wehub-resource-sync
97 lines
3.0 KiB
Swift
97 lines
3.0 KiB
Swift
import AppKit
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import CoreVideo
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import Observation
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import QuartzCore
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/// Minimal display link driver using NSScreen.displayLink on macOS 15+,
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/// and CVDisplayLink on macOS 14.
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/// Publishes ticks on the main thread at the requested frame rate.
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@MainActor
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@Observable
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final class DisplayLinkDriver {
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// Published counter used to drive SwiftUI updates.
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var tick: Int = 0
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private var displayLink: CADisplayLink?
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private var cvDisplayLink: CVDisplayLink?
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private var targetInterval: CFTimeInterval = 1.0 / 60.0
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private var lastTickTimestamp: CFTimeInterval = 0
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private let onTick: (() -> Void)?
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init(onTick: (() -> Void)? = nil) {
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self.onTick = onTick
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}
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func start(fps: Double = 12) {
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guard self.displayLink == nil, self.cvDisplayLink == nil else { return }
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let clampedFps = max(fps, 1)
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self.targetInterval = 1.0 / clampedFps
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self.lastTickTimestamp = 0
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if #available(macOS 15, *), let screen = NSScreen.main {
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// NSScreen.displayLink is macOS 15+ only.
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let displayLink = screen.displayLink(target: self, selector: #selector(self.step))
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let rate = Float(clampedFps)
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displayLink.preferredFrameRateRange = CAFrameRateRange(
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minimum: rate,
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maximum: rate,
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preferred: rate)
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displayLink.add(to: .main, forMode: .common)
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self.displayLink = displayLink
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} else {
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self.startCVDisplayLink()
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}
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}
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func stop() {
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self.displayLink?.invalidate()
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self.displayLink = nil
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if let cvDisplayLink = self.cvDisplayLink {
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CVDisplayLinkStop(cvDisplayLink)
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}
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self.cvDisplayLink = nil
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}
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@objc private func step(_: AnyObject) {
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self.handleTick()
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}
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private func handleTick() {
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let now = CACurrentMediaTime()
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if self.lastTickTimestamp > 0, now - self.lastTickTimestamp < self.targetInterval {
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return
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}
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self.lastTickTimestamp = now
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// Safe on main runloop; drives SwiftUI updates.
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self.tick &+= 1
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self.onTick?()
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}
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private func startCVDisplayLink() {
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var link: CVDisplayLink?
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if CVDisplayLinkCreateWithActiveCGDisplays(&link) != kCVReturnSuccess {
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return
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}
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guard let link else { return }
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let callback: CVDisplayLinkOutputCallback = { _, _, _, _, _, userInfo in
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guard let userInfo else { return kCVReturnSuccess }
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let driver = Unmanaged<DisplayLinkDriver>.fromOpaque(userInfo).takeUnretainedValue()
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driver.scheduleTick()
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return kCVReturnSuccess
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}
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CVDisplayLinkSetOutputCallback(link, callback, Unmanaged.passUnretained(self).toOpaque())
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CVDisplayLinkStart(link)
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self.cvDisplayLink = link
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}
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private nonisolated func scheduleTick() {
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Task { @MainActor [weak self] in
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self?.handleTick()
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}
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}
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deinit {
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Task { @MainActor [weak self] in
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self?.stop()
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}
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}
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}
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