Code
class AnalogClock extends JPanel {
protected LocalTime time = LocalTime.now(ZoneId.systemDefault());
protected Timer timer = new Timer(200, e -> {
time = LocalTime.now(ZoneId.systemDefault());
repaint();
});
private transient HierarchyListener listener;
@Override public void updateUI() {
removeHierarchyListener(listener);
super.updateUI();
listener = e -> {
if ((e.getChangeFlags() & HierarchyEvent.SHOWING_CHANGED) != 0) {
if (e.getComponent().isShowing()) {
// System.out.println("start");
timer.start();
} else {
// System.out.println("stop");
timer.stop();
}
}
};
addHierarchyListener(listener);
}
@Override protected void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g.create();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Rectangle rect = SwingUtilities.calculateInnerArea(this, null);
g2.setColor(Color.BLACK);
g2.fill(rect);
float radius = Math.min(rect.width, rect.height) / 2f - 10f;
g2.translate(rect.getCenterX(), rect.getCenterY());
// Drawing the hour and minute markers
float hourMarkerLen = radius / 6f - 10f;
Shape hourMarker = new Line2D.Float(0f, hourMarkerLen - radius, 0f, -radius);
Shape minuteMarker = new Line2D.Float(0f, hourMarkerLen / 2f - radius, 0f, -radius);
AffineTransform at = AffineTransform.getRotateInstance(0d);
g2.setStroke(new BasicStroke(2f));
g2.setColor(Color.WHITE);
for (int i = 0; i < 60; i++) {
if (i % 5 == 0) {
g2.draw(at.createTransformedShape(hourMarker));
} else {
g2.draw(at.createTransformedShape(minuteMarker));
}
at.rotate(Math.PI / 30d);
}
// Drawing the hour hand
float hourHandLen = radius / 2f;
Shape hourHand = new Line2D.Float(0f, 0f, 0f, -hourHandLen);
double minuteRot = time.getMinute() * Math.PI / 30d;
double hourRot = time.getHour() * Math.PI / 6d + minuteRot / 12d;
g2.setStroke(new BasicStroke(8f));
g2.setPaint(Color.LIGHT_GRAY);
g2.draw(AffineTransform.getRotateInstance(hourRot).createTransformedShape(hourHand));
// Drawing the minute hand
float minuteHandLen = 5f * radius / 6f;
Shape minuteHand = new Line2D.Float(0f, 0f, 0f, -minuteHandLen);
g2.setStroke(new BasicStroke(4f));
g2.setPaint(Color.WHITE);
g2.draw(AffineTransform.getRotateInstance(minuteRot).createTransformedShape(minuteHand));
// Drawing the second hand
float r = radius / 6f;
float secondHandLen = radius - r;
Shape secondHand = new Line2D.Float(0f, r, 0f, -secondHandLen);
double secondRot = time.getSecond() * Math.PI / 30d;
g2.setPaint(Color.RED);
g2.setStroke(new BasicStroke(1f));
g2.draw(AffineTransform.getRotateInstance(secondRot).createTransformedShape(secondHand));
g2.fill(new Ellipse2D.Float(-r / 4f, -r / 4f, r / 2f, r / 2f));
g2.dispose();
}
}
References
