From 1794616b35c9413096a3b3c64d5cd14580d653be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Mon, 17 Dec 2018 11:43:35 +0800
Subject: [PATCH 01/12] [macos] Add FLEEventChannel

---
 library/macos/FLEEventChannel.h               | 98 +++++++++++++++++++
 library/macos/FLEEventChannel.m               | 97 ++++++++++++++++++
 .../project.pbxproj                           |  8 ++
 3 files changed, 203 insertions(+)
 create mode 100644 library/macos/FLEEventChannel.h
 create mode 100644 library/macos/FLEEventChannel.m

diff --git a/library/macos/FLEEventChannel.h b/library/macos/FLEEventChannel.h
new file mode 100644
index 000000000..8c127443c
--- /dev/null
+++ b/library/macos/FLEEventChannel.h
@@ -0,0 +1,98 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import <Foundation/Foundation.h>
+
+#import "FLEBinaryMessenger.h"
+#import "FLEMethodCodec.h"
+
+/**
+ * An event sink callback.
+ *
+ * @param event The event.
+ */
+typedef void (^FLEEventSink)(id _Nullable event);
+/**
+ * A constant used with `FLEEventChannel` to indicate end of stream.
+ */
+extern NSObject const* FLEEndOfEventStream;
+/**
+ * A strategy for exposing an event stream to the Flutter side.
+ */
+@protocol FLEStreamHandler
+/**
+ * Sets up an event stream and begin emitting events.
+ *
+ * Invoked when the first listener is registered with the Stream associated to
+ * this channel on the Flutter side.
+ *
+ * @param arguments Arguments for the stream.
+ * @param events A callback to asynchronously emit events. Invoke the
+ *     callback with a `FLEMethodError` to emit an error event. Invoke the
+ *     callback with `FLEEndOfEventStream` to indicate that no more
+ *     events will be emitted. Any other value, including `nil` are emitted as
+ *     successful events.
+ * @return A FLEMethodError instance, if setup fails.
+ */
+- (FLEMethodError* _Nullable)onListenWithArguments:(id _Nullable)arguments
+                                       eventSink:(FLEEventSink)events;
+/**
+ * Tears down an event stream.
+ *
+ * Invoked when the last listener is deregistered from the Stream associated to
+ * this channel on the Flutter side.
+ *
+ * The channel implementation may call this method with `nil` arguments
+ * to separate a pair of two consecutive set up requests. Such request pairs
+ * may occur during Flutter hot restart.
+ *
+ * @param arguments Arguments for the stream.
+ * @return A FLEMethodError instance, if teardown fails.
+ */
+- (FLEMethodError* _Nullable)onCancelWithArguments:(id _Nullable)arguments;
+@end
+/**
+ * A channel for communicating with the Flutter side using event streams.
+ */
+@interface FLEEventChannel : NSObject
+/**
+ * Creates a `FLEEventChannel` with the specified name and binary messenger.
+ *
+ * The channel name logically identifies the channel; identically named channels
+ * interfere with each other's communication.
+ *
+ * The binary messenger is a facility for sending raw, binary messages to the
+ * Flutter side. This protocol is implemented by `FLEViewController`.
+ *
+ * The channel uses `FLEMethodCodec` to decode stream setup and
+ * teardown requests, and to encode event envelopes.
+ *
+ * @param name The channel name.
+ * @param messenger The binary messenger.
+ * @param codec The method codec.
+ */
++ (instancetype)eventChannelWithName:(nonnull NSString *)name
+                     binaryMessenger:(nonnull id<FLEBinaryMessenger>)messenger
+                               codec:(nonnull id<FLEMethodCodec>)codec;
+/**
+ * Registers a handler for stream setup requests from the Flutter side.
+ *
+ * Replaces any existing handler. Use a `nil` handler for unregistering the
+ * existing handler.
+ *
+ * @param handler The stream handler.
+ */
+- (void)setStreamHandler:(nullable id<FLEStreamHandler>)handler;
+@end
+
diff --git a/library/macos/FLEEventChannel.m b/library/macos/FLEEventChannel.m
new file mode 100644
index 000000000..19bcec07e
--- /dev/null
+++ b/library/macos/FLEEventChannel.m
@@ -0,0 +1,97 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "FLEEventChannel.h"
+
+NSObject const* FLEEndOfEventStream = @"EndOfEventStream";
+
+@implementation FLEEventChannel {
+    NSString* _name;
+    __weak id<FLEBinaryMessenger> _messenger;
+    id<FLEMethodCodec> _codec;
+}
+
++ (instancetype)eventChannelWithName:(nonnull NSString*)name
+                     binaryMessenger:(nonnull id<FLEBinaryMessenger>)messenger
+                               codec:(nonnull id<FLEMethodCodec>)codec {
+    return [[FLEEventChannel alloc] initWithName:name binaryMessenger:messenger codec:codec];
+}
+
+- (instancetype)initWithName:(nonnull NSString*)name
+             binaryMessenger:(nonnull id<FLEBinaryMessenger>)messenger
+                       codec:(nonnull id<FLEMethodCodec>)codec {
+    self = [super init];
+    NSAssert(self, @"Super init cannot be nil");
+    _name = name;
+    _messenger = messenger;
+    _codec = codec;
+    
+    return self;
+}
+
+- (void)setStreamHandler:(NSObject<FLEStreamHandler>*)handler {
+    if (!handler) {
+        [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:nil];
+        return;
+    }
+
+    id<FLEMethodCodec> codec = _codec;
+    __weak id<FLEBinaryMessenger> messenger =  _messenger;
+    NSString *channelName = _name;
+    
+    __block FLEEventSink currentSink = nil;
+    FLEBinaryMessageHandler messageHandler = ^(NSData* message, FLEBinaryReply callback) {
+        FLEMethodCall* call = [codec decodeMethodCall:message];
+        if ([call.methodName isEqual:@"listen"]) {
+            if (currentSink) {
+                FLEMethodError* error = [handler onCancelWithArguments:nil];
+                if (error)
+                    NSLog(@"Failed to cancel existing stream: %@. %@ (%@)", error.code, error.message,
+                          error.details);
+            }
+            currentSink = ^(id event) {
+                if (event == FLEEndOfEventStream)
+                    [messenger sendOnChannel:channelName message:nil];
+                else if ([event isKindOfClass:[FLEMethodError class]])
+                    [messenger sendOnChannel:channelName
+                                      message:[codec encodeErrorEnvelope:(FLEMethodError*)event]];
+                else
+                    [messenger sendOnChannel:channelName message:[codec encodeSuccessEnvelope:event]];
+            };
+            FLEMethodError* error = [handler onListenWithArguments:call.arguments eventSink:currentSink];
+            if (error)
+                callback([codec encodeErrorEnvelope:error]);
+            else
+                callback([codec encodeSuccessEnvelope:nil]);
+        } else if ([call.methodName isEqual:@"cancel"]) {
+            if (!currentSink) {
+                callback(
+                         [codec encodeErrorEnvelope:[[FLEMethodError alloc] initWithCode:@"error"
+                                                                                 message:@"No active stream to cancel"
+                                                                                 details:nil]]);
+                return;
+            }
+            currentSink = nil;
+            FLEMethodError* error = [handler onCancelWithArguments:call.arguments];
+            if (error)
+                callback([codec encodeErrorEnvelope:error]);
+            else
+                callback([codec encodeSuccessEnvelope:nil]);
+        } else {
+            callback(nil);
+        }
+    };
+    [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:messageHandler];
+}
+@end
diff --git a/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj b/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj
index 0b730ac53..2b1896191 100644
--- a/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj
+++ b/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj
@@ -30,6 +30,8 @@
 		1E2492411FCF50BE00DD3BBB /* FlutterEmbedderMac.h in Headers */ = {isa = PBXBuildFile; fileRef = 1E2492371FCF50BE00DD3BBB /* FlutterEmbedderMac.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		1EEF8E071FD1F0C300DD563C /* FLEView.h in Headers */ = {isa = PBXBuildFile; fileRef = 1EEF8E051FD1F0C300DD563C /* FLEView.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		1EEF8E081FD1F0C300DD563C /* FLEView.m in Sources */ = {isa = PBXBuildFile; fileRef = 1EEF8E061FD1F0C300DD563C /* FLEView.m */; };
+		2CCADF9A21C74690001B4026 /* FLEEventChannel.m in Sources */ = {isa = PBXBuildFile; fileRef = 2CCADF9821C74690001B4026 /* FLEEventChannel.m */; };
+		2CCADF9B21C74690001B4026 /* FLEEventChannel.h in Headers */ = {isa = PBXBuildFile; fileRef = 2CCADF9921C74690001B4026 /* FLEEventChannel.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		3389A6872159359200A27898 /* FLEBinaryMessenger.h in Headers */ = {isa = PBXBuildFile; fileRef = 3389A6862159359200A27898 /* FLEBinaryMessenger.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		3389A68D215949CB00A27898 /* FLEMethodError.m in Sources */ = {isa = PBXBuildFile; fileRef = 3389A68C215949CB00A27898 /* FLEMethodError.m */; };
 		3389A68F215949D600A27898 /* FLEMethodError.h in Headers */ = {isa = PBXBuildFile; fileRef = 3389A68E215949D600A27898 /* FLEMethodError.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -91,6 +93,8 @@
 		1E2492381FCF50BE00DD3BBB /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist; path = Info.plist; sourceTree = "<group>"; };
 		1EEF8E051FD1F0C300DD563C /* FLEView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLEView.h; sourceTree = "<group>"; };
 		1EEF8E061FD1F0C300DD563C /* FLEView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FLEView.m; sourceTree = "<group>"; };
+		2CCADF9821C74690001B4026 /* FLEEventChannel.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FLEEventChannel.m; sourceTree = "<group>"; };
+		2CCADF9921C74690001B4026 /* FLEEventChannel.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLEEventChannel.h; sourceTree = "<group>"; };
 		3389A6862159359200A27898 /* FLEBinaryMessenger.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLEBinaryMessenger.h; sourceTree = "<group>"; };
 		3389A68C215949CB00A27898 /* FLEMethodError.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FLEMethodError.m; sourceTree = "<group>"; };
 		3389A68E215949D600A27898 /* FLEMethodError.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLEMethodError.h; sourceTree = "<group>"; };
@@ -134,6 +138,7 @@
 				1E2492371FCF50BE00DD3BBB /* FlutterEmbedderMac.h */,
 				1E2492451FCF536200DD3BBB /* Public */,
 				33C0FA1821B845EF008F8959 /* FLEBasicMessageChannel.m */,
+				2CCADF9821C74690001B4026 /* FLEEventChannel.m */,
 				33C0FA1C21B84810008F8959 /* FLEJSONMessageCodec.m */,
 				33A87EB520F6BCDB0086D21D /* FLEJSONMethodCodec.m */,
 				64C76C2620D7BDFB00B16256 /* FLEKeyEventPlugin.h */,
@@ -167,6 +172,7 @@
 			children = (
 				33C0FA1921B845F0008F8959 /* FLEBasicMessageChannel.h */,
 				3389A6862159359200A27898 /* FLEBinaryMessenger.h */,
+				2CCADF9921C74690001B4026 /* FLEEventChannel.h */,
 				33C0FA1E21B84810008F8959 /* FLEJSONMessageCodec.h */,
 				33C0FA1D21B84810008F8959 /* FLEJSONMethodCodec.h */,
 				33C0FA1F21B84810008F8959 /* FLEMessageCodec.h */,
@@ -201,6 +207,7 @@
 				33E202A6212BC0ED00337F48 /* FLEKeyEventPlugin.h in Headers */,
 				33C0FA2621B84AA4008F8959 /* FLEMethodCall.h in Headers */,
 				1E24923B1FCF50BE00DD3BBB /* FLEPlugin.h in Headers */,
+				2CCADF9B21C74690001B4026 /* FLEEventChannel.h in Headers */,
 				3389A6872159359200A27898 /* FLEBinaryMessenger.h in Headers */,
 				33D7B59920A4F54400296EFC /* FLEMethodChannel.h in Headers */,
 				1E24923F1FCF50BE00DD3BBB /* FLEViewController.h in Headers */,
@@ -321,6 +328,7 @@
 				1E24923E1FCF50BE00DD3BBB /* FLETextInputPlugin.m in Sources */,
 				1EEF8E081FD1F0C300DD563C /* FLEView.m in Sources */,
 				33A87EB720F6BCDB0086D21D /* FLEJSONMethodCodec.m in Sources */,
+				2CCADF9A21C74690001B4026 /* FLEEventChannel.m in Sources */,
 				AA8AE8BA1FD948BA00B6FB31 /* FLETextInputModel.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

