How to paint only visible area of my custom control in Swing?

Question

Suppose I have big custom control inscribed inside JScrollPane or clipped by other reasons. How to determine from within paintComponent() method which coordinates are to paint?

score 4 · Accepted Answer · answered Feb 13 '13 at 21:03

4

Take a look at Painting in AWT and Swing, it has an excellent explanation.

But the general gist is, when your component is painted, its clipping rectangle is already set (nb need to check how this works for view ports, but I suspect its the same) to the visible area needing to be updated.

You can check the clip rectangle of the Graphics context past to your paint method and determine what area you should update.

answered Feb 13 '13 at 21:03

MadProgrammer

343,457
22
230
366

[for example](http://stackoverflow.com/a/11330436/714968), then I'm not sure if is there only visible rectangle painted (by default) – mKorbel Feb 13 '13 at 21:54

score 2 · Answer 2 · answered Feb 13 '13 at 21:22

2

You can find out the JScrollPane viewport with

jScrollPane.getViewport()

once there you can know the rectangle shown by the JScrollPane with

jScrollPane.getViewport().getViewRect()

so the you can you that Rectangle to paint your custom component

Regards

answered Feb 13 '13 at 21:22

ultraklon

590
4
9

I need my control does not know it is inside scroll pane. – Suzan Cioc Feb 13 '13 at 23:22

How to paint only visible area of my custom control in Swing?

2 Answers2