Feat: SpringMotionPanel with SpringMotionWindowProtocol conformance

Sources/Model/SpringMotionPhysics.swift

@@ -10,7 +10,7 @@ import Foundation
 /// Implements the physics of spring motion.
 ///
 /// The math is inspired by [this great post](https://www.ryanjuckett.com/damped-springs).
-final class SpringMotionPhysics {
+public final class SpringMotionPhysics {
 
     private let posPosCoef: Double
     private let posVelCoef: Double

Sources/Model/SpringMotionState.swift

@@ -7,7 +7,7 @@
 
 import Foundation
 
-final class SpringMotionState {
+public final class SpringMotionState {
 
     struct Velocity {
 

Sources/SpringMotionPanel.swift

@@ -0,0 +1,51 @@
+//
+//  SpringMotionPanel.swift
+//
+//
+//  Created by Oryna Semenets on 17.10.2024.
+//
+
+#if canImport(AppKit)
+import AppKit
+
+open class SpringMotionPanel: NSPanel, SpringMotionWindowProtocol {
+    /// Implement the shared protocol in the NSPanel subclass.
+
+    public var configuration: SpringConfiguration = .default {
+        didSet {
+            motionPhysics = .init(configuration: configuration, timeStep: 0.008)
+        }
+    }
+
+    public var destinationPoint: NSPoint? {
+        didSet {
+            startMotion()
+        }
+    }
+    lazy public var motionPhysics = SpringMotionPhysics(configuration: configuration, timeStep: 0.008)
+    public var currentMotionState: SpringMotionState?
+    public var displayLink: CVDisplayLink?
+    public var anchorWindowFrameObservation: NSKeyValueObservation?
+}
+
+// MARK: - Mouse events
+extension SpringMotionPanel {
+
+    override open func mouseDown(with event: NSEvent) {
+        super.mouseDown(with: event)
+        /// Stop window from moving if the user grabbed it.
+        if isMovableByWindowBackground {
+            stopMotion()
+        }
+    }
+
+    override open func mouseUp(with event: NSEvent) {
+        super.mouseUp(with: event)
+        /// Continue movement after the user lets go.
+        if isMovableByWindowBackground {
+            startMotion()
+        }
+    }
+}
+
+#endif