From acfa9f793c9e76914cb6ac4c899ea1b4ceffb531 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Fri, 4 Jan 2019 17:07:57 +0800
Subject: [PATCH 02/12] Fixed code styles.

---
 library/macos/FLEEventChannel.h | 24 +++++++++++++-------
 library/macos/FLEEventChannel.m | 39 +++++++++++++++++----------------
 2 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/library/macos/FLEEventChannel.h b/library/macos/FLEEventChannel.h
index 8c127443c..e5aaf7e69 100644
--- a/library/macos/FLEEventChannel.h
+++ b/library/macos/FLEEventChannel.h
@@ -23,14 +23,17 @@
  * @param event The event.
  */
 typedef void (^FLEEventSink)(id _Nullable event);
+
 /**
  * A constant used with `FLEEventChannel` to indicate end of stream.
  */
-extern NSObject const* FLEEndOfEventStream;
+extern NSString const *_Nonnull FLEEndOfEventStream;
+
 /**
  * A strategy for exposing an event stream to the Flutter side.
  */
 @protocol FLEStreamHandler
+
 /**
  * Sets up an event stream and begin emitting events.
  *
@@ -45,8 +48,9 @@ extern NSObject const* FLEEndOfEventStream;
  *     successful events.
  * @return A FLEMethodError instance, if setup fails.
  */
-- (FLEMethodError* _Nullable)onListenWithArguments:(id _Nullable)arguments
-                                       eventSink:(FLEEventSink)events;
+- (FLEMethodError *_Nonnull)onListenWithArguments:(id _Nullable)arguments
+                                        eventSink:(FLEEventSink)events;
+
 /**
  * Tears down an event stream.
  *
@@ -60,12 +64,14 @@ extern NSObject const* FLEEndOfEventStream;
  * @param arguments Arguments for the stream.
  * @return A FLEMethodError instance, if teardown fails.
  */
-- (FLEMethodError* _Nullable)onCancelWithArguments:(id _Nullable)arguments;
+- (FLEMethodError *_Nonnull)onCancelWithArguments:(id _Nullable)arguments;
 @end
+
 /**
  * A channel for communicating with the Flutter side using event streams.
  */
 @interface FLEEventChannel : NSObject
+
 /**
  * Creates a `FLEEventChannel` with the specified name and binary messenger.
  *
@@ -81,10 +87,12 @@ extern NSObject const* FLEEndOfEventStream;
  * @param name The channel name.
  * @param messenger The binary messenger.
  * @param codec The method codec.
+ * @return A new channel.
  */
-+ (instancetype)eventChannelWithName:(nonnull NSString *)name
-                     binaryMessenger:(nonnull id<FLEBinaryMessenger>)messenger
-                               codec:(nonnull id<FLEMethodCodec>)codec;
++ (nonnull instancetype)eventChannelWithName:(nonnull NSString *)name
+                             binaryMessenger:(nonnull id<FLEBinaryMessenger>)messenger
+                                       codec:(nonnull id<FLEMethodCodec>)codec;
+
 /**
  * Registers a handler for stream setup requests from the Flutter side.
  *
@@ -94,5 +102,5 @@ extern NSObject const* FLEEndOfEventStream;
  * @param handler The stream handler.
  */
 - (void)setStreamHandler:(nullable id<FLEStreamHandler>)handler;
-@end
 
+@end
diff --git a/library/macos/FLEEventChannel.m b/library/macos/FLEEventChannel.m
index 19bcec07e..61076f645 100644
--- a/library/macos/FLEEventChannel.m
+++ b/library/macos/FLEEventChannel.m
@@ -14,33 +14,33 @@
 
 #import "FLEEventChannel.h"
 
-NSObject const* FLEEndOfEventStream = @"EndOfEventStream";
+NSString const *FLEEndOfEventStream = @"EndOfEventStream";
 
 @implementation FLEEventChannel {
-    NSString* _name;
+    NSString *_name;
     __weak id<FLEBinaryMessenger> _messenger;
     id<FLEMethodCodec> _codec;
 }
 
