I don't think it is possible to make the background transparent.  From what I've read, it ignores the alpha value.  So even if you did something like background(color(0,0,0,1));  It would still be black.  Not sure if it's possible to modify it in the main().

The second one should be pretty easy.  
Add this Code:

public void init(){
  // to make a frame not displayable, you can
  // use frame.removeNotify()

  frame.removeNotify();
  frame.setUndecorated(true);

  // addNotify, here i am not sure if you have 
  // to add notify again.  
  frame.addNotify();
  super.init();
}
 

To position your frame, you can put this in setup():
Code:

 frame.setLocation(0,0);
 

Hi

I was kind of interested in this as well.
I found that the transparent window worked fine. Also the shaped window which is demonstrated here. If labbed with some more you should find that you could do pretty much all you want to do, by tweaking the shaped window or tweaking the setOpaque or setOpacity which is two different things. Depending on what you want to do and depending on platform. Note! This code does not work on MacOSX. Due to Java different implementations I guess. AND it's hackish. No exception handling and there is alot of stuff that can go wrong I guess.
Read more on the subject right here:
http://java.sun.com/developer/technicalArticles/GUI/translucent_shaped_windows/#Enabling-Per-Pixel-Translucency

http://java.sun.com/docs/books/tutorial/uiswing/misc/trans_shaped_windows.html

Heres the code I got working on Windows XP:

import com.sun.awt.AWTUtilities;
import  java.awt.GraphicsDevice.*; // PC only
import java.awt.Shape;
import java.awt.geom.*;
import javax.swing.*;

public void init(){
 // to make a frame not displayable, you can
 // use frame.removeNotify()

 frame.removeNotify();
 frame.setUndecorated(true);

 // addNotify, here i am not sure if you have
 // to add notify again.
 //  frame.addNotify();
 // frame.removeNotify();
 super.init();
}


void setup() {
 size(200, 200);
 noStroke();
 frame.setAlwaysOnTop(true); // Alltid på topp
 frame.setLocation(0,0);
 AWTUtilities.setWindowOpaque(frame, false);
 AWTUtilities.setWindowOpacity(frame, 0.9f);

Shape shape = null;
      //shape = new Ellipse2D.Float(0, 0, frame.getWidth(), frame.getHeight());
      //shape = new Ellipse2D.Float(0, 0, 200, 200);
    //  shape = new RoundRectangle2D.Float(0, 0, 200, 200, 20, 20);
      //shape = new Polygon(int[] xpoints, int[] ypoints, int npoints) ;
      int[] myXes = new int[4];
      myXes[0]=0;
      myXes[1]=150;
      myXes[2]=150;
      myXes[3]=0;
      int[] myYs = new int[4];
      myYs[0]=0;
      myYs[1]=20;
      myYs[2]=180;
      myYs[3]=0;
      shape = new Polygon(myXes, myYs, 4) ;
      AWTUtilities.setWindowShape(frame, shape);


}

void draw() {
 setBackground(new Color(0,0,0,255)); // should work with normal background(255) command
 //  frame.setVisible(true);

 fill(255, 0, 0, 255); // the alpha is not in play at this point - but it come into play when doing per-pixel translucency
 rect(23, 23, 54, 54);
}


/JohanWastring
http://visualinformation.org

Johan_Wastring wrote on Sep 24^th, 2009, 10:50pm:

Indeed, the feature have been "introduced in the Java SE 6u10 release", and Mac (in 32bit versions) didn't have Java 1.6 until Snow Leopard, and I don't know what is the release number (if Apple follows Sun numbering! or list of features) of this version.

Anyway, thanks for doing the research, it is cool.

Nice demo of what is possible using these features.

Quote:

Necessarily, since that's the software layer responsible of abstracting (and implementing access to) native GUI. When possible...

Hi,

could somebody achieve to make windows with a per-pixel translucency? It should be able with java on win xp, as seen on a link at visualinformation.org:
http://java.sun.com/developer/technicalArticles/GUI/translucent_shaped_windows/#Enabling-Per-Pixel-Translucency

but somehow, i don't get it wokrin with processing. Somebody got an idea?

cheers

but it should be working... at least for windows. just check this link:

http://java.sun.com/developer/technicalArticles/GUI/translucent_shaped_windows/#...

this example worked on my machine... however i don't get, how to do it in processing.