How to reproduce this Xcode blue drag line

Question

I\'d like to reproduce the Xcode blue drag line in my app.

Do you know a way to code this ?

I know how to draw a line using Core Graphics ... But th

Answer 1

Using a transparent NSWindow :

var window: NSWindow!

func createLinePath(from: NSPoint, to: NSPoint) -> CGPath {
    let path = CGMutablePath()

    path.move(to: from)
    path.addLine(to: to)

    return path
}

override func viewDidLoad() {
    super.viewDidLoad()

    //Transparent window
    window = NSWindow()
    window.styleMask = .borderless
    window.backgroundColor = .clear
    window.isOpaque = false
    window.hasShadow = false

    //Line
    let line = CAShapeLayer()

    line.path = createLinePath(from: NSPoint(x: 0, y: 0), to: NSPoint(x: 100, y: 100))
    line.lineWidth = 10.0
    line.strokeColor = NSColor.blue.cgColor

    //Update
    NSEvent.addLocalMonitorForEvents(matching: [.mouseMoved]) {
        let newPos = NSEvent.mouseLocation()

        line.path = self.createLinePath(from: NSPoint(x: 0, y: 0), to: newPos)

        return $0
    }

    window.contentView!.layer = line
    window.contentView!.wantsLayer = true

    window.setFrame(NSScreen.main()!.frame, display: true)

    window.makeKeyAndOrderFront(nil)
}