libmpv2

Rust binding to libmpv's OpenGL render API, letting mpv draw video frames into our own GL context instead of opening its own window — needed to embed video inside the Slint window (SPEC.md: "Rust + Slint + libmpv").

The original libmpv crate is unmaintained and lacks the render API; libmpv2 is an actively maintained fork with a complete render module. libmpv2-sys links against the system's libmpv.so directly using pre-generated bindings (no bindgen) — libmpv-dev/mpv-libs-devel must be installed to build.

crates/app/src/video_player.rs owns the Mpv core and RenderContext, tied to Slint's window via set_rendering_notifier — see Video playback for the mechanism.

Pitfalls

• RenderContext<'a> borrows from Mpv; video_player.rs sidesteps the resulting self-reference with a deliberate Box::leak (fine — one player per process).
• OpenGLInitParams::get_proc_address wants a plain fn pointer, not a closure — gl_proc_address_bridge.rs bridges Slint's borrowed loader closure through a thread-local.
• set_update_callback's closure runs on an mpv-internal thread and must not call mpv/GL APIs — it only signals via slint::invoke_from_event_loop.
• mpv's render call always draws at (0, 0) of the given framebuffer with no offset parameter — confining it to a sub-rectangle needs an offscreen FBO (see video-playback.md).