feat: windows on mouse screen, implements #28

squash of pull-request corrections and improvements

refactor: better mimic apple centering

Also use enum instead of bool to self-document the interface

docs: clarify the show-on-screen preference wording

Discussion on this SO (https://stackoverflow.com/a/864432/2249756) seem to indicate that .main is not the screen with the menubar, however in my tests, it is always that window. I think macOS changed the behavior of .main without updating the documentation

refactor: shorter method names as swift promotes + removed debug code

fix: all methods in screen should use visibleFrame not frame

refactor: (hopefully) made code intent clearer

fix: panel and collection layout now use dynamic screen variable

fix: fix vertical origin from 4c44100

alt-tab-macos/logic/Preferences.swift

@@ -52,8 +52,8 @@ class Preferences {
         MacroPreference("⌘ command", ([kVK_Command, kVK_RightCommand], .command))
     ])
     static var showOnScreenMacro = MacroPreferenceHelper<ShowOnScreenPreference>([
-        MacroPreference("with keyboard focus", ShowOnScreenPreference.MAIN),
-        MacroPreference("with mouse pointer", ShowOnScreenPreference.MOUSE),
+        MacroPreference("Main screen", ShowOnScreenPreference.MAIN),
+        MacroPreference("Screen including mouse", ShowOnScreenPreference.MOUSE),
     ])
 
     private static let defaultsFile = fileFromPreferencesFolder("alt-tab-macos-defaults.json")

alt-tab-macos/logic/Screen.swift

@@ -2,55 +2,44 @@ import Foundation
 import Cocoa
 
 class Screen {
-    // currently not in use (but kept for reference & future use), earlier registered by Application.applicationDidFinishLaunching()
-    static func listenToChanges() {
-        NotificationCenter.default.addObserver(
-                forName: NSApplication.didChangeScreenParametersNotification,
-                object: NSApplication.shared,
-                queue: OperationQueue.main
-        ) { notification -> Void in
-            // do something
-        }
-    }
-
-    static func calcThumbnailMaxSize(_ screen: NSScreen) -> NSSize {
-        let width: CGFloat = (screen.frame.size.width * Preferences.maxScreenUsage! - Preferences.windowPadding * 2) / Preferences.maxThumbnailsPerRow! - Preferences.interItemPadding
-        let height: CGFloat = width * (screen.frame.height / screen.frame.width)
-        return NSSize(width: width, height: height)
-    }
-
-    static func calcFrameMaxSize(_ screen: NSScreen) -> NSSize {
-        return NSSize(width: screen.frame.width * Preferences.maxScreenUsage!, height: screen.frame.height * Preferences.maxScreenUsage!)
-    }
-
-    // TODO: currently unknown and unhandled error use-case possible: NSScreen.main being nil
-    static func getPreferredScreen() -> NSScreen {
+    static func preferredScreen() -> NSScreen {
         switch Preferences.showOnScreen! {
         case .MOUSE:
-            return getScreenWithMouse() ?? NSScreen.main!; // .main as fall-back
+            return screenWithMouse() ?? NSScreen.main!; // .main as fall-back
         case .MAIN:
             return NSScreen.main!;
         }
     }
 
-    static func getScreenWithMouse() -> NSScreen? {
+    private static func screenWithMouse() -> NSScreen? {
         return NSScreen.screens.first { NSMouseInRect(NSEvent.mouseLocation, $0.frame, false) }
     }
 
-    /*
-    usage notes:
-    - useAppleVerticalOffset: applies a vertical offset (higher positioning) attempting to approximate the NSView.center() results but only if we are not dealing with screen filling frames (height)
-    */
-    static func showCenteredFrontPanel(_ panel: NSPanel, _ screen: NSScreen, _ useAppleVerticalOffset: Bool = true) {
-        var verticalOffset: CGFloat = 0
+    static func thumbnailMaxSize(_ screen: NSScreen) -> NSSize {
+        let frame = screen.visibleFrame
+        let width = (frame.width * Preferences.maxScreenUsage! - Preferences.windowPadding * 2) / Preferences.maxThumbnailsPerRow! - Preferences.interItemPadding
+        let height = width * (frame.height / frame.width)
+        return NSSize(width: width, height: height)
+    }
 
-        if useAppleVerticalOffset && panel.frame.height < screen.visibleFrame.height / 1.5 {
-            verticalOffset = CGFloat(screen.visibleFrame.height * 0.175)
-        }
+    static func thumbnailPanelMaxSize(_ screen: NSScreen) -> NSSize {
+        let frame = screen.visibleFrame
+        return NSSize(width: frame.width * Preferences.maxScreenUsage!, height: frame.height * Preferences.maxScreenUsage!)
+    }
 
