Re: [platform-swt-dev] swt on gtk slow

[Steve Northover <Steve_Northover@xxxxxxxxxx>]

We already tried this idea for measuring
only and it didn't make that much difference.  We cached the measurement
of the last 64 strings. We are aware of slow string drawing and looking
for ideas.

Personally, I believe that there is
no single answer to this problem.  Eclipse is a large, multi-threaded
Java program that really drives SWT and the rest of the Java libraries
hard and the combination makes it very difficult to find one single culprit.
For example, we are unable to confirm excessive slowness in StyledText
outside of Eclipse.

//bugs.eclipse.org/bugs/show_bug.cgi?id=37683
is the place that is tracking these kinds of issues.  We are interested
in any ideas you may have. Thanks.

Steen Jansdal <steen@xxxxxxxxxx> Sent by: platform-swt-dev-admin@xxxxxxxxxxx 12/15/2003 09:40 AM Please respond to platform-swt-dev

To:        platform-swt-dev@xxxxxxxxxxx         cc:                 Subject:        Re: [platform-swt-dev] swt on gtk slow

Bradley Schatz wrote:
> Any suggestions on how to get eclipse running as snappily as it does
on
> windows when running swt/gtk?
> 
> thanks
> 
> 

Suggestion for the SWT developers:

The editor under GTK is painfully slow and I suspect
pango is to blame for this. When drawing the editor
a lot of slow GC.drawText calls are made. Each time
a GC.drawText call are made pango has to do a slow
relayout calculation because SWT is using the same
pango layout for all GC.drawText calls. Perhaps it
would be faster to implement some kind of cache of
layouts.

For example when displaying a typical java source
file, it contains a lot of "if"'s, "while"'s, "int"'s,
equal-signs, parentheses,...
If it were possible to get a previously calculated
pango-layout of the same text and font, the drawing
would theoretically be faster. But would it be faster
than the added maintenance of the cache?

What do you think about this approach?

Steen Jansdal

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