Code
class BalloonToolTip extends JToolTip {
private static final int TRI_HEIGHT = 4;
private HierarchyListener listener;
@Override public void updateUI() {
removeHierarchyListener(listener);
super.updateUI();
listener = e -> {
Component c = e.getComponent();
if ((e.getChangeFlags() & HierarchyEvent.SHOWING_CHANGED) != 0
&& c.isShowing()) {
Optional.ofNullable(SwingUtilities.getRoot(c))
.filter(JWindow.class::isInstance).map(JWindow.class::cast)
.ifPresent(w -> w.setBackground(new Color(0x0, true)));
}
};
addHierarchyListener(listener);
setOpaque(false);
setForeground(Color.WHITE);
setBackground(new Color(0xC8_00_00_00, true));
setBorder(BorderFactory.createEmptyBorder(5, 5, 5 + TRI_HEIGHT, 5));
}
@Override public Dimension getPreferredSize() {
Dimension d = super.getPreferredSize();
d.height = 32;
return d;
}
@Override protected void paintComponent(Graphics g) {
Shape s = makeBalloonShape();
Graphics2D g2 = (Graphics2D) g.create();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(getBackground());
g2.fill(s);
g2.dispose();
super.paintComponent(g);
}
private Shape makeBalloonShape() {
int w = getWidth() - 1;
int h = getHeight() - TRI_HEIGHT - 1;
int r = 10;
int cx = getWidth() / 2;
Polygon triangle = new Polygon();
triangle.addPoint(cx - TRI_HEIGHT, h);
triangle.addPoint(cx, h + TRI_HEIGHT);
triangle.addPoint(cx + TRI_HEIGHT, h);
Area area = new Area(new RoundRectangle2D.Float(0, 0, w, h, r, r));
area.add(new Area(triangle));
return area;
}
}
// ...
@Override public String getToolTipText(MouseEvent e) {
Point p = e.getPoint();
int idx = locationToIndex(p);
Rectangle rect = getCellBounds(idx, idx);
if (idx < 0 || !rect.contains(p.x, p.y)) {
return null;
}
Contribution value = getModel().getElementAt(idx);
String act = value.activity == 0 ? "No" : Objects.toString(value.activity);
return "<html>" + act + " contribution <span style='color:#C8C8C8'> on "
+ value.date.toString();
}
@Override public Point getToolTipLocation(MouseEvent e) {
Point p = e.getPoint();
int i = locationToIndex(p);
Rectangle rect = getCellBounds(i, i);
String toolTipText = getToolTipText(e);
if (Objects.nonNull(toolTipText)) {
JToolTip tip = createToolTip();
tip.setTipText(toolTipText);
Dimension d = tip.getPreferredSize();
int gap = 2;
return new Point((int) (rect.getCenterX() - d.getWidth() / 2d),
rect.y - d.height - gap);
}
return null;
}
@Override public JToolTip createToolTip() {
if (tip == null) {
tip = new BalloonToolTip();
tip.setComponent(this);
}
return tip;
}
References
