Closes#1545
Not that `SoftwareRenderer::new()` takes the Weak by value instead of
by reference, because coercing a reference to a `Weak` to a `&Weak<dyn>`
is not possible, while converting a Weak to a `Weak<dyn>` just works.
Before the change:
- calling the_timer.start(...) in the_timer's callback resulted in the_timer
keeping the old callback;
- calling the_timer.stop() in the_timer's callback was ignored.
The test backend can no longer support this.
Because Tests might be called from different thread and the backend