From 3a7b283bb3bbcb8d9f66fc9facaae80895c78887 Mon Sep 17 00:00:00 2001
From: Emmanuel Garcia <egarciad@google.com>
Date: Tue, 15 Sep 2020 14:10:55 -0700
Subject: [PATCH] Account for current open image in FlutterImageView
 (flutter/engine#21191)

---
 .../embedding/android/FlutterImageView.java   |  6 +++-
 .../embedding/android/FlutterViewTest.java    | 32 +++++++++++++++----
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterImageView.java b/engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterImageView.java
index 7482c1f398e..85f3ce4c273 100644
--- a/engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterImageView.java
+++ b/engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterImageView.java
@@ -195,7 +195,11 @@ public class FlutterImageView extends View implements RenderSurface {
     // While the engine will also stop producing frames, there is a race condition.
     //
     // To avoid exceptions, check if a new image can be acquired.
-    if (imageQueue.size() < imageReader.getMaxImages()) {
+    int imageOpenedCount = imageQueue.size();
+    if (currentImage != null) {
+      imageOpenedCount++;
+    }
+    if (imageOpenedCount < imageReader.getMaxImages()) {
       final Image image = imageReader.acquireLatestImage();
       if (image != null) {
         imageQueue.add(image);
diff --git a/engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterViewTest.java b/engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterViewTest.java
index ccafbc1c160..204799d3618 100644
--- a/engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterViewTest.java
+++ b/engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterViewTest.java
@@ -590,11 +590,13 @@ public class FlutterViewTest {
   }
 
   @Test
+  @SuppressLint("WrongCall") /*View#onDraw*/
   public void flutterImageView_acquiresMaxImagesAtMost() {
     final ImageReader mockReader = mock(ImageReader.class);
-    when(mockReader.getMaxImages()).thenReturn(2);
+    when(mockReader.getMaxImages()).thenReturn(3);
 
     final Image mockImage = mock(Image.class);
+    when(mockImage.getPlanes()).thenReturn(new Plane[0]);
     when(mockReader.acquireLatestImage()).thenReturn(mockImage);
 
     final FlutterImageView imageView =
@@ -606,13 +608,31 @@ public class FlutterViewTest {
 
     final FlutterJNI jni = mock(FlutterJNI.class);
     imageView.attachToRenderer(new FlutterRenderer(jni));
-
     doNothing().when(imageView).invalidate();
-    assertTrue(imageView.acquireLatestImage());
-    assertTrue(imageView.acquireLatestImage());
-    assertTrue(imageView.acquireLatestImage());
 
-    verify(mockReader, times(2)).acquireLatestImage();
+    assertTrue(imageView.acquireLatestImage()); // 1 image
+    assertTrue(imageView.acquireLatestImage()); // 2 images
+    assertTrue(imageView.acquireLatestImage()); // 3 images
+    assertTrue(imageView.acquireLatestImage()); // 3 images
+    verify(mockReader, times(3)).acquireLatestImage();
+
+    imageView.onDraw(mock(Canvas.class)); // 3 images
+    assertTrue(imageView.acquireLatestImage()); // 3 images
+    verify(mockReader, times(3)).acquireLatestImage();
+
+    imageView.onDraw(mock(Canvas.class)); // 2 images
+    assertTrue(imageView.acquireLatestImage()); // 3 images
+    verify(mockReader, times(4)).acquireLatestImage();
+
+    imageView.onDraw(mock(Canvas.class)); // 2 images
+    imageView.onDraw(mock(Canvas.class)); // 1 image
+    imageView.onDraw(mock(Canvas.class)); // 1 image
+
+    assertTrue(imageView.acquireLatestImage()); // 2 images
+    assertTrue(imageView.acquireLatestImage()); // 3 images
+    assertTrue(imageView.acquireLatestImage()); // 3 images
+    assertTrue(imageView.acquireLatestImage()); // 3 images
+    verify(mockReader, times(6)).acquireLatestImage();
   }
 
   @Test