How to draw to a NSView from a Core Video DisplayLink thread?

UI Frameworks AppKit
DannyNiu-NJF OP
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I have a DLP-Link 3D projector which I'd like to make use of by means of a hand-made player.

So far in my project: A class MovieView : NSView within a NSWindow, with stub drawing codes.

I know that, if I place drawing codes in the func draw(...) function, then NSGraphicsContext.current will be set up for me to use. But I'm drawing from a high-priority thread (the DisplayLink), so I obviously have to set it up myself.

How should I do that in Swift?

Answered by DannyNiu-NJF in 719506022

Prepare all the graphical assets in the DisplayLink thread, and asynchronously mark the view as need updating with:

DispatchQueue.main.async {
    view.needsDisplay = true
}

Then do as little as possible and as much as necessary in draw to draw the contents.

Remarks

  • The context to which drawing commands are issued to is not static - it's instantiated on-demand.

  • NSView have the requirement that many of its interfaces be invoked only on the main thread.

Replies  1
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DannyNiu-NJF OP
Accepted Answer

Prepare all the graphical assets in the DisplayLink thread, and asynchronously mark the view as need updating with:

DispatchQueue.main.async {
    view.needsDisplay = true
}

Then do as little as possible and as much as necessary in draw to draw the contents.

Remarks

  • The context to which drawing commands are issued to is not static - it's instantiated on-demand.

  • NSView have the requirement that many of its interfaces be invoked only on the main thread.