chore: more performance improvements (#166)

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## Next
 
+- recording: improve ios session recording performance by avoiding redrawing after screen updates ([#166](https://github.com/PostHog/posthog-ios/pull/166))
+  - `debouncerDelay` is changed from 500ms to 1s since the iOS screenshot has to be taken in the main thread and its more sensitive to performance issues
+
 ## 3.7.1 - 2024-08-13
 
 - recording: improve ios session recording performance by doing some work off of the main thread ([#158](https://github.com/PostHog/posthog-ios/pull/158))

PostHog/Replay/PostHogReplayIntegration.swift

@@ -460,9 +460,6 @@
         }
 
         @objc private func snapshot() {
-            // TODO: add debouncer with debouncerDelayMs to take into account how long it takes to execute the
-            // snapshot method
-
             if !PostHogSDK.shared.isSessionReplayActive() {
                 return
             }

PostHog/Replay/PostHogSessionReplayConfig.swift

@@ -33,8 +33,8 @@
         /// Deboucer delay used to reduce the number of snapshots captured and reduce performance impact
         /// This is used for capturing the view as a wireframe or screenshot
         /// The lower the number more snapshots will be captured but higher the performance impact
-        /// Defaults to 500ms
-        @objc public var debouncerDelay: TimeInterval = 1.0 / 2.0
+        /// Defaults to 1s
+        @objc public var debouncerDelay: TimeInterval = 1.0
 
         // TODO: sessionRecording config such as networkPayloadCapture, captureConsoleLogs, sampleRate, etc
     }

PostHog/Replay/UIView+Util.swift

@@ -34,17 +34,25 @@
         }
 
         func toImage() -> UIImage? {
-            let size = bounds.size
+            // Avoid Rendering Offscreen Views
+            let bounds = superview?.bounds ?? bounds
+            let size = bounds.intersection(bounds).size
 
             if !size.hasSize() {
                 return nil
             }
 
-            let renderer = UIGraphicsImageRenderer(size: size)
+            let rendererFormat = UIGraphicsImageRendererFormat.default()
 
-            let image = renderer.image { context in
-                // Render the view's layer into the current context
-                layer.render(in: context.cgContext)
+            // This can significantly improve rendering performance because the renderer won't need to
+            // process transparency.
+            rendererFormat.opaque = isOpaque
+            // Another way to improve rendering performance is to scale the renderer's content.
+            // rendererFormat.scale = 0.5
+            let renderer = UIGraphicsImageRenderer(size: size, format: rendererFormat)
+
+            let image = renderer.image { _ in
+                drawHierarchy(in: bounds, afterScreenUpdates: false)
             }
 
             return image