From 065769e2e5c44dc68202d175b16753fb3397d71d Mon Sep 17 00:00:00 2001
From: Jason Simmons <jason-simmons@users.noreply.github.com>
Date: Wed, 10 Oct 2018 15:01:48 -0700
Subject: [PATCH] Use an older version of
 SurfaceTexture.setOnFrameAvailableListener when running on pre-Lollipop
 devices (flutter/engine#6489)

Fixes https://github.com/flutter/flutter/issues/21730
---
 .../android/io/flutter/view/FlutterView.java  | 41 +++++++++++--------
 1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/engine/src/flutter/shell/platform/android/io/flutter/view/FlutterView.java b/engine/src/flutter/shell/platform/android/io/flutter/view/FlutterView.java
index 072a5b462a..fe7002c3be 100644
--- a/engine/src/flutter/shell/platform/android/io/flutter/view/FlutterView.java
+++ b/engine/src/flutter/shell/platform/android/io/flutter/view/FlutterView.java
@@ -1041,24 +1041,33 @@ public class FlutterView extends SurfaceView
         SurfaceTextureRegistryEntry(long id, SurfaceTexture surfaceTexture) {
             this.id = id;
             this.surfaceTexture = surfaceTexture;
-            this.surfaceTexture.setOnFrameAvailableListener(new SurfaceTexture.OnFrameAvailableListener() {
-                @Override
-                public void onFrameAvailable(SurfaceTexture texture) {
-                    if (released) {
-                        // Even though we make sure to unregister the callback before releasing, as of Android O
-                        // SurfaceTexture has a data race when accessing the callback, so the callback may
-                        // still be called by a stale reference after released==true and mNativeView==null.
-                        return;
-                    }
-                    nativeMarkTextureFrameAvailable(mNativeView.get(), SurfaceTextureRegistryEntry.this.id);
-                }
-            },
-            // The callback relies on being executed on the UI thread (unsynchronised read of mNativeView
-            // and also the engine code check for platform thread in Shell::OnPlatformViewMarkTextureFrameAvailable),
-            // so we explicitly pass a Handler for the current thread.
-            new Handler());
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+                // The callback relies on being executed on the UI thread (unsynchronised read of mNativeView
+                // and also the engine code check for platform thread in Shell::OnPlatformViewMarkTextureFrameAvailable),
+                // so we explicitly pass a Handler for the current thread.
+                this.surfaceTexture.setOnFrameAvailableListener(onFrameListener, new Handler());
+            } else {
+                // Android documentation states that the listener can be called on an arbitrary thread.
+                // But in practice, versions of Android that predate the newer API will call the listener
+                // on the thread where the SurfaceTexture was constructed.
+                this.surfaceTexture.setOnFrameAvailableListener(onFrameListener);
+            }
         }
 
+        private SurfaceTexture.OnFrameAvailableListener onFrameListener = new SurfaceTexture.OnFrameAvailableListener() {
+            @Override
+            public void onFrameAvailable(SurfaceTexture texture) {
+                if (released) {
+                    // Even though we make sure to unregister the callback before releasing, as of Android O
+                    // SurfaceTexture has a data race when accessing the callback, so the callback may
+                    // still be called by a stale reference after released==true and mNativeView==null.
+                    return;
+                }
+                nativeMarkTextureFrameAvailable(mNativeView.get(), SurfaceTextureRegistryEntry.this.id);
+            }
+        };
+
         @Override
         public SurfaceTexture surfaceTexture() {
             return surfaceTexture;