Window transparency in Mac Cocoa

General
1

Neither of these correctly control the transparency of Mac OS window any longer in Xojo 2021.

Soft Declare Sub SetAlphaValue Lib “Cocoa” selector “setAlphaValue:” ( windowRef As Integer, alphaValue As Single )
SetAlphaValue( wind.Handle, value )

Declare Sub setAlphaValue Lib “Cocoa” Selector “setAlphaValue:” (NSWindow As Ptr, alphaValue As Single)
setAlphaValue(Ptr(wind.Handle), value)

regardless of the value assigned to value, the window disappears. Can anyone provide some assistance. Thank you.

2

What value(s) have you tried? I bet 0.0 is fully transparent and 1.0 is opaque.

3

That’s not the Xojo version, it is because you are using 32 Bit code.
Replace Single by Double or CGFloat to keep 32 Bit compatibility.

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4

Thank you. That was the issue, it should be double not single. I should have caught that. It is always good to have another set of eyes look at the code.

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5

Make it easier on yourself in the future.

// --- Mac OS X 10.5 +, values range from 0.0 ~ 1.0
declare sub NSWindow_setAlphaValue Lib “AppKit” selector “setAlphaValue:” ( NSWindowInstance As Integer, value As CGFloat )
NSWindow_setAlphaValue( wind.Handle, value )

This way, the code provides more hints on itself, as you now include the className, the framework, if this API applies to a class instance or the class object, and minimum supported OS Version.

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