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swt.widgets.Text error when append [message #664386]

Fri, 08 April 2011 15:32

Peter Boccia

Messages: 38
Registered: December 2010

Member

Hi all again,

I resolved the previous issue with swt.widgets.Text in multi-line form.

Now I have redirected all the output in a handler for append the new messages:

private void redirectSystemStreams() {
OutputStream out = new OutputStream() {
@Override
public void write(final int b) throws IOException {
updateTextPane(String.valueOf((char) b));
}

@Override
public void write(byte[] b, int off, int len) throws IOException {
updateTextPane(new String(b, off, len));
}

@Override
public void write(byte[] b) throws IOException {
write(b, 0, b.length);
}
};

System.setOut(new PrintStream(out, true));
}

//with this method to append text to the Text
private void updateTextPane(final String text) {
Display.getDefault().syncExec(new Runnable() {
public void run() {
//receivedText is a private Text
receivedText.append(text);
}
});
}

Now I receive this error:

org.eclipse.swt.SWTException: Invalid thread access
at org.eclipse.swt.SWT.error(SWT.java:3526)
at org.eclipse.swt.SWT.error(SWT.java:3446)
at org.eclipse.swt.SWT.error(SWT.java:3417)
at org.eclipse.swt.widgets.Widget.error(Widget.java:953)
at org.eclipse.swt.widgets.Widget.checkWidget(Widget.java:886)
...

It's clear an error linked to the method UpdateText but why? I have also tried with .asyncExec but still the same error.

Give me the last help please! Sad

Peter

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Re: swt.widgets.Text error when append [message #664528 is a reply to message #664386]

Sun, 10 April 2011 21:12

Ralf Sternberg

Messages: 1313
Registered: July 2009

Senior Member

Hi Peter,

Invalid thread access means that you access a widget method from a thread
that is not the UIThread of this widget's display. If you call asyncExec
() on another session's display, you will also get this exception. You
should therefore replace Display.getDefault() with receivedText.getDisplay
().

And you should always prefer asyncExec() over syncExec() unless you have
a very good reason to use the latter.

HTH, Ralf

--
Ralf Sternberg

Twitter: @EclipseRAP
Blog: http://eclipsesource.com/blogs/

Professional services for RAP and RCP?
http://eclipsesource.com/services/rap/

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Re: swt.widgets.Text error when append [message #664530 is a reply to message #664528]

Sun, 10 April 2011 22:16

Peter Boccia

Messages: 38
Registered: December 2010

Member

Ralf,

I'm sorry I've just read the API for Text
http://help.eclipse.org/galileo/index.jsp?topic=/org.eclipse .platform.doc.isv/reference/api/org/eclipse/swt/widgets/Text .html
and Text don't have getDisplay(). Which method are you talking about?

Thank you for the reply,
Peter

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Re: swt.widgets.Text error when append [message #664553 is a reply to message #664530]

Mon, 11 April 2011 06:52

Rüdiger Herrmann

Messages: 335
Registered: July 2009

Senior Member

Peter,

read on to the "members inherited from ..." section. Text is derived
from Widget, which provides getDisplay().

HTH
Rüdiger

On 11.04.2011 00:16, Peter Boccia wrote:
> Ralf,
>
> I'm sorry I've just read the API for Text
> http://help.eclipse.org/galileo/index.jsp?topic=/org.eclipse .platform.doc.isv/reference/api/org/eclipse/swt/widgets/Text .html
> and Text don't have getDisplay(). Which method are you talking about?
>
> Thank you for the reply,
> Peter

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Re: swt.widgets.Text error when append [message #664595 is a reply to message #664553]

Mon, 11 April 2011 10:20

Peter Boccia

Messages: 38
Registered: December 2010

Member

Thank you Ralf!
It works but in RAP it does NOT scroll automatically at the end of the text? I just read a bug of this issue, it's dated July 2010, but no one fixed it.
How can I auto-scroll to the end?
I try putting a personal ScrollBar but it doesn't work.

Thank you.

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Re: swt.widgets.Text error when append [message #664604 is a reply to message #664595]

Mon, 11 April 2011 11:04

Ivan Furnadjiev

Messages: 2426
Registered: July 2009
Location: Sofia, Bulgaria

Senior Member

Hi Peter,
we have this bug opened:
319227: [Text] Multi text does not auto-scroll on append, insert operation
https://bugs.eclipse.org/bugs/show_bug.cgi?id=319227
but, it's hard (or even impossible) to fix it with current client side
implementation.
The only way (currently) to scroll to the end is to call setText with
the complete text. Of course, this will lead to performance problems
with really large texts - like in your case, append to the log and set
the complete log. Maybe a console with last events/logs on the top
(instead of the bottom) will solve your problem - no need for scrolling.
HTH,
Ivan

On 4/11/2011 1:20 PM, Peter Boccia wrote:
> Thank you Ralf!
> It works but in RAP it does NOT scroll automatically at the end of the
> text? I just read a bug of this issue, it's dated July 2010, but no
> one fixed it.
> How can I auto-scroll to the end?
> I try putting a personal ScrollBar but it doesn't work.
>
> Thank you.

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Re: swt.widgets.Text error when append [message #664904 is a reply to message #664604]

Tue, 12 April 2011 13:15

Peter Boccia

Messages: 38
Registered: December 2010

Member

Yes Ivan,

I was talking right about that bug.
I resolved in a simple way:

//set a selection at the beginning of the text
text.setSelection(0);
//insert the text at the head +\n if is not yet in the string
text.insert(newMessage+"\n")

It's easy to understand: to make all the new messages always displayed I choose the contrariway solution: the newest message at the head of the text instead of the end.

Typically in a chat the newest message go in the end and the scrollbar go down at the end, but on RAP this is not possible.

So this might be the easiest way to do it.

I hope this time is me to had help someone.

Peter

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