XSane issues

[reggler]

Hi,

I got a Canon MP490 printer,scanner and copier. It worked very well in Kubuntu 11.10 but as soon as I got a new PC and installed 12.04, I get the scanner seems to cause probelms...
XSane says this:

reg@reg-Desktop:~$ xsane --sync
Xlib:  extension "RANDR" missing on display ":0".
The program 'xsane' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 41413 error_code 8 request_code 150 minor_code 5)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)
reg@reg-Desktop:~$

What can I do to get my scanner working again?

Thank you!
Ron

[claydoh]

I can't get my xsane to give me any errors, but have you checked out skanlite? This will at least verify that your scanner is working - xsane and skanlite are both simply graphical interfaces to sane, which is the part that is doing the actual work. Xsane crashing does not automatically mean that scanning is broken, just one gui is.

[SysGhost]

Possible solution (or workaround):

KDE:
Open "System Settings".
Open "Application Appearance"
Select "GTK+ Appearance" on the left.
Change the Widget style.

Now try again. If it still crashes, try another Widget style.
These are the ones that causes xsane to crash/close for me:

• QtCurve
• ClearLooks
• Oxygen-gtk

According to some other posts I've found about this, it seems to be a GTK Theme Engine bug.

Some also reports that XLIB_SKIP_ARGB_VISUALS=1 should work, but it didn't for me.

[reggler]

Possible solution (or workaround):

KDE:
Open "System Settings".
Open "Application Appearance"
Select "GTK+ Appearance" on the left.
Change the Widget style.

Now try again. If it still crashes, try another Widget style.
These are the ones that causes xsane to crash/close for me:

• QtCurve
• ClearLooks
• Oxygen-gtk

According to some other posts I've found about this, it seems to be a GTK Theme Engine bug.

Some also reports that XLIB_SKIP_ARGB_VISUALS=1 should work, but it didn't for me.

Yep,

That seemed to help! Cool thanks!

Ron

[Guest]

same problem with an hp office jet 6500A, worked under everything but xsane and pyscan. This fixed it. What is this GTK engine issue?

[SysGhost]

same problem with an hp office jet 6500A, worked under everything but xsane and pyscan. This fixed it. What is this GTK engine issue?

It has nothing todo with the scanners or any hardware at all. It's all about the Window theme and GTK drawing the Window elements such as borders, buttons, lists, etc.
I suspect the scanner window from SANE uses an old GTK element that has been overlooked and yet to be updated.

I'm only guessing here, but I suspect it has to do with the transparency effect in some elements.
Colours are coded with a 24 bit value, a group of three 8 bit values, one for each of Red, Green and Blue value. In short: RGB.
Transparency has been added in, and are coded with a 32 bit value, a group of four 8 bit values: Red, Green, Blue and Alpha (Alpha is the amount of transparency). In short: RGBA

My guess:
RGBA values has been poorly implemented in later versions of the GTK Engine, and some themes adds RGBA values to elements where GTK doesn't understand it, and expect a 24 bit non transparent values instead.

In other words: Use old themes without transparent effects.
New themes with RGBA colours can cause these glitches and bugs to appear whenever the GTK engine tries to call an element that hasn't been updated to understand RGBA yet.
At least until the developers behind GTK have solved this.

This is why enabling XLIB_SKIP_ARGB_VISUALS works in some cases.