fix(android): speed up helper captures on animating apps and wait for the window list

android/snapshot-helper/src/main/java/com/callstack/agentdevice/snapshothelper/AccessibilityNodeReads.java

@@ -0,0 +1,34 @@
+package com.callstack.agentdevice.snapshothelper;
+
+import android.os.Build;
+import android.view.accessibility.AccessibilityNodeInfo;
+import android.view.accessibility.AccessibilityWindowInfo;
+
+/**
+ * Reads window roots and children from the app with uninterruptible descendant prefetch.
+ *
+ * <p>Every read that misses the connection cache is a round trip served on the app's main thread
+ * after the frame it is drawing, so on an app that never stops animating each miss costs about a
+ * frame. Of the prefetch strategies, uninterruptible depth-first traversed such an app fastest.
+ */
+final class AccessibilityNodeReads {
+  private static final int PREFETCH_STRATEGY =
+      AccessibilityNodeInfo.FLAG_PREFETCH_DESCENDANTS_DEPTH_FIRST
+          | AccessibilityNodeInfo.FLAG_PREFETCH_UNINTERRUPTIBLE;
+
+  private AccessibilityNodeReads() {}
+
+  static AccessibilityNodeInfo root(AccessibilityWindowInfo window) {
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+      return window.getRoot(PREFETCH_STRATEGY);
+    }
+    return window.getRoot();
+  }
+
+  static AccessibilityNodeInfo child(AccessibilityNodeInfo node, int index) {
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+      return node.getChild(index, PREFETCH_STRATEGY);
+    }
+    return node.getChild(index);
+  }
+}

android/snapshot-helper/src/main/java/com/callstack/agentdevice/snapshothelper/AccessibilityTreeCapture.java

@@ -10,6 +10,8 @@
 
 /** Captures and serializes the Android accessibility window tree. */
 final class AccessibilityTreeCapture {
+  private static final long WINDOW_LIST_SETTLE_TIMEOUT_MS = 1_000;
+
   private AccessibilityTreeCapture() {}
 
   static Result capture(
@@ -98,23 +100,59 @@ private static void clearAccessibilityCacheViaServiceInfo(UiAutomation automatio
     }
   }
 
-  static void enableInteractiveWindowRetrieval(UiAutomation automation) {
+  /**
+   * Turns on interactive-window retrieval and, when this call turned it on, waits a bounded time for
+   * the window list to name an active window. The platform fills the list after the flag is set, so
+   * a read straight after it can list only the status bar and none of the app's windows.
+   */
+  static void enableInteractiveWindowRetrieval(UiAutomation automation)
+      throws InterruptedException {
+    if (!turnOnInteractiveWindowRetrieval(automation)) {
+      return;
+    }
+    try {
+      AccessibilityCaptureStabilizer.capture(
+          () -> () -> listsActiveWindow(automation), WINDOW_LIST_SETTLE_TIMEOUT_MS);
+    } catch (AccessibilityCaptureStabilizer.IncompleteCaptureException ignored) {
+      // Capture what the platform lists; the host judges whether it holds the app.
+    }
+  }
+
+  private static boolean turnOnInteractiveWindowRetrieval(UiAutomation automation) {
     AccessibilityServiceInfo serviceInfo;
     try {
       serviceInfo = automation.getServiceInfo();
     } catch (RuntimeException error) {
-      return;
+      return false;
     }
     if (serviceInfo == null
         || (serviceInfo.flags & AccessibilityServiceInfo.FLAG_RETRIEVE_INTERACTIVE_WINDOWS) != 0) {
-      return;
+      return false;
     }
     serviceInfo.flags |= AccessibilityServiceInfo.FLAG_RETRIEVE_INTERACTIVE_WINDOWS;
     try {
       automation.setServiceInfo(serviceInfo);
+      return true;
     } catch (RuntimeException ignored) {
       // Fall back to active-window capture if the platform rejects dynamic service flags.
+      return false;
+    }
+  }
+
+  @SuppressWarnings("deprecation")
+  private static boolean listsActiveWindow(UiAutomation automation) {
+    List<AccessibilityWindowInfo> windows;
+    try {
+      windows = automation.getWindows();
+    } catch (RuntimeException error) {
+      return false;
+    }
+    boolean active = false;
+    for (AccessibilityWindowInfo window : windows) {
+      active |= isActiveWindow(window);
+      window.recycle();
     }
+    return active;
   }
 
   @SuppressWarnings("deprecation")
@@ -144,7 +182,7 @@ private static int appendInteractiveWindowRoots(
       AccessibilityTreeXml.WindowMetadata windowMetadata = null;
       try {
         windowMetadata = AccessibilityTreeXml.readWindowMetadata(window, windowCount);
-        root = window.getRoot();
+        root = AccessibilityNodeReads.root(window);
         if (root == null) {
           missingRootWindowTypes.add(windowMetadata.type);
           stats.activeWindowRootMissing |= activeWindow;

android/snapshot-helper/src/main/java/com/callstack/agentdevice/snapshothelper/AccessibilityTreeXml.java

@@ -117,7 +117,7 @@ static void appendNode(
         stats.truncated = true;
         break;
       }
-      AccessibilityNodeInfo child = node.getChild(index);
+      AccessibilityNodeInfo child = AccessibilityNodeReads.child(node, index);
       if (child == null) {
         continue;
       }

android/snapshot-helper/src/main/java/com/callstack/agentdevice/snapshothelper/GestureViewportReader.java

@@ -58,7 +58,7 @@ Rect toRect() {
   }
 
   @SuppressWarnings("deprecation")
-  static Reading readReading(UiAutomation automation) {
+  static Reading readReading(UiAutomation automation) throws InterruptedException {
     try {
       automation.waitForIdle(100, 2_000);
     } catch (TimeoutException ignored) {
@@ -138,10 +138,6 @@ static WindowEdges struckInputMethod(List<WindowEdges> inputMethodWindows, Windo
     return struck;
   }
 
-  static Rect read(UiAutomation automation) {
-    return readReading(automation).application;
-  }
-
   private static Rect resolveApplication(
       UiAutomation automation, Rect activeBounds, Rect fallbackBounds) {
     if (activeBounds != null) return activeBounds;

android/snapshot-helper/src/main/java/com/callstack/agentdevice/snapshothelper/SnapshotInstrumentation.java

@@ -147,7 +147,7 @@ private static void putCaptureMetadata(
     }
   }
 
-  private void runOneShotViewport(Bundle result) {
+  private void runOneShotViewport(Bundle result) throws InterruptedException {
     TouchCommandHandler.populateViewport(result, getConnectedUiAutomationUnchecked());
     finishSafely(0, result);
   }

android/snapshot-helper/src/main/java/com/callstack/agentdevice/snapshothelper/TouchCommandHandler.java

@@ -14,7 +14,8 @@
 final class TouchCommandHandler {
   private TouchCommandHandler() {}
 
-  static void populateViewport(Bundle result, UiAutomation automation) {
+  static void populateViewport(Bundle result, UiAutomation automation)
+      throws InterruptedException {
     GestureViewportReader.Reading reading = GestureViewportReader.readReading(automation);
     result.putString("ok", "true");
     result.putString("kind", "viewport");