HOW TO: Two finger scrolling on Acer Aspire One

[mikespug]

A feature that many would consider the Aspire One to be "lacking" is the ability to scroll using two fingers, similar to what you are able to do on current Apple laptops. Generally linux will allow you to enable this feature on any synaptic trackpad that is able to report the number of fingers touching the trackpad. You can enable this on any standard finger reporting trackpad by editing your /etc/X11/xorg.conf file and inserting the following code under the "input device" section:

Code: Select all

   Option      "VertTwoFingerScroll"   "1"

The trouble with the Aspire One is that the trackpad does not report the number of fingers touching the pad. This is evident by enabling the SHMConfig option in your xorg file and running the command "synclient -m 10" in a terminal. By doing so you will recieve a screen similar to the following"

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time   x    y    z  f   w   l   r  u  d  m        multi   gl  gm  gr  gdx  gdy
0.000    1 5855    0  0   0   0  0  0  0  0  00000000    0    0    0     0      0

The columns we are focusing on are f and w. Move your mouse around and take a look at what is reported. Column f shows the number of fingers touching the trackpad and will change dynamically on trackpads that are able to report this. On the Aspire One, however, the trackpad will only report the finger width which is displayed in column w. The ability to report the width of a finger on a trackpad is a feature typically used to allow a trackpad to detect when a users palm has touched the pad and, thus, will not move the mouse as it considers it to be an accidental "touch". It is this ability that we are going to utilize to enable two finger scrolling on the Aspire One.

By default there is no way to utilize the finger width reporting feature in any manner, than I know of, other than to detect accidental trackpad touches. I, in searching for a way to utilize this feature, have recently made the aquaintence of a gentleman by the name of Luca who, only two days before I began working on a solution myself, had developed a patch for debian to enable this feature in the Synaptics driver. With his permission I edited the patch to allow it to compile under Ubuntu and am happy to say the feature works wonderfully.

I've attached the newly compiled synaptic driver and am posting a copy of my xorg.conf file that will allow you to enable two finger scrolling on your own system. Let's get started:

1. Download the attached file "xserver-xorg-input-synaptics_0.15.2-0ubuntu7_i386.zip"
2. Open a terminal and navigate to the directory where you you saved the file (typically your desktop)
3. Rename the file by issuing the command "mv xserver-xorg-input-synaptics_0.15.2-0ubuntu7_i386.zip xserver-xorg-input-synaptics_0.15.2-0ubuntu7_i386.deb" (I had to rename the file to a .zip to allow it to upload)
4. Install the file by issuing the command "dpkg -i xserver-xorg-input-synaptics_0.15.2-0ubuntu7_i386.deb"
5. After it finishes installing open your xorg.conf file for editing by issuing the command "sudo gedit /etc/X11/xorg.conf"
6. Edit your xorg.conf file to reflect the following changes:

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Section "InputDevice"
   Identifier     "Synaptics Touchpad"
   Driver         "synaptics"
   Option         "SendCoreEvents"      "true"
   Option         "Device"            "/dev/psaux"
   Option         "Protocol"         "auto-dev"
   Option         "HorizEdgeScroll"      "0"
   Option         "SHMConfig"         "true"
   Option         "VertTwoFingerScroll"   "1"
   Option         "EmulateTwoFingerMinW"   "7"
EndSection

Section "ServerLayout"
   Identifier    "Default Server Layout"
   Screen        "Default Screen"
   InputDevice   "Keyboard"      "Core Keyboard"
   InputDevice   "Synaptics Touchpad"   "Core Pointer"
EndSection


The line of code that you should take notice of is the one containing EmulateTwoFingerMinW. This sets the minimum finger width that should be considered to be "two fingers" touching the pad. At this point you should be able to reboot and enjoy two finger scrolling. I would recommend disabling the vertical scroll feature under the Preferences > Mouse > Touchpad menu and unchecking "Enable vertical scrolling".

