When opting into the Skia renderer, we default to metal on macOS and D3D on Windows.
However if you want to develop a cross-platform application with Skia and
for example rely on OpenGL to be able to implement an OpenGL underlay or overlay,
then we need the ability to explicitly opt into skia's GL renderer.
cc #1445
This way we don't have to add defmt, esp32-println and others as features to corelib and the slint api crate
(which would also expose them as public dependencies),
but instead this can be simply delegated to the Platform trait.
We used to have SLINT_FEATURE_BACKEND_GL_ALL, but when we introduced the
renderer and event loop distinction in the features, we removed the "all" suffix from
the event loop that includes x11 and wayland support.
When building against a Yocto SDK, CFLAGS isn't set, only CC. When
building inside Yocto, CC is set to just the target compiler and CFLAGS
contains the target specific options. Just like with commit
5bc56a3924 we need to cover also
HOST_CFLAGS by making them empty.
and use Rc<dyn PlatformWindow> instead. The alias has to stay with the ffi
functions though and the item vtable definitions,
because we don't have an Rc<> template in C++.
One key difference to the Rust way is what `slint::Window` means. In
Rust that holds the `WindowInner` and `slint::Window` is only exposed as
`&slint::Window`. This is possible because the component owns the
`Rc<dyn PlatformWindow>`, which has a function to return the
`&slint::Window`.
In C++ `slint::Window` is also exposed as `slint::Window&` in the
`window()` getter, but there's no way to get a reference to a C++
wrapper for the Rust `&slint::Window` that the `PlatformWindow` trait
returns. Therefore in C++ `slint::Window` wraps `Rc<dyn
PlatformWindow>`.
Previously: Window is an Rc<WindowInner>, which has an Rc<dyn
PLatformWindow> - and weak references the other way around.
Now: Rc<dyn PlatformWindow> is the root of window ownership. The impl
PlatformWindow has a slint::api::Window, which just holds a WindowInner.
This change is incomplete on a few levels, mainly that neither of the
code generators nor the interpreter is ported.
Because re-generating the Skia image is slow and there is no point
storing both the image buffer and the SkiaImage in the cache as it
is basically the same information.
Split backend-gl-* into eventloop-winit-* and renderer-femtovg.
The old feature names are still available.
For consistency eventloop-qt and renderer-qt are aliases for backend-qt.
