Tinting Images (SF Symbols, App Kit, NSImage)

NSImageExtensions.fs

[<AutoOpen>]
module NSImageExtensions =
    open AppKit
    
    type NSImage with

        static member GetSystemSymbolTinted (symbolName: string, accessibilityDescription: string, tint: NSColor) : NSImage =
            let original = NSImage.GetSystemSymbol(symbolName, accessibilityDescription)
            
            NSImage.ImageWithSize(original.Size, false, (fun bounds ->
                let ctx = NSGraphicsContext.CurrentContext.CGContext
                
                // using `original.CGImage` does return null. use `AsCGImage` instead in this case.
                let mask = original.AsCGImage(ref bounds, NSGraphicsContext.CurrentContext, null)
                
                ctx.ClipToMask(bounds, mask)
                ctx.SetFillColor (tint.CGColor)
                ctx.FillRect(bounds)
                
                // optional
                ctx.Flush()
                
                true
            ))