RE: Slow Rendering?

[Tony Denault <denault hawaii edu>]

On Thu, 20 Nov 2003, Dennie, Brooke wrote:

> > The answer to your question about speed issues on remote displays is
> > that you could try to use X11 core fonts by setting the environment
> > variable GDK_ENABLE_XFT to 0. This would disable antialiased fonts
> > which are likely causing your speed issues. Does your X-Server
> > implement the RENDER extension?
> >
> Any other ideas? Thanks again!
>

You might want to experiment with the types of fonts you used in your GTK
app.

I am also getting into using PANGO, as our new project will use gtk 2.2x.
We initially started using 1.2 API, now converting to pure
2.2 API. I recently switched from using gdk_font_load() to the PANGO
stuff. My app is just using a large drawing area 1200x600 pixels. I am
just filling the area with text display with various colors. I have a GTK
timer that grab data from shared memory and refreshes the drawing area.

When using gdk_font_load ("-*-fixed-*-*-*-*-14-*-*-*-*-*-*-*"),
my timer function runs in 0.27 ms (fixed is a 8x17 font).
This .27 ms is very steady.

My initial test using pango caused the timer function to
take >270 ms (over 1000x slower). After picking up the maillist thread, I
decide to experiment using different font as I though PANGO might
be rendering everything and sending images to the X11 client windows.
Here is a table of different fonts using Pango;

Font               Pango     PangoGDK_ENABLE_XFT=0   size
----------------------------------------------------------
San 8                  270   250                     7x15
Serif 10               360   362                     8x19
miscFixed  9           6.8   6.7                     6x14
miscFixed 10           6.9   6.8                     9x15
console8x16            6.9   6.8                     8x16
Courier 10             372   372                     9x18
Fixed                  6.8   6.9                     9x15
LucidaTyperwriter 9    361   361                     8x17

Also note the Pango time varies widely, for example the
360 ms can jump about upto 700ms. I wrote the 'best' time
for the table.

GDK_ENABLE_XFT=0 help a little (sometimes).
For me picking a better font will help. 6.8 ms is OK, but I would
like better -> This is still 25x slower that gdk_font_load().

My GTK app runs on a linux box running Fedora Core release 0.94 (Severn).
I am displaying on a XP computer running X-Win32 X11 server.

Running the app directly on the linux console improves things somewhat
(ie: 6.8ms -> 4.8ms).

Tony

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| Tony Denault                     | Email: denault irtf ifa hawaii edu |
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