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Wednesday, August 26, 2009

Wacom Draw Tablet under X-Windows

Problems with Monitor and Draw Tablet Screen
I have been using my draw tablet for about a year in Linux. While Ubuntu now makes the installation as easy as a KDE/X-Windows session restart, I still have some problems. Over the years I have tried every option I can think of to get things "perfect" but nothing has quite worked. But I have managed a workable solution for when I draw, so I will share it.

If anyone knows a better solution that what I am have here, please feel free to comment.

My System
I use an Nvidia 9400 GT with my Dell 2407WFPHC and my Wacom Cintiq 12WX CRT. I also use the Nvidia provided graphical configuration program for my display. (The package is called nvidia-settings. The program shares the same name.)

Using the Nvidia program, I have the following options:
  • Disable
  • Separate X screen
  • TwinView
Let's talk about them.

Separate X Screen
This is pretty straightforward. X-Windows treats the displays like separate X-screens. But for me, this option has had major problem since KDE 3.5 until even now in KDE 4.3 (and every version of Xorg in between). X-Windows does indeed create an X-screen on each device. But when using this, KDE creates a session on Screen 0, but fails to create a session on Screen 1. I had hoped that KDE 4.3 would have added this feature, now that they have improved Multiple Monitor support, but no such luck yet.

On top of not KDE not opening/creating a session on screen 1, there is a pen-tool error between both displays. The pen-tool's movement is radically distorted with the cursor movement between the screens, making it completely unusable. No positions or orientations I have tried have fixed this even a little.

Xinerama (under Separate X Screen mode)
When using Separate mode, I can choose to enable Xinerama. Unfortunately that breaks Compositing, which means Alpha-transparency and other desktop effects are disabled.

But the real deal-breaker is the unusable cursor-movement with the pen-tool. There is a problem with the cursor jumping between the two displays after moving a percentage of the way across the screen. The distance roughly corresponds to the difference in resolution pixel size between my tablet and my monitor. So, depending on the positioning of each display in my Xorg.conf (left of, right of, below, above, etc), the areas of the screen where the cursor will jump to-and-from varies but the square area is generally the same.

This is, I believe, an unfortunately reality of Xinerama from what little research I have done on the subject. If my tablet were able to do a resolution like 1920x1200, like my desktop monitor, perhaps this would not be a problem. Sadly it is, and I have never found even the slightest hint of a solution or work around for this.

TwinView
TwinView mode works great for multiple desktops in KDE. Using KDE 4.3, the system detects both displays and works very nicely. Compositing and all those lovely eye-candies are still present.

Unfortunately, the pen-tool error between both displays still occurs. The pen-tool's movement is radically distorted with the cursor movement between the screens, making it completely unusable. No positions or orientations I have tried have fixed this even a little.

Workaround Solution
The only workaround solution I know that does let me use my tablet with no distorted cursor/pen-tool movement is disable my monitor display and use the tablet as the primary display. This always makes me a little sad, but I live with it. I keep hoping one day this will be fixed.

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