Making a program without a window border (and no background, just the shape)

[mnse]

Hi,

@glv’s example slightly modified…

Cheers
— mnse

Code

// Display an image without window border and transparent background
// Author: glv
// Date:   2023-10-15
// Insight gleaned from various sources; seek and you shall find.

// slightly modified @mnse ;)

import processing.awt.*;
import java.awt.*;
import javax.swing.*;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.net.URL;

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

ImageIcon img;
BufferedImage bimg;

MouseAndKeyHandler mouseAndKeyHandler; // moving by mouse and exit on ESC key

void setup() {
  surface.setVisible(false);
  PSurfaceAWT.SmoothCanvas canvas = (PSurfaceAWT.SmoothCanvas) surface.getNative();
  JFrame frame = (JFrame) canvas.getFrame();
  frame.dispose();
  String imgPath = dataPath("hand.gif"); // you can use also an animated gif :)
  img = new ImageIcon(imgPath);
  frame = new JFrame();
  frame.setPreferredSize(new Dimension(img.getIconWidth(), img.getIconHeight()));
  frame.add(new JLabel(img));
  mouseAndKeyHandler = new MouseAndKeyHandler(frame);
  frame.addMouseListener(mouseAndKeyHandler);
  frame.addMouseMotionListener(mouseAndKeyHandler);
  frame.addKeyListener(mouseAndKeyHandler);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setUndecorated(true);
  frame.setBackground(new Color(0, 0, 0, 0));
  frame.pack();
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
}

class MouseAndKeyHandler implements MouseListener, MouseMotionListener, KeyListener {
  JFrame frame;
  PVector mouse;

  public MouseAndKeyHandler(JFrame f) {
    frame=f;
    mouse = new PVector();
  }

  @Override public void mousePressed(MouseEvent e) {
    mouse.set(e.getX(), e.getY());
  }

  @Override public void mouseReleased(MouseEvent e) {
    mouse.mult(0);
  }

  @Override public void mouseDragged(MouseEvent e) {
    frame.setLocation(floor(frame.getLocation().x + (e.getX() - mouse.x))
      , floor(frame.getLocation().y + (e.getY() - mouse.y)));
  }

  @Override public void mouseMoved(MouseEvent e) {
  }

  @Override public void mouseClicked(MouseEvent e) {
  }

  @Override public void mouseEntered(MouseEvent e) {
  }

  @Override public void mouseExited(MouseEvent e) {
  }

  @Override public void keyPressed(KeyEvent e) {
  }
  @Override public void keyTyped(KeyEvent e) {
  }
  @Override public void keyReleased(KeyEvent e) {
    if (e.getKeyCode() == KeyEvent.VK_ESCAPE) {
      frame.dispose();
    }
  }
}

hand.gif (to download, right click and save as):