Swing Hacks

287

Chapter 8

C H A P T E R E I G H T

Rendering

Hacks 56–64

Sometimes it’s not what you put into your GUI, but how you draw it. The

hacks in this chapter are based in some way on using (or abusing) how

AWT and Swing render the graphic contents of a GUI. In several cases, we

use Java2D to bring graphic transformations and color-handling to Swing

components. In others, we use AWT’s font handling to change compo-

nents; not just

JTextComponents, but any components that need to draw text

to render themselves. And in still other cases, we mess with the process by

which Swing renders its contents.

H A C K

#56

Create a Magnifying Glass Component Hack #56

Zoom in on those pixels with a little creative abuse of the AWT’s debugging-

oriented

Robot class.

Some graphics programs use a component that shows a magnified view of

what the cursor is currently hovering over. This can be very helpful for doing

pixel-accurate editing of a picture.

It should be simple enough to do in Swing—get pixels from one component

and put them in another—but there are some missing pieces. Specifically,

how do you get the pixels out of the source component as an

Image so you

can

drawImage( ) them into the magnified component? You could do this if

you owned the source component and set it up with a double-buffer because

creating the offscreen buffer would require creating an

Image, which is

exactly what you needed anyway. But for an arbitrary ...