feat: click outside alt-tab main window to cancel (closes #341)

* also fix issue where clicking a thumbnail would give alt-tab focus, removing it from the app currently focused
* also use click on a thumbnail to focus it instead of only mouse-down

alt-tab-macos.xcodeproj/project.pbxproj

@@ -87,6 +87,7 @@
 		D04BACE5702CEB1819866875 /* menubar-icon@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = D04BA399F1DF2C61FC2C9599 /* menubar-icon@2x.png */; };
 		D04BAD1BE9DC22C48C53D195 /* AboutTab.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04BA4A26987F67DD94C827F /* AboutTab.swift */; };
 		D04BAD2A7F2E8BF64EE982E9 /* TextArea.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04BA7C836A8CE8C0B8D128B /* TextArea.swift */; };
+		D04BAD43C122A1C7E88B0362 /* MouseEvents.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04BAF320F4D43F0DDFE063E /* MouseEvents.swift */; };
 		D04BAD451966B43720120D2E /* Menubar.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04BAD905546AA93E5117B0A /* Menubar.swift */; };
 		D04BADCDA9F9A6C3D6499877 /* SystemPermissions.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04BA7C6F2519091717F4B4E /* SystemPermissions.swift */; };
 		D04BAE8B16A06A10E2FA94DE /* AccessibilityEvents.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04BA8FDCF137D892114F5F3 /* AccessibilityEvents.swift */; };
@@ -272,6 +273,7 @@
 		D04BAEF1D194C2379C9970F1 /* setup_ci_master.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = setup_ci_master.sh; sourceTree = "<group>"; };
 		D04BAF076A30A1BAFEDBEA66 /* 5 windows - 2 lines.jpg */ = {isa = PBXFileReference; lastKnownFileType = image.jpeg; path = "5 windows - 2 lines.jpg"; sourceTree = "<group>"; };
 		D04BAF1058D2599E6E8ABBA6 /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.info; path = Info.plist; sourceTree = "<group>"; };
+		D04BAF320F4D43F0DDFE063E /* MouseEvents.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MouseEvents.swift; sourceTree = "<group>"; };
 		D04BAF6F617FCA44D1F75B60 /* alt_tab_macos.entitlements */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.entitlements; path = alt_tab_macos.entitlements; sourceTree = "<group>"; };
 		D04BAF77F9D94C397EB646AE /* 1-row.jpg */ = {isa = PBXFileReference; lastKnownFileType = image.jpeg; path = "1-row.jpg"; sourceTree = "<group>"; };
 		D04BAF9052D852CD38B03EF6 /* icon_512x512@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "icon_512x512@2x.png"; sourceTree = "<group>"; };
@@ -820,6 +822,7 @@
 				D04BA4A621A8A15660F973C1 /* KeyboardEvents.swift */,
 				D04BA76AEE37D6656EB80126 /* WorkspaceEvents.swift */,
 				D04BA5D9B4EBEB9E4333AE39 /* UserDefaultsEvents.swift */,
+				D04BAF320F4D43F0DDFE063E /* MouseEvents.swift */,
 			);
 			path = events;
 			sourceTree = "<group>";
@@ -1081,6 +1084,7 @@
 				D04BAFB90E00AA5D662EAF24 /* PermissionsWindow.swift in Sources */,
 				D04BA7E39FA539DD8316447A /* PermissionView.swift in Sources */,
 				D04BA446D702C5E252AF2319 /* TitleLabel.swift in Sources */,
+				D04BAD43C122A1C7E88B0362 /* MouseEvents.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

src/logic/BackgroundWork.swift

@@ -2,19 +2,24 @@ import Foundation
 
 // queues and dedicated threads to observe background events such as keyboard inputs, or accessibility events
 class BackgroundWork {
-    static let mainQueueConcurrentWorkQueue = DispatchQueue.globalConcurrent("mainQueueConcurrentWorkQueue", .userInteractive)
+    static var mainQueueConcurrentWorkQueue: DispatchQueue!
-    static let accessibilityCommandsQueue = DispatchQueue.globalConcurrent("accessibilityCommandsQueue", .userInteractive)
+    static var accessibilityCommandsQueue: DispatchQueue!
-    static let axCallsQueue = DispatchQueue.globalConcurrent("axCallsQueue", .userInteractive)
+    static var axCallsQueue: DispatchQueue!
-    static let accessibilityEventsThread = BackgroundThreadWithRunLoop("accessibilityEventsThread")
+    static var accessibilityEventsThread: BackgroundThreadWithRunLoop!
-    static let keyboardEventsThread = BackgroundThreadWithRunLoop("keyboardEventsThread")
+    static var keyboardEventsThread: BackgroundThreadWithRunLoop!
+    static var mouseEventsThread: BackgroundThreadWithRunLoop!
 
