Increase frame capture quality, apply scaling after DPI normalization

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/inspector/FrameTimingsObserver.kt

@@ -38,12 +38,35 @@ internal class FrameTimingsObserver(
 
   @Volatile private var currentWindow: Window? = null
 
-  private val frameMetricsListener =
-      Window.OnFrameMetricsAvailableListener { _, frameMetrics, _dropCount ->
-        val beginTimestamp = frameMetrics.getMetric(FrameMetrics.VSYNC_TIMESTAMP)
-        val endTimestamp = beginTimestamp + frameMetrics.getMetric(FrameMetrics.TOTAL_DURATION)
-        emitFrameTiming(beginTimestamp, endTimestamp)
-      }
+  fun start() {
+    if (!isSupported) {
+      return
+    }
+
+    frameCounter = 0
+    isStarted = true
+
+    // Capture initial screenshot to ensure there's always at least one frame
+    // recorded at the start of tracing, even if no UI changes occur
+    val timestamp = System.nanoTime()
+    emitFrameTiming(timestamp, timestamp)
+
+    currentWindow?.addOnFrameMetricsAvailableListener(frameMetricsListener, handler)
+  }
+
+  fun stop() {
+    if (!isSupported) {
+      return
+    }
+
+    isStarted = false
+
+    currentWindow?.removeOnFrameMetricsAvailableListener(frameMetricsListener)
+    handler.removeCallbacksAndMessages(null)
+
+    bitmapBuffer?.recycle()
+    bitmapBuffer = null
+  }
 
   fun setCurrentWindow(window: Window?) {
     if (!isSupported || currentWindow === window) {
@@ -57,6 +80,32 @@ internal class FrameTimingsObserver(
     }
   }
 
+  private val frameMetricsListener =
+      Window.OnFrameMetricsAvailableListener { _, frameMetrics, _ ->
+        val beginTimestamp = frameMetrics.getMetric(FrameMetrics.VSYNC_TIMESTAMP)
+        val endTimestamp = beginTimestamp + frameMetrics.getMetric(FrameMetrics.TOTAL_DURATION)
+        emitFrameTiming(beginTimestamp, endTimestamp)
+      }
+
+  private fun emitFrameTiming(beginTimestamp: Long, endTimestamp: Long) {
+    val frameId = frameCounter++
+    val threadId = Process.myTid()
+
+    CoroutineScope(Dispatchers.Default).launch {
+      val screenshot = if (screenshotsEnabled) captureScreenshot() else null
+
+      onFrameTimingSequence(
+          FrameTimingSequence(
+              frameId,
+              threadId,
+              beginTimestamp,
+              endTimestamp,
+              screenshot,
+          )
+      )
+    }
+  }
+
   private suspend fun captureScreenshot(): String? = suspendCoroutine { continuation ->
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
       continuation.resume(null)
@@ -75,14 +124,11 @@ internal class FrameTimingsObserver(
 
     // Reuse bitmap if dimensions haven't changed
     val bitmap =
-        bitmapBuffer?.let {
-          if (it.width == width && it.height == height) {
-            it
-          } else {
-            it.recycle()
-            null
-          }
-        } ?: Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888).also { bitmapBuffer = it }
+        bitmapBuffer?.takeIf { it.width == width && it.height == height }
+            ?: run {
+              bitmapBuffer?.recycle()
+              Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888).also { bitmapBuffer = it }
+            }
 
     PixelCopy.request(
         window,
@@ -92,19 +138,19 @@ internal class FrameTimingsObserver(
             CoroutineScope(Dispatchers.Default).launch {
               var scaledBitmap: Bitmap? = null
               try {
-                val scaleFactor = 0.25f
-                val scaledWidth = (width * scaleFactor).toInt()
-                val scaledHeight = (height * scaleFactor).toInt()
+                val density = window.context.resources.displayMetrics.density
+                val scaledWidth = (width / density * SCREENSHOT_SCALE_FACTOR).toInt()
+                val scaledHeight = (height / density * SCREENSHOT_SCALE_FACTOR).toInt()
                 scaledBitmap = Bitmap.createScaledBitmap(bitmap, scaledWidth, scaledHeight, true)
 
                 val compressFormat =
                     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R)
                         Bitmap.CompressFormat.WEBP_LOSSY
-                    else Bitmap.CompressFormat.WEBP
+                    else Bitmap.CompressFormat.JPEG
 
                 val base64 =
                     ByteArrayOutputStream().use { outputStream ->
-                      scaledBitmap.compress(compressFormat, 0, outputStream)
+                      scaledBitmap.compress(compressFormat, SCREENSHOT_QUALITY, outputStream)
                       Base64.encodeToString(outputStream.toByteArray(), Base64.NO_WRAP)
                     }
 
@@ -123,52 +169,8 @@ internal class FrameTimingsObserver(
     )
   }
 
-  fun start() {
-    if (!isSupported) {
-      return
-    }
-
-    frameCounter = 0
-    isStarted = true
-
-    // Capture initial screenshot to ensure there's always at least one frame
-    // recorded at the start of tracing, even if no UI changes occur
-    val timestamp = System.nanoTime()
-    emitFrameTiming(timestamp, timestamp)
-
-    currentWindow?.addOnFrameMetricsAvailableListener(frameMetricsListener, handler)
-  }
-
-  private fun emitFrameTiming(beginTimestamp: Long, endTimestamp: Long) {
-    val frameId = frameCounter++
-    val threadId = Process.myTid()
-
-    CoroutineScope(Dispatchers.Default).launch {
-      val screenshot = if (screenshotsEnabled) captureScreenshot() else null
-
-      onFrameTimingSequence(
-          FrameTimingSequence(
-              frameId,
-              threadId,
-              beginTimestamp,
-              endTimestamp,
-              screenshot,
-          )
-      )
-    }
-  }
-
-  fun stop() {
-    if (!isSupported) {
-      return
-    }
-
-    isStarted = false
-
-    currentWindow?.removeOnFrameMetricsAvailableListener(frameMetricsListener)
-    handler.removeCallbacksAndMessages(null)
-
-    bitmapBuffer?.recycle()
-    bitmapBuffer = null
+  companion object {
+    private const val SCREENSHOT_SCALE_FACTOR = 0.75f
+    private const val SCREENSHOT_QUALITY = 80
   }
 }