius * 2;
      }
  
      @Override
      public int getHeight() {
          return radius * 2;
      }
  
      public void paint(Graphics graphics) {
          super.paint(graphics);
          graphics.drawOval(x, y, getWidth() - 1, getHeight() - 1);
      }
  }

• shapes/CompoundShape.java

  package refactoring_guru.composite.example.shapes;
  
  import java.awt.*;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  public class CompoundShape extends BaseShape {
      protected List<Shape> children = new ArrayList<>();
  
      public CompoundShape(Shape... components) {
          super(0, 0, Color.BLACK);
          add(components);
      }
  
      public void add(Shape component) {
          children.add(component);
      }
  
      public void add(Shape... components) {
          children.addAll(Arrays.asList(components));
      }
  
      public void remove(Shape child) {
          children.remove(child);
      }
  
      public void remove(Shape... components) {
          children.removeAll(Arrays.asList(components));
      }
  
      public void clear() {
          children.clear();
      }
  
      @Override
      public int getX() {
          if (children.size() == 0) {
              return 0;
          }
          int x = children.get(0).getX();
          for (Shape child : children) {
              if (child.getX() < x) {
                  x = child.getX();
              }
          }
          return x;
      }
  
      @Override
      public int getY() {
          if (children.size() == 0) {
              return 0;
          }
          int y = children.get(0).getY();
          for (Shape child : children) {
              if (child.getY() < y) {
                  y = child.getY();
              }
          }
          return y;
      }
  
      @Override
      public int getWidth() {
          int maxWidth = 0;
          int x = getX();
          for (Shape child : children) {
              int childsRelativeX = child.getX() - x;
              int childWidth = childsRelativeX + child.getWidth();
              if (childWidth > maxWidth) {
                  maxWidth = childWidth;
              }
          }
          return maxWidth;
      }
  
      @Override
      public int getHeight() {
          int maxHeight = 0;
          int y = getY();
          for (Shape child : children) {
              int childsRelativeY = child.getY() - y;
              int childHeight = childsRelativeY + child.getHeight();
              if (childHeight > maxHeight) {
                  maxHeight = childHeight;
              }
          }
          return maxHeight;
      }
  
      @Override
      public void move(int x, int y) {
          for (Shape child : children) {
              child.move(x, y);
          }
      }
  
      @Override
      public boolean isInsideBounds(int x, int y) {
          for (Shape child : children) {
              if (child.isInsideBounds(x, y)) {
                  return true;
              }
          }
          return false;
      }
  
      @Override
      public void unSelect() {
          super.unSelect();
          for (Shape child : children) {
              child.unSelect();
          }
      }
  
      public boolean selectChildAt(int x, int y) {
          for (Shape child : children) {
              if (child.isInsideBounds(x, y)) {
                  child.select();
                  return true;
              }
          }
          return false;
      }
  
      @Override
      public void paint(Graphics graphics) {
          if (isSelected()) {
              enableSelectionStyle(graphics);
              graphics.drawRect(getX() - 1, getY() - 1, getWidth() + 1, getHeight() + 1);
              disableSelectionStyle(graphics);
          }
  
          for (refactoring_guru.composite.example.shapes.Shape child : children) {
              child.paint(graphics);
          }
      }
  }

• shapes/Dot.java

  package refactoring_guru.composite.example.shapes;
  
  import java.awt.*;
  
  public class Dot extends BaseShape {
      private final int DOT_SIZE = 3;
  
      public Dot(int x, int y, Color color) {
          super(x, y, color);
      }
  
      @Override
      public int getWidth() {
          return DOT_SIZE;
      }
  
      @Override
      public int getHeight() {
          return DOT_SIZE;
      }
  
      @Override
      public void paint(Graphics graphics) {
          super.paint(graphics);
          graphics.fillRect(x - 1, y - 1, getWidth(), getHeight());
      }
  }

• shapes/Rectangle.java

  package refactoring_guru.composite.example.shapes;
  
  import java.awt.*;
  
  public class Rectangle extends BaseShape {
      public int width;
      public int height;
  
      public Rectangle(int x, int y, int width, int height, Color color) {
          super(x, y, color);
          this.width = width;
          this.height = height;
      }
  
      @Override
      public int getWidth() {
          return width;
      }
  
      @Override
      public int getHeight() {
          return height;
      }
  
      @Override
      public void paint(Graphics graphics) {
          super.paint(graphics);
          graphics.drawRect(x, y, getWidth() - 1, getHeight() - 1);
      }
  }

• shapes/Shape.java

  package refactoring_guru.composite.example.shapes;
  
  import java.awt.*;
  
  public interface Shape {
      int getX();
      int getY();
      int getWidth();
      int getHeight();
      void move(int x, int y);
      boolean isInsideBounds(int x, int y);
      void select();
      void unSelect();
      boolean isSelected();
      void paint(Graphics graphics);
  }

• Demo.java

package refactoring_guru.composite.example;

import refactoring_guru.composite.example.editor.ImageEditor;
import refactoring_guru.composite.example.shapes.Circle;
import refactoring_guru.composite.example.shapes.CompoundShape;
import refactoring_guru.composite.example.shapes.Dot;
import refactoring_guru.composite.example.shapes.Rectangle;

import java.awt.*;

public class Demo {
    public static void main(String[] args) {
        ImageEditor editor = new ImageEditor();

        editor.loadShapes(
                new Circle(10, 10, 10, Color.BLUE),

                new CompoundShape(
                    new Circle(110, 110, 50, Color.RED),
                    new Dot(160, 160, Color.RED)
                ),

                new CompoundShape(
                        new Rectangle(250, 250, 100, 100, Color.GREEN),
                        new Dot(240, 240, Color.GREEN),
                        new Dot(240, 360, Color.GREEN),
                        new Dot(360, 360, Color.GREEN),
                        new Dot(360, 240, Color.GREEN)
                )
        );
    }
}