CODEWITHSUNDEEP
javaswingjpaneltransparencylook-and-feel
OffLuffy
OffLuffy

Reputation: 95

How to solve graphical glitching with JDialog, JPanel?

So the intial setup for this issue is that there's a JDialog, and inside that I've placed a JPanel that would house the rest of the components (since painting the JDialog itself is apparently a bad idea). This JPanel has an overriden paintComponent(Graphics g) method that only paints the background and adds a faint border for aesthetic purposes.

Now inside that is a series of JPanels that categorize the contained form components, and each JPanel has an overridden paintComponent(Graphics g) as well, painting a semi-transparent background.

Inside each of those JPanels is where I start to have some issues, presumably with transparency. I have JTextFields, JCheckBoxes, JLabels, JSliders, etc inside these panels, and when you interact with one (hover, click, etc), the background goes from transparent to opaque, with an occassional ghosted image from another field (which appears slightly random sometimes). I'm using a custom LAF called Web, but I tested with other built-in LAFs and the same thing happens.

Is this a glitch with Java or did I mess something up? If so, how can I patch this up? I can paste code fragments later if necessary, but I've used several custom classes and nine-patch style image stitching which may make the code fragments hard to follow. Thanks in advance!

Upvotes: 0

Views: 240

Answers (1)

MadProgrammer
MadProgrammer

Reputation: 347204

If you are painting components with a transparent background it is very important that the component is marked as transparent (setOpaue(false)) so that the repaint manager knows that it must paint the components below it.

It is also very important that when you are performing custom painting that you call super.paintComponent first.

This is especially important in the case of transparent components, as this prepares the Graphics context for painting.

Graphics is a shared resource. All the components painted in your window will share the same Graphics object, meaning that if you don't allow paintComponent to first prepare it, then you will see what was previously painted on it.

Upvotes: 4

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