-+ (instancetype)eventChannelWithName:(nonnull NSString*)name
-                     binaryMessenger:(nonnull id<FLEBinaryMessenger>)messenger
-                               codec:(nonnull id<FLEMethodCodec>)codec {
-    return [[FLEEventChannel alloc] initWithName:name binaryMessenger:messenger codec:codec];
++ (instancetype)eventChannelWithName:(NSString *)name
+                     binaryMessenger:(id<FLEBinaryMessenger>)messenger
+                               codec:(id<FLEMethodCodec>)codec {
+    return [[[self class] alloc] initWithName:name binaryMessenger:messenger codec:codec];
 }
 
-- (instancetype)initWithName:(nonnull NSString*)name
-             binaryMessenger:(nonnull id<FLEBinaryMessenger>)messenger
-                       codec:(nonnull id<FLEMethodCodec>)codec {
+- (instancetype)initWithName:(NSString *)name
+             binaryMessenger:(id<FLEBinaryMessenger>)messenger
+                       codec:(id<FLEMethodCodec>)codec {
     self = [super init];
-    NSAssert(self, @"Super init cannot be nil");
-    _name = name;
-    _messenger = messenger;
-    _codec = codec;
-    
+    if (self) {
+        _name = [name copy];
+        _messenger = messenger;
+        _codec = codec;
+    }
     return self;
 }
 
-- (void)setStreamHandler:(NSObject<FLEStreamHandler>*)handler {
+- (void)setStreamHandler:(NSObject<FLEStreamHandler> *)handler {
     if (!handler) {
         [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:nil];
         return;
@@ -51,7 +51,7 @@ - (void)setStreamHandler:(NSObject<FLEStreamHandler>*)handler {
     NSString *channelName = _name;
     
     __block FLEEventSink currentSink = nil;
-    FLEBinaryMessageHandler messageHandler = ^(NSData* message, FLEBinaryReply callback) {
+    FLEBinaryMessageHandler messageHandler = ^(NSData *message, FLEBinaryReply callback) {
         FLEMethodCall* call = [codec decodeMethodCall:message];
         if ([call.methodName isEqual:@"listen"]) {
             if (currentSink) {
@@ -65,11 +65,11 @@ - (void)setStreamHandler:(NSObject<FLEStreamHandler>*)handler {
                     [messenger sendOnChannel:channelName message:nil];
                 else if ([event isKindOfClass:[FLEMethodError class]])
                     [messenger sendOnChannel:channelName
-                                      message:[codec encodeErrorEnvelope:(FLEMethodError*)event]];
+                                      message:[codec encodeErrorEnvelope:(FLEMethodError *)event]];
                 else
                     [messenger sendOnChannel:channelName message:[codec encodeSuccessEnvelope:event]];
             };
-            FLEMethodError* error = [handler onListenWithArguments:call.arguments eventSink:currentSink];
+            FLEMethodError *error = [handler onListenWithArguments:call.arguments eventSink:currentSink];
             if (error)
                 callback([codec encodeErrorEnvelope:error]);
             else
@@ -83,7 +83,7 @@ - (void)setStreamHandler:(NSObject<FLEStreamHandler>*)handler {
                 return;
             }
             currentSink = nil;
-            FLEMethodError* error = [handler onCancelWithArguments:call.arguments];
+            FLEMethodError *error = [handler onCancelWithArguments:call.arguments];
             if (error)
                 callback([codec encodeErrorEnvelope:error]);
             else
@@ -94,4 +94,5 @@ - (void)setStreamHandler:(NSObject<FLEStreamHandler>*)handler {
     };
     [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:messageHandler];
 }
+
 @end

From 413b8434f5bbaddb975181ae554d170d58723cdf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Fri, 4 Jan 2019 18:21:18 +0800
Subject: [PATCH 03/12] Update.

---
 library/macos/FLEEventChannel.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/library/macos/FLEEventChannel.h b/library/macos/FLEEventChannel.h
index e5aaf7e69..a1b5f1080 100644
--- a/library/macos/FLEEventChannel.h
+++ b/library/macos/FLEEventChannel.h
@@ -48,7 +48,7 @@ extern NSString const *_Nonnull FLEEndOfEventStream;
  *     successful events.
  * @return A FLEMethodError instance, if setup fails.
  */
-- (FLEMethodError *_Nonnull)onListenWithArguments:(id _Nullable)arguments
+- (nullable FLEMethodError *)onListenWithArguments:(id _Nullable)arguments
                                         eventSink:(FLEEventSink)events;
 
 /**
@@ -64,7 +64,8 @@ extern NSString const *_Nonnull FLEEndOfEventStream;
  * @param arguments Arguments for the stream.
  * @return A FLEMethodError instance, if teardown fails.
  */
-- (FLEMethodError *_Nonnull)onCancelWithArguments:(id _Nullable)arguments;
+- (nullable FLEMethodError *)onCancelWithArguments:(id _Nullable)arguments;
+
 @end
 
 /**

From 713fd8282598a64761af983be0ed4467b67550ea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Fri, 4 Jan 2019 19:03:41 +0800
Subject: [PATCH 04/12] Remove unnecessary comments.

---
 library/macos/FLEEventChannel.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/macos/FLEEventChannel.h b/library/macos/FLEEventChannel.h
index a1b5f1080..6d98fcb52 100644
--- a/library/macos/FLEEventChannel.h
+++ b/library/macos/FLEEventChannel.h
@@ -80,7 +80,7 @@ extern NSString const *_Nonnull FLEEndOfEventStream;
  * interfere with each other's communication.
  *
  * The binary messenger is a facility for sending raw, binary messages to the
- * Flutter side. This protocol is implemented by `FLEViewController`.
+ * Flutter side.
  *
  * The channel uses `FLEMethodCodec` to decode stream setup and
  * teardown requests, and to encode event envelopes.

From a33f8e3b04e4da34bdf8bd12912b5366e291a2b9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Fri, 4 Jan 2019 19:15:04 +0800
Subject: [PATCH 05/12] Move the EventSink block to the outside.

---
 library/macos/FLEEventChannel.m | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/library/macos/FLEEventChannel.m b/library/macos/FLEEventChannel.m
index 61076f645..f722ea021 100644
--- a/library/macos/FLEEventChannel.m
+++ b/library/macos/FLEEventChannel.m
@@ -48,8 +48,17 @@ - (void)setStreamHandler:(NSObject<FLEStreamHandler> *)handler {
 
     id<FLEMethodCodec> codec = _codec;
     __weak id<FLEBinaryMessenger> messenger =  _messenger;
-    NSString *channelName = _name;
-    
+    NSString *name = _name;
+    FLEEventSink eventSink = ^(id event) {
+        if (event == FLEEndOfEventStream)
+            [messenger sendOnChannel:name message:nil];
+        else if ([event isKindOfClass:[FLEMethodError class]])
+            [messenger sendOnChannel:name
+                             message:[codec encodeErrorEnvelope:(FLEMethodError *)event]];
+        else
+            [messenger sendOnChannel:name message:[codec encodeSuccessEnvelope:event]];
+    };
+
     __block FLEEventSink currentSink = nil;
     FLEBinaryMessageHandler messageHandler = ^(NSData *message, FLEBinaryReply callback) {
         FLEMethodCall* call = [codec decodeMethodCall:message];
@@ -60,15 +69,7 @@ - (void)setStreamHandler:(NSObject<FLEStreamHandler> *)handler {
                     NSLog(@"Failed to cancel existing stream: %@. %@ (%@)", error.code, error.message,
                           error.details);
             }
-            currentSink = ^(id event) {
-                if (event == FLEEndOfEventStream)
-                    [messenger sendOnChannel:channelName message:nil];
-                else if ([event isKindOfClass:[FLEMethodError class]])
-                    [messenger sendOnChannel:channelName
-                                      message:[codec encodeErrorEnvelope:(FLEMethodError *)event]];
-                else
-                    [messenger sendOnChannel:channelName message:[codec encodeSuccessEnvelope:event]];
-            };
+            currentSink = eventSink;
             FLEMethodError *error = [handler onListenWithArguments:call.arguments eventSink:currentSink];
             if (error)
                 callback([codec encodeErrorEnvelope:error]);

From b2fc8b9989374c6210c1209c1bd27883c57e0da3 Mon Sep 17 00:00:00 2001
From: Stuart Morgan <stuartmorgan@google.com>
Date: Tue, 8 Jan 2019 15:37:24 -0800
Subject: [PATCH 06/12] Minor adjustments

