Synaptics: y movements moves 2 pixels each step, why?

[Mildred Ki'Lya]

Le Sat 08/11/2008 à 18:37 Mildred Ki'Lya à écrit:

> So ...
> The problem seems to be down further in the Xorg internals.
> Can someone help me there?


Sorry, i already solved the problem. I just had the idea to look into
the initialisation code and I found (around line 777 in synaptics.c):

    /* X valuator */
    if (priv->minx < priv->maxx)
	xf86InitValuatorAxisStruct(dev, 0, priv->minx, priv->maxx, 1, 0, 1);
    else
	xf86InitValuatorAxisStruct(dev, 0, 0, -1, 1, 0, 1);
    xf86InitValuatorDefaults(dev, 0);
    /* Y valuator */
    if (priv->miny < priv->maxy)
	xf86InitValuatorAxisStruct(dev, 1, priv->miny, priv->maxy, 1, 0, 1);
    else
	xf86InitValuatorAxisStruct(dev, 1, 0, -1, 1, 0, 1);


It seems that synaptics reports the size of the trackpad to Xorg. And
it seems that Xorg uses that information so when synaptics reports that
the mouse has moved one unit downwards, Xorg, cleverly, moves the mouse
cursor by two pixels to compensate the fact that the trackpad is wider
(900 units) than higher (300 units)

i changed the previous code to:

    /* X valuator */
    xf86InitValuatorAxisStruct(dev, 0, 0, -1, 1, 0, 1);
    xf86InitValuatorDefaults(dev, 0);
    xf86InitValuatorAxisStruct(dev, 1, 0, -1, 1, 0, 1);

So now synaptics doesn't report the trackpad size. This has a drawback
though: vertical movements are slower.

So i guess I would be adding few additional options to the synaptics
driver:

Option "DontReportTrackpadSize" "boolean"

	This option prevent the synaptics driver from reporting the
	size of the trackpad to Xorg. This way, Xorg doesn't amplify
	the vertical movements (since most trackpads are wider than
	higher)

Option "HorizSpeed" "float"

	Horizontal speed. This number is multiplied by the x movement
	to produce the horizontal movement of the mouse cursor

Option "VertSpeed" "float"

	Vertical speed. This number is multiplied by the x movement
	to produce the horizontal movement of the mouse cursor



Do you think it's a good solution?

Mildred


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Mildred Ki'Lya
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