mirror-ghostty/macos/Sources/Features/QuickTerminal/QuickTerminalScreenStateCac...

117 lines
4.5 KiB
Swift

import Foundation
import Cocoa
/// Manages cached window state per screen for the quick terminal.
///
/// This cache tracks the last closed window frame for each screen, allowing the quick terminal
/// to restore to its previous size and position when reopened. It uses stable display UUIDs
/// to survive NSScreen garbage collection and automatically prunes stale entries.
class QuickTerminalScreenStateCache {
typealias Entries = [UUID: DisplayEntry]
/// The maximum number of saved screen states we retain. This is to avoid some kind of
/// pathological memory growth in case we get our screen state serializing wrong. I don't
/// know anyone with more than 10 screens, so let's just arbitrarily go with that.
private static let maxSavedScreens = 10
/// Time-to-live for screen entries that are no longer present (14 days).
private static let screenStaleTTL: TimeInterval = 14 * 24 * 60 * 60
/// Keyed by display UUID to survive NSScreen garbage collection.
private(set) var stateByDisplay: Entries = [:]
init(stateByDisplay: Entries = [:]) {
self.stateByDisplay = stateByDisplay
NotificationCenter.default.addObserver(
self,
selector: #selector(onScreensChanged(_:)),
name: NSApplication.didChangeScreenParametersNotification,
object: nil)
}
deinit {
NotificationCenter.default.removeObserver(self)
}
/// Save the window frame for a screen.
func save(frame: NSRect, for screen: NSScreen) {
guard let key = screen.displayUUID else { return }
let entry = DisplayEntry(
frame: frame,
screenSize: screen.frame.size,
scale: screen.backingScaleFactor,
lastSeen: Date()
)
stateByDisplay[key] = entry
pruneCapacity()
}
/// Retrieve the last closed frame for a screen, if valid.
func frame(for screen: NSScreen) -> NSRect? {
guard let key = screen.displayUUID, var entry = stateByDisplay[key] else { return nil }
// Drop on dimension/scale change that makes the entry invalid
if !entry.isValid(for: screen) {
stateByDisplay.removeValue(forKey: key)
return nil
}
entry.lastSeen = Date()
stateByDisplay[key] = entry
return entry.frame
}
@objc private func onScreensChanged(_ note: Notification) {
let screens = NSScreen.screens
let now = Date()
let currentIDs = Set(screens.compactMap { $0.displayUUID })
for screen in screens {
guard let key = screen.displayUUID else { continue }
if var entry = stateByDisplay[key] {
// Drop on dimension/scale change that makes the entry invalid
if !entry.isValid(for: screen) {
stateByDisplay.removeValue(forKey: key)
} else {
// Update the screen size if it grew (keep entry valid for larger screens)
entry.screenSize = screen.frame.size
entry.lastSeen = now
stateByDisplay[key] = entry
}
}
}
// TTL prune for non-present screens
stateByDisplay = stateByDisplay.filter { key, entry in
currentIDs.contains(key) || now.timeIntervalSince(entry.lastSeen) < Self.screenStaleTTL
}
pruneCapacity()
}
private func pruneCapacity() {
guard stateByDisplay.count > Self.maxSavedScreens else { return }
let toRemove = stateByDisplay
.sorted { $0.value.lastSeen < $1.value.lastSeen }
.prefix(stateByDisplay.count - Self.maxSavedScreens)
for (key, _) in toRemove {
stateByDisplay.removeValue(forKey: key)
}
}
struct DisplayEntry: Codable {
var frame: NSRect
var screenSize: CGSize
var scale: CGFloat
var lastSeen: Date
/// Returns true if this entry is still valid for the given screen.
/// Valid if the scale matches and the cached size is not larger than the current screen size.
/// This allows entries to persist when screens grow, but invalidates them when screens shrink.
func isValid(for screen: NSScreen) -> Bool {
guard scale == screen.backingScaleFactor else { return false }
return screenSize.width <= screen.frame.size.width && screenSize.height <= screen.frame.size.height
}
}
}