- Add a missing nullability specifier.
- Use simplified nullability annotations when possible.
- clang-format using project style file.
- Add braces to conditionals to match project style.
- Add new header to umbrella header.
---
 library/macos/FLEEventChannel.h    |   8 +-
 library/macos/FLEEventChannel.m    | 125 +++++++++++++++--------------
 library/macos/FlutterEmbedderMac.h |   1 +
 3 files changed, 69 insertions(+), 65 deletions(-)

diff --git a/library/macos/FLEEventChannel.h b/library/macos/FLEEventChannel.h
index 6d98fcb52..7dac85821 100644
--- a/library/macos/FLEEventChannel.h
+++ b/library/macos/FLEEventChannel.h
@@ -35,7 +35,7 @@ extern NSString const *_Nonnull FLEEndOfEventStream;
 @protocol FLEStreamHandler
 
 /**
- * Sets up an event stream and begin emitting events.
+ * Sets up an event stream and begins emitting events.
  *
  * Invoked when the first listener is registered with the Stream associated to
  * this channel on the Flutter side.
@@ -48,8 +48,8 @@ extern NSString const *_Nonnull FLEEndOfEventStream;
  *     successful events.
  * @return A FLEMethodError instance, if setup fails.
  */
-- (nullable FLEMethodError *)onListenWithArguments:(id _Nullable)arguments
-                                        eventSink:(FLEEventSink)events;
+- (nullable FLEMethodError *)onListenWithArguments:(nullable id)arguments
+                                         eventSink:(FLEEventSink _Nonnull)events;
 
 /**
  * Tears down an event stream.
@@ -64,7 +64,7 @@ extern NSString const *_Nonnull FLEEndOfEventStream;
  * @param arguments Arguments for the stream.
  * @return A FLEMethodError instance, if teardown fails.
  */
-- (nullable FLEMethodError *)onCancelWithArguments:(id _Nullable)arguments;
+- (nullable FLEMethodError *)onCancelWithArguments:(nullable id)arguments;
 
 @end
 
diff --git a/library/macos/FLEEventChannel.m b/library/macos/FLEEventChannel.m
index f722ea021..931e4929e 100644
--- a/library/macos/FLEEventChannel.m
+++ b/library/macos/FLEEventChannel.m
@@ -17,83 +17,86 @@
 NSString const *FLEEndOfEventStream = @"EndOfEventStream";
 
 @implementation FLEEventChannel {
-    NSString *_name;
-    __weak id<FLEBinaryMessenger> _messenger;
-    id<FLEMethodCodec> _codec;
+  NSString *_name;
+  __weak id<FLEBinaryMessenger> _messenger;
+  id<FLEMethodCodec> _codec;
 }
 
 + (instancetype)eventChannelWithName:(NSString *)name
                      binaryMessenger:(id<FLEBinaryMessenger>)messenger
                                codec:(id<FLEMethodCodec>)codec {
-    return [[[self class] alloc] initWithName:name binaryMessenger:messenger codec:codec];
+  return [[[self class] alloc] initWithName:name binaryMessenger:messenger codec:codec];
 }
 
 - (instancetype)initWithName:(NSString *)name
              binaryMessenger:(id<FLEBinaryMessenger>)messenger
                        codec:(id<FLEMethodCodec>)codec {
-    self = [super init];
-    if (self) {
-        _name = [name copy];
-        _messenger = messenger;
-        _codec = codec;
-    }
-    return self;
+  self = [super init];
+  if (self) {
+    _name = [name copy];
+    _messenger = messenger;
+    _codec = codec;
+  }
+  return self;
 }
 
 - (void)setStreamHandler:(NSObject<FLEStreamHandler> *)handler {
-    if (!handler) {
-        [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:nil];
-        return;
-    }
+  if (!handler) {
+    [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:nil];
+    return;
+  }
 
-    id<FLEMethodCodec> codec = _codec;
-    __weak id<FLEBinaryMessenger> messenger =  _messenger;
-    NSString *name = _name;
-    FLEEventSink eventSink = ^(id event) {
-        if (event == FLEEndOfEventStream)
-            [messenger sendOnChannel:name message:nil];
-        else if ([event isKindOfClass:[FLEMethodError class]])
-            [messenger sendOnChannel:name
-                             message:[codec encodeErrorEnvelope:(FLEMethodError *)event]];
-        else
-            [messenger sendOnChannel:name message:[codec encodeSuccessEnvelope:event]];
-    };
+  id<FLEMethodCodec> codec = _codec;
+  __weak id<FLEBinaryMessenger> messenger = _messenger;
+  NSString *name = _name;
+  FLEEventSink eventSink = ^(id event) {
+    if (event == FLEEndOfEventStream) {
+      [messenger sendOnChannel:name message:nil];
+    } else if ([event isKindOfClass:[FLEMethodError class]]) {
+      [messenger sendOnChannel:name message:[codec encodeErrorEnvelope:(FLEMethodError *)event]];
+    } else {
+      [messenger sendOnChannel:name message:[codec encodeSuccessEnvelope:event]];
+    }
+  };
 
-    __block FLEEventSink currentSink = nil;
-    FLEBinaryMessageHandler messageHandler = ^(NSData *message, FLEBinaryReply callback) {
-        FLEMethodCall* call = [codec decodeMethodCall:message];
-        if ([call.methodName isEqual:@"listen"]) {
-            if (currentSink) {
-                FLEMethodError* error = [handler onCancelWithArguments:nil];
-                if (error)
-                    NSLog(@"Failed to cancel existing stream: %@. %@ (%@)", error.code, error.message,
-                          error.details);
-            }
-            currentSink = eventSink;
-            FLEMethodError *error = [handler onListenWithArguments:call.arguments eventSink:currentSink];
-            if (error)
-                callback([codec encodeErrorEnvelope:error]);
-            else
-                callback([codec encodeSuccessEnvelope:nil]);
-        } else if ([call.methodName isEqual:@"cancel"]) {
-            if (!currentSink) {
-                callback(
-                         [codec encodeErrorEnvelope:[[FLEMethodError alloc] initWithCode:@"error"
-                                                                                 message:@"No active stream to cancel"
-                                                                                 details:nil]]);
-                return;
-            }
-            currentSink = nil;
-            FLEMethodError *error = [handler onCancelWithArguments:call.arguments];
-            if (error)
-                callback([codec encodeErrorEnvelope:error]);
-            else
-                callback([codec encodeSuccessEnvelope:nil]);
-        } else {
-            callback(nil);
+  __block FLEEventSink currentSink = nil;
+  FLEBinaryMessageHandler messageHandler = ^(NSData *message, FLEBinaryReply callback) {
+    FLEMethodCall *call = [codec decodeMethodCall:message];
+    if ([call.methodName isEqual:@"listen"]) {
+      if (currentSink) {
+        FLEMethodError *error = [handler onCancelWithArguments:nil];
+        if (error) {
+          NSLog(@"Failed to cancel existing stream: %@. %@ (%@)", error.code, error.message,
+                error.details);
         }
-    };
-    [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:messageHandler];
+      }
+      currentSink = eventSink;
+      FLEMethodError *error = [handler onListenWithArguments:call.arguments eventSink:currentSink];
+      if (error) {
+        callback([codec encodeErrorEnvelope:error]);
+      } else {
+        callback([codec encodeSuccessEnvelope:nil]);
+      }
+    } else if ([call.methodName isEqual:@"cancel"]) {
+      if (!currentSink) {
+        callback([codec
+            encodeErrorEnvelope:[[FLEMethodError alloc] initWithCode:@"error"
+                                                             message:@"No active stream to cancel"
+                                                             details:nil]]);
+        return;
+      }
+      currentSink = nil;
+      FLEMethodError *error = [handler onCancelWithArguments:call.arguments];
+      if (error) {
+        callback([codec encodeErrorEnvelope:error]);
+      } else {
+        callback([codec encodeSuccessEnvelope:nil]);
+      }
+    } else {
+      callback(nil);
+    }
+  };
+  [_messenger setMessageHandlerOnChannel:_name binaryMessageHandler:messageHandler];
 }
 
 @end
diff --git a/library/macos/FlutterEmbedderMac.h b/library/macos/FlutterEmbedderMac.h
index 18ccefa39..4416dfd45 100644
--- a/library/macos/FlutterEmbedderMac.h
+++ b/library/macos/FlutterEmbedderMac.h
@@ -14,6 +14,7 @@
 
 #import "FLEBasicMessageChannel.h"
 #import "FLEBinaryMessenger.h"
+#import "FLEEventChannel.h"
 #import "FLEJSONMessageCodec.h"
 #import "FLEJSONMethodCodec.h"
 #import "FLEMessageCodec.h"

From 1f147f32900c15cb34db0b5e549006877fe3b3af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Thu, 31 Jan 2019 23:29:33 +0800
Subject: [PATCH 07/12] Add Texture for FLE.