Sources/SpringMotionWindow.swift

@@ -9,122 +9,8 @@
 
 import AppKit
 
-open class SpringMotionWindow: NSWindow {
-
-    /// Configuration that adjusts the spring physics behind the animation.
-    public var configuration: SpringConfiguration = .default {
-        didSet {
-            motionPhysics = .init(configuration: configuration, timeStep: 0.008)
-        }
-    }
-
-    // MARK: Private
-    private var destinationPoint: NSPoint? {
-        didSet {
-            startMotion()
-        }
-    }
-
-    private lazy var motionPhysics = SpringMotionPhysics(configuration: configuration, timeStep: 0.008)
-    private var currentMotionState: SpringMotionState?
-    private var displayLink: CVDisplayLink?
-    private var anchorWindowFrameObservation: NSKeyValueObservation?
-}
-
-// MARK: - API
-public extension SpringMotionWindow {
-
-    /// Moves the window to the specified point with spring animation.
-    ///
-    /// - Parameter point: a `CGPoint` that defines the window's destination and represents the window's center point.
-    func move(to point: NSPoint) {
-        destinationPoint = point
-    }
-
-    /// Starts following the given window with a certain offset from its center.
-    ///
-    /// - Parameter anchorWindow: an `NSWindow` that this window will follow.
-    /// - Parameter offsetFromCenter: the difference between this window's center and the anchor window's center.
-    func pinToWindow(_ anchorWindow: NSWindow, offsetFromCenter: NSPoint) {
-        unpinFromWindow()
-        move(to: anchorWindow.frame.center + offsetFromCenter)
-        anchorWindowFrameObservation = anchorWindow.observe(\.frame, changeHandler: { [weak self] _, _ in
-            self?.move(to: anchorWindow.frame.center + offsetFromCenter)
-        })
-    }
-
-    /// Stops following a previously followed window, if any.
-    func unpinFromWindow() {
-        anchorWindowFrameObservation?.invalidate()
-        anchorWindowFrameObservation = nil
-    }
-}
-
-// MARK: - Mouse events
-extension SpringMotionWindow {
-
-    override open func mouseDown(with event: NSEvent) {
-        super.mouseDown(with: event)
-        // Stop window from moving if the user grabbed it.
-        if isMovableByWindowBackground {
-            stopMotion()
-        }
-    }
-
-    override open func mouseUp(with event: NSEvent) {
-        super.mouseUp(with: event)
-        // Continue movement after the user lets go.
-        if isMovableByWindowBackground {
-            startMotion()
-        }
-    }
-}
-
-// MARK: - Start/stop motion
-private extension SpringMotionWindow {
-
-    func startMotion() {
-        guard displayLink == nil,
-              let screenDescription = NSScreen.main?.deviceDescription,
-              let screenNumber = screenDescription[.init("NSScreenNumber")] as? NSNumber else { return }
-
-        CVDisplayLinkCreateWithCGDisplay(screenNumber.uint32Value, &displayLink)
-        guard let displayLink else { return }
-
-        CVDisplayLinkSetOutputHandler(displayLink) { [weak self] _, inNow, _, _, _ in
-            DispatchQueue.main.async { [weak self] in
-                guard let self = self, let destinationPoint = self.destinationPoint else {
-                    self?.stopMotion()
-                    return
-                }
-
-                let currentState = self.currentMotionState ?? .init(position: self.frame.center, velocity: .zero)
-                let nextState = self.motionPhysics.calculateNextState(from: currentState, destinationPoint: destinationPoint)
-
-                if abs(nextState.velocity.horizontal) < 0.01 && abs(nextState.velocity.vertical) < 0.01 {
-                    self.stopMotion()
-                    return
-                }
-
-                self.setFrame(.init(x: nextState.position.x - self.frame.width / 2,
-                                    y: nextState.position.y - self.frame.height / 2,
-                                    width: self.frame.width,
-                                    height: self.frame.height), display: false)
-                self.currentMotionState = nextState
-            }
-
-            return kCVReturnSuccess
-        }
-
-        CVDisplayLinkStart(displayLink)
-    }
-
-    func stopMotion() {
-        guard let link = displayLink else { return }
-        CVDisplayLinkStop(link)
-        displayLink = nil
-        currentMotionState = nil
-    }
+open class SpringMotionWindow: SpringMotionBase {
+    /// This class inherits all functionality from SpringMotionBase.
 }
 
