Camera and editor improvements

submodules/TelegramUI/Components/MediaEditor/Sources/MediaEditorUtils.swift

@@ -0,0 +1,41 @@
+import Foundation
+import AVFoundation
+import SwiftSignalKit
+
+extension AVPlayer {
+    func fadeVolume(from: Float, to: Float, duration: Float, completion: (() -> Void)? = nil) -> SwiftSignalKit.Timer? {
+        self.volume = from
+        guard from != to else { return nil }
+        
+        let interval: Float = 0.1
+        let range = to - from
+        let step = (range * interval) / duration
+        
+        func reachedTarget() -> Bool {
+            guard self.volume >= 0, self.volume <= 1 else {
+                self.volume = to
+                return true
+            }
+            
+            if to > from {
+                return self.volume >= to
+            }
+            return self.volume <= to
+        }
+        
+        var invalidateImpl: (() -> Void)?
+        let timer = SwiftSignalKit.Timer(timeout: Double(interval), repeat: true, completion: { [weak self] in
+            if let self, !reachedTarget() {
+                self.volume += step
+            } else {
+                invalidateImpl?()
+                completion?()
+            }
+        }, queue: Queue.mainQueue())
+        invalidateImpl = { [weak timer] in
+            timer?.invalidate()
+        }
+        timer.start()
+        return timer
+    }
+}