With this tutorial we shall show you how to draw simple shapes in a Java Desktop Application. This is a very important step when designing your own graphics for your App.
Basically, all you have to do in order to draw shapes in a Java application is:
- Create a new
Frame. - Create a class that extends the
Componentclass and override thepaintmethod. - Use
Graphics2D.drawLineto draw a simple line. - Use
Graphics2D.drawOvalto draw an oval shape in the screen. - Use
Graphics2D.drawRectto draw a rectangle on the screen. - Use
Graphics2D.drawArcto draw an arch. - Create a new
Polygonto add a polygon to your drawing, and useaddPointto add more points to the polygon.
Let’s see the code snippet that follows:
package com.javacodegeeks.snippets.desktop;
import java.awt.Component;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
public class DrawShapesExample {
public static void main(String[] args) {
// Create a frame
Frame frame = new Frame();
// Add a component with a custom paint method
frame.add(new CustomPaintComponent());
// Display the frame
int frameWidth = 300;
int frameHeight = 300;
frame.setSize(frameWidth, frameHeight);
frame.setVisible(true);
}
/**
* To draw on the screen, it is first necessary to subclass a Component
* and override its paint() method. The paint() method is automatically called
* by the windowing system whenever component's area needs to be repainted.
*/
static class CustomPaintComponent extends Component {
public void paint(Graphics g) {
// Retrieve the graphics context; this object is used to paint shapes
Graphics2D g2d = (Graphics2D)g;
// Draw an oval that fills the window
int x = 0;
int y = 0;
int w = getSize().width-1;
int h = getSize().height-1;
/**
* The coordinate system of a graphics context is such that the origin is at the
* northwest corner and x-axis increases toward the right while the y-axis increases
* toward the bottom.
*/
g2d.drawLine(x, y, w, h);
// to draw a filled oval use : g2d.fillOval(x, y, w, h) instead
g2d.drawOval(x, y, w, h);
// to draw a filled rectangle use : g2d.fillRect(x, y, w, h) instead
g2d.drawRect(x, y, w, h);
// A start angle of 0 represents a 3 o'clock position, 90 represents a 12 o'clock position,
// and -90 (or 270) represents a 6 o'clock position
int startAngle = 45;
int arcAngle = -60;
// to draw a filled arc use : g2d.fillArc(x, y, w, h, startAngle, arcAngle) instead
g2d.drawArc(x, y, w/2, h/2, startAngle, arcAngle);
// to draw a filled round rectangle use : g2d.fillRoundRect(x, y, w, h, arcWidth, arcHeight) instead
g2d.drawRoundRect(x, y, w, h, w/2, h/2);
Polygon polygon = new Polygon();
polygon.addPoint(w/4, h/2);
polygon.addPoint(0, h/2);
polygon.addPoint(w/4, 3*h/4);
polygon.addPoint(w/2, 3*h/4);
// Add more points...
// to draw a filled round rectangle use : g2d.fillPolygon(polygon) instead
g2d.drawPolygon(polygon);
}
}
}
This was an example on how to draw shapes in a Java Desktop Application.
