Lazarus on Debian is slow
lazarus / 9-Editor

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mrdebug · 2012-10-24 12:04

The code editor of Lazarus on Debian Squeeze is very slow. Is slow on
scrolling, on showing popups (such as code auto completion)... What do
you think about?

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Martin_fr · 2012-10-24 12:20

Have you tried another font?

The editor only supports monospaced. But this is not enforced in the
options. Choosing a none monospaced font, requires extra time for
displaying.

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mrdebug · 2012-10-24 12:51

Using monospace the problem persists.

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Leledumbo · 2012-10-24 13:09

What widgetset? In my experience, gtk2 was always damn slow and I move
to qt completely (well, I still distribute my programs in gtk2 flavour
in case somebody wants it).

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mrdebug · 2012-10-24 13:49

Yes, you're right. Using qt instead of gtk Lazarus comes very fast.

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Martin_fr · 2012-10-24 14:06

GTK has one of the slower text painting, compared to other WidgetSet
(in Lazarus).

Yet, it can work decent. There are several things that affect it:

1) Proportional fonts, as mentioned. Includes some monospaced fonts,
that for some reasons are not 100% monospaced (maybe replace some
chars that are not in the font)

2) Sub pixel painting, same effect. SynEdit requires every char to
start at a full pixel. If it does not, it slows down

Both of the above can be tested for:
Compile the IDE with "SYNFONTDEBUG" defined ( -dSYNFONTDEBUG .
 Then start it from console. The output will contain many lines like:
QuoteTheFontStock.CalcFontAdvance: Final result for %s  Width=%d 
Overhang=%d  eto=%s"eto" is either followed by true, or false. If it
is followed by "true" (even if only once, out of many) then it will be
slower.

3) scrolling. There is a very very low percentage of GTK systems, that
do not scroll correctly. That is the call to just move the existing
bitmap, does not do anything. On those platforms, when scrolling
SynEdit must repaint the entire text each time, instead of just
painting the line(s) that scrolled in.

Define "SYNSCROLLDEBUG"
slow: ScrollAfterTopLineChanged does invalided (scroll failed) Delta=
fast: ScrollAfterTopLineChanged did scroll Delta=