Windows 8, Calibre 64-bit, and QtGui4.dll error

[toddos]

I'm running into this issue that seems to be very specific to Windows 8 and 64-bit calibre. 64-bit runs fine on my Windows 7 machines, and 32-bit runs fine on my Windows 8 machines. But when I try to run 64-bit on my Windows 8 machine, it crashes. I can force the crash immediately by attempting to convert a book, or I can just sit and wait for it to crash.

From the debug log:

calibre Debug log
calibre 0.9.32 [64bit]  isfrozen: True is64bit: True
Windows-8-6.2.9200 Windows ('64bit', 'WindowsPE')
('Windows', '8', '6.2.9200')
Python 2.7.4
Windows: ('8', '6.2.9200', '', 'Multiprocessor Free')
Starting up...
Started up in 61.66 seconds with 557 books
QAccessibleWidget::rect: This implementation does not support subelements! (ID 1 unknown for QWidget)

And I see this in eventvwr:

Log Name:      Application
Source:        Application Error
Date:          5/24/2013 10:46:36 PM
Event ID:      1000
Task Category: (100)
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      irrelevant
Description:
Faulting application name: calibre-debug.exe, version: 0.9.32.0, time stamp: 0x519ee17b
Faulting module name: QtGui4.dll, version: 4.8.3.0, time stamp: 0x50a06c97
Exception code: 0xc0000005
Fault offset: 0x00000000000a2e4f
Faulting process id: 0x2488
Faulting application start time: 0x01ce590aeed88700
Faulting application path: C:\Program Files\Calibre2\calibre-debug.exe
Faulting module path: C:\Program Files\Calibre2\DLLs\QtGui4.dll
Report Id: 7606c559-c4fe-11e2-be89-c4850895cd05
Faulting package full name: 
Faulting package-relative application ID:

Seems like an issue with the 64-bit Qt library in Windows 8?

Now obviously I can continue to just use 32-bit calibre just fine, but given that I have a 64-bit machine running a 64-bit OS with > 4GB of RAM it sure would be nice to be able to take advantage of that.

Edit: I should also point out that I tried with Windows Defender disabled. Same crash, same error. I have no other anti-virus or other apps running. This is otherwise plain stock Windows 8 (not even Pro, at the moment).

[kovidgoyal]

Since there's a message about accessibility in the debug log, I suggest turning of any accessibility tools in your windows install, like screen readers. In my experience, Qt's accessibility implementation often causes crashes.

[toddos]

Odd. I have no accessibility tools installed, nor do I have any of the Windows accessibility features turned on. The only thing I can think this might be is that I have a touchscreen on my laptop, which means that the on-screen keyboard is always available (though not open). Not exactly something I can turn off, since that's built into Win8 and always available when a touchscreen is present.

Edit: To be clear, I'm not using my touchscreen to interact with Calibre. I'm using a regular old trackpad (elantech).

[kovidgoyal]

Something is querying the accessibility framework in Qt, I doubt it si a on screen keyboard, why would an on screen keyboard need access to accesibility info?

[toddos]

On-screen keyboard is the closest thing to "accessibility" that would be running on my system. However, that did give me a path to go down. I attached a debugger and ended up seeing this:

(119c.f2c): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for C:\Program Files\Calibre2\DLLs\QtGui4.dll - 
QtGui4!QWidgetPrivate::winSetupGestures+0x26f:
00000000`61662e4f 4c8b11          mov     r10,qword ptr [rcx] ds:00000000`00000068=????????????????

winSetupGestures in QWidgetPrivate seems to be related to supporting multitouch functionality in Qt. I assume that because I have a touch screen, that's why it's being called. Since calibre isn't targeting touch in any way, this must be something internal to Qt that it does automatically, and that's broken in the 64-bit version. It may be somewhat related to this Qt bug.

Since I can't (or won't) disable my touchscreen, I guess I'm stuck with 32-bit calibre until Qt fixes this issue.

[kovidgoyal]

Hmm, well there are a few things I can try:

1) Upgrading the qt build to 4.8.4 in case the crash was fixed (currently the 64 bit build uses 4.8.3)
2) Disabling gestures in the Qt build.

I'll create a build with (1) in a bit (compiling Qt takes forever), see if it fixes your issue, if not I'll create another build with (2).

[toddos]

This change looks promising. 4.8.3 was released 2012-09-13, this patch was committed 2012-09-27, and 4.8.4 was released 2012-11-29.

[kovidgoyal]

Here's the build with Qt 4.8.4 http://calibre-ebook.com/downloads/b...bit-0.9.32.msi

[toddos]

Thanks! That solved the problem.

Based on what happens immediately after the conversion window closes, which is where the crash was, it must've had something to do with the animated arrow pointing down to the job status. Had I noticed that, I probably could've disabled animations as a workaround. But now I don't need a workaround. Awesome!