---
 library/macos/FLEExternalTexture.h            | 36 ++++++++
 library/macos/FLEExternalTexture.m            | 92 +++++++++++++++++++
 library/macos/FLETexture.h                    | 32 +++++++
 library/macos/FLEViewController.h             |  3 +-
 library/macos/FLEViewController.mm            | 38 ++++++++
 .../project.pbxproj                           | 12 +++
 6 files changed, 212 insertions(+), 1 deletion(-)
 create mode 100644 library/macos/FLEExternalTexture.h
 create mode 100644 library/macos/FLEExternalTexture.m
 create mode 100644 library/macos/FLETexture.h

diff --git a/library/macos/FLEExternalTexture.h b/library/macos/FLEExternalTexture.h
new file mode 100644
index 000000000..13838e9db
--- /dev/null
+++ b/library/macos/FLEExternalTexture.h
@@ -0,0 +1,36 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import <Foundation/Foundation.h>
+#import <FlutterEmbedder/FlutterEmbedder.h>
+
+#import "FLETexture.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface FLEExternalTexture : NSObject
+
+-(nonnull instancetype)initExternalTexture:(id<FLETexture>)external_texture;
+
+-(BOOL)populateTextureWidth:(size_t)width
+                      height:(size_t)height
+                     texture:(FlutterOpenGLTexture *)texture;
+
+-(int64_t)textureId;
+
+@property(nullable, weak) id<FLETexture> external_texture;
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/library/macos/FLEExternalTexture.m b/library/macos/FLEExternalTexture.m
new file mode 100644
index 000000000..7ed2b88f5
--- /dev/null
+++ b/library/macos/FLEExternalTexture.m
@@ -0,0 +1,92 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import "FLEExternalTexture.h"
+
+#import <AppKit/NSOpenGL.h>
+#import <CoreVideo/CVOpenGLBuffer.h>
+#import <CoreVideo/CVOpenGLTextureCache.h>
+#import <OpenGL/gl.h>
+
+@implementation FLEExternalTexture {
+    CVOpenGLTextureCacheRef _textureCache;
+    CVPixelBufferRef _pixelBuffer;
+}
+
+@synthesize external_texture;
+
+-(instancetype) initExternalTexture:(id<FLETexture>)external_texture {
+    self = [super init];
+
+    if (self) {
+        self.external_texture = external_texture;
+    }
+
+    return self;
+}
+
+static void OnGLTextureRelease(CVPixelBufferRef pixelBuffer) {
+    CVPixelBufferRelease(pixelBuffer);
+}
+
+-(int64_t)textureId {
+    return (NSInteger)(self);
+}
+
+-(BOOL)populateTextureWidth:(size_t)width
+                     height:(size_t)height
+                    texture:(FlutterOpenGLTexture *)texture{
+
+    if(_pixelBuffer == NULL || external_texture == NULL){
+        return NO;
+    }
+
+    // Copy image buffer from external texture.
+    _pixelBuffer = [external_texture copyPixelBuffer];
+
+    // Create the texture cache if necessary.
+    if (_textureCache == NULL) {
+        CGLContextObj context = [NSOpenGLContext currentContext].CGLContextObj;
+        CGLPixelFormatObj format = CGLGetPixelFormat(context);
+        if (CVOpenGLTextureCacheCreate(kCFAllocatorDefault, NULL, context, format, NULL, &_textureCache) != kCVReturnSuccess) {
+            NSLog(@"Could not create texture cache.");
+            CVPixelBufferRelease(_pixelBuffer);
+            return NO;
+        }
+    }
+
+    // Try to clear the cache of OpenGL textures to save memory.
+    CVOpenGLTextureCacheFlush(_textureCache, 0);
+    
+    CVOpenGLTextureRef openGLTexture = NULL;
+    if (CVOpenGLTextureCacheCreateTextureFromImage(kCFAllocatorDefault, _textureCache, _pixelBuffer, NULL, &openGLTexture) != kCVReturnSuccess) {
+        CVPixelBufferRelease(_pixelBuffer);
+        return NO;
+    }
+
+    texture->target = CVOpenGLTextureGetTarget(openGLTexture);
+    texture->name = CVOpenGLTextureGetName(openGLTexture);
+    texture->format = GL_RGBA8;
+    texture->destruction_callback = (VoidCallback)&OnGLTextureRelease;
+    texture->user_data = openGLTexture;
+
+    CVPixelBufferRelease(_pixelBuffer);
+    return YES;
+}
+
+-(void) dealloc {
+    CVOpenGLTextureCacheRelease(_textureCache);
+}
+
+@end
diff --git a/library/macos/FLETexture.h b/library/macos/FLETexture.h
new file mode 100644
index 000000000..c16b8f510
--- /dev/null
+++ b/library/macos/FLETexture.h
@@ -0,0 +1,32 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#import <Foundation/Foundation.h>
+#import <CoreVideo/CVPixelBuffer.h>
+
+@protocol FLETexture<NSObject>
+
+- (nullable CVPixelBufferRef)copyPixelBuffer;
+
+@end
+
+@protocol FLETextureRegistrar<NSObject>
+
+- (int64_t)registerTexture:(nonnull id<FLETexture>)texture;
+
+- (void)textureFrameAvailable:(int64_t)textureId;
+
+- (void)unregisterTexture:(int64_t)textureId;
+
+@end
diff --git a/library/macos/FLEViewController.h b/library/macos/FLEViewController.h
index 10eb0ea5b..5d2af4d64 100644
--- a/library/macos/FLEViewController.h
+++ b/library/macos/FLEViewController.h
@@ -20,6 +20,7 @@
 #import "FLEPlugin.h"
 #import "FLEPluginRegistrar.h"
 #import "FLEReshapeListener.h"
+#import "FLETexture.h"
 
 /**
  * Controls embedder plugins and communication with the underlying Flutter engine, managing a view
@@ -29,7 +30,7 @@
  * Flutter engine in non-interactive mode, or with a drawable Flutter canvas.
  */
 @interface FLEViewController
-    : NSViewController <FLEBinaryMessenger, FLEPluginRegistrar, FLEReshapeListener>
+    : NSViewController <FLEBinaryMessenger, FLEPluginRegistrar, FLEReshapeListener, FLETextureRegistrar>
 
 /**
  * The view this controller manages when launched in interactive mode (headless set to false). Must
diff --git a/library/macos/FLEViewController.mm b/library/macos/FLEViewController.mm
index 254e82294..ba3ad520d 100644
--- a/library/macos/FLEViewController.mm
+++ b/library/macos/FLEViewController.mm
@@ -22,6 +22,7 @@
 #import "FLEReshapeListener.h"
 #import "FLETextInputPlugin.h"
 #import "FLEView.h"
+#import "FLEExternalTexture.h"
 
 static NSString *const kXcodeExtraArgumentOne = @"-NSDocumentRevisionsDebugMode";
 static NSString *const kXcodeExtraArgumentTwo = @"YES";
@@ -95,6 +96,10 @@ - (void)dispatchMouseEvent:(nonnull NSEvent *)event phase:(FlutterPointerPhase)p
  */
 - (void)dispatchKeyEvent:(NSEvent *)event ofType:(NSString *)type;
 
+-(BOOL) populateTextureWithIdentifier:(int64_t)texture_identifier
+                                width:(size_t)width
+                               height:(size_t)height
+                              texture:(FlutterOpenGLTexture *)texture;
 @end
 
 #pragma mark - Static methods provided to engine configuration
@@ -144,6 +149,14 @@ static bool OnMakeResourceCurrent(FLEViewController *controller) {
   return true;
 }
 
+static bool OnAcquireExternalTexture(FLEViewController *controller,
+                                     int64_t texture_identifier,
+                                     size_t width,
+                                     size_t height,
+                                     FlutterOpenGLTexture *texture) {
+    return [controller populateTextureWithIdentifier:texture_identifier width:width height:height texture:texture];
+}
+
 #pragma mark Static methods provided for headless engine configuration
 
 static bool HeadlessOnMakeCurrent(FLEViewController *controller) { return false; }
@@ -173,6 +186,9 @@ @implementation FLEViewController {
   // A message channel for passing key events to the Flutter engine. This should be replaced with
   // an embedding API; see Issue #47.
   FLEBasicMessageChannel *_keyEventChannel;
+
+  // A mapping of external textures.
+  NSMutableDictionary<NSNumber *, FLEExternalTexture *> *_textures;
 }
 
