Thursday 5 July 2012

Rotate Text in Java using Graphics2D

Today I will post how to continously rotate a text i.e string in Java Graphics2D. As you know that there are 4 types of transformation available in Java which are translation,rotation,scaling and shearing. Here I will use translation and rotation for this purpose. The text will be placed exactly at the center of the screen such that mid-point of text and screen coincide. Then the text will be rotated with screen center as the anchor point of rotation. Here is the code for you ->

import java.awt.*;
import java.awt.geom.*;
import java.awt.font.*;
import javax.swing.*;

public class RotateText extends JPanel{
    static int angdeg=0;
  
    @Override
    public void paint(Graphics g){
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,                         RenderingHints.VALUE_ANTIALIAS_ON);
         g2d.setColor(Color.white); //
to remove trail of painting
         g2d.fillRect(0,0,getWidth(),getHeight());
         Font font =  new Font("serif",Font.BOLD,50);
         g2d.setFont(font); 
//setting font of surface
         FontRenderContext frc = g2d.getFontRenderContext();
         TextLayout layout = new TextLayout("JAVA", font, frc);
        
//getting width & height of the text
         double sw = layout.getBounds().getWidth();
         double sh = layout.getBounds().getHeight();
        
//getting original transform instance
        AffineTransform saveTransform=g2d.getTransform();
        g2d.setColor(Color.black);
        Rectangle rect = this.getBounds();
        //
drawing the axis
        g2d.drawLine((int)(rect.width)/2,0,(int)(rect.width)/2,rect.height);
        g2d.drawLine(0,(int)(rect.height)/2,rect.width,(int)(rect.height)/2);
        AffineTransform affineTransform = new AffineTransform(); //
creating instance
       //set the translation to the mid of the component
       affineTransform.setToTranslation((rect.width)/2,(rect.height)/2);
      
//rotate with the anchor point as the mid of the text
       affineTransform.rotate(Math.toRadians(angdeg), 0, 0);
       g2d.setTransform(affineTransform);
       g2d.drawString("JAVA",(int)-sw/2,(int)sh/2);
       g2d.setTransform(saveTransform); //
restoring original transform
    }
   
    public static void main(String[] args) throws Exception{
         JFrame frame = new JFrame("Rotated text");
         RotateText rt=new RotateText();
        frame.add(rt);
        frame.setSize(500, 500);
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
      while(true){
             Thread.sleep(10);
//sleeping then increasing angle by 5
             angdeg=(angdeg>=360)?0:angdeg+5; //
             rt.repaint();
//repainting the surface
         }
    }
}

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