Is Display.addFilter(...) the best way to add a glbal shortcut? I tried Display.addListener(...) but this didn't receive any events at all.
Yes, normally Display.addFilter(...)
is the best way to add a glbal shortcut because they have higher preference over the event listeners. See the below comment from Display.addFilter(...)
javadoc.
Because event filters run before other
listeners, event filters can both
block other listeners and set
arbitrary fields within an event. For
this reason, event filters are both
powerful and dangerous. They should
generally be avoided for performance,
debugging and code maintenance
reasons.
For your second question:
Why don't I get the pressed character when I'm holding down ctrl? When I hold down alt or shift I get the expected mask and the pressed character.
The problem is that you are looking at the wrong place. Instead of querying e.character
you should be using e.keyCode
. As per javadoc of e.character
you won't get just character f
:
Depending on the event, the character
represented by the key that was typed.
This is the final character that
results after all modifiers have been
applied. For example, when the user
types Ctrl+A, the character value is
0x01 (ASCII SOH).
So when you press CTRL+f then it converts in 0x06
(ASCII ACK). Which is not the case when you do ALT+f or SHIFT+f.
On the other hand the javadoc of e.keyCode
says:
depending on the event, the key code
of the key that was typed, as defined
by the key code constants in class
SWT. When the character field of the
event is ambiguous, this field
contains the unaffected value of the
original character. For example,
typing Ctrl+M or Enter both result in
the character '
' but the keyCode
field will also contain '
' when
Enter was typed and 'm' when Ctrl+M
was typed.
Check the below code for more details. For demo I have tried to put listener on Display
and Test
.
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;
public class ControlF
{
public static void main(String[] args)
{
Display display = new Display ();
final Shell shell = new Shell (display);
final Color green = display.getSystemColor (SWT.COLOR_GREEN);
final Color orig = shell.getBackground();
display.addFilter(SWT.KeyDown, new Listener() {
public void handleEvent(Event e) {
if(((e.stateMask & SWT.CTRL) == SWT.CTRL) && (e.keyCode == 'f'))
{
System.out.println("From Display I am the Key down !!" + e.keyCode);
}
}
});
shell.addKeyListener(new KeyListener() {
public void keyReleased(KeyEvent e) {
if(((e.stateMask & SWT.CTRL) == SWT.CTRL) && (e.keyCode == 'f'))
{
shell.setBackground(orig);
System.out.println("Key up !!");
}
}
public void keyPressed(KeyEvent e) {
if(((e.stateMask & SWT.CTRL) == SWT.CTRL) && (e.keyCode == 'f'))
{
shell.setBackground(green);
System.out.println("Key down !!");
}
}
});
shell.setSize (200, 200);
shell.open ();
while (!shell.isDisposed()) {
if (!display.readAndDispatch ()) display.sleep ();
}
display.dispose ();
}
}
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…