From d38bb1212588ead1bd320f4763b3bc90409208f1 Mon Sep 17 00:00:00 2001
From: Luke De Feo <lukedefeo@meta.com>
Date: Fri, 2 Feb 2024 02:51:04 -0800
Subject: [PATCH] Use curtains to get phone window from decor view

Summary:
The official api only let you access this window by going through a views activity, but if a doesn't belong to an activity there is no possible way without  reflection tricks.  Curtains is a nice library that does this reflection adn a lot of the other reflection hacks that the UIdebugger needs.

## The reason this is important

When snapshotting a dialog fragment  we were using pixel copy using tryCopyViaInternalSurface approach. The issue is this is the lowest level api and doesnt consider 'surface insets' Surface insets seems to be related to the fact that a surface may be bigger than the content it draws.  This ended up manifesting like this

{F1372530065}

the issue is we create a bitmap sized to the decor view, but we were snapshotting the whole surface which is actually a bit bigger due to the black bars / surface insets.

When you pass a android.view.Window to pixel copy it has code to account for the surface insets. https://cs.android.com/android/platform/superproject/main/+/main:frameworks/base/graphics/java/android/view/PixelCopy.java;l=291;drc=228276a74bc36e8c0f0fadbb4a15ef013ff6ce24

Before we couldn't pass a window for dialogs since there was no activity to provide it, now curtains gives us this window and we can use the high level api in pxiel copy that does the right thing w.r.t surface insets

Reviewed By: passy

Differential Revision: D53090570

fbshipit-source-id: 969695198cfa5b848238e734d6ddec29681930e5
---
 android/build.gradle                            |  1 +
 .../flipper/plugins/uidebugger/core/Snapshot.kt | 17 +++++++++--------
 build.gradle                                    |  1 +
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/android/build.gradle b/android/build.gradle
index 763ebccef18..70264e3b7ae 100644
--- a/android/build.gradle
+++ b/android/build.gradle
@@ -76,6 +76,7 @@ android {
         implementation deps.openssl
         implementation deps.fbjni
         implementation deps.soloader
+        implementation deps.curtains
         implementation deps.jsr305
         implementation deps.supportAppCompat
         implementation deps.supportSqlite
diff --git a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/Snapshot.kt b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/Snapshot.kt
index dc4f6b9fb49..51102e1a27a 100644
--- a/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/Snapshot.kt
+++ b/android/src/main/java/com/facebook/flipper/plugins/uidebugger/core/Snapshot.kt
@@ -7,7 +7,6 @@
 
 package com.facebook.flipper.plugins.uidebugger.core
 
-import android.app.Activity
 import android.graphics.Canvas
 import android.os.Build
 import android.os.Handler
@@ -17,6 +16,7 @@ import android.view.PixelCopy
 import android.view.View
 import androidx.annotation.RequiresApi
 import com.facebook.flipper.plugins.uidebugger.LogTag
+import curtains.phoneWindow
 import kotlin.coroutines.Continuation
 import kotlin.coroutines.resume
 import kotlin.coroutines.suspendCoroutine
@@ -92,25 +92,26 @@ class PixelCopySnapshotter(
 
     return if (view.isHardwareAccelerated) {
       SnapshotCommon.doSnapshotWithErrorHandling(bitmapPool, view, fallback) {
-        tryCopyViaActivityWindow(view, it) || tryCopyViaInternalSurface(view, it)
+        tryCopyViaPhoneWindow(view, it) || tryCopyViaInternalSurface(view, it)
       }
     } else {
       fallback.takeSnapshot(view)
     }
   }
 
-  private suspend fun tryCopyViaActivityWindow(
+  /**
+   * This is the preferred method, passing a window into pixel copy correctly accounts for the
+   * surface insets, this means dialog fragments are snapshotted correctly
+   */
+  private suspend fun tryCopyViaPhoneWindow(
       view: View,
       bitmap: BitmapPool.ReusableBitmap
   ): Boolean {
 
-    val decorViewToActivity: Map<View, Activity> = ActivityTracker.decorViewToActivityMap
-
-    val activityForDecorView = decorViewToActivity[view] ?: return false
+    val window = view.phoneWindow ?: return false
 
     return suspendCoroutine { continuation ->
-      PixelCopy.request(
-          activityForDecorView.window, bitmap.bitmap, pixelCopyCallback(continuation), handler)
+      PixelCopy.request(window, bitmap.bitmap, pixelCopyCallback(continuation), handler)
     }
   }
 
diff --git a/build.gradle b/build.gradle
index a0e016e7470..e1c92cdccc9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -78,6 +78,7 @@ ext.deps = [
         fbjni              : "com.facebook.fbjni:fbjni:$FBJNI_VERSION",
         screenshot         : 'com.facebook.testing.screenshot:core:0.15.0',
         boltsTasks         : 'com.parse.bolts:bolts-tasks:1.4.0',
+        curtains           : 'com.squareup.curtains:curtains:1.2.5',
         // Third-party
         websocket          : 'org.java-websocket:Java-WebSocket:1.5.4',
         openssl            : 'com.android.ndk.thirdparty:openssl:1.1.1l-beta-1',