I want to trasform a java.awt.Image realized from a Component using
PixelGrabber, but I always have a
NullPointerException. How can I doin in order to avoid it?

This is the code:

 public static java.awt.Image getImage(Canvas c)

//creates an Image from graphics method of the Canvas

  {
   java.awt.Dimension d = c.getSize();
   d.setSize(c.dimx,c.dimy);
   java.awt.Frame f = new java.awt.Frame();
   f.addNotify();
   f.setSize(d.width+10,d.height+40);
   c.setBackground(Color.white);
   java.awt.Image i = f.createImage(d.width,d.height);
   c.paint(i.getGraphics());
   return i;
  }

 private static com.lowagie.text.Image getItextImage(Canvas c) throws
DocumentException,IOException

//transforms a java.awt.Image in an array of byte;
// this is necessary because com.lowagie.text.Image i =
com.lowagie.text.Image.getInstance(i0,null);
//don't correctly works.

  {
   java.awt.Dimension d = c.getSize();
   java.awt.Image i0=getImage(c);
   com.lowagie.text.Image i = com.lowagie.text.Image.getInstance(i0,null);
   int[] pixels=new int[d.width*d.height];
   java.awt.image.PixelGrabber pg=new
java.awt.image.PixelGrabber(i0,0,0,d.width,d.height,pixels,0,d.width);
   try
    {pg.grabPixels();}
// ^^^^^^^^^^^^^^^
//here I have a NullPointerException

   catch (InterruptedException e)
    {pixels=null;}
   if ((pg.getStatus() & ImageObserver.ABORT) != 0)
    {pixels=null;}
   if (pixels!=null)
    {
     byte[] bytepixels=new byte[pixels.length*3];
     for (int n=0;n<pixels.length;n++)
      {
      bytepixels[3*n]=(byte)(pixels[n]>>16);//red
      bytepixels[3*n+1]=(byte)(pixels[n]>>8);//green
      bytepixels[3*n+2]=(byte)(pixels[n]);//blue
      }
     i=com.lowagie.text.Image.getInstance(d.width,d.height,3,8,bytepixels);
    }
   return(i);
  }

Exception occurred during event dispatching:
java.lang.NullPointerException
       at sun.awt.image.OffScreenImageSource.sendPixels(Compiled Code)
       at
sun.awt.image.OffScreenImageSource.produce(OffScreenImageSource.java:
168)
       at
sun.awt.image.OffScreenImageSource.addConsumer(OffScreenImageSource.j
ava:44)
       at
sun.awt.image.OffScreenImageSource.startProduction(OffScreenImageSour
ce.java:58)
       at java.awt.image.PixelGrabber.grabPixels(Compiled Code)
       at java.awt.image.PixelGrabber.grabPixels(PixelGrabber.java:215)
       at output.pdf.getItextImage(Compiled Code)