 #endif

Sources/SpringMotionWindowProtocol.swift

@@ -0,0 +1,141 @@
+//
+//  SpringMotionWindowProtocol.swift
+//
+//
+//  Created by Oryna Semenets on 17.10.2024.
+//
+
+#if canImport(AppKit)
+import AppKit
+
+public protocol SpringMotionWindowProtocol: NSWindow {
+    var configuration: SpringConfiguration { get set }
+    var destinationPoint: NSPoint? { get set }
+    var motionPhysics: SpringMotionPhysics { get set }
+    var currentMotionState: SpringMotionState? { get set }
+    var displayLink: CVDisplayLink? { get set }
+    var anchorWindowFrameObservation: NSKeyValueObservation? { get set }
+
+    func move(to point: NSPoint)
+    func pinToWindow(_ anchorWindow: NSWindow, offsetFromCenter: NSPoint)
+    func unpinFromWindow()
+    func startMotion()
+    func stopMotion()
+}
+
+// MARK: - API
+public extension SpringMotionWindowProtocol {
+
+    /// Moves the window to the specified point with spring animation.
+    ///
+    /// - Parameter point: a `CGPoint` that defines the window's destination and represents the window's center point.
+    func move(to point: NSPoint) {
+        destinationPoint = point
+    }
+
+    /// Starts following the given window with a certain offset from its center.
+    ///
+    /// - Parameter anchorWindow: an `NSWindow` that this window will follow.
+    /// - Parameter offsetFromCenter: the difference between this window's center and the anchor window's center.
+    func pinToWindow(_ anchorWindow: NSWindow, offsetFromCenter: NSPoint) {
+        unpinFromWindow()
+        move(to: anchorWindow.frame.center + offsetFromCenter)
+        anchorWindowFrameObservation = anchorWindow.observe(\.frame, changeHandler: { [weak self] _, _ in
+            self?.move(to: anchorWindow.frame.center + offsetFromCenter)
+        })
+    }
+
+    /// Stops following a previously followed window, if any.
+    func unpinFromWindow() {
+        anchorWindowFrameObservation?.invalidate()
+        anchorWindowFrameObservation = nil
+    }
+}
+
+// MARK: - Start/stop motion
+public extension SpringMotionWindowProtocol {
+
+    func startMotion() {
+        guard displayLink == nil,
+              let screenDescription = NSScreen.main?.deviceDescription,
+              let screenNumber = screenDescription[.init("NSScreenNumber")] as? NSNumber else { return }
+
+        CVDisplayLinkCreateWithCGDisplay(screenNumber.uint32Value, &displayLink)
+        guard let displayLink else { return }
+
+        CVDisplayLinkSetOutputHandler(displayLink) { [weak self] _, inNow, _, _, _ in
+            DispatchQueue.main.async { [weak self] in
+                guard let self, let destinationPoint else {
+                    self?.stopMotion()
+                    return
+                }
+
+                let currentState = self.currentMotionState ?? .init(position: self.frame.center, velocity: .zero)
+                let nextState = self.motionPhysics.calculateNextState(from: currentState, destinationPoint: destinationPoint)
+
+                if abs(nextState.velocity.horizontal) < 0.01 && abs(nextState.velocity.vertical) < 0.01 {
+                    self.stopMotion()
+                    return
+                }
+
+                self.setFrame(.init(x: nextState.position.x - self.frame.width / 2,
+                                    y: nextState.position.y - self.frame.height / 2,
+                                    width: self.frame.width,
+                                    height: self.frame.height), display: false)
+                self.currentMotionState = nextState
+            }
+
+            return kCVReturnSuccess
+        }
+
+        CVDisplayLinkStart(displayLink)
+    }
+
+    func stopMotion() {
+        guard let link = displayLink else { return }
+        CVDisplayLinkStop(link)
+        displayLink = nil
+        currentMotionState = nil
+    }
+}
+
+open class SpringMotionBase: NSWindow, SpringMotionWindowProtocol {
+
+    public var configuration: SpringConfiguration = .default {
+        didSet {
+            motionPhysics = .init(configuration: configuration, timeStep: 0.008)
+        }
+    }
+
+    public var destinationPoint: NSPoint? {
+        didSet {
+            startMotion()
+        }
+    }
+    lazy public var motionPhysics = SpringMotionPhysics(configuration: configuration, timeStep: 0.008)
+    public var currentMotionState: SpringMotionState?
+    public var displayLink: CVDisplayLink?
+    public var anchorWindowFrameObservation: NSKeyValueObservation?
+}
+
+// MARK: - Mouse events
+extension SpringMotionBase {
+
+    override open func mouseDown(with event: NSEvent) {
+        super.mouseDown(with: event)
+        // Stop window from moving if the user grabbed it.
+        if isMovableByWindowBackground {
+            stopMotion()
+        }
+    }
+
+    override open func mouseUp(with event: NSEvent) {
+        super.mouseUp(with: event)
+        // Continue movement after the user lets go.
+        if isMovableByWindowBackground {
+            startMotion()
+        }
+    }
+}
+
+#endif