Transparent UI (+UIManager) artifacts

Question

I've got an application which draws a background image on a panel, but to achieve the optimal UI, I need to set Component backgrounds Transparent:

I made every component transparent by using the UI Manager: uimanager.put(Button, background(new color(0, 0, 0, 0); <- something like that, this works perfectly, except..

onMouseOver the component redraws itself (I guess) and causes Artifacts.. How can I avoid this in the UIManager?

(I created a class: uidefaults.java with all the UIManager settings)

Thanks in advance!!

for better help sooner post an [SSCCE](http://sscce.org/) demonstrated your issue(s) with `Transparency` and `UIManager`, otherwise you have to waiting for some of psychics that will post you correct answer — mKorbel, Jun 01 '12 at 11:24

score 3 · Answer 1 · answered Jun 01 '12 at 12:43

Well, that is pretty simple - DO NOT use transparent background colors with components (any JComponent ancestor to be exact) that are OPAQUE.

To remove component background you don't need to set transparent color - just use this method:

component.setOpaque ( false );

This will hide component background and will also change component repaint strategy so it won't create any artifacts on repaint calls.

Also, if you still want to have semi-transparent background behind your component you can override paintComponent method like this:

    JLabel label = new JLabel ( "Transparent background" )
    {
        protected void paintComponent ( Graphics g )
        {
            g.setColor ( getBackground () );
            g.fillRect ( 0, 0, getWidth (), getHeight () );
            super.paintComponent ( g );
        }
    };
    label.setOpaque ( false );
    label.setBackground ( new Color ( 255, 0, 0, 128 ) );

This will force label to hide its default background and also paint your own background (that depends on component's background property).

Is it thát simple? I'll let you know in about an hour when I get home! Thanks — Wouter Krooshof, Jun 01 '12 at 14:26
Yes, its that simple. And by the way - don't use UIManager unless you want to change any properties globally (they will affect all comonents of the specific kind). For example in your code all buttons created/updated after you have set "Button.background" will use that background. If you want to modify single button instance - call its methods instead (setBackground in this case). — Mikle Garin, Jun 01 '12 at 16:35

Transparent UI (+UIManager) artifacts

1 Answers1