[
Date Prev][
Date Next][
Thread Prev][
Thread Next][
Date Index][
Thread Index]
[
List Home]
|
Re: [platform-swt-dev] SWT Bidi Text Support
|
I'm posting this for Lynne, she is having mailer problems.
----- Forwarded by Lynne Kues/RAL/OTI on 11/15/01 02:42 PM -----
Lynne Kues
11/15/01 05:17 PM
To: platform-swt-dev@xxxxxxxxxxx
cc:
Subject: Re: [platform-swt-dev] SWT Bidi Text Support
Steve is referring to the portion of BidiUtil that provides a listener for
WM_INPUTLANGCHANGE (i.e., so that the application can be notified when the
user changes the keyboard language via Alt-Shift). For most cases, one
would add the listener at the canvas level, but technically the code is
incorrect. A bug report has been opened for the problem http://bugs.eclipse.org/bugs/show_bug.cgi?id=5986.
Lynne
"Steve Northover/OTT/OTI" <Steve_Northover@xxxxxxx>
Sent by: platform-swt-dev-admin@xxxxxxxxxxx
11/15/01 01:34 PM
Please respond to platform-swt-dev
To: platform-swt-dev@xxxxxxxxxxx
cc:
Subject: Re: [platform-swt-dev] SWT Bidi Text Support
Please note that there is a serious problem in the current BidiUtil
if it is used with anything other than a Canvas or subclass of Canvas.
"Lynne Kues/RAL/OTI" <Lynne_Kues@xxxxxxx>
Sent by: platform-swt-dev-admin@xxxxxxxxxxx
11/15/01 12:51 PM
Please respond to platform-swt-dev
To: platform-swt-dev@xxxxxxxxxxx
cc: stori@xxxxxxxxxx
Subject: [platform-swt-dev] SWT Bidi Text Support
Adrian I am posting your question and my reply to the SWT mailing list so
that others can be involved. You can find out about the mailing lists and
how to subscribe at http://www.eclipsecorner.org/.
>> Lynne,
>>
>> Is there any decision on making the bidi API public and/or when will
>> Eclipse move to Java 1.4?
>>
>> Thank you. Best regards -
>> Adrian.
>>
>> Adrian Storisteanu
>> IBM Toronto Lab, Canada
>> Tie line 8-969-3156 * Phone 905-413-3156 * Fax 905-413-4850
Currently SWT includes an internal class,
org.eclipse.swt.internal.BidiUtil, which wraps the Win32 bidi platform
calls (specifically - GetCharacterPlacement, GetFontLanguageInfo,
ExtTextOut, GetKeyboardLayout, GetKeyboardLayoutList). This class is used
by the org.eclipse.swt.custom.StyledText widget to provide bidi support.
The class is internal because it is only a Windows solution. This class
does nothing on the other platforms that SWT supports.
That said, you may use BidiUtil. It should be sufficient for LPEX since
it is sufficient for bidi text support in Eclipse (i.e., via the
StyledText widget), BUT it will most likely change in the future as we
move towards bidi support for other platforms. Until we investigate a
multi-platform solution, we are not in the position to make any of the
bidi API truly public (i.e., supported and maintained).
Looking at the list of the support you said you needed:
>> - detection of RTL environment (active native RTL locale),
>> - cursor (caret) navigation (i.e., detect RTL - LTR boundaries &
direction
>> changes),
>> - cursor <-> text index corelation (index n in String text <-> position
m
>> on display),
>> - text String <-> displayed text corelation (important in Arabic,
where n
>> text characters may display as a smaller m glyphs as a result of
>> autoshaping).
BidiUtil will supply you with what you need except for detection of RTL
environment. You can look at the current code page using
System.getProperty("file encoding") to determine this.
org.eclipse.swt.custom.StyledTextBidi will give you an example of how to
utilize the information that BidiUtil gives you.
You probably also want to look at the classes
org.eclipse.swt.custom.BidiSegmentListener and
org.eclipse.swt.custom.BidiSegmentEvent (in R2.0 stream). In some
instances (e.g., source code editors), you may want the bidi algorithm to
be applied separately to portions of the line vs. the whole line.
If you decide to use BidiUtil, we can certainly answer questions for you,
discuss the issues we ran into, etc.. It would also be useful to get your
feedback as to what you (or anyone for that matter) think API for bidi
support should look like.
Lynne
