CocoaExtension // Introduce Alexis Bridoux's NSWindowPositioner.

Packages/vChewing_CocoaExtension/Sources/CocoaExtension/CocoaExtension_NSWindowPositioner.swift

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+// Free to use
+// Written by Alexis Bridoux - https://github.com/ABridoux
+// Ref: https://gist.github.com/ABridoux/b935c21c7ead92033d39b357fae6366b
+
+import Cocoa
+import SwiftUI
+
+// MARK: Model
+
+extension NSWindow {
+  public struct Position {
+    public static let defaultPadding: CGFloat = 16
+
+    public var vertical: Vertical
+    public var horizontal: Horizontal
+    public var padding = Self.defaultPadding
+  }
+}
+
+extension NSWindow.Position {
+  public enum Horizontal {
+    case left, center, right
+  }
+
+  public enum Vertical {
+    case top, center, bottom
+  }
+}
+
+// MARK: Logic
+
+extension NSWindow.Position {
+  public func value(forWindow windowRect: CGRect, inScreen screenRect: CGRect) -> CGPoint {
+    let xPosition = horizontal.valueFor(
+      screenRange: screenRect.minX..<screenRect.maxX,
+      width: windowRect.width,
+      padding: padding
+    )
+
+    let yPosition = vertical.valueFor(
+      screenRange: screenRect.minY..<screenRect.maxY,
+      height: windowRect.height,
+      padding: padding
+    )
+
+    return CGPoint(x: xPosition, y: yPosition)
+  }
+}
+
+extension NSWindow.Position.Horizontal {
+  public func valueFor(
+    screenRange: Range<CGFloat>,
+    width: CGFloat,
+    padding: CGFloat
+  )
+    -> CGFloat
+  {
+    switch self {
+      case .left: return screenRange.lowerBound + padding
+      case .center: return (screenRange.upperBound + screenRange.lowerBound - width) / 2
+      case .right: return screenRange.upperBound - width - padding
+    }
+  }
+}
+
+extension NSWindow.Position.Vertical {
+  public func valueFor(
+    screenRange: Range<CGFloat>,
+    height: CGFloat,
+    padding: CGFloat
+  )
+    -> CGFloat
+  {
+    switch self {
+      case .top: return screenRange.upperBound - height - padding
+      case .center: return (screenRange.upperBound + screenRange.lowerBound - height) / 2
+      case .bottom: return screenRange.lowerBound + padding
+    }
+  }
+}
+
+// MARK: - AppKit extension
+
+extension NSWindow {
+  public func setPosition(_ position: Position, in screen: NSScreen?) {
+    guard let visibleFrame = (screen ?? self.screen)?.visibleFrame else { return }
+    let origin = position.value(forWindow: frame, inScreen: visibleFrame)
+    setFrameOrigin(origin)
+  }
+
+  public func setPosition(
+    vertical: Position.Vertical,
+    horizontal: Position.Horizontal,
+    padding: CGFloat = Position.defaultPadding,
+    screen: NSScreen? = nil
+  ) {
+    setPosition(
+      Position(vertical: vertical, horizontal: horizontal, padding: padding),
+      in: screen
+    )
+  }
+}
+
+// MARK: - SwiftUI modifier
+
+#if canImport(SwiftUI)
+
+  /// - note: Idea from [LostMoa](https://lostmoa.com/blog/ReadingTheCurrentWindowInANewSwiftUILifecycleApp/)
+  @available(macOS 10.15, *)
+  public struct HostingWindowFinder: NSViewRepresentable {
+    public var callback: (NSWindow?) -> Void
+
+    public func makeNSView(context _: Self.Context) -> NSView {
+      let view = NSView()
+      DispatchQueue.main.async { self.callback(view.window) }
+      return view
+    }
+
+    public func updateNSView(_ nsView: NSView, context _: Context) {
+      DispatchQueue.main.async { self.callback(nsView.window) }
+    }
+  }
+
+  @available(macOS 10.15, *)
+  private struct WindowPositionModifier: ViewModifier {
+    let position: NSWindow.Position
+    let screen: NSScreen?
+
+    func body(content: Content) -> some View {
+      content.background(
+        HostingWindowFinder {
+          $0?.setPosition(position, in: screen)
+        }
+      )
+    }
+  }
+
+  @available(macOS 10.15, *)
+  extension View {
+    public func hostingWindowPosition(
+      vertical: NSWindow.Position.Vertical,
+      horizontal: NSWindow.Position.Horizontal,
+      padding: CGFloat = NSWindow.Position.defaultPadding,
+      screen: NSScreen? = nil
+    ) -> some View {
+      modifier(
+        WindowPositionModifier(
+          position: NSWindow.Position(
+            vertical: vertical,
+            horizontal: horizontal,
+            padding: padding
+          ),
+          screen: screen
+        )
+      )
+    }
+  }
+#endif