     // we cap concurrent tasks to .processorCount to avoid thread explosion on the .global queue
     static let globalSemaphore = DispatchSemaphore(value: ProcessInfo.processInfo.processorCount)
 
     // swift static variables are lazy; we artificially force the threads to init
     static func start() {
-        _ = accessibilityEventsThread
+        mainQueueConcurrentWorkQueue = DispatchQueue.globalConcurrent("mainQueueConcurrentWorkQueue", .userInteractive)
-        _ = keyboardEventsThread
+        accessibilityCommandsQueue = DispatchQueue.globalConcurrent("accessibilityCommandsQueue", .userInteractive)
+        axCallsQueue = DispatchQueue.globalConcurrent("axCallsQueue", .userInteractive)
+        accessibilityEventsThread = BackgroundThreadWithRunLoop("accessibilityEventsThread")
+        keyboardEventsThread = BackgroundThreadWithRunLoop("keyboardEventsThread")
+        mouseEventsThread = BackgroundThreadWithRunLoop("mouseEventsThread")
     }
 }
 

src/logic/events/KeyboardEvents.swift

@@ -1,14 +1,14 @@
 import Cocoa
 import Carbon.HIToolbox.Events
 
+fileprivate var eventTap: CFMachPort?
+
 class KeyboardEvents {
     static func observe() {
         observe_()
     }
 }
 
-private var eventTap: CFMachPort?
-
 private func observe_() {
     let eventMask = [CGEventType.keyDown, CGEventType.keyUp, CGEventType.flagsChanged].reduce(CGEventMask(0), { $0 | (1 << $1.rawValue) })
     // CGEvent.tapCreate returns null if ensureAccessibilityCheckboxIsChecked() didn't pass

src/logic/events/MouseEvents.swift

@@ -0,0 +1,53 @@
+import Cocoa
+import Carbon.HIToolbox.Events
+
+fileprivate var eventTap: CFMachPort!
+fileprivate var shouldBeEnabled: Bool!
+
+class MouseEvents {
+    static func observe() {
+        observe_()
+    }
+
+    static func disable() {
+        shouldBeEnabled = false
+        CGEvent.tapEnable(tap: eventTap, enable: false)
+    }
+
+    static func enable() {
+        shouldBeEnabled = true
+        CGEvent.tapEnable(tap: eventTap, enable: true)
+    }
+}
+
+
+private func observe_() {
+    let eventMask = [CGEventType.leftMouseDown, CGEventType.leftMouseUp].reduce(CGEventMask(0), { $0 | (1 << $1.rawValue) })
+    // CGEvent.tapCreate returns null if ensureAccessibilityCheckboxIsChecked() didn't pass
+    eventTap = CGEvent.tapCreate(
+        tap: .cgSessionEventTap,
+        place: .headInsertEventTap,
+        options: .defaultTap,
+        eventsOfInterest: eventMask,
+        callback: mouseHandler,
+        userInfo: nil)
+    MouseEvents.disable()
+    let runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, eventTap, 0)
+    CFRunLoopAddSource(BackgroundWork.mouseEventsThread.runLoop, runLoopSource, .commonModes)
+}
+
+private func mouseHandler(proxy: CGEventTapProxy, type: CGEventType, cgEvent: CGEvent, userInfo: UnsafeMutableRawPointer?) -> Unmanaged<CGEvent>? {
+    if type == .leftMouseDown && !isPointerInsideUi() {
+        return nil // focused app won't receive the event
+    } else if type == .leftMouseUp && cgEvent.getIntegerValueField(.mouseEventClickState) >= 1 && !isPointerInsideUi() {
+        App.app.hideUi()
+        return nil // focused app won't receive the event
+    } else if (type == .tapDisabledByUserInput || type == .tapDisabledByTimeout) && shouldBeEnabled {
+        CGEvent.tapEnable(tap: eventTap!, enable: true)
+    }
+    return Unmanaged.passRetained(cgEvent) // focused app will receive the event
+}
+
+private func isPointerInsideUi() -> Bool {
+    App.app.thumbnailsPanel.contentLayoutRect.contains(App.app.thumbnailsPanel.mouseLocationOutsideOfEventStream)
+}

