feat: handle hidden app windows (closes #108)

alt-tab-macos/api-wrappers/AXUIElement.swift

@@ -49,15 +49,26 @@ extension AXUIElement {
         return attribute(.windows, [AXUIElement].self)
     }
 
+    func window(_ id: CGWindowID) -> AXUIElement? {
+        return windows()?.first(where: { return id == $0.cgId() })
+    }
+
     func isMinimized() -> Bool {
         return attribute(.minimized, Bool.self) == true
     }
 
     func focus(_ id: CGWindowID) {
+        // implementation notes: the following sequence of actions repeats some calls. This is necessary for
+        // minimized windows on other spaces, and focuses windows faster (e.g. the Security & Privacy window)
+        // macOS bug: when switching to a System Preferences window in another space, it switches to that space,
+        // but quickly switches back to another window in that space
+        // You can reproduce this buggy behaviour by clicking on the dock icon, proving it's an OS bug
         var elementConnection = UInt32(0)
         CGSGetWindowOwner(cgsMainConnectionId, id, &elementConnection)
         var psn = ProcessSerialNumber()
         CGSGetConnectionPSN(elementConnection, &psn)
+        AXUIElementPerformAction(self, kAXRaiseAction as CFString)
+        makeKeyWindow(psn, id)
         _SLPSSetFrontProcessWithOptions(&psn, id, .userGenerated)
         makeKeyWindow(psn, id)
         AXUIElementPerformAction(self, kAXRaiseAction as CFString)

alt-tab-macos/api-wrappers/CGWindowID.swift

@@ -2,13 +2,13 @@ import Cocoa
 import Foundation
 
 extension CGWindowID {
-    func AXUIElement(_ ownerPid: pid_t) -> AXUIElement? {
+    func AXUIElementApplication(_ ownerPid: pid_t) -> AXUIElement {
-        return AXUIElementCreateApplication(ownerPid).windows()?.first(where: { return $0.cgId() == self })
+        return AXUIElementCreateApplication(ownerPid)
     }
 
-    func AXUIElementOfOtherSpaceWindow(_ ownerPid: pid_t) -> AXUIElement? {
+    func AXUIElementOfOtherSpaceWindow(_ axApp: AXUIElement) -> AXUIElement? {
         CGSAddWindowsToSpaces(cgsMainConnectionId, [self], [Spaces.currentSpaceId])
-        let axWindow = AXUIElement(ownerPid)
+        let axWindow = axApp.window(self)
         CGSRemoveWindowsFromSpaces(cgsMainConnectionId, [self], [Spaces.currentSpaceId])
         return axWindow
     }

alt-tab-macos/logic/TrackedWindow.swift

@@ -3,42 +3,44 @@ import Foundation
 
 class TrackedWindow {
     var cgWindow: CGWindow
-    var ownerPid: pid_t
     var id: CGWindowID
     var title: String
     var thumbnail: NSImage?
     var icon: NSImage?
-    var app: NSRunningApplication?
+    var app: NSRunningApplication
+    var axApp: AXUIElement
     var axWindow: AXUIElement?
+    var isHidden: Bool
     var isMinimized: Bool
     var spaceId: CGSSpaceID?
     var spaceIndex: SpaceIndex?
     var rank: WindowRank?
 
-    init(_ cgWindow: CGWindow, _ cgId: CGWindowID, _ ownerPid: pid_t, _ isMinimized: Bool, _ axWindow: AXUIElement?, _ spaceId: CGSSpaceID?, _ spaceIndex: SpaceIndex?, _ rank: WindowRank?) {
+    init(_ cgWindow: CGWindow, _ cgId: CGWindowID, _ app: NSRunningApplication, _ axApp: AXUIElement, _ isHidden: Bool, _ isMinimized: Bool, _ axWindow: AXUIElement?, _ spaceId: CGSSpaceID?, _ spaceIndex: SpaceIndex?, _ rank: WindowRank?) {
         self.cgWindow = cgWindow
         self.id = cgId
-        self.ownerPid = ownerPid
         let cgTitle = cgWindow.value(.name, String.self)
         let cgOwnerName = cgWindow.value(.ownerName, String.self)
         // for some reason Google Chrome uses a unicode 0-width no-break space character in their empty window title
         self.title = cgTitle != nil && cgTitle != "" && cgTitle != "" ? cgTitle! : cgOwnerName ?? ""
-        self.app = NSRunningApplication(processIdentifier: ownerPid)
+        self.app = app
-        self.icon = self.app?.icon
+        self.axApp = axApp
+        self.icon = self.app.icon
         if let cgImage = cgId.screenshot() {
             self.thumbnail = NSImage(cgImage: cgImage, size: NSSize(width: cgImage.width, height: cgImage.height))
         }
         self.axWindow = axWindow
+        self.isHidden = isHidden
         self.isMinimized = isMinimized
         self.spaceId = spaceId
-        // System Preferences windows appear on all spaces, so we make them the current space
+        self.spaceIndex = spaceIndex
-        self.spaceIndex = app?.bundleIdentifier == "com.apple.systempreferences" ? Spaces.currentSpaceIndex : spaceIndex
         self.rank = rank
     }
 
