[Swing] Runde Buttons mit Swing
Ralph Graf
Andreas Schuster <Andreas....@young-world.com> schrieb in im
Newsbeitrag: 7u93u6$jc3$2...@news04.btx.dtag.de...
> Im Java-Tutorial von Sun steht unter "About the JFC and Swing" folgendes:
> "Swing components don't have to be rectangular. Buttons, for example, can
be
> round."
> Wie kann ich denn die Form (nicht die Größe!!) eines Buttons ändern? Ich
> habe bisher nichts dazu gefunden.
>
>
Ralph Graf
Volker Belli
folgendes:
> > "Swing components don't have to be rectangular. Buttons, for example,
can
> > be round."
> > Wie kann ich denn die Form (nicht die Größe!!) eines Buttons ändern? Ich
> > habe bisher nichts dazu gefunden.
Ich glaube du unterliegst hier einem Mißverständnis:
Buttons in Swing müssen nicht rund sein. Das kannst du erreichen, in dem du
z.B. ein anderes Look&Feel implementierst (z.B. beim Mac-L&F haben die
Buttons abgerundete Ecken). Hierzu gibt es für die Buttons eine Methode, die
zurückliefert, ob ein gegebener Punkt (innerhalb der umschließenden
Rectangle) von dem Button überdeckt wird.
Das heißt aber nicht, daß du die Form eines Buttons eines gegebenen L&Fs
ändern kannst. Das geht (mit den vorgegebenen L&Fs) nicht.
Ich hoffe das war das, was du wissen wolltest.
Cu,
Dr.Krabbe
--
----------------------------------------------------------------------
Volker Belli (DrKr...@bigfoot.de)
developing high quality games and animations in Java
watch out for GBO at <http://ki.informatik.uni-wuerzburg.de/~belli>
Dirk Wimmer
> Im Java-Tutorial von Sun steht unter "About the JFC and Swing" folgendes:
> "Swing components don't have to be rectangular. Buttons, for example, can be
> round."
> Wie kann ich denn die Form (nicht die Größe!!) eines Buttons ändern? Ich
> habe bisher nichts dazu gefunden.
Ich hoffe das es das ist was du gesucht hast:
Tech Tips
August 26, 1999
This issue presents tips, techniques, and sample code for
the following topics:
Creating Round Swing Buttons
Formatting BigDecimal Numbers
CREATING ROUND SWING BUTTONS
This tip is about round Swing buttons. Actually, the
information in this tip applies to a button of any arbitrary
shape but to keep the discussion simple, we're just going
to use a round shape.
There are two things you need to do when creating a round
button. The first is to override the appropriate
painting methods in order to paint the round shape. The
second is to set things up so that the button responds
only when you click within the round button (not just
within the rectangle that contains the round button).
Here's an example program that implements a round button:
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
public class RoundButton extends JButton {
public RoundButton(String label) {
super(label);
// These statements enlarge the button so that it
// becomes a circle rather than an oval.
Dimension size = getPreferredSize();
size.width = size.height = Math.max(size.width,
size.height);
setPreferredSize(size);
// This call causes the JButton not to paint
// the background.
// This allows us to paint a round background.
setContentAreaFilled(false);
}
// Paint the round background and label.
protected void paintComponent(Graphics g) {
if (getModel().isArmed()) {
// You might want to make the highlight color
// a property of the RoundButton class.
g.setColor(Color.lightGray);
} else {
g.setColor(getBackground());
}
g.fillOval(0, 0, getSize().width-1,
getSize().height-1);
// This call will paint the label and the
// focus rectangle.
super.paintComponent(g);
}
// Paint the border of the button using a simple
stroke.
protected void paintBorder(Graphics g) {
g.setColor(getForeground());
g.drawOval(0, 0, getSize().width-1,
getSize().height-1);
}
// Hit detection.
Shape shape;
public boolean contains(int x, int y) {
// If the button has changed size,
// make a new shape object.
if (shape == null ||
!shape.getBounds().equals(getBounds())) {
shape = new Ellipse2D.Float(0, 0,
getWidth(), getHeight());
}
return shape.contains(x, y);
}
// Test routine.
public static void main(String[] args) {
// Create a button with the label "Jackpot".
JButton button = new RoundButton("Jackpot");
button.setBackground(Color.green);
// Create a frame in which to show the button.
JFrame frame = new JFrame();
frame.getContentPane().setBackground(Color.yellow);
frame.getContentPane().add(button);
frame.getContentPane().setLayout(new FlowLayout());
frame.setSize(150, 150);
frame.setVisible(true);
}
}
The RoundButton class extends JButton because we want to
keep most of functionality of a JButton. In the
RoundButton constructor, the method setContentAreaFilled()
is called. This causes the button to paint the focus
rectangle, but not to paint the background.
Now we need to paint the circular background. That's done
by overriding the paintComponent() method. That
method uses Graphics.fillOval() to paint a solid circle.
Then paintComponent() calls super.paintComponent() to
paint the label on top of the solid circle.
This example also overrides paintBorder() in order to paint
a border around the round button. If you don't want a
border, you would not override this method. This method
calls Graphics.drawOval() to paint a thin border around
the circle.
This example also overrides paintBorder() in order to paint
a border around the round button. If you don't want a
border, you would not override this method. This method
calls Graphics.drawOval() to paint a thin border around
the circle.
Note: In JDKTM 1.2.2, there's a small bug in how JButton
behaves when you drag the mouse in and out of its
perimeter. Ideally, if you clickon the circular button and
then drag the mouse outside of the button's perimeter,
the button should change its appearance. When you drag the
mouse back into the circular button's perimeter, the
button should restore its appearance. Unfortunately, the
code that implements this behavior does not call the
contains() method. Instead it just uses the 'bounds' of the
button (this is the smallest rectangular area
containing the button). Notice that if you drag the mouse
slightly beyond the circular perimeter, that is, outside
of the circle but not outside the bounds, the button won't
change it's appearance. There is no workaround for this
minor bug except to implement all of the functionality
yourself.