Remove context assertion from Android platform views using Virtual Display (flutter#35997)

Author: stuartmorgan-g

shell/platform/android/io/flutter/plugin/platform/SingleViewPresentation.java

@@ -53,6 +53,7 @@
 @Keep
 @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
 class SingleViewPresentation extends Presentation {
+  private static final String TAG = "PlatformViewsController";
 
   /*
    * When an embedded view is resized in Flutterverse we move the Android view to a new virtual display
@@ -184,10 +185,20 @@ protected void onCreate(Bundle savedInstanceState) {
       MutableContextWrapper currentContext = (MutableContextWrapper) embeddedView.getContext();
       currentContext.setBaseContext(baseContext);
     } else {
-      throw new IllegalStateException(
-          "Unexpected platform view context. "
-              + "When constructing a platform view in the factory, use the context from PlatformViewFactory#create, view id: "
-              + viewId);
+      // In some cases, such as when using LayoutInflator, the original context
+      // may not be preserved. For backward compatibility with previous
+      // implementations of Virtual Display, which didn't validate the context,
+      // continue, but log a warning indicating that some functionality may not
+      // work as expected.
+      // See https://github.com/flutter/flutter/issues/110146 for context.
+      Log.w(
+          TAG,
+          "Unexpected platform view context for view ID "
+              + viewId
+              + "; some functionality may not work correctly. When constructing a platform view "
+              + "in the factory, ensure that the view returned from PlatformViewFactory#create "
+              + "returns the provided context from getContext(). If you are unable to associate "
+              + "the view with that context, consider using Hybrid Composition instead.");
     }
 
     container.addView(embeddedView);

testing/scenario_app/android/BUILD.gn

@@ -13,6 +13,7 @@ _android_sources = [
   "app/src/androidTest/java/dev/flutter/scenariosui/MemoryLeakTests.java",
   "app/src/androidTest/java/dev/flutter/scenariosui/PlatformTextureUiTests.java",
   "app/src/androidTest/java/dev/flutter/scenariosui/PlatformViewUiTests.java",
+  "app/src/androidTest/java/dev/flutter/scenariosui/PlatformViewWithSurfaceViewBadContextUiTest.java",
   "app/src/androidTest/java/dev/flutter/scenariosui/PlatformViewWithSurfaceViewUiTest.java",
   "app/src/androidTest/java/dev/flutter/scenariosui/PlatformViewWithTextureViewUiTest.java",
   "app/src/androidTest/java/dev/flutter/scenariosui/ScreenshotUtil.java",

testing/scenario_app/android/app/src/androidTest/java/dev/flutter/scenariosui/PlatformViewWithSurfaceViewBadContextUiTest.java

@@ -0,0 +1,45 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dev.flutter.scenariosui;
+
+import android.content.Intent;
+import androidx.annotation.NonNull;
+import androidx.test.filters.LargeTest;
+import androidx.test.rule.ActivityTestRule;
+import androidx.test.runner.AndroidJUnit4;
+import dev.flutter.scenarios.PlatformViewsActivity;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+@LargeTest
+public class PlatformViewWithSurfaceViewBadContextUiTest {
+  Intent intent;
+
+  @Rule @NonNull
+  public ActivityTestRule<PlatformViewsActivity> activityRule =
+      new ActivityTestRule<>(
+          PlatformViewsActivity.class, /*initialTouchMode=*/ false, /*launchActivity=*/ false);
+
+  private static String goldName(String suffix) {
+    return "PlatformViewWithSurfaceViewBadContextUiTest_" + suffix;
+  }
+
+  @Before
+  public void setUp() {
+    intent = new Intent(Intent.ACTION_MAIN);
+    // Render a texture.
+    intent.putExtra("use_android_view", false);
+    intent.putExtra("view_type", PlatformViewsActivity.SURFACE_VIEW_BAD_CONTEXT_PV);
+  }
+
+  @Test
+  public void testPlatformView() throws Exception {
+    intent.putExtra("scenario_name", "platform_view");
+    ScreenshotUtil.capture(activityRule.launchActivity(intent), goldName("testPlatformView"));
+  }
+}

testing/scenario_app/android/app/src/main/java/dev/flutter/scenarios/PlatformViewsActivity.java

@@ -8,8 +8,12 @@
 import io.flutter.embedding.engine.FlutterEngine;
 
 public class PlatformViewsActivity extends TestActivity {
+  // WARNING: These strings must all be exactly the same length to avoid
+  // breaking the 'create' method's manual encoding in the test. See the
+  // TODO(stuartmorgan) about encoding alignment in platform_view.dart
   public static final String TEXT_VIEW_PV = "scenarios/textPlatformView";
   public static final String SURFACE_VIEW_PV = "scenarios/surfacePlatformV";
+  public static final String SURFACE_VIEW_BAD_CONTEXT_PV = "scenarios/surfaceVBadCntxt";
   public static final String TEXTURE_VIEW_PV = "scenarios/texturePlatformV";
 
   @Override
@@ -23,7 +27,12 @@ public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
     flutterEngine
         .getPlatformViewsController()
         .getRegistry()
-        .registerViewFactory(SURFACE_VIEW_PV, new SurfacePlatformViewFactory());
+        .registerViewFactory(SURFACE_VIEW_PV, new SurfacePlatformViewFactory(true));
+
+    flutterEngine
+        .getPlatformViewsController()
+        .getRegistry()
+        .registerViewFactory(SURFACE_VIEW_BAD_CONTEXT_PV, new SurfacePlatformViewFactory(false));
 
     flutterEngine
         .getPlatformViewsController()

testing/scenario_app/android/app/src/main/java/dev/flutter/scenarios/SurfacePlatformViewFactory.java

@@ -6,6 +6,7 @@
 
 import android.annotation.TargetApi;
 import android.content.Context;
+import android.content.ContextWrapper;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
@@ -24,7 +25,9 @@
 
 @TargetApi(23)
 public final class SurfacePlatformViewFactory extends PlatformViewFactory {
-  SurfacePlatformViewFactory() {
+  private boolean preserveContext;
+
+  SurfacePlatformViewFactory(boolean preserveContext) {
     super(
         new MessageCodec<Object>() {
           @Nullable
@@ -42,13 +45,19 @@ public Object decodeMessage(@Nullable ByteBuffer byteBuffer) {
             return StringCodec.INSTANCE.decodeMessage(byteBuffer);
           }
         });
+    this.preserveContext = preserveContext;
   }
 
   @SuppressWarnings("unchecked")
   @Override
   @NonNull
   public PlatformView create(@NonNull Context context, int id, @Nullable Object args) {
-    return new SurfacePlatformView(context);
+    if (preserveContext) {
+      return new SurfacePlatformView(context);
+    } else {
+      final Context differentContext = new ContextWrapper(context);
+      return new SurfacePlatformView(differentContext);
+    }
   }
 
   private static class SurfacePlatformView implements PlatformView {

testing/scenario_app/lib/src/platform_view.dart

@@ -1144,6 +1144,11 @@ void addPlatformView(
       valueString,
       'width'.length,
       ...utf8.encode('width'),
+      // This is missing the 64-bit boundary alignment, making the entire
+      // message encoding fragile to changes before this point. Do not add new
+      // variable-length values such as strings before this point.
+      // TODO(stuartmorgan): Fix this to use the actual encoding logic,
+      // including alignment: https://github.com/flutter/flutter/issues/111188
       valueFloat64,
       ..._to64(width),
       valueString,