src/ui/App.swift

@@ -47,6 +47,7 @@ class App: NSApplication, NSApplicationDelegate {
             Applications.initialDiscovery()
             self.loadPreferencesWindow()
             KeyboardEvents.observe()
+            MouseEvents.observe()
             // TODO: undeterministic; events in the queue may still be processing; good enough for now
             DispatchQueue.main.async { () -> () in Windows.sortByLevel() }
             self.preloadWindows()
@@ -116,6 +117,7 @@ class App: NSApplication, NSApplicationDelegate {
         debugPrint("hideUi")
         appIsBeingUsed = false
         isFirstSummon = true
+        MouseEvents.disable()
         thumbnailsPanel.orderOut(nil)
     }
 

src/ui/main-window/ThumbnailView.swift

@@ -10,7 +10,7 @@ class ThumbnailView: NSStackView {
     var hiddenIcon = ThumbnailFontIconView(ThumbnailFontIconView.sfSymbolCircledSlashSign, Preferences.fontIconSize, .white)
     var spaceIcon = ThumbnailFontIconView(ThumbnailFontIconView.sfSymbolCircledNumber0, Preferences.fontIconSize, .white)
     var hStackView: NSStackView!
-    var mouseDownCallback: (() -> Void)!
+    var mouseUpCallback: (() -> Void)!
     var mouseMovedCallback: (() -> Void)!
     var dragAndDropTimer: Timer?
     var isHighlighted = false
@@ -96,7 +96,7 @@ class ThumbnailView: NSStackView {
         let fontIconWidth = CGFloat([fullscreenIcon, minimizedIcon, hiddenIcon, spaceIcon].filter { !$0.isHidden }.count) * (Preferences.fontIconSize + Preferences.intraCellPadding)
         assignIfDifferent(&label.textContainer!.size.width, frame.width - Preferences.iconSize - Preferences.intraCellPadding * 3 - fontIconWidth)
         assignIfDifferent(&subviews.first!.frame.size, frame.size)
-        self.mouseDownCallback = { () -> Void in App.app.focusSelectedWindow(element) }
+        self.mouseUpCallback = { () -> Void in App.app.focusSelectedWindow(element) }
         self.mouseMovedCallback = { () -> Void in Windows.updateFocusedWindowIndex(index) }
         // force a display to avoid flickering; see https://github.com/lwouis/alt-tab-macos/issues/197
         // quirk: display() should be called last as it resets thumbnail.frame.size somehow
@@ -120,7 +120,7 @@ class ThumbnailView: NSStackView {
 
     override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
         dragAndDropTimer = Timer.scheduledTimer(withTimeInterval: 2, repeats: false, block: { _ in
-            self.mouseDownCallback()
+            self.mouseUpCallback()
         })
         return .link
     }
@@ -144,8 +144,10 @@ class ThumbnailView: NSStackView {
         }
     }
 
-    override func mouseDown(with theEvent: NSEvent) {
+    override func mouseUp(with theEvent: NSEvent) {
-        mouseDownCallback()
+        if theEvent.clickCount >= 1 {
+            mouseUpCallback()
+        }
     }
 
     static func makeShadow(_ color: NSColor) -> NSShadow {

src/ui/main-window/ThumbnailsPanel.swift

@@ -11,6 +11,7 @@ class ThumbnailsPanel: NSPanel {
         hasShadow = false
         titleVisibility = .hidden
         styleMask.remove(.titled)
+        styleMask.update(with: .nonactivatingPanel)
         backgroundColor = .clear
         contentView!.addSubview(thumbnailsView)
         // 2nd highest level possible; this allows the app to go on top of context menus
@@ -25,7 +26,8 @@ class ThumbnailsPanel: NSPanel {
     }
 
     func show() {
-        makeKeyAndOrderFront(nil)
+        orderFrontRegardless()
+        MouseEvents.enable()
         thumbnailsView.scrollView.flashScrollers()
     }