如何使用GUI在Java中创建笑脸图章

Question

I'm trying to write a function that will draw the pictured smiley face

I need to pass in parameters for location and size of the smiley face. For example, if the location passed in was (0,0) and size 100, then the yellow circle would be a width and height of 100, the eyes are black circles located at (30,30) and (60,30) with a width and height of 5, and the mouth is a black semi-circle inset by 10 pixels. Lastly I need to call the smiley function from paintComponent then use it as a stamp to draw at least 5 different smileys in different locations and sizes.

I know I need to create a equation that will do all of this but am unaware as to how to accomplish this because when I change the x and y coordinates the eyes of the smiley face are not in the proper position as they were before the change. anything helps, thanks.

public class GuiApp extends JFrame
{
    private DrawingPanel panel;
public class DrawingPanel extends JPanel 
{
    public DrawingPanel()
    {
        this.setBackground(Color.RED);
    }
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g); 
       // drawFlower(g, 20, 10, 10);
       drawSmiley(g, 25, 25, 100);
    }
}
public GuiApp()
{
    setBounds(100, 100, 450, 300);//x,y,w,h of window
    panel = new DrawingPanel();
    this.setContentPane(panel);
}
public static void main(String [] args)
{
    GuiApp f = new GuiApp();
    f.setTitle("Smiley");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
}
public void drawFlower(Graphics g,int x,int y,int s)
{
     g.drawOval(60, 60, 200, 200);
     g.fillOval(90, 120, 50, 20);
     g.fillOval(190, 120, 50, 20);
     g.drawArc(110, 130, 95, 95, 0, -180);     
}
public void drawSmiley(Graphics g, int x, int y, int s)
{
    g.setColor((Color.YELLOW));
    g.fillOval(x-s/2, y-s/2, s, s);
    g.setColor((Color.blue));
    g.fillOval((int)(1+(x-s/2)+(x-s/2)*.3), (int)(1+(y-s/2)+(y-s/2)*.3),(int)(s*.10),(int)(s*.10));
    g.fillOval((int)(1+(x-s/2)+(x-s/2)*.9), (int)(1+(y-s/2)+(y-s/2)*.3),(int)(s*.10),(int)(s*.10));
    g.drawArc((int)(1+(x-s/2)+(x-s/2)*.1), (int)(1+(y-s/2)-(y-s/2)*.15), (int)(s*.9), (int)(s), 0, -180);
}

}

Answer 1

Remember, most graphical operations occur from the top/left corner, so when drawing something like an oval, the x/y is the top/left corner of the oval and it will expand right/down.

So, this means that when drawing the right eye, for example, you will not only need to calculate the x/y position as a factor of the diameter of the circle, but you may need to subtract the width of the eye itself from the horizontal to make it "look" right

Now, you can make your life easier by using Graphics#translate to move the origin/starting point of all graphical operations to that new location, this will reduce the amount of calculations you need to make. This also means that you could, technically, write two methods, one which did the actual painting of the smiley face starting from position 0x0 and one which translated the position (based on the parameters) and then called the first, but that's just an example idea ;)

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Smile {

    public static void main(String[] args) {
        new Smile();
    }

    public Smile() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            drawSmiley(g, 25, 25, 100);
        }

        public void drawSmiley(Graphics g, int x, int y, int s) {
            Graphics copy = g.create();
            copy.translate(x, y);
            copy.setColor((Color.YELLOW));
            copy.fillOval(0, 0, s, s);
            copy.setColor((Color.blue));
            copy.fillOval((int) (1 + s * .3), (int) (1 + s * .3), (int) (s * .10), (int) (s * .10));
            copy.fillOval((int) ((1 + s * .7) - (s * .10)), (int) (1 + s * .3), (int) (s * .10), (int) (s * .10));

            double width = s * 0.8;
            double height = s * 0.8;

            copy.drawArc((int)((s - width) / 2d), (int)((s - height) / 2d), (int)width, (int)height, 0, -180);
            copy.dispose();
        }
    }

}

Answer 2

package guimodule;

import processing.core.PApplet;

public class MyDisplay extends PApplet {

  public void setup() {
    size(400, 400);
    background(200, 200, 200);

  }

  public void draw() {
    fill(255, 255, 0);
    ellipse(200, 200, 390, 390);
    fill(0, 0, 0);
    ellipse(120, 130, 50, 70);
    ellipse(280, 130, 50, 70);
    noFill();
    fill(0, 0, 0);
    arc(200, 280, 145, 120, 0, PI);
  }
}