ref: Session replay performance for SwiftUI (#4419)

Improved Performance for SwiftUI session replay

CHANGELOG.md

@@ -21,6 +21,7 @@ via the option `swizzleClassNameExclude`.
 ### Improvements
 
 - Serializing profile on a BG Thread (#4377) to avoid potentially slightly blocking the main thread.
+- Session Replay performance for SwiftUI (#4419)
 
 ## 8.38.0-beta.1
 

Sources/Sentry/SentrySessionReplayIntegration.m

@@ -295,7 +295,7 @@ - (void)startWithOptions:(SentryReplayOptions *)replayOptions
 
     [self.sessionReplay
         startWithRootView:SentryDependencyContainer.sharedInstance.application.windows.firstObject
-              fullSession:[self shouldReplayFullSession:replayOptions.sessionSampleRate]];
+              fullSession:shouldReplayFullSession];
 
     [_notificationCenter addObserver:self
                             selector:@selector(pause)

Sources/Swift/Tools/SentryViewPhotographer.swift

@@ -45,18 +45,24 @@ class SentryViewPhotographer: NSObject, SentryViewScreenshotProvider {
         dispatchQueue.dispatchAsync {
             let screenshot = UIGraphicsImageRenderer(size: imageSize, format: .init(for: .init(displayScale: 1))).image { context in
 
+                let imageRect = CGRect(origin: .zero, size: imageSize)
                 context.cgContext.addRect(CGRect(origin: CGPoint.zero, size: imageSize))
                 context.cgContext.clip(using: .evenOdd)
                 UIColor.blue.setStroke()
 
                 context.cgContext.interpolationQuality = .none
                 image.draw(at: .zero)
 
+                var latestRegion: RedactRegion?
                 for region in redact {
                     let rect = CGRect(origin: CGPoint.zero, size: region.size)
                     var transform = region.transform
                     let path = CGPath(rect: rect, transform: &transform)
 
+                    defer { latestRegion = region }
+
+                    guard latestRegion?.canReplace(as: region) != true && imageRect.intersects(path.boundingBoxOfPath) else { continue }
+
                     switch region.type {
                     case .redact, .redactSwiftUI:
                         (region.color ?? UIImageHelper.averageColor(of: context.currentImage, at: rect.applying(region.transform))).setFill()

Sources/Swift/Tools/UIRedactBuilder.swift

@@ -39,6 +39,10 @@ struct RedactRegion {
         self.type = type
         self.color = color
     }
+
+    func canReplace(as other: RedactRegion) -> Bool {
+        size == other.size && transform == other.transform && type == other.type
+    }
 }
 
 class UIRedactBuilder {
@@ -170,7 +174,7 @@ class UIRedactBuilder {
         }
 
         //The swiftUI type needs to appear first in the list so it always get masked
-        return swiftUIRedact + otherRegions.reversed()
+        return (otherRegions + swiftUIRedact).reversed()
     }
 
     private func shouldIgnore(view: UIView) -> Bool {

Tests/SentryTests/SentryViewPhotographerTests.swift

@@ -180,6 +180,21 @@ class SentryViewPhotographerTests: XCTestCase {
         assertColor(pixel2, .white)
     }
 
+    func testSkipSameRegion() throws {
+        let label1 = UILabel(frame: CGRect(x: 0, y: 0, width: 50, height: 25))
+        label1.text = "Test"
+        label1.textColor = .red
+
+        let label2 = UILabel(frame: CGRect(x: 0, y: 0, width: 50, height: 25))
+        label2.text = "Test"
+        label2.textColor = .green
+
+        let image = try XCTUnwrap(prepare(views: [label1, label2]))
+        let pixel1 = color(at: CGPoint(x: 10, y: 10), in: image)
+
+        assertColor(pixel1, .green)
+    }
+
     private func assertColor(_ color1: UIColor, _ color2: UIColor) {
         let sRGBColor1 = color1.cgColor.converted(to: CGColorSpace(name: CGColorSpace.sRGB)!, intent: .defaultIntent, options: nil)
         let sRGBColor2 = color2.cgColor.converted(to: CGColorSpace(name: CGColorSpace.sRGB)!, intent: .defaultIntent, options: nil)