SnappyWindow – A NSWindow that acts like the PIP Video Window from Safari

readme.md

To use;

• Simply download SnappyWindow.swift from this gist and add it to your Xcode project
• Instantiate a window with SnappyWindow()

example.swift

import Cocoa
import SwiftUI

@main
class AppDelegate: NSObject, NSApplicationDelegate {
    var window: SnappyWindow!

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        let contentView = ContentView()

        // Create the window and set the content view.
        window = SnappyWindow(
            contentRect: NSRect(x: 0, y: 0, width: 480, height: 300),
            styleMask: [.titled, .closable, .miniaturizable, .resizable, .fullSizeContentView],
            backing: .buffered, defer: false)
        window.isReleasedWhenClosed = false
        window.center()
        window.isMovableByWindowBackground = true
        window.contentView = NSHostingView(rootView: contentView)
        window.makeKeyAndOrderFront(nil)
    }

    func applicationWillTerminate(_ aNotification: Notification) {
        // Insert code here to tear down your application
    }
}

SnappyWindow.swift

//
//  SnappyWindow.swift
//  A NSWindow that snaps to corners
//
//  Created by Alasdair Monk on 03/02/2021.
//

import Foundation
import Cocoa

/// An NSWindow with the super power to snap to corners of the screen
class SnappyWindow: NSWindow, NSWindowDelegate {
    enum SnapPosition: Int {
        case bottomLeft = 1
        case bottomRight = 4
        case topLeft = 2
        case topRight = 3
    }
    
    /// Padding from edge of screen
    let padding: CGFloat = 10
    
    /// The latest position the window was snapped to
    var snapPosition: SnapPosition?
    
    private var hasBeenDragged: Bool = false
    
    
    override func mouseDragged(with event: NSEvent) {
        print("Drag")
        self.hasBeenDragged = true
    }
    
    override func mouseUp(with event: NSEvent) {
        print("Mouse up")
        if self.hasBeenDragged {
            let mouseY = NSEvent.mouseLocation.y
            let mouseX = NSEvent.mouseLocation.x
            
            if mouseY > (NSScreen.main?.frame.height)! / 2 && mouseX < (NSScreen.main?.frame.width)! / 2 {
                self.snapTo(position: .topLeft)
                self.snapPosition = .topLeft
            }
            
            if mouseY <= (NSScreen.main?.frame.height)! / 2 && mouseX < (NSScreen.main?.frame.width)! / 2 {
                self.snapTo(position: .bottomLeft)
                self.snapPosition = .bottomLeft
            }
            
            if mouseY > (NSScreen.main?.frame.height)! / 2 && mouseX >= (NSScreen.main?.frame.width)! / 2 {
                self.snapTo(position: .topRight)
                self.snapPosition = .topRight
            }
            
            if mouseY <= (NSScreen.main?.frame.height)! / 2 && mouseX >= (NSScreen.main?.frame.width)! / 2 {
                self.snapTo(position: .bottomRight)
                self.snapPosition = .bottomRight
            }
 
            self.hasBeenDragged = false
        }
    }
    
    func snapTo(position: SnapPosition) {
        switch position {
        case .bottomLeft:
            self.animator().setFrame(NSRect(x: padding, y: padding + padding, width: self.frame.width, height: self.frame.height), display: false, animate: true)
        case .topLeft:
            let position = (NSScreen.main?.frame.height)! - self.frame.height - padding
            self.animator().setFrame(NSRect(x: padding, y: position, width: self.frame.width, height: self.frame.height), display: false, animate: true)
        case .bottomRight:
            self.animator().setFrame(NSRect(x: (NSScreen.main?.frame.width)! - self.frame.width - padding, y: padding + padding, width: self.frame.width, height: self.frame.height), display: false, animate: true)
        case .topRight:
            self.animator().setFrame(NSRect(x: (NSScreen.main?.frame.width)! - self.frame.width - padding, y: (NSScreen.main?.frame.height)! - self.frame.height - padding, width: self.frame.width, height: self.frame.height), display: false, animate: true)
        }
    }
}