Implement on-focus-changed and on-focused-monitor-changed callbacks

#12
#230

Sources/AppBundle/config/Config.swift

@@ -35,10 +35,14 @@ struct Config: Copyable {
     var startAtLogin: Bool = false
     var accordionPadding: Int = 30
     var enableNormalizationOppositeOrientationForNestedContainers: Bool = true
-    var execOnWorkspaceChange: [String] = []
+    var execOnWorkspaceChange: [String] = [] // todo deprecate
     var keyMapping = KeyMapping()
     var execConfig: ExecConfig = ExecConfig()
 
+    var onFocusChanged: [any Command] = []
+    // var onFocusedWorkspaceChanged: [any Command] = []
+    var onFocusedMonitorChanged: [any Command] = []
+
     var gaps: Gaps = .zero
     var workspaceToMonitorForceAssignment: [String: [MonitorDescription]] = [:]
     var modes: [String: Mode] = [:]

Sources/AppBundle/config/parseConfig.swift

@@ -86,6 +86,10 @@ private let configParser: [String: any ParserProtocol<Config>] = [
     "after-login-command": Parser(\.afterLoginCommand, { parseCommandOrCommands($0).toParsedToml($1) }),
     "after-startup-command": Parser(\.afterStartupCommand, { parseCommandOrCommands($0).toParsedToml($1) }),
 
+    "on-focus-changed": Parser(\.onFocusChanged, { parseCommandOrCommands($0).toParsedToml($1) }),
+    "on-focused-monitor-changed": Parser(\.onFocusedMonitorChanged, { parseCommandOrCommands($0).toParsedToml($1) }),
+    // "on-focused-workspace-changed": Parser(\.onFocusedWorkspaceChanged, { parseCommandOrCommands($0).toParsedToml($1) }),
+
     "enable-normalization-flatten-containers": Parser(\.enableNormalizationFlattenContainers, parseBool),
     "enable-normalization-opposite-orientation-for-nested-containers": Parser(\.enableNormalizationOppositeOrientationForNestedContainers, parseBool),
 

Sources/AppBundle/focus.swift

@@ -106,20 +106,38 @@ var prevFocusedWorkspace: Workspace? { _prevFocusedWorkspaceName.map { Workspace
 var _prevFocus: FrozenFocus? = nil
 var prevFocus: LiveFocus? { _prevFocus?.live }
 
+// Should be called in refreshSession
 func checkOnFocusChangedCallbacks() {
-    let focus = focus.frozen
-    if focus.workspaceName != _lastKnownFocus.workspaceName {
-        onWorkspaceChanged(_lastKnownFocus.workspaceName, focus.workspaceName)
-        _prevFocusedWorkspaceName = _lastKnownFocus.workspaceName
+    let liveFocus = focus
+    let frozenFocus = liveFocus.frozen
+    if frozenFocus != _lastKnownFocus {
+        onFocusChanged(liveFocus)
+        _prevFocus = _lastKnownFocus
     }
-    if focus.monitorId != _lastKnownFocus.monitorId {
-        // todo onMonitorChanged
+    if frozenFocus.workspaceName != _lastKnownFocus.workspaceName {
+        onWorkspaceChanged(_lastKnownFocus.workspaceName, frozenFocus.workspaceName)
+        _prevFocusedWorkspaceName = _lastKnownFocus.workspaceName
     }
-    if focus != _lastKnownFocus {
-        // todo onFocusChanged
-        _prevFocus = _lastKnownFocus
+    if frozenFocus.monitorId != _lastKnownFocus.monitorId {
+        onFocusedMonitorChanged(liveFocus)
     }
-    _lastKnownFocus = focus
+    _lastKnownFocus = frozenFocus
+}
+
+private var onFocusChangedRecursionGuard = false
+private func onFocusedMonitorChanged(_ newFocus: LiveFocus) {
+    if onFocusChangedRecursionGuard { return }
+    onFocusChangedRecursionGuard = true
+    defer { onFocusChangedRecursionGuard = false }
+    if config.onFocusedMonitorChanged.isEmpty { return }
+    _ = config.onFocusedMonitorChanged.run(CommandMutableState(focus.asLeaf.asCommandSubject))
+}
+private func onFocusChanged(_ newFocus: LiveFocus) {
+    if onFocusChangedRecursionGuard { return }
+    onFocusChangedRecursionGuard = true
+    defer { onFocusChangedRecursionGuard = false }
+    if config.onFocusChanged.isEmpty { return }
+    _ = config.onFocusChanged.run(CommandMutableState(focus.asLeaf.asCommandSubject))
 }
 
 private func onWorkspaceChanged(_ oldWorkspace: String, _ newWorkspace: String) {

docs/config-examples/default-config.toml

@@ -38,6 +38,12 @@ default-root-container-orientation = 'auto'
 # See https://nikitabobko.github.io/AeroSpace/guide#key-mapping
 key-mapping.preset = 'qwerty'
 
+# Mouse follows focus when focused monitor changes
+# Drop it from your config, if you don't like this behavior
+# See https://nikitabobko.github.io/AeroSpace/guide#on-focus-changed-callbacks
+# See https://nikitabobko.github.io/AeroSpace/commands#move-mouse
+on-focused-monitor-changed = ['move-mouse monitor-lazy-center']
+
 # Gaps between windows (inner-*) and between monitor edges (outer-*).
 # Possible values:
 # - Constant:     gaps.outer.top = 8

docs/config-examples/i3-like-config-example.toml

@@ -7,6 +7,9 @@
 enable-normalization-flatten-containers = false
 enable-normalization-opposite-orientation-for-nested-containers = false
 
+# Mouse follows focus when focused monitor changes
+on-focused-monitor-changed = ['move-mouse monitor-lazy-center']
+
 [mode.main.binding]
 alt-enter = 'exec-and-forget open -n /System/Applications/Utilities/Terminal.app'
 

docs/guide.adoc

@@ -469,6 +469,27 @@ check-further-callbacks = true
 run = 'layout floating'
 ----
 
+[#on-focus-changed-callbacks]
+=== 'on-focus-changed' callbacks
+
+You can track focus changes using the following callbacks: `on-focus-changed` and `on-focused-monitor-changed`.
+
+* `on-focus-changed` is called every time focused window or workspace changes.
+* `on-focused-monitor-changed` is called every time focused monitor changes.
+
+A common use case for the callbacks is to implement "mouse follows focus" behavior. All you need is to combine the callback of your choice with xref:commands.adoc#move-mouse[move-mouse command]:
+[source,toml]
+----
+on-focused-monitor-changed = ['move-mouse monitor-lazy-center']
+# or
+on-focus-changed = ['move-mouse window-lazy-center']
+----
+
+You shouldn't rely on the order callback are called, since it's an implementation detail and can change from version to version.
+
+The callbacks are "recursion resistant", which means that any focus change within the callback won't retrigger the callback.
+Changing the focus within these callbacks is a bad idea anyway, and the way it's handled will probably change in future versions.
+
 [#exec-on-workspace-change-callback]
 === 'exec-on-workspace-change' callback