How to get GLFW window Id of FlutterWindow - flutter

Question

I am trying to build a video player using flutter for Desktop. There is a video_player plugin available for iOS and Android, but not for Desktop. So, for the time being thought of trying to use gstreamer for decoding and hardware rendering in C++ code as back-end to flutter. The idea is to pass the Window Id of the flutter window to gstreamer's glimagesink plugin for rendering the video.
I am using the latest code from https://github.com/google/flutter-desktop-embedding as the base for my experiments. Below mentioned points are with reference to this repo.
In file flutter-desktop-embedding/example/linux/main.cc, FlutterWindowController object is created as shown below.
flutter::FlutterWindowController flutter_controller(icu_data_path);
This internally calls
FlutterDesktopInit();
While hovering the mouse pointer on the above method, VS code shows the following
bool FlutterDesktopInit()
Sets up the library's graphic context. Must be called before any other
methods.
Note: Internally, this library uses GLFW, which does not support multiple
copies within the same process. Internally this calls glfwInit, which will
fail if you have called glfwInit elsewhere in the process.
It is clear that FlutterDesktopInit() uses GLFW to create window. Checked whether I can get the window handle. But, no luck. I could only get the FlutterWindow object as shown below.
flutter::FlutterWindow *win = flutter_controller.window();
Appreciate if somebody can give some hint on how to get the GLFW window handle, which can be used with glimagesink.

Answer 1

You can't get references to any GLFW objects through that API. This is by design because, as the comment you quoted says, you can't have multiple copies of GLFW within the same process. GLFW is statically linked into the Linux Flutter embedding, so you can't use GLFW in the runner or a plugin.
Implementing a video player should be done using the texture APIs, which will be added for GLFW in this PR.