 @dynamic view;
@@ -183,6 +199,7 @@ @implementation FLEViewController {
 static void CommonInit(FLEViewController *controller) {
   controller->_messageHandlers = [[NSMutableDictionary alloc] init];
   controller->_additionalKeyResponders = [[NSMutableOrderedSet alloc] init];
+  controller->_textures = [[NSMutableDictionary alloc] init];
 }
 
 - (instancetype)initWithCoder:(NSCoder *)coder {
@@ -342,6 +359,27 @@ - (void)makeResourceContextCurrent {
   [_resourceContext makeCurrentContext];
 }
 
+-(BOOL) populateTextureWithIdentifier:(int64_t) textureId width:(size_t) width height:(size_t) height texture:(FlutterOpenGLTexture *) texture {
+    return [_textures[@(textureId)] populateTextureWidth:width height:height texture:texture];
+}
+
+- (int64_t)registerTexture:(NSObject<FLETexture>*)texture {
+    FLEExternalTexture *fleTexture = [[FLEExternalTexture alloc] initExternalTexture:texture];
+    int64_t textureId = [fleTexture textureId];
+    FlutterEngineRegisterExternalTexture(_engine, textureId);
+    _textures[@(textureId)] = fleTexture;
+    return textureId;
+}
+
+- (void)textureFrameAvailable:(int64_t)textureId {
+    FlutterEngineMarkExternalTextureFrameAvailable(_engine, textureId);
+}
+
+- (void)unregisterTexture:(int64_t)textureId {
+    FlutterEngineUnregisterExternalTexture(_engine, textureId);
+    [_textures removeObjectForKey:@(textureId)];
+}
+
 - (void)handlePlatformMessage:(const FlutterPlatformMessage *)message {
   NSData *messageData = [NSData dataWithBytesNoCopy:(void *)message->message
                                              length:message->message_size
diff --git a/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj b/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj
index bbc1a68f4..c842660ee 100644
--- a/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj
+++ b/library/macos/FlutterEmbedderMac.xcodeproj/project.pbxproj
@@ -30,6 +30,9 @@
 		1E2492411FCF50BE00DD3BBB /* FlutterEmbedderMac.h in Headers */ = {isa = PBXBuildFile; fileRef = 1E2492371FCF50BE00DD3BBB /* FlutterEmbedderMac.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		1EEF8E071FD1F0C300DD563C /* FLEView.h in Headers */ = {isa = PBXBuildFile; fileRef = 1EEF8E051FD1F0C300DD563C /* FLEView.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		1EEF8E081FD1F0C300DD563C /* FLEView.m in Sources */ = {isa = PBXBuildFile; fileRef = 1EEF8E061FD1F0C300DD563C /* FLEView.m */; };
+		2CC5E74022033D53000EF5F5 /* FLETexture.h in Headers */ = {isa = PBXBuildFile; fileRef = 2CC5E73F22033D53000EF5F5 /* FLETexture.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		2CC5E7432203444A000EF5F5 /* FLEExternalTexture.h in Headers */ = {isa = PBXBuildFile; fileRef = 2CC5E7412203444A000EF5F5 /* FLEExternalTexture.h */; };
+		2CC5E7442203444A000EF5F5 /* FLEExternalTexture.m in Sources */ = {isa = PBXBuildFile; fileRef = 2CC5E7422203444A000EF5F5 /* FLEExternalTexture.m */; };
 		2CCADF9A21C74690001B4026 /* FLEEventChannel.m in Sources */ = {isa = PBXBuildFile; fileRef = 2CCADF9821C74690001B4026 /* FLEEventChannel.m */; };
 		2CCADF9B21C74690001B4026 /* FLEEventChannel.h in Headers */ = {isa = PBXBuildFile; fileRef = 2CCADF9921C74690001B4026 /* FLEEventChannel.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		3389A6872159359200A27898 /* FLEBinaryMessenger.h in Headers */ = {isa = PBXBuildFile; fileRef = 3389A6862159359200A27898 /* FLEBinaryMessenger.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -92,6 +95,9 @@
 		1E2492381FCF50BE00DD3BBB /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist; path = Info.plist; sourceTree = "<group>"; };
 		1EEF8E051FD1F0C300DD563C /* FLEView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLEView.h; sourceTree = "<group>"; };
 		1EEF8E061FD1F0C300DD563C /* FLEView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FLEView.m; sourceTree = "<group>"; };
+		2CC5E73F22033D53000EF5F5 /* FLETexture.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLETexture.h; sourceTree = "<group>"; };
+		2CC5E7412203444A000EF5F5 /* FLEExternalTexture.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = FLEExternalTexture.h; sourceTree = "<group>"; };
+		2CC5E7422203444A000EF5F5 /* FLEExternalTexture.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = FLEExternalTexture.m; sourceTree = "<group>"; };
 		2CCADF9821C74690001B4026 /* FLEEventChannel.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FLEEventChannel.m; sourceTree = "<group>"; };
 		2CCADF9921C74690001B4026 /* FLEEventChannel.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLEEventChannel.h; sourceTree = "<group>"; };
 		3389A6862159359200A27898 /* FLEBinaryMessenger.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FLEBinaryMessenger.h; sourceTree = "<group>"; };
@@ -132,6 +138,8 @@
 		1E24921A1FCF504200DD3BBB = {
 			isa = PBXGroup;
 			children = (
+				2CC5E7412203444A000EF5F5 /* FLEExternalTexture.h */,
+				2CC5E7422203444A000EF5F5 /* FLEExternalTexture.m */,
 				C4C1FE431FD74F6400691968 /* FlutterEmbedder.framework */,
 				1E2492371FCF50BE00DD3BBB /* FlutterEmbedderMac.h */,
 				1E2492451FCF536200DD3BBB /* Public */,
@@ -169,6 +177,7 @@
 				33C0FA1921B845F0008F8959 /* FLEBasicMessageChannel.h */,
 				3389A6862159359200A27898 /* FLEBinaryMessenger.h */,
 				2CCADF9921C74690001B4026 /* FLEEventChannel.h */,
+				2CC5E73F22033D53000EF5F5 /* FLETexture.h */,
 				33C0FA1E21B84810008F8959 /* FLEJSONMessageCodec.h */,
 				33C0FA1D21B84810008F8959 /* FLEJSONMethodCodec.h */,
 				33C0FA1F21B84810008F8959 /* FLEMessageCodec.h */,
@@ -202,8 +211,10 @@
 			buildActionMask = 2147483647;
 			files = (
 				33C0FA2621B84AA4008F8959 /* FLEMethodCall.h in Headers */,
+				2CC5E7432203444A000EF5F5 /* FLEExternalTexture.h in Headers */,
 				1E24923B1FCF50BE00DD3BBB /* FLEPlugin.h in Headers */,
 				2CCADF9B21C74690001B4026 /* FLEEventChannel.h in Headers */,
+				2CC5E74022033D53000EF5F5 /* FLETexture.h in Headers */,
 				3389A6872159359200A27898 /* FLEBinaryMessenger.h in Headers */,
 				33D7B59920A4F54400296EFC /* FLEMethodChannel.h in Headers */,
 				1E24923F1FCF50BE00DD3BBB /* FLEViewController.h in Headers */,
@@ -325,6 +336,7 @@
 				1EEF8E081FD1F0C300DD563C /* FLEView.m in Sources */,
 				33A87EB720F6BCDB0086D21D /* FLEJSONMethodCodec.m in Sources */,
 				2CCADF9A21C74690001B4026 /* FLEEventChannel.m in Sources */,
+				2CC5E7442203444A000EF5F5 /* FLEExternalTexture.m in Sources */,
 				AA8AE8BA1FD948BA00B6FB31 /* FLETextInputModel.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

From 96230c114220fb90064fe08c3ab77206c4b583f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Thu, 31 Jan 2019 23:37:30 +0800
Subject: [PATCH 08/12] Add missing callback parameters for RendererConfig.