This driver was compiled under ubuntu 8.10. Keep in mind that these instruction are newly written. If edits are needed or users experience trouble please notify me and I will update to the instructions to accomodate. Also, this driver and instructions should work on any finger width reporting synaptics touchpad so if you know someone who has a trackpad that won't allow them to enable two finger scrolling because it won't report the number of fingers I would encourage you to try it out. Thanks.

Here's my entire xorg.conf for comparison:

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Section "ServerLayout"
   Identifier    "Default Server Layout"
   Screen      "Default Screen"
   InputDevice   "Keyboard"      "Core Keyboard"
   InputDevice   "Synaptics Touchpad"   "Core Pointer"
EndSection

Section "Device"
   Identifier   "Configured Video Device"
EndSection

Section "InputDevice"
   Identifier      "Synaptics Touchpad"
   Driver         "synaptics"
   Option         "SHMConfig"         "true"     
   Option         "SendCoreEvents"      "true"
   Option         "Device"            "/dev/psaux"
   Option         "Protocol"         "auto-dev"
   Option         "HorizEdgeScroll"      "0"
   Option      "VertTwoFingerScroll"   "1"
   Option      "EmulateTwoFingerMinW"   "7"
EndSection

Section "InputDevice"
   Identifier   "Keyboard"
   Driver      "kbd"
EndSection

Section "Monitor"
   Identifier   "Configured Monitor"
EndSection

Section "Screen"
   Identifier   "Default Screen"
   Monitor      "Configured Monitor"
   Device      "Configured Video Device"
EndSection

[Rince77]

Doesn't work for me on my A110L. I'm getting a huge misconfiguration error and Ubuntu only starts in a very basic graphical environment.

[mikespug]

What is the error exactly?

[Rince77]

OK, i solved the issue. The point was that there has been no "Keyboard" section in my xorg.conf. I added a the section and now it works like a charm. Thanks!!!!:)

[mikespug]

You're welcome. I'm glad you got it sorted out.

[jeffyeh]

Thanks! I had the same issue as Rince77. After adding the keyboard section from your xorg.conf, it works like a charm!

[annafil]

omg i have been trying to figure this out for ages! thank you thank you!

Going to try it out right now

[annafil]

It works - woot!!

I have a question though - you seem to understand how the driver works better than I do so maybe you can help me clear this up.

Is the inability to do traditional two finger scrolling a hardware or software limitation do you think?

I wonder how the windows driver goes about enabling this functionality - it's a lot more polished, much more like the original synaptics one.

I was convinced that on these new touchpads (AAO, Asus n10j have similar issues) the limitation was purely software, and synaptics not reporting the number of fingers correctly was a problem with the way the driver read the touchpad capabilities when it was initialized - I read in one of the manuals that the capabilities are encoded within something like the firmware, and that they may vary for different families of touchpads (ie, older and newer).

Unfortunately my research bottlenecked at that point - I couldn't figure out how to modify the driver so that the multi finger capability was forced and not checked for at startup - to see if my theory about the hardware was true...

[mikespug]

Is the inability to do traditional two finger scrolling a hardware or software limitation do you think?

Both...in a way. Traditionally the two finger scrolling feature takes advantage of a trackpads ability to report the number of fingers on the trackpad. The ability to report the number of fingers on a trackpad can be used, as I'm certain you are aware, for more than just two finger scrolling. The trouble we have is that the trackpad on the AAO does not report the number of fingers...so in that respect it is a hardware issue. What we have done here is added a "feature", if you will, to take advantage of another hardware function to "mimic" two fingers being on the trackpad. In the same way that two fingers on a trackpad would register as "2"...two fingers on our trackpad changes the reported finger width to...lets say...8. The modified driver simply adds the ability to utilize the detected finger width for something other than detecting a palm on the trackpad. So in that sense...it was a software restriction.

[annafil]

Right I see