/*

 Copyright (C) 2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 WindowDraggableButton is an NSButton subclass that allows the button to behave like a normal button when clicked, but begins a system drag when the user clicks and drags a certain distance inside the button.

 */

import Cocoa

class WindowDraggableButton: NSButton {

    // Allow the window to still be dragged from this button

    override func mouseDown(with mouseDownEvent: NSEvent) {

        let window = self.window!

        let startingPoint = mouseDownEvent.locationInWindow

        highlight(true)

        // Track events until the mouse is up (in which we interpret as a click), or a drag starts (in which we pass off to the Window Server to perform the drag)

        var shouldCallSuper = false

        // trackEvents won't return until after the tracking all ends

        window.trackEvents(matching: [.leftMouseDragged, .leftMouseUp], timeout:NSEventDurationForever, mode: .defaultRunLoopMode) { event, stop in

            switch event.type {

                case .leftMouseUp:

                    // Stop on a mouse up; post it back into the queue and call super so it can handle it

                    shouldCallSuper = true

                    NSApp.postEvent(event, atStart: false)

                    stop.pointee = true

                case .leftMouseDragged:

                    // track mouse drags, and if more than a few points are moved we start a drag

                    let currentPoint = event.locationInWindow

                    if (fabs(currentPoint.x - startingPoint.x) >= 5 || fabs(currentPoint.y - startingPoint.y) >= 5) {

                        self.highlight(false)

                        stop.pointee = true

                        window.performDrag(with: event)

                    }

                default:

                    break

            }

        }

        if (shouldCallSuper) {

            super.mouseDown(with: mouseDownEvent)

        }

    }

}