Swing Hacks

Debug Components with a Custom Glass Pane #96

Chapter 12, Miscellany

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481

HACK

from/subject of one email message, the details of a downloaded file, etc.). In

cases like these, I’ll try to see if a

JList with a multi-line cell renderer [Hack #16]

can keep all the data together in a visually pleasing form. So, when is hori-

zontal scrolling OK? I think it’s appropriate when the data you’re displaying

is not row-oriented, and instead you’re scrolling up, down, and across a

single cohesive thing, like a large image or, in this case, a stack trace.

H A C K

#96

Debug Components with a Custom Glass PaneHack #96

Show component boundaries at runtime using a glass pane.

Sometimes when I’m building a really complicated Swing layout, I start to

lose track of what I’m looking at. Which component is this? Does that panel

extend all the way to the end of the frame? A way to visualize the layout

would be a useful addition to the usual development tools. This hack

explores using a custom glass pane to highlight each component and its

classname.

A glass pane is a normally transparent Swing component that is drawn on

top of all of the other components in a frame, as you saw when you put

dialog-like “sheets” into the glass pane

[Hack #44]. It is this ability that forms

the center of the hack. The custom glass pane will traverse the entire tree of

components in the frame, filling a translucent rectangle over each compo-

nent. ...