Showing Image in JFrame with g.drawImage() - increasing memory usage by switching image

[Pascal Jay]

Hi guys,
I'm now to this forum and also a java beginner.

I've a problem with the image viewer I build. If I change the picture which will be showed (via drawImage(). repaint()) my memory usage increases everytime. So when I just switched through 20 pictures the memory usage of program ist near 250mb. The JFrame contains only a JPanel (in this Panel ist the ImagePanel on which the picture ist drawn) and 2 Buttons to switch through the pictures.

here's the code to draw the image on the ImagePanel (which extends JPanel) [ImagePanel class]:

public void paintComponent(Graphics g) {
	Graphics2D g2 = (Graphics2D) g;
	
	Image img = new ImageIcon(this.sPicture).getImage();
	Dimension resize = ImagePanel.getScaledSize(this.getWidth(), this.getHeight(), img.getWidth(this), img.getHeight(this));		
		
	this.iWidth  = resize.width;
	this.iHeight = resize.height;
	
	setSize(resize);
	g2.setColor(new Color(0, 0, 0));
	g2.fillRect(0, 0, this.getWidth(), this.getHeight());
	g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
	g2.drawImage(img, 0, 0, resize.width, resize.height, this);
	
	// Draw borders
	g2.setColor(new Color(180, 180, 180));
	g2.drawLine(0, 0, resize.width, 0);
	g2.drawLine(0, resize.height-1, resize.width, resize.height-1);
	g2.drawLine(0, 0, 0, resize.height-1);
	g2.drawLine(resize.width-1, 0, resize.width-1, resize.height-1);
}

After clicking on the "next image"-button I call this method from [class which rendering the gui and holds the ImagePanel (ip) object]:

private void redrawPicture() {
	this.setTitle(this.programName + " [" +this.getPicture()+"]");
	ip.setPicture(this.getPicture());
	ip.repaint();
}

Does someone have a idea how to hold the memory usage low?
Thanks for any answer !

best regards,
Pascal Jay Jonasson

[Pascal Jay]

I got a solution from another forum, thanks to KrokoDiehl from java-forum.org.
The solution ist to use a BufferedImage with Image.IO instead of an Image with ImageIcon.

In sourcecode:

public void paintComponent(Graphics g) {  
    Graphics2D g2 = (Graphics2D) g;  
       
    File f = new File(this.sPicture);
    try {
        BufferedImage img = ImageIO.read(f);

        Dimension resize = ImagePanel.getScaledSize(this.getWidth(), this.getHeight(), img.getWidth(this), img.getHeight(this));          
          
        this.iWidth  = resize.width;  
        this.iHeight = resize.height;  
       
        setSize(resize);  
        g2.setColor(new Color(0, 0, 0));  
        g2.fillRect(0, 0, this.getWidth(), this.getHeight());  
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);  
        g2.drawImage(img, 0, 0, resize.width, resize.height, this);  
      
        // Draw borders  
        g2.setColor(new Color(180, 180, 180));  
        g2.drawLine(0, 0, resize.width, 0);  
        g2.drawLine(0, resize.height-1, resize.width, resize.height-1);  
        g2.drawLine(0, 0, 0, resize.height-1);  
        g2.drawLine(resize.width-1, 0, resize.width-1, resize.height-1);  
    }
    catch (IOException ioe) {
        ioe.getStackTrace();
    }
}