Wacom causes erratic mouse cursor movement

[idefix]

When you hold the Wacom pen in one position, you'll notice that the mouse cursor erratically moves a couple of pixels around one spot. In BeOS, Ubuntu and Windows this movement is a lot less, if not non-existent.

I noticed that the Linux Wacom driver uses a simple moving average filter to provide noise correction, so I hacked-up a patch​ that implements this in the Haiku driver.

Unfortunately this filter doesn't fix the erratic movements completely, so I decided to compare the 'raw' tablet data:

• x-movement (BeOS on the left, Haiku on the right):
• y-movement (BeOS on the left, Haiku on the right):

The horizontal gridlines represent the pixel-boundaries on my monitor.
You can see that the 'raw' movement is a lot bigger in Haiku than in BeOS, but I have no idea where the cause of this difference lies.

Also note the difference in the time between two samples, between BeOS (left) and Haiku (right):

Although this could have been caused by the different methods used to capture the data: to a file in BeOS, to the serial port in Haiku.

[idefix]

patch implementing moving average filter in Wacom input_server addon

[idefix]

'raw' movement in x direction (BeOS)

[idefix]

'raw' movement in x direction (Haiku)

[idefix]

'raw' movement in y direction (BeOS)

[idefix]

'raw' movement in y direction (Haiku)

[idefix]

time between samples (BeOS)

[idefix]

time between samples (Haiku)

[stippi]

Thanks! This is the way to go about this problem. I remember working on something similar in the Touchpad driver, and thinking this could be used to make the mouse work like a real mouse in the Wacom driver. Interested?

[stippi]

Forgot to mention, Haiku seems to schedule a lot more interrupt transfers per second compared to BeOS. This is also the reason for the higher CPU usage when moving and USB mouse. I worked around this somewhat in the Mouse input_server add-on, but it seems to be a problem still.

[idefix]

Replying to stippi:

Thanks! This is the way to go about this problem. I remember working on something similar in the Touchpad driver, and thinking this could be used to make the mouse work like a real mouse in the Wacom driver. Interested?

I'm sorry, but I don't think I understand you completely. Am I interested in what exactly? What similar thing? The filter? How would that make the Wacom mouse work like a real mouse?

[idefix]

Finally got round to capture some data in Ubuntu (using xidump):

This image shows the filtered x-movement of the cursor in Haiku, BeOS and Ubuntu.

This image shows the filtered y-movement of the cursor in Haiku, BeOS and Ubuntu.

The amplitude of the mouse-cursor movement in Ubuntu lies between those of BeOS and Haiku. Although the difference between Ubuntu and Haiku is a lot less in the y-movement than in the x-movement.

[idefix]

filtered x-movement of the cursor in Haiku, BeOS and Ubuntu

[idefix]

filtered y-movement of the cursor in Haiku, BeOS and Ubuntu

[idefix]

Lets try that again...

Finally got round to capture some data in Ubuntu (using xidump):

This image shows the filtered x-movement of the cursor in Haiku, BeOS and Ubuntu.

This image shows the filtered y-movement of the cursor in Haiku, BeOS and Ubuntu.

The amplitude of the mouse-cursor movement in Ubuntu lies between those of BeOS and Haiku. Although the difference between Ubuntu and Haiku is a lot less in the y-movement than in the x-movement.

[waddlesplash]

component -> USB-HID (new)