-        let centerPosition = NSPoint(x: screen.visibleFrame.midX - panel.frame.width / 2, y: screen.visibleFrame.midY - panel.frame.height / 2 + verticalOffset)
-        panel.setFrameOrigin(centerPosition)
+    static func showPanel(_ panel: NSPanel, _ screen: NSScreen, _ alignment: VerticalAlignment) {
+        let screenFrame = screen.visibleFrame
+        let panelFrame = panel.frame
+        let x = screenFrame.minX + max(screenFrame.width - panelFrame.width, 0) * 0.5
+        let y = screenFrame.minY + max(screenFrame.height - panelFrame.height, 0) * alignment.rawValue
+        panel.setFrameOrigin(NSPoint(x: x, y: y))
         panel.makeKeyAndOrderFront(nil)
         Application.shared.arrangeInFront(nil)
     }
 }
+
+enum VerticalAlignment: CGFloat {
+    case centered = 0.5
+    // vertically centered but with an upward offset, similar to a book title; mimics NSView.center()
+    case appleCentered = 0.75
+}

alt-tab-macos/logic/WindowManager.swift

@@ -35,7 +35,7 @@ class OpenWindow {
 
 func computeDownscaledSize(_ image: NSImage, _ screen: NSScreen) -> (Int, Int) {
     let imageRatio = image.size.width / image.size.height
-    let thumbnailMaxSize = Screen.calcThumbnailMaxSize(screen)
+    let thumbnailMaxSize = Screen.thumbnailMaxSize(screen)
     let thumbnailWidth = Int(floor(thumbnailMaxSize.height * imageRatio))
     if thumbnailWidth <= Int(thumbnailMaxSize.width) {
         return (thumbnailWidth, Int(thumbnailMaxSize.height))

alt-tab-macos/ui/Application.swift

@@ -28,7 +28,7 @@ class Application: NSApplication, NSApplicationDelegate, NSWindowDelegate {
         SystemPermissions.ensureAccessibilityCheckboxIsChecked()
         Preferences.loadFromDiskAndUpdateValues()
         statusItem = StatusItem.make(self)
-        thumbnailsPanel = ThumbnailsPanel(self, Screen.getPreferredScreen())
+        thumbnailsPanel = ThumbnailsPanel(self)
         preferencesPanel = PreferencesPanel()
         Keyboard.listenToGlobalEvents(self)
     }
@@ -58,8 +58,8 @@ class Application: NSApplication, NSApplicationDelegate, NSWindowDelegate {
         }
     }
 
-    @objc func showCenteredPreferencesPanel() {
-        Screen.showCenteredFrontPanel(preferencesPanel!, Screen.getPreferredScreen())
+    @objc func showPreferencesPanel() {
+        Screen.showPanel(preferencesPanel!, Screen.preferredScreen(), .appleCentered)
     }
 
     func computeOpenWindows() {
@@ -101,12 +101,12 @@ class Application: NSApplication, NSApplicationDelegate, NSWindowDelegate {
                 return
             }
             selectedOpenWindow = cellWithStep(step)
-            let currentScreen = Screen.getPreferredScreen() // we want all computations and renderings to use the same screen for this summon (in case mouse movements switching screens etc.)
             var workItem: DispatchWorkItem!
             workItem = DispatchWorkItem {
+                let currentScreen = Screen.preferredScreen() // fix screen between steps since it could change (e.g. mouse moved to another screen)
                 if !workItem.isCancelled { self.thumbnailsPanel!.computeThumbnails(currentScreen) }
                 if !workItem.isCancelled { self.thumbnailsPanel!.highlightCellAt(step) }
-                if !workItem.isCancelled { Screen.showCenteredFrontPanel(self.thumbnailsPanel!, currentScreen, true) }
+                if !workItem.isCancelled { Screen.showPanel(self.thumbnailsPanel!, currentScreen, .appleCentered) }
             }
             workItems.append(workItem)
             DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + Preferences.windowDisplayDelay!, execute: workItem)

alt-tab-macos/ui/Cell.swift

@@ -35,8 +35,6 @@ class Cell: NSCollectionViewItem {
         }
     }
 
-
-
     func updateWithNewContent(_ element: OpenWindow, _ mouseDownCallback: @escaping MouseDownCallback, _ mouseMovedCallback: @escaping MouseMovedCallback, _ screen: NSScreen) {
         openWindow = element
         thumbnail.image = element.thumbnail

alt-tab-macos/ui/CollectionViewCenterFlowLayout.swift

@@ -1,16 +1,7 @@
 import Cocoa
 
 class CollectionViewCenterFlowLayout: NSCollectionViewFlowLayout {
-    let currentScreen: NSScreen
-
-    init(_ screen: NSScreen) {
-        currentScreen = screen
-        super.init()
-    }
-
-    required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
-    }
+    var currentScreen: NSScreen?
 
