Bug 38513 - Cocoa supports threaded drawing
Summary: Cocoa supports threaded drawing
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
Depends on:
Reported: 2016-02-06 01:51 UTC by Alex Corrado [MSFT]
Modified: 2016-02-18 18:19 UTC (History)
2 users (show)

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

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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.

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