Detach from GL context before attaching (flutter#31390)

Author: Emmanuel Garcia

shell/platform/android/io/flutter/embedding/engine/renderer/SurfaceTextureWrapper.java

@@ -19,6 +19,7 @@
 public class SurfaceTextureWrapper {
   private SurfaceTexture surfaceTexture;
   private boolean released;
+  private boolean attached;
 
   public SurfaceTextureWrapper(@NonNull SurfaceTexture surfaceTexture) {
     this.surfaceTexture = surfaceTexture;
@@ -45,6 +46,7 @@ public void release() {
       if (!released) {
         surfaceTexture.release();
         released = true;
+        attached = false;
       }
     }
   }
@@ -53,16 +55,33 @@ public void release() {
   @SuppressWarnings("unused")
   public void attachToGLContext(int texName) {
     synchronized (this) {
-      if (!released) {
-        surfaceTexture.attachToGLContext(texName);
+      if (released) {
+        return;
+      }
+      // When the rasterizer tasks run on a different thread, the GrContext is re-created.
+      // This causes the texture to be in an uninitialized state.
+      // This should *not* be an issue once platform views are always rendered as TextureLayers
+      // since thread merging will be always disabled on Android.
+      // For more see: AndroidExternalTextureGL::OnGrContextCreated in
+      // android_external_texture_gl.cc, and
+      // https://github.com/flutter/flutter/issues/98155
+      if (attached) {
+        surfaceTexture.detachFromGLContext();
       }
+      surfaceTexture.attachToGLContext(texName);
+      attached = true;
     }
   }
 
   // Called by native.
   @SuppressWarnings("unused")
   public void detachFromGLContext() {
-    surfaceTexture.detachFromGLContext();
+    synchronized (this) {
+      if (attached && !released) {
+        surfaceTexture.detachFromGLContext();
+        attached = false;
+      }
+    }
   }
 
   // Called by native.

shell/platform/android/test/io/flutter/embedding/engine/renderer/SurfaceTextureWrapperTest.java

@@ -0,0 +1,82 @@
+package io.flutter.embedding.engine.renderer;
+
+import static junit.framework.TestCase.*;
+import static org.mockito.Mockito.*;
+
+import android.graphics.SurfaceTexture;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+public class SurfaceTextureWrapperTest {
+
+  @Test
+  public void attachToGLContext() {
+    final SurfaceTexture tx = mock(SurfaceTexture.class);
+    final SurfaceTextureWrapper wrapper = new SurfaceTextureWrapper(tx);
+
+    wrapper.attachToGLContext(0);
+    verify(tx, times(1)).attachToGLContext(0);
+    verifyNoMoreInteractions(tx);
+  }
+
+  @Test
+  public void attachToGLContext_detachesFromCurrentContext() {
+    final SurfaceTexture tx = mock(SurfaceTexture.class);
+    final SurfaceTextureWrapper wrapper = new SurfaceTextureWrapper(tx);
+
+    wrapper.attachToGLContext(0);
+
+    reset(tx);
+
+    wrapper.attachToGLContext(0);
+    verify(tx, times(1)).detachFromGLContext();
+    verify(tx, times(1)).attachToGLContext(0);
+    verifyNoMoreInteractions(tx);
+  }
+
+  @Test
+  public void attachToGLContext_doesNotDetacheFromCurrentContext() {
+    final SurfaceTexture tx = mock(SurfaceTexture.class);
+    final SurfaceTextureWrapper wrapper = new SurfaceTextureWrapper(tx);
+
+    wrapper.attachToGLContext(0);
+
+    wrapper.detachFromGLContext();
+
+    reset(tx);
+
+    wrapper.attachToGLContext(0);
+    verify(tx, times(1)).attachToGLContext(0);
+    verifyNoMoreInteractions(tx);
+  }
+
+  @Test
+  public void detachFromGLContext() {
+    final SurfaceTexture tx = mock(SurfaceTexture.class);
+    final SurfaceTextureWrapper wrapper = new SurfaceTextureWrapper(tx);
+
+    wrapper.attachToGLContext(0);
+    reset(tx);
+
+    wrapper.detachFromGLContext();
+    verify(tx, times(1)).detachFromGLContext();
+    verifyNoMoreInteractions(tx);
+  }
+
+  @Test
+  public void release() {
+    final SurfaceTexture tx = mock(SurfaceTexture.class);
+    final SurfaceTextureWrapper wrapper = new SurfaceTextureWrapper(tx);
+
+    wrapper.release();
+
+    verify(tx, times(1)).release();
+    reset(tx);
+
+    wrapper.detachFromGLContext();
+    wrapper.attachToGLContext(0);
+    verifyNoMoreInteractions(tx);
+  }
+}