     func focus() {
-        if axWindow == nil {
+        let onCurrentSpace = axWindow != nil
-            axWindow = id.AXUIElementOfOtherSpaceWindow(ownerPid)
+        if !onCurrentSpace {
+            axWindow = id.AXUIElementOfOtherSpaceWindow(axApp)
         }
         axWindow?.focus(id)
     }

alt-tab-macos/logic/TrackedWindows.swift

@@ -35,7 +35,7 @@ class TrackedWindows {
         Spaces.singleSpace = true
     }
 
-    private static func mapWindowsWithRankAndSpace(_ spaces: [(CGSSpaceID, SpaceIndex)]) -> [CGWindowID: (CGSSpaceID, SpaceIndex, WindowRank)] {
+    private static func mapWindowsWithRankAndSpace(_ spaces: [(CGSSpaceID, SpaceIndex)]) -> WindowsMap {
         var windowSpaceMap: [CGWindowID: (CGSSpaceID, SpaceIndex, WindowRank?)] = [:]
         for (spaceId, spaceIndex) in spaces {
             Spaces.windowsInSpaces([spaceId]).forEach {
@@ -45,7 +45,7 @@ class TrackedWindows {
         Spaces.windowsInSpaces(spaces.map { $0.0 }).enumerated().forEach {
             windowSpaceMap[$0.element]!.2 = $0.offset
         }
-        return windowSpaceMap as! [CGWindowID: (CGSSpaceID, SpaceIndex, WindowRank)]
+        return windowSpaceMap as! WindowsMap
     }
 
     private static func sortList() {
@@ -60,31 +60,44 @@ class TrackedWindows {
         })
     }
 
-    private static func filterAndAddToList(_ windowsMap: [CGWindowID: (CGSSpaceID, SpaceIndex, WindowRank)]) {
+    private static func filterAndAddToList(_ windowsMap: WindowsMap) {
+        // order and short-circuit of checks in this method is important for performance
         for cgWindow in CGWindow.windows(.optionAll) {
             guard let cgId = cgWindow.value(.number, CGWindowID.self),
                   let ownerPid = cgWindow.value(.ownerPID, pid_t.self),
+                  let app = NSRunningApplication(processIdentifier: ownerPid),
                   cgWindow.isNotMenubarOrOthers(),
                   cgWindow.isReasonablyBig() else {
                 continue
             }
+            let axApp = cgId.AXUIElementApplication(ownerPid)
             let (spaceId, spaceIndex, rank) = windowsMap[cgId] ?? (nil, nil, nil)
-            if let axWindow = cgId.AXUIElement(ownerPid), axWindow.isActualWindow() {
+            if let (isMinimized, isHidden, axWindow) = filter(cgId, spaceId, app, axApp) {
-                // window is in the current space
+                list.append(TrackedWindow(cgWindow, cgId, app, axApp, isHidden, isMinimized, axWindow, spaceId, spaceIndex, rank))
-                if spaceId != nil {
-                    list.append(TrackedWindow(cgWindow, cgId, ownerPid, false, axWindow, spaceId, spaceIndex, rank))
-                }
-                // window is minimized
-                else if axWindow.isMinimized() {
-                    list.append(TrackedWindow(cgWindow, cgId, ownerPid, true, axWindow, nil, nil, rank))
-                }
-            }
-            // window is on another space
-            else if spaceId != nil && spaceId != Spaces.currentSpaceId {
-                list.append(TrackedWindow(cgWindow, cgId, ownerPid, false, nil, spaceId, spaceIndex, rank))
             }
         }
     }
+
+    private static func filter(_ cgId: CGWindowID, _ spaceId: CGSSpaceID?, _ app: NSRunningApplication, _ axApp: AXUIElement) -> (Bool, Bool, AXUIElement?)? {
+        // window is in another space
+        if spaceId != nil && spaceId != Spaces.currentSpaceId {
+            return (false, false, nil)
+        }
+        // window is in the current space, or is hidden/minimized
+        if let axWindow = axApp.window(cgId), axWindow.isActualWindow() {
+            if spaceId != nil {
+                return (false, false, axWindow)
+            }
+            if app.isHidden {
+                return (axWindow.isMinimized(), true, axWindow)
+            }
+            if axWindow.isMinimized() {
+                return (true, false, axWindow)
+            }
+        }
+        return nil
+    }
 }
 
