composite and smooth moving (double buffering?)

[Anders Storsveen]

Anders Storsveen wrote:

>Thomas Lübking wrote:
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>>Am Mittwoch, 5. Oktober 2005 03:26 schrieb Anders Storsveen:
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>>>When I enable composite and try to drag the konqueror window around
>>>fast, the window will move very smooth, although very slow to, but
>>>that's another issue (probably nvidia's rendr acceleration that is slow
>>>right?).
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>>rather xaa composite implementation (i.e cache limitation?, try to reduce 
>>resolution and/or bpp) or because you didn't activate the
>>Option     "RenderAccel" "true"
>>(btw, randr but rend_e_r)
>>also it might be that the "nvidia" driver (nVidias CSS stuff) is faster than 
>>the "nv" driver that comes with X
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>>>However, this smooth moving, which only happens to qt apps, why is this?
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>>hää? toolkit doesn't matter here (i.e. xterm is as smooth as konsole or 
>>gnome-terminal) - what exactly do you mean by run "not smooth"?
>>however, i guess it's rather a matter of the window size
>>also gtk1 apps run ARGB, i.e. they eat more cache space for the alpha channel 
>>- try to run it exporting XLIB_SKIP_ARGB_VISUALS="1"
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>by noy smooth I mean, my konqueror window runs with out like any
>tearing/misrendering when moving fast, however my eterm window, and
>thunderbird window runs much faster, but not as smooth (and
>"error"-free, since I see rendering glitches or "tearing". so it seems
>that the konqueror window is running just as fast as the compositer can
>run it and also render each frame complelty, however eterm and
>thunderbird seem to run unhindered, but with tearing, i did mean RENDER
>and I have RenderAccel "1".
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Another observation here is, what I mean by smooth, but slow is that. If
I move a window that I feel is smooth around, like konq or kcontrol, it
moves with a kind of lag, like if I move my mouse from point a to point
b, when I'm finished moving the mouse, the window comes
"dragging"-after. Like if I use TIME to move the mouse, the window uses
TIME+(SMALLTIME) :) however xterm, and konq, and even konsole is instant.

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>>>Could someone please explain this to me, also how it works :)
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>>basically the window content is rendered into an offscreen buffer, redirected 
>>into an application (the compmgr, probably kompmgr for kde) and there used to 
>>draw a fullsize picture onto the root window.
>>the compmgr then can do funny things on this (like adding translucency or 
>>shadows etc.)
>>
>>Thomas
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