Saturday, August 15, 2009

Fix Touchpad Scroll Area in Xubuntu 9.04

I have a 6 years old Compaq Presario X1000 that I use occasionally for web browsing and programming. I installed Xubuntu 9.04 on it the other day and found out that the scroll area is too wide for the touchpad.

As my usual trouble shooting procedure, I googled around for answers and I found pieces of information spread across several websites.

Step 1 - Enable SHMConfig

First of all, we need to enable the SHMConfig in order to determine the correct scroll area width with synclient. I am pretty sure I used to enable this from the X11 configuration file, however in Ubuntu 9.04 based distributions you are supposed to create a HAL fdi file for this.

sudo vi /etc/hal/fdi/policy/touchpad.fdi

Put this into the file

<?xml version="1.0" encoding="UTF-8"?>
<deviceinfo version="0.2">
  <device>
    <match key="input.x11_driver" string="synaptics">
      <merge key="input.x11_options.SHMConfig" type="string">True</merge>
    </match>
  </device>
</deviceinfo>

Save and close the file then reboot the machine. You can read more about this topic on Ubuntu community wiki.

Step 2 - Determine the correct scroll area with synclient

synclient helps you to determine the correct scroll area offset and is pre-installed on my Xubuntu.

Run

synclient -m 1

Now if you try to touch the touchpad, you will be able to see the coordinate of your finger in following format

 time     x     y ...
0.000  5468  3475 ...

After you determined the correct boundary of the scroll area you can then test it with

synclient RightEdge=<your value>

On my laptop, when I move my finger to the right edge of the mouse movement area the x-coordinate is 5942 and it jumps to 8176 as soon as I touch the scroll area. So I tried:

synclient RightEdge=8175

but for some reason, it disabled the scroll area all together. After some head scratching, I found out that I had to use the x-coordinate right before the scroll area (i.e. 5942).

Final step

After figuring out your RightEdge value, you have to save it by adding it to the touchpad.fdi file created eariler. In my case:

<merge key="input.x11_options.RightEdge" type="string">5942</merge>

So the touchpad.fdi file now looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<deviceinfo version="0.2">
  <device>
    <match key="input.x11_driver" string="synaptics">
      <merge key="input.x11_options.SHMConfig" type="string">True</merge>
      <merge key="input.x11_options.RightEdge" type="string">5942</merge>
    </match>
  </device>
</deviceinfo>

Save and close the file then reboot and your touchpad scroll should work correctly now.

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.