 typealias WindowRank = Int
+typealias WindowsMap = [CGWindowID: (CGSSpaceID, SpaceIndex, WindowRank)]

alt-tab-macos/ui/Cell.swift

@@ -9,6 +9,7 @@ class Cell: NSCollectionViewItem {
     var appIcon = NSImageView()
     var label = CellTitle(Preferences.fontHeight!)
     var minimizedIcon = FontIcon(FontIcon.sfSymbolCircledMinusSign, Preferences.fontIconSize, .white)
+    var hiddenIcon = FontIcon(FontIcon.sfSymbolCircledDotSign, Preferences.fontIconSize, .white)
     var spaceIcon = FontIcon(FontIcon.sfSymbolCircledNumber0, Preferences.fontIconSize, .white)
     var openWindow: TrackedWindow?
     var mouseDownCallback: MouseDownCallback?
@@ -50,13 +51,14 @@ class Cell: NSCollectionViewItem {
         label.string = element.title
         // workaround: setting string on NSTextView change the font (most likely a Cocoa bug)
         label.font = Preferences.font!
-        let fontIconWidth = Spaces.singleSpace && !openWindow!.isMinimized ? 0 : Preferences.fontIconSize + Preferences.interItemPadding
+        hiddenIcon.isHidden = !openWindow!.isHidden
-        label.textContainer!.size.width = thumbnail.frame.width - Preferences.iconSize! - Preferences.interItemPadding - fontIconWidth
         minimizedIcon.isHidden = !openWindow!.isMinimized
-        spaceIcon.isHidden = openWindow!.isMinimized || Spaces.singleSpace || Preferences.hideSpaceNumberLabels
+        spaceIcon.isHidden = element.spaceIndex == nil || Spaces.singleSpace || Preferences.hideSpaceNumberLabels
         if !spaceIcon.isHidden {
             spaceIcon.setNumber(UInt32(element.spaceIndex!))
         }
+        let fontIconWidth = CGFloat([minimizedIcon, hiddenIcon, spaceIcon].filter { !$0.isHidden }.count) * (Preferences.fontIconSize + Preferences.interItemPadding)
+        label.textContainer!.size.width = thumbnail.frame.width - Preferences.iconSize! - Preferences.interItemPadding - fontIconWidth
         self.mouseDownCallback = mouseDownCallback
         self.mouseMovedCallback = mouseMovedCallback
         if view.trackingAreas.count > 0 {
@@ -92,6 +94,7 @@ class Cell: NSCollectionViewItem {
         hStackView.spacing = Preferences.interItemPadding
         hStackView.addView(appIcon, in: .leading)
         hStackView.addView(label, in: .leading)
+        hStackView.addView(hiddenIcon, in: .leading)
         hStackView.addView(minimizedIcon, in: .leading)
         hStackView.addView(spaceIcon, in: .leading)
         return hStackView

alt-tab-macos/ui/FontIcon.swift

@@ -4,6 +4,7 @@ import Cocoa
 // see https://developer.apple.com/design/human-interface-guidelines/sf-symbols/overview/
 class FontIcon: CellTitle {
     static let sfSymbolCircledMinusSign = "􀁎"
+    static let sfSymbolCircledDotSign = "􀍷"
     static let sfSymbolCircledNumber0 = "􀀸"
     static let sfSymbolCircledNumber10 = "􀓵"