# The GIMP and latest linuxwacom drivers [SOLVED]

## Donald Wallace Rouse II

Thanks to the latest release (as of 2007-12-31) of linuxwacom, using my tablet no longer crashes the X server.

Everything seems to be working now, except for the GIMP.

When I try to turn on the special features of the tablet, so that I can use the pressure-sensitive stylus, the stylus doesn't work at all.

(In fact, it disables button 1 on my mouse until I move the cursor off the image window, then back on.)

This stuff worked last summer, before the Xorg server ABI changes caused the previous linuxwacom to crash the X server when I tried to use it.

Problem #1: Permissions.

When I first tried to set up the wacom tablet in the GIMP ([File|Preferences/Input Devices/Input Controllers/Linux Input] set to "Wacom Graphire ..."), it stated that it could not open /dev/input/event3 (to which /dev/input/wacom is symbolically linked), due to permissions problems.

/dev/input/event3 is mode 640 root:root.

I worked around this problem by changing it to mode 660 root:users.

Problem #2: Stylus, eraser, etc.

When I enable these in the GIMP ([File|Preferences/Input Devices|Configure Extended Input Devices]) by setting to "Screen", they stop working.

If I disable them, they start working again, but only as mouse substitutes, with no pressure-sensitivity.

(The buttons on the stylus, which act as mouse buttons 2 and 3, work regardless of how I have the other stuff set up.)

So my questions are as follows:

1. Should I have changed the permissions and group on /dev/input/event3?

I don't think that I had to do anything special with permissions when it was working last summer, but I can't be sure.

2. How should I set up the GIMP so that I can use pressure-sensitivity?

I got it working last summer by following the directions here and here, but those directions didn't work this time around.

Note that the versions of Xorg, linuxwacom, and the GIMP have all changed since last summer, so things may have to be done differently.

I can post all of my configs here if anyone wants to see them, but my guess is that I am missing something really simple that someone can point out off the top of their head and make me really embarrassed that I hadn't thought of that myself first.

Thanks for any help that you can give me.

[SOLVED] (2008-03-02)

It now works properly again with linuxwacom driver version 0.7.9_p7 and gimp version 2.4.4.

I guess (hope!) that it was a bug that got fixed.

(The max values from xidump are now 1600x1200 (the size of my screen), so it looks like it was a bug in linuxwacom, not in the GIMP.)Last edited by Donald Wallace Rouse II on Sun Mar 02, 2008 4:13 pm; edited 2 times in total

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## Donald Wallace Rouse II

With a new GIMP upgrade, I tried to use my tablet again, and discovered something strange: the pressure-sensitivity and so forth do work, but the drawing is scaled down to a small area in the upper-left-hand corner of my screen.

(My guess is that it was doing this before, but I didn't know about it because my drawing window wasn't up there.)

After some experimentation, I determined that stylus movements are scaled down by a factor of about 6.4 in the X direction, and by about 6.18 in the Y direction.

In other words, if I move the stylus to the lower right-hand corner of the screen, to absolute screen coordinates 1599x1199, the GIMP thinks that it's actually at absolute screen coordinates 250x195 (approx.), and draws there instead.

As you can imagine, this is very annoying.

So anyway, I went back and looked through the step-by-step instructions for manually installing the Wacom software, and found out about a utility called xidump, which will show exactly what the GIMP is getting from the Wacom drivers.

Here is the output from xidump:

```
xidump v0.7.7

InputDevice: stylus

Valuators: Absolute   ID:         0  Serial Number: Undefined

             x-axis    y-axis   pressure   x-tilt    y-tilt     wheel

     data:  +01599    +01199    +00170    +00000    +00000    +00000

      min:  +00000    +00000    +00000    -00064    -00064    +00000

      max:  +10208    +07424    +00511    +00063    +00063    +01023

      res:  +02032    +02032    +00001    +00001    +00001    +00001
```

This is with the stylus in the lower-right-hand corner, at coordinates 1599x1199.

Note that the "data" line shows the x- and y- axes as screen coordinates, whereas the "min" and "max" lines show tablet coordinates.

10208/1599 = 6.38+, and 7424/1199 = 6.19+, which are pretty close to 6.4 and 6.18, well within the margin of measurement error, and too close to be a coincidence.

Apparently, the GIMP is interpreting the data it gets as being in tablet coordinates, and scales accordingly.

To test this, I used xsetwacom to change the active area of the tablet to 0-1600x0-1200:

```
$ xsetwacom -v set stylus BottomY 1200

Set: sending 4 1200 (0x4B0)

$ xsetwacom -v set stylus BottomX 1600

Set: sending 3 1600 (0x640)
```

I started up the GIMP, and voila!, I can now paint over the entire screen using the stylus.

Unfortunately, to do that, I have to use only very small area in the upper-left-hand corner of my tablet.

So my choices seem to be:Paint to a tiny area on the screen using the entire tablet,Paint to the entire screen using a tiny area on the tablet, orDon't use the fancy features of the tablet (like pressure-sensitivity, etc.).Has anybody else encountered this problem?

Is it a bug in the GIMP, a bug in the linuxwacom drivers, a simple misconfiguration problem, or what?

Any help would be greatly appreciated.

Thank you.

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## Alastore

Teh problem solved by downgrading xorg-server from 1.4.0 to 1.3.0

At least it helped me with teh same problem.

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