Qt and 64-bit Support in Mac OS X 10.5 "Leopard"

20 June - 2007 - At WWDC 2007, Apple announced that they are not planning to ship the 64-bit version of the Carbon API with OS X 10.5 (“Leopard”). This decision has later been confirmed on the Carbon-dev mailing list.

Qt will be impacted by this last minute change, as we are currently basing our Mac version on Carbon. If Apple’s current decision holds, it will regrettably not be possible to create 64-bit Qt-based GUI applications on Leopard. Non-GUI Qt libraries not relying on HIView (Core, Network, SQL, XML, etc) can however be built in 64-bit mode for Leopard.  

We will continue to work to shield Qt customers against changes in the underlying platforms. Qt-based 32-bit applications will of course work great on Leopard.  Over time, we will gradually transition Qt to also use Cocoa for 64-bit applications, so our customers will be able to create full 64-bit binaries without having to rewrite their code.

For more information, please contact Trolltech at info@trolltech.com.

 

Questions and Answers

 

 

Q: Is all of Qt affected by this?
A: No, only Qt on Mac, and only the Qt libraries that depend on HIView (Qt GUI, Qt OpenGL and Qt3Support). The remaining Qt libraries (Core, Network, SQL, XML, etc.) are not affected.

Q: I really need a 64-bit application with a GUI for Leopard, what can I do?
A: You may be able to use the approach outlined in this article: http://developer.apple.com/macosx/64bit.html, with a 32-bit GUI interacting with a 64-bit process. This method has been available since Tiger.

Q: When will you provide 64-bit support for Qt GUI applications on the Mac?
A: As soon as we can. We are still analyzing the impact on our codebase. At the moment, it is not entirely clear which parts of Carbon will be available in 64-bit versions for Leopard. Obviously, if Apple decides to revive the 64bit Carbon GUI APIs we'll be able to do so much sooner than if we have to complete the entire port to Cocoa first.

Q: I need 64-bit GUI applications on Windows and Linux. Do I need to worry?
A: Not at all. Qt can and will help you build 64-bit applications on all platforms where underlying APIs makes this possible, such as the 64-bit versions of Windows and Linux.

Q: Can I do something about this?
A: We have shared our views on this decision with Apple. Our plans have been based on the assumption that 64-bit Carbon would be available in Leopard. We were not aware of the change of plans until the 2007 WWDC keynote.

If you'd like to share your feedback with Apple, please see this  message: http://lists.apple.com/archives/Carbon-dev/2007/Jun/msg00316.html and provide your feedback to Apple's Application Frameworks Evangelist,  Deric Horn <deric at apple dot com>.