Translucent AWT button: the parent doesn't redraw
Hello,
I'm trying to create a custom button based on AWT Canvas.
My problem is that I can't get the background cleared and thus
I see the artifacts from the previously drawn button states.
I've created a runnable test case for you (please see the
bottom of this posting) and hope for useful comments.
Some notes on the test case:
I've tried calling getParent().repaint() in the button
but then the picture freezes completely (dunno why...?)
I've tried calling super.paint(g) and paintComponents(g) in the
parent frame (or just omitting paint() and update() completely) -
but this doesn't change anything.
I use opaque colors for now (i.e. pixels[i] = 0xFF...... below)
Also I don't want to use Swing as my application is actually
an applet (a russian card game at http://preferans.de )
which should run in all browsers, including MSIE
Thank you in advance
Alex
// A custom translucent button
// Usage: java TransButton.java && java TransButton
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
public class TransButton extends Canvas
{
// the shadow offset
private static final int OFFSET = 6;
// the 4 possible button states
private static final int ENABLED = 0;
private static final int SELECTED = 1;
private static final int PRESSED = 2;
private static final int DISABLED = 3;
private int state = ENABLED;
private String label;
private static Image dark, lite, shadow;
private ActionListener listener;
public TransButton(String label) {
this.label = label;
enableEvents(AWTEvent.MOUSE_EVENT_MASK);
}
public void setLabel(String label) {
this.label = label;
}
public String getLabel() {
return label;
}
public void setBounds(int x, int y, int w, int h) {
System.err.println("setBounds(" + x + ", " +
y + ", " + w + ", " + h + ") on " + label);
super.setBounds(x, y, w, h);
releaseImages();
}
public void createImages(int w, int h) {
System.out.println("createImages(" + w + ", " + h + ")");
h -= OFFSET;
w -= OFFSET;
if (w <= 0 || h <= 0)
return;
int[] pixels = new int[w * h];
for (int i = 0; i < pixels.length; i++)
pixels[i] = 0xFF008000;
//pixels[i] = 0x80008000;
dark = createImage(new
MemoryImageSource(w, h, pixels, 0, w));
pixels = new int[w * h];
for (int i = 0; i < pixels.length; i++)
pixels[i] = 0xFF80FF80;
//pixels[i] = 0x8080FF80;
lite = createImage(new
MemoryImageSource(w, h, pixels, 0, w));
pixels = new int[w * h];
for (int i = 0; i < pixels.length; i++)
pixels[i] = 0xFF808080;
//pixels[i] = 0x80000000;
shadow = createImage(new
MemoryImageSource(w, h, pixels, 0, w));
}
public boolean contains(int x, int y) {
return (x >= getLocation().x &&
x < getLocation().x + getSize().width &&
y >= getLocation().y &&
y < getLocation().y + getSize().height);
}
private static void releaseImages() {
if (dark != null) {
dark.flush();
dark = null;
}
if (lite != null) {
lite.flush();
lite = null;
}
}
public void update(Graphics g) {
paint(g);
}
public void paint(Graphics g) {
int w = getSize().width;
int h = getSize().height;
// catch negative dimensions or out of memory
try {
if (dark == null || lite == null || shadow==null)
createImages(w, h);
if (state != PRESSED) {
g.drawImage(shadow, OFFSET, OFFSET, this);
g.drawImage((state == ENABLED ? dark : lite),
0, 0, this);
// draw the label over the translucent image
g.drawString(label, h / 3, h * 2 / 3);
} else {
g.drawImage((state == ENABLED ? dark : lite),
OFFSET, OFFSET, this);
// draw the label over the translucent image
g.drawString(label, OFFSET + h / 3,
OFFSET + h * 2 / 3);
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
public void addActionListener(ActionListener l) {
listener = AWTEventMulticaster.add(listener, l);
}
public void removeActionListener(ActionListener l) {
listener = AWTEventMulticaster.remove(listener, l);
}
protected void processMouseEvent(MouseEvent ev) {
System.out.println("MouseEvent: " + ev);
switch(ev.getID()) {
case MouseEvent.MOUSE_ENTERED:
state = SELECTED;
break;
case MouseEvent.MOUSE_EXITED:
state = ENABLED;
break;
case MouseEvent.MOUSE_PRESSED:
state = PRESSED;
break;
case MouseEvent.MOUSE_CLICKED:
if (listener != null)
listener.actionPerformed(
new ActionEvent(this,
ActionEvent.ACTION_PERFORMED,
label));
state = ENABLED;
break;
}
//getParent().repaint();
repaint();
}
public Dimension getMinimumSize() {
FontMetrics metrics = getFontMetrics(getFont());
int w = metrics.stringWidth(label);
int h = metrics.getHeight();
return new Dimension(w, h);
}
public Dimension getPreferredSize() {
FontMetrics metrics = getFontMetrics(getFont());
int w = metrics.stringWidth(label) * 3 / 2;
int h = metrics.getHeight() * 3 / 2;
return new Dimension(w, h);
}
public static void main(String args[]) {
TestFrame tf = new TestFrame("TransButton Test");
tf.setFont(new Font("SansSerif", Font.BOLD, 24));
tf.setForeground(Color.white);
tf.setSize(400, 300);
tf.setVisible(true);
}
}
class TestFrame extends Frame implements ActionListener {
//Button b1, b2, b3;
TransButton b1, b2, b3;
public TestFrame(String title) {
super(title);
setBackground(Color.red);
// use GridLayout because the dimensions of the TransButtons
// must be same (as they use same static images dark+lite)
GridLayout layout = new GridLayout(3, 1);
layout.setVgap(8);
setLayout(layout);
//b1 = new Button("Button One");
//b2 = new Button("Button Two");
//b3 = new Button("Button Three");
b1 = new TransButton("Button One");
b2 = new TransButton("Button Two");
b3 = new TransButton("Button Three");
b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
add(b1);
add(b2);
add(b3);
}
public void actionPerformed(ActionEvent ev) {
Component srcComp = (Component) ev.getSource();
String args = ev.getActionCommand();
System.out.println(ev + ", args: " + args);
}
public void update(Graphics g) {
paint(g);
}
public void paint(Graphics g) {
System.err.println("paint(" + g +
"), w = " + getSize().width +
", h = " + getSize().height);
g.clearRect(0, 0, getSize().width, getSize().height);
//super.paint(g);
//paintComponents(g);
}
}