     override func layoutAttributesForElements(in rect: CGRect) -> [NSCollectionViewLayoutAttributes] {
         let attributes = super.layoutAttributesForElements(in: rect)
@@ -25,7 +16,7 @@ class CollectionViewCenterFlowLayout: NSCollectionViewFlowLayout {
         var widestRow = CGFloat(0)
         var totalHeight = CGFloat(0)
         attributes.enumerated().forEach {
-            let isNewRow = abs($1.frame.origin.y - currentRowY) > Screen.calcThumbnailMaxSize(currentScreen).height
+            let isNewRow = abs($1.frame.origin.y - currentRowY) > Screen.thumbnailMaxSize(currentScreen!).height
             if isNewRow {
                 computeOriginXForAllItems(currentRowWidth - minimumInteritemSpacing, previousRowMaxY, currentRow)
                 currentRow.removeAll()

alt-tab-macos/ui/PreferencesPanel.swift

@@ -33,7 +33,7 @@ class PreferencesPanel: NSPanel, NSTextViewDelegate {
             makeLabelWithInput(\PreferencesPanel.iconSize, "Apps icon size (px)", "iconSize"),
             makeLabelWithInput(\PreferencesPanel.fontHeight, "Font size (px)", "fontHeight"),
             makeLabelWithInput(\PreferencesPanel.windowDisplayDelay, "Window apparition delay (ms)", "windowDisplayDelay"),
-            makeLabelWithDropdown(\PreferencesPanel.showOnScreen, "Show on Screen", "showOnScreen", Preferences.showOnScreenMacro.labels)
+            makeLabelWithDropdown(\PreferencesPanel.showOnScreen, "Show on", "showOnScreen", Preferences.showOnScreenMacro.labels)
         ]
     }
 

alt-tab-macos/ui/StatusItem.swift

@@ -11,7 +11,7 @@ class StatusItem {
                 keyEquivalent: "")
         item.menu!.addItem(
                 withTitle: "Preferences…",
-                action: #selector(application.showCenteredPreferencesPanel),
+                action: #selector(application.showPreferencesPanel),
                 keyEquivalent: ",")
         item.menu!.addItem(
                 withTitle: "Quit \(ProcessInfo.processInfo.processName)",

alt-tab-macos/ui/ThumbnailsPanel.swift

@@ -11,10 +11,9 @@ class ThumbnailsPanel: NSPanel, NSCollectionViewDataSource, NSCollectionViewDele
         super.init(contentRect: contentRect, styleMask: style, backing: backingStoreType, defer: flag)
     }
 
-    convenience init(_ application: Application, _ currentScreen: NSScreen) {
+    convenience init(_ application: Application) {
         self.init()
         self.application = application
-        self.currentScreen = currentScreen
         isFloatingPanel = true
         animationBehavior = .none
         hidesOnDeactivate = false
@@ -51,8 +50,8 @@ class ThumbnailsPanel: NSPanel, NSCollectionViewDataSource, NSCollectionViewDele
     }
 
     func makeLayout() -> CollectionViewCenterFlowLayout {
-        let layout = CollectionViewCenterFlowLayout(currentScreen!)
-        layout.estimatedItemSize = Screen.calcThumbnailMaxSize(currentScreen!)
+        let layout = CollectionViewCenterFlowLayout()
+        layout.estimatedItemSize = NSSize(width: 200, height: 200)
         layout.minimumInteritemSpacing = 5
         layout.minimumLineSpacing = 5
         return layout
@@ -95,8 +94,9 @@ class ThumbnailsPanel: NSPanel, NSCollectionViewDataSource, NSCollectionViewDele
 
     func computeThumbnails(_ currentScreen: NSScreen) {
         self.currentScreen = currentScreen
-        collectionView_!.setFrameSize(Screen.calcFrameMaxSize(currentScreen))
-        collectionView_!.collectionViewLayout = makeLayout()
+        (collectionView_.collectionViewLayout as! CollectionViewCenterFlowLayout).currentScreen = currentScreen
+        collectionView_!.setFrameSize(Screen.thumbnailPanelMaxSize(currentScreen))
+        collectionView_!.collectionViewLayout!.invalidateLayout()
         collectionView_!.reloadData()
         collectionView_!.layoutSubtreeIfNeeded()
         setContentSize(NSSize(width: collectionView_!.frame.size.width + Preferences.windowPadding * 2, height: collectionView_!.frame.size.height + Preferences.windowPadding * 2))