Rotate a Swing JLabel
- by Johannes Rössel
I am currently trying to implement a Swing component, inheriting from JLabel which should simply represent a label that can be oriented vertically.
Beginning with this:
public class RotatedLabel extends JLabel {
public enum Direction {
HORIZONTAL,
VERTICAL_UP,
VERTICAL_DOWN
}
private Direction direction;
I thought it's be a nice idea to just alter the results from getPreferredSize():
@Override
public Dimension getPreferredSize() {
// swap size for vertical alignments
switch (getDirection()) {
case VERTICAL_UP:
case VERTICAL_DOWN:
return new Dimension(super.getPreferredSize().height, super
.getPreferredSize().width);
default:
return super.getPreferredSize();
}
}
and then simply transform the Graphics object before I offload painting to the original JLabel:
@Override
protected void paintComponent(Graphics g) {
Graphics2D gr = (Graphics2D) g.create();
switch (getDirection()) {
case VERTICAL_UP:
gr.translate0, getPreferredSize().getHeight());
gr.transform(AffineTransform.getQuadrantRotateInstance(-1));
break;
case VERTICAL_DOWN:
// TODO
break;
default:
}
super.paintComponent(gr);
}
}
It seems to work—somehow—in that the text is now displayed vertically. However, placement and size are off:
Actually, the width of the background (orange in this case) is identical with the height of the surrounding JFrame which is ... not quite what I had in mind.
Any ideas how to solve that in a proper way? Is delegating rendering to superclasses even encouraged?
