Bug 38513 - Cocoa supports threaded drawing
Summary: Cocoa supports threaded drawing
Status: RESOLVED FIXED
Alias: None
Product: Xamarin.Mac
Classification: Desktop
Component: Library (Xamarin.Mac.dll) ()
Version: Master
Hardware: PC Mac OS
: Normal normal
Target Milestone: master
Assignee: Timothy Risi
URL:
Depends on:
Blocks:
 
Reported: 2016-02-06 01:51 UTC by Alex Corrado [MSFT]
Modified: 2016-02-18 18:19 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.


Please create a new report on Developer Community or GitHub with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:
Status:
RESOLVED FIXED

Description Alex Corrado [MSFT] 2016-02-06 01:51:58 UTC
See https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Multithreading/ThreadSafetySummary/ThreadSafetySummary.html :

> Drawing from secondary threads is thread-safe as long as you bracket
> drawing calls with calls to lockFocusIfCanDraw and unlockFocus

Actual behavior:
Our NSView.LockFocusIfCanDraw() method throws if you call it from a background thread. It's possible that UnlockFocus() and the drawing APIs throw too.

Expected behavior:
These should not throw because this is explicitly supported.

Workaround:
NSApplication.CheckForIllegalCrossThreadCalls = false;
Comment 1 Timothy Risi 2016-02-18 18:19:21 UTC
Fixed on master 062d0026f00980fef43d6f395ced10e9d573f48b