Code
class DropLocationLayerUI extends LayerUI<DnDTabbedPane> {
private static final int LINEWIDTH = 3;
private final Rectangle lineRect = new Rectangle();
@Override public void paint(Graphics g, JComponent c) {
super.paint(g, c);
if (c instanceof JLayer) {
JLayer layer = (JLayer) c;
DnDTabbedPane tabbedPane = (DnDTabbedPane) layer.getView();
DnDTabbedPane.DropLocation loc = tabbedPane.getDropLocation();
if (loc != null && loc.isDroppable() && loc.getIndex() >= 0) {
Graphics2D g2 = (Graphics2D) g.create();
g2.setComposite(
AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .5f));
g2.setColor(Color.RED);
initLineRect(tabbedPane, loc);
g2.fill(lineRect);
g2.dispose();
}
}
}
private void initLineRect(JTabbedPane tabbedPane, DnDTabbedPane.DropLocation loc) {
int index = loc.getIndex();
int a = index == 0 ? 0 : 1;
Rectangle r = tabbedPane.getBoundsAt(a * (index - 1));
if (tabbedPane.getTabPlacement() == JTabbedPane.TOP
|| tabbedPane.getTabPlacement() == JTabbedPane.BOTTOM) {
lineRect.setBounds(
r.x - LINE_WIDTH / 2 + r.width * a, r.y, LINE_WIDTH, r.height);
} else {
lineRect.setBounds(
r.x, r.y - LINE_WIDTH / 2 + r.height * a, r.width, LINE_WIDTH);
}
}
}
// ...
private final JLabel label = new JLabel() {
@Override public boolean contains(int x, int y) {
return false;
}
};
private final JWindow dialog = new JWindow();
public TabTransferHandler() {
dialog.add(label);
// dialog.setAlwaysOnTop(true); // Web Start
dialog.setOpacity(.5f);
// com.sun.awt.AWTUtilities.setWindowOpacity(dialog, .5f); // JDK 1.6.0
DragSource.getDefaultDragSource().addDragSourceMotionListener(
new DragSourceMotionListener() {
@Override public void dragMouseMoved(DragSourceDragEvent dsde) {
Point pt = dsde.getLocation();
pt.translate(5, 5); // offset
dialog.setLocation(pt);
}
});
// ...
References