---
 library/macos/FLEViewController.mm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/library/macos/FLEViewController.mm b/library/macos/FLEViewController.mm
index ba3ad520d..a0ddac991 100644
--- a/library/macos/FLEViewController.mm
+++ b/library/macos/FLEViewController.mm
@@ -344,7 +344,8 @@ + (FlutterRendererConfig)createRenderConfigHeadless:(BOOL)headless {
         .open_gl.clear_current = (BoolCallback)OnClearCurrent,
         .open_gl.present = (BoolCallback)OnPresent,
         .open_gl.fbo_callback = (UIntCallback)OnFBO,
-        .open_gl.make_resource_current = (BoolCallback)OnMakeResourceCurrent};
+        .open_gl.make_resource_current = (BoolCallback)OnMakeResourceCurrent,
+        .open_gl.gl_external_texture_frame_callback = (TextureFrameCallback)OnAcquireExternalTexture};
     return config;
   }
 }

From 8862833ba498cc54dc2f78606caefb4842aab630 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Thu, 31 Jan 2019 23:43:03 +0800
Subject: [PATCH 09/12] Add FLETexture.h include to FlutterEmbedderMac.h.

---
 library/macos/FlutterEmbedderMac.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/library/macos/FlutterEmbedderMac.h b/library/macos/FlutterEmbedderMac.h
index 8d5ed477b..7fc61f091 100644
--- a/library/macos/FlutterEmbedderMac.h
+++ b/library/macos/FlutterEmbedderMac.h
@@ -26,5 +26,6 @@
 #import "FLEPlugin.h"
 #import "FLEPluginRegistrar.h"
 #import "FLEReshapeListener.h"
+#import "FLETexture.h"
 #import "FLEView.h"
 #import "FLEViewController.h"

From c2f6f6f583ac361ff4033ef371ccc1d6963371dc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Fri, 1 Feb 2019 11:26:46 +0800
Subject: [PATCH 10/12] Add the necessary comments and code style changes for
 FLETexture.

---
 library/macos/FLEExternalTexture.h | 24 +++++---
 library/macos/FLEExternalTexture.m | 96 +++++++++++++++---------------
 library/macos/FLETexture.h         | 20 +++++++
 library/macos/FLEViewController.mm | 27 +++++----
 4 files changed, 100 insertions(+), 67 deletions(-)

diff --git a/library/macos/FLEExternalTexture.h b/library/macos/FLEExternalTexture.h
index 13838e9db..43de560be 100644
--- a/library/macos/FLEExternalTexture.h
+++ b/library/macos/FLEExternalTexture.h
@@ -17,20 +17,30 @@
 
 #import "FLETexture.h"
 
-NS_ASSUME_NONNULL_BEGIN
-
+/**
+ * Used to bridge external FLETexture objects,
+ * so the implementer only needs to return the CVPixelBufferRef object,
+ * which will make the interface consistent with the FlutterTexture.
+ */
 @interface FLEExternalTexture : NSObject
 
--(nonnull instancetype)initExternalTexture:(id<FLETexture>)external_texture;
+/**
+ *
+ */
+- (nonnull instancetype)initWithExternalTexture:(id<FLETexture>)external_texture;
 
--(BOOL)populateTextureWidth:(size_t)width
+/**
+ * Accept texture rendering notifications from the flutter engine.
+ */
+- (BOOL)populateTextureWidth:(size_t)width
                       height:(size_t)height
                      texture:(FlutterOpenGLTexture *)texture;
 
--(int64_t)textureId;
+/**
+ *
+ */
+- (int64_t)textureId;
 
 @property(nullable, weak) id<FLETexture> external_texture;
 
 @end
-
-NS_ASSUME_NONNULL_END
diff --git a/library/macos/FLEExternalTexture.m b/library/macos/FLEExternalTexture.m
index 7ed2b88f5..35b3b9c3d 100644
--- a/library/macos/FLEExternalTexture.m
+++ b/library/macos/FLEExternalTexture.m
@@ -20,73 +20,73 @@
 #import <OpenGL/gl.h>
 
 @implementation FLEExternalTexture {
-    CVOpenGLTextureCacheRef _textureCache;
-    CVPixelBufferRef _pixelBuffer;
+  CVOpenGLTextureCacheRef _textureCache;
+  CVPixelBufferRef _pixelBuffer;
 }
 
 @synthesize external_texture;
 
--(instancetype) initExternalTexture:(id<FLETexture>)external_texture {
-    self = [super init];
+- (instancetype)initWithExternalTexture:(id<FLETexture>)external_texture {
+  self = [super init];
 
-    if (self) {
-        self.external_texture = external_texture;
-    }
+  if (self) {
+    self.external_texture = external_texture;
+  }
 
-    return self;
+  return self;
 }
 
 static void OnGLTextureRelease(CVPixelBufferRef pixelBuffer) {
-    CVPixelBufferRelease(pixelBuffer);
+  CVPixelBufferRelease(pixelBuffer);
 }
 
--(int64_t)textureId {
-    return (NSInteger)(self);
+- (int64_t)textureId {
+  return (NSInteger)(self);
 }
 
--(BOOL)populateTextureWidth:(size_t)width
-                     height:(size_t)height
-                    texture:(FlutterOpenGLTexture *)texture{
-
-    if(_pixelBuffer == NULL || external_texture == NULL){
-        return NO;
-    }
-
-    // Copy image buffer from external texture.
-    _pixelBuffer = [external_texture copyPixelBuffer];
-
-    // Create the texture cache if necessary.
-    if (_textureCache == NULL) {
-        CGLContextObj context = [NSOpenGLContext currentContext].CGLContextObj;
-        CGLPixelFormatObj format = CGLGetPixelFormat(context);
-        if (CVOpenGLTextureCacheCreate(kCFAllocatorDefault, NULL, context, format, NULL, &_textureCache) != kCVReturnSuccess) {
-            NSLog(@"Could not create texture cache.");
-            CVPixelBufferRelease(_pixelBuffer);
-            return NO;
-        }
+- (BOOL)populateTextureWidth:(size_t)width
+           height:(size_t)height
+          texture:(FlutterOpenGLTexture *)texture {
+
+  if(_pixelBuffer == NULL || external_texture == NULL){
+    return NO;
+  }
+
+  // Copy image buffer from external texture.
+  _pixelBuffer = [external_texture copyPixelBuffer];
+
+  // Create the texture cache if necessary.
+  if (_textureCache == NULL) {
+    CGLContextObj context = [NSOpenGLContext currentContext].CGLContextObj;
+    CGLPixelFormatObj format = CGLGetPixelFormat(context);
+    if (CVOpenGLTextureCacheCreate(kCFAllocatorDefault, NULL, context, format, NULL, &_textureCache) != kCVReturnSuccess) {
+      NSLog(@"Could not create texture cache.");
+      CVPixelBufferRelease(_pixelBuffer);
+      return NO;
     }
+  }
 
-    // Try to clear the cache of OpenGL textures to save memory.
-    CVOpenGLTextureCacheFlush(_textureCache, 0);
-    
-    CVOpenGLTextureRef openGLTexture = NULL;
-    if (CVOpenGLTextureCacheCreateTextureFromImage(kCFAllocatorDefault, _textureCache, _pixelBuffer, NULL, &openGLTexture) != kCVReturnSuccess) {
-        CVPixelBufferRelease(_pixelBuffer);
-        return NO;
-    }
+  // Try to clear the cache of OpenGL textures to save memory.
+  CVOpenGLTextureCacheFlush(_textureCache, 0);
+  
+  CVOpenGLTextureRef openGLTexture = NULL;
+  if (CVOpenGLTextureCacheCreateTextureFromImage(kCFAllocatorDefault, _textureCache, _pixelBuffer, NULL, &openGLTexture) != kCVReturnSuccess) {
+    CVPixelBufferRelease(_pixelBuffer);
+    return NO;
+  }
 
-    texture->target = CVOpenGLTextureGetTarget(openGLTexture);
-    texture->name = CVOpenGLTextureGetName(openGLTexture);
-    texture->format = GL_RGBA8;
-    texture->destruction_callback = (VoidCallback)&OnGLTextureRelease;
-    texture->user_data = openGLTexture;
+  texture->target = CVOpenGLTextureGetTarget(openGLTexture);
+  texture->name = CVOpenGLTextureGetName(openGLTexture);
+  texture->format = GL_RGBA8;
+  texture->destruction_callback = (VoidCallback)&OnGLTextureRelease;
+  texture->user_data = openGLTexture;
 
-    CVPixelBufferRelease(_pixelBuffer);
-    return YES;
+  CVPixelBufferRelease(_pixelBuffer);
+  return YES;
 }
 
--(void) dealloc {
-    CVOpenGLTextureCacheRelease(_textureCache);
+- (void)dealloc {
+  CVOpenGLTextureCacheRelease(_textureCache);
 }
 
 @end
diff --git a/library/macos/FLETexture.h b/library/macos/FLETexture.h
index c16b8f510..5808c86a3 100644
--- a/library/macos/FLETexture.h
+++ b/library/macos/FLETexture.h
@@ -15,18 +15,38 @@
 #import <Foundation/Foundation.h>
 #import <CoreVideo/CVPixelBuffer.h>
 
+/**
+ * Implement a texture object for the FLE plugin side.
+ */
 @protocol FLETexture<NSObject>
 
+/**
+ * When the texture on the platform side is ready,
+ * the flutter engine will copy the texture buffer
+ * using copyPixelBuffer.
+ */
 - (nullable CVPixelBufferRef)copyPixelBuffer;
 
 @end
 
+/**
+ * The protocol for an object managing registration for texture.
+ */
 @protocol FLETextureRegistrar<NSObject>
 
+/**
+ * Register a |texture| object and return a textureId.
+ */
 - (int64_t)registerTexture:(nonnull id<FLETexture>)texture;
 
+/**
+ * Mark a texture buffer is ready.
+ */
 - (void)textureFrameAvailable:(int64_t)textureId;
 
+/**
+ * Unregister an existing Texture object.
+ */
 - (void)unregisterTexture:(int64_t)textureId;
 
 @end
diff --git a/library/macos/FLEViewController.mm b/library/macos/FLEViewController.mm
index a0ddac991..b0bed74d5 100644
--- a/library/macos/FLEViewController.mm
+++ b/library/macos/FLEViewController.mm
@@ -154,7 +154,7 @@ static bool OnAcquireExternalTexture(FLEViewController *controller,
                                      size_t width,
                                      size_t height,
                                      FlutterOpenGLTexture *texture) {
-    return [controller populateTextureWithIdentifier:texture_identifier width:width height:height texture:texture];
+  return [controller populateTextureWithIdentifier:texture_identifier width:width height:height texture:texture];
 }
 
 #pragma mark Static methods provided for headless engine configuration
@@ -360,25 +360,28 @@ - (void)makeResourceContextCurrent {
   [_resourceContext makeCurrentContext];
 }
 
--(BOOL) populateTextureWithIdentifier:(int64_t) textureId width:(size_t) width height:(size_t) height texture:(FlutterOpenGLTexture *) texture {
-    return [_textures[@(textureId)] populateTextureWidth:width height:height texture:texture];
+- (BOOL)populateTextureWithIdentifier:(int64_t)textureId
+                                width:(size_t)width
+                               height:(size_t) height
+                              texture:(FlutterOpenGLTexture *)texture {
+  return [_textures[@(textureId)] populateTextureWidth:width height:height texture:texture];
 }
 
-- (int64_t)registerTexture:(NSObject<FLETexture>*)texture {
-    FLEExternalTexture *fleTexture = [[FLEExternalTexture alloc] initExternalTexture:texture];
-    int64_t textureId = [fleTexture textureId];
-    FlutterEngineRegisterExternalTexture(_engine, textureId);
-    _textures[@(textureId)] = fleTexture;
-    return textureId;
+- (int64_t)registerTexture:(id<FLETexture>)texture {
+  FLEExternalTexture *fleTexture = [[FLEExternalTexture alloc] initWithExternalTexture:texture];
+  int64_t textureId = [fleTexture textureId];
+  FlutterEngineRegisterExternalTexture(_engine, textureId);
+  _textures[@(textureId)] = fleTexture;
+  return textureId;
 }
 
 - (void)textureFrameAvailable:(int64_t)textureId {
-    FlutterEngineMarkExternalTextureFrameAvailable(_engine, textureId);
+  FlutterEngineMarkExternalTextureFrameAvailable(_engine, textureId);
 }
 
 - (void)unregisterTexture:(int64_t)textureId {
-    FlutterEngineUnregisterExternalTexture(_engine, textureId);
-    [_textures removeObjectForKey:@(textureId)];
+  FlutterEngineUnregisterExternalTexture(_engine, textureId);
+  [_textures removeObjectForKey:@(textureId)];
 }
 
 - (void)handlePlatformMessage:(const FlutterPlatformMessage *)message {

From ae5c364dd46eb2e5dbdcb62363b924b469e3eafc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Fri, 1 Feb 2019 18:03:38 +0800
Subject: [PATCH 11/12] Export the texture registrar declaration from
 FLEPluginRegistrar.

---
 library/macos/FLEExternalTexture.m | 6 +++++-
 library/macos/FLEPluginRegistrar.h | 6 ++++++
 library/macos/FLEViewController.mm | 4 ++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/library/macos/FLEExternalTexture.m b/library/macos/FLEExternalTexture.m
index 35b3b9c3d..6d9cca26f 100644
--- a/library/macos/FLEExternalTexture.m
+++ b/library/macos/FLEExternalTexture.m
@@ -48,13 +48,17 @@ - (BOOL)populateTextureWidth:(size_t)width
            height:(size_t)height
           texture:(FlutterOpenGLTexture *)texture {
 
-  if(_pixelBuffer == NULL || external_texture == NULL){
+  if(external_texture == NULL) {
     return NO;
   }
 
   // Copy image buffer from external texture.
   _pixelBuffer = [external_texture copyPixelBuffer];
 
+  if(_pixelBuffer == NULL) {
+    return NO;
+  }
+
   // Create the texture cache if necessary.
   if (_textureCache == NULL) {
     CGLContextObj context = [NSOpenGLContext currentContext].CGLContextObj;
diff --git a/library/macos/FLEPluginRegistrar.h b/library/macos/FLEPluginRegistrar.h
index 20401863e..f5660549d 100644
--- a/library/macos/FLEPluginRegistrar.h
+++ b/library/macos/FLEPluginRegistrar.h
@@ -16,6 +16,7 @@
 
 #import "FLEBinaryMessenger.h"
 #import "FLEMethodChannel.h"
+#import "FLETexture.h"
 
 /**
  * The protocol for an object managing registration for a plugin. It provides access to application
@@ -31,6 +32,11 @@
  */
 @property(nonnull, readonly) id<FLEBinaryMessenger> messenger;
 
+/**
+ * Returns a `FLETextureRegistry` for registering textures provided by the plugin.
+ */
+@property(nonnull, readonly) id<FLETextureRegistrar> textures;
+
 /**
  * The view displaying Flutter content.
  *
diff --git a/library/macos/FLEViewController.mm b/library/macos/FLEViewController.mm
index b0bed74d5..7c909ed5a 100644
--- a/library/macos/FLEViewController.mm
+++ b/library/macos/FLEViewController.mm
@@ -482,6 +482,10 @@ - (void)setMessageHandlerOnChannel:(nonnull NSString *)channel
   return self;
 }
 
+- (id<FLETextureRegistrar>)textures {
+    return self;
+}
+
 - (void)addMethodCallDelegate:(nonnull id<FLEPlugin>)delegate
                       channel:(nonnull FLEMethodChannel *)channel {
   [channel setMethodCallHandler:^(FLEMethodCall *call, FLEMethodResult result) {

From 93225f29fa011c436e610210451191c42b82ded3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=B9=96=E5=8C=97=E6=8D=B7=E6=99=BA=E4=BA=91=E6=8A=80?=
 =?UTF-8?q?=E6=9C=AF=E6=9C=89=E9=99=90=E5=85=AC=E5=8F=B8?=
 <duanweiwei1982@gmail.com>
Date: Fri, 1 Feb 2019 21:31:07 +0800
Subject: [PATCH 12/12] Update FLEExternalTexture.h

---
 library/macos/FLEExternalTexture.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/macos/FLEExternalTexture.h b/library/macos/FLEExternalTexture.h
index 43de560be..ceaa25e97 100644
--- a/library/macos/FLEExternalTexture.h
+++ b/library/macos/FLEExternalTexture.h
@@ -27,7 +27,7 @@
 /**
  *
  */
-- (nonnull instancetype)initWithExternalTexture:(id<FLETexture>)external_texture;
+- (nonnull instancetype)initWithExternalTexture:(nonnull id<FLETexture>)external_texture;
 
 /**
  * Accept texture rendering notifications from the flutter engine.