documented fluttertexture.h (flutter/engine#16950)

engine/src/flutter/shell/platform/darwin/common/framework/Headers/FlutterTexture.h

@@ -13,7 +13,13 @@
 NS_ASSUME_NONNULL_BEGIN
 
 FLUTTER_EXPORT
+/**
+ * Represents a texture that can be shared with Flutter.
+ *
+ * See also: https://github.com/flutter/plugins/tree/master/packages/camera
+ */
 @protocol FlutterTexture <NSObject>
+/** Copy the contents of the texture into a `CVPixelBuffer`. */
 - (CVPixelBufferRef _Nullable)copyPixelBuffer;
 
 /**
@@ -26,9 +32,26 @@ FLUTTER_EXPORT
 @end
 
 FLUTTER_EXPORT
+/**
+ * A collection of registered `FlutterTexture`'s.
+ */
 @protocol FlutterTextureRegistry <NSObject>
+/**
+ * Registers a `FlutterTexture` for usage in Flutter and returns an id that can be used to reference
+ * that texture when calling into Flutter with channels.
+ */
 - (int64_t)registerTexture:(NSObject<FlutterTexture>*)texture;
+/**
+ * Notifies Flutter that the content of the previously registered texture has been updated.
+ *
+ * This will trigger a call to `-[FlutterTexture copyPixelBuffer]` on the GPU thread.
+ */
 - (void)textureFrameAvailable:(int64_t)textureId;
+/**
+ * Unregisters a `FlutterTexture` that has previously regeistered with `registerTexture:`.
+ *
+ * @param textureId The result that was previously returned from `registerTexture:`.
+ */
 - (void)unregisterTexture:(int64_t)textureId;
 @end