Re: [Xrdp-devel] font rendering over slow connections

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Re: [Xrdp-devel] font rendering over slow connections

mail@beta-centauri.de
On 29/11/14 11:44, [hidden email] wrote:
> Hi,
>
> I am using xrdp with X11rdp quite often over slow connections (long
> distance internet connections). In doing so, I noticed that some
> programs (e.g. gedit, gnome-terminal - probably any gtk and qt based
> program) seem to have a quite slow font rendering. Other programs (e.g.
> nedit, xterm - more simple programs, probably those using the
> fontserver) are very fast - more or less same speed as a text-only ssh
> connection. My impression is that the slower programs result in bitmap
> screen updates to be send to the client, while the fast programs render
> the fonts differently so high-level updates can be sent and the fonts
> are rendered on the client.
>
> Is this correct?

Yes

If yes, is there any way to enable the more modern
> programs not using the fontserver (but probably xrender) to also use
> client-side font rendering?

No

>
> Btw: I am using a very recent git version of xrdp (pulled from the
> master branch), but I observed this problem also with a much much older
> version 0.6.0 with a separate X11rdp package. Maybe I am installing or
> configuring it wrong?
>

No.

Font handling in X11 is stone age. Anything modern it is all rendered in
the widget set (aka gtk/qt) and sent as a bitmap. For the older programs
it is done in the Xserver and hence it is much more efficient.

It is one of the issues as to why things like Wayland are being pushed.

Thanks for this clarification. It seems to me that NX (as used e.g. in x2go) does a better job at this actually. As far as I understand, they use some kind of glyph cache, so the bitmap for each character has to be transmitted only once. This would imply that it is technically not impossible, unless maybe the rdp protocol does not allow something like this?

Cheers,
Martin

PS: I hope replying to a digested mail works like this. If not, I apologise for whatever mess I created... :-)


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