CGWindowListCopyWindowInfo, CFArrayRef, NSArray, and __bridge

[trevordevore]

I'm trying to convert some code that lists all windows in a session on macOS. In order to do that I need to wrap CGWindowListCopyWindowInfo() <https://developer.apple.com/documentati ... guage=objc>.

The definition is as follows:

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CFArrayRef CGWindowListCopyWindowInfo(CGWindowListOption option, CGWindowID relativeToWindow);

A CFArrayRef can be bridge toll-free to NSArray but I'm guessing that I can't return an ObjcId for a CFArrayRef and have it work properly. In the Objective-C version of the code the bridge as handled as follows:

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(__bridge NSArray *)CGWindowListCopyWindowInfo(listOptions, kCGNullWindowID);

How should I handle this in FFI?

[LCMark]

@trevordevore: The CF types and the corresponding NS types are all compatible at the pointer level - the only thing which differs is that the CF APIs never returned autoreleased objects - so in this case it would return an ObjcRetainedId. Once put into an ObjcObject you can use it like you would the NS object..

[trevordevore]

Fantastic!

[trevordevore]

@LCMark - how does one go about wrapping up CoreGraphics handlers? I see on Windows we use the `userlib>` syntax and parameters are passed directly to the function. In `objc:` we define the property names that are set in the "binds" syntax. My guess is that it behaves like Windows but either of the following syntax just gives me a crash.

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private foreign handler CGWindowListCopyWindowInfo(in pListOptions as Integer, in pRelativeToWindow as optional CUint) returns ObjcRetainedId binds to "CGWindowListCopyWindowInfo"

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private foreign handler CGWindowListCopyWindowInfo(in pListOptions as Integer, in pRelativeToWindow as optional CUint) returns ObjcRetainedId binds to "CoreGraphics>CGWindowListCopyWindowInfo"

[trevordevore]

Monte helped me figure this out. Here is the correct FFI syntax:

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private foreign handler CGWindowListCopyWindowInfo(in pListOptions as Integer, in pRelativeToWindow as CUint) returns ObjcRetainedId binds to "c:CoreGraphics.framework>CGWindowListCopyWindowInfo"

[PaulDaMacMan]

Monte helped me figure this out. Here is the correct FFI syntax:

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private foreign handler CGWindowListCopyWindowInfo(in pListOptions as Integer, in pRelativeToWindow as CUint) returns ObjcRetainedId binds to "c:CoreGraphics.framework>CGWindowListCopyWindowInfo"

So for CF CoreFoundation / C APIs that are part of the macOS system the binding string formula is c:FrameWorkBundleName.framework>functionName. This answers one of my questions too, thanks for the update!

[trevordevore]

For anyone interested, you can see the final implementation of CGWindowListCopyWindowInfo in the `NSWindowGetInfoForOpenWindows` handler in the following code:

https://github.com/trevordevore/lc-maco ... window.lcb