The Qt example already does this. I hoped this was restricted to
QApplication only, but apparently Qt repeated this mistake with
QGuiApplication (QGuiApplication was specifically added for QtQuick at a
much later point, even though QApplication inherits from it).
C++ is the worst language ever, and allows throwing any type, even if it
doesn't make sense. In this case, we were throwing char*, which the
runtime typically treats as opaque, instead of printing it as message if
such an exception was not caught.
Until now, calling mpv_opengl_cb_uninit_gl() at a "bad moment" could
make the whole thing to explode. The API user was asked to avoid such
situations by calling it only in "good moments". But this was probably a
bit too subtle and could easily be overlooked.
Integrate the approach the qml example uses directly into the
implementation. If the OpenGL context is to be unitialized, forcefully
disable video, and block until this is done.
Destruction (e.g. when closing the window) was a bit broken. This commit
fixes some possible crashes, and should make lifetime management
relatively sane. (Still a bit complex, though. Maybe this code should be
moved into a tiny library.)
QtQuick runs the renderer on a separate thread. This thread is rather
loosely connected to the main thread. The loose separation is enforced
by the API, which also makes coordination of initialization and
destruction harder. Throw refcounting at the problem, which fixes it.
The refcounting wrapper introduced in the previous commit is used for
this.
Also contains some general cleanups.
This adds API to libmpv that lets host applications use the mpv opengl
renderer. This is a more flexible (and possibly more portable) option to
foreign window embedding (via --wid).
This assumes that methods like context sharing and multithreaded OpenGL
rendering are infeasible, and that a way is needed to integrate it with
an application that uses a single thread to render everything.
Add an example that does this with QtQuick/qml. The example is
relatively lazy, but still shows how relatively simple the integration
is. The FBO indirection could probably be avoided, but would require
more work (and would probably lead to worse QtQuick integration, because
it would have to ignore transformations like rotation).
Because this makes mpv directly use the host application's OpenGL
context, there is no platform specific code involved in mpv, except
for hw decoding interop.
main.qml is derived from some Qt example.
The following things are still missing:
- a way to do better video timing
- expose GL renderer options, allow changing them at runtime
- support for color equalizer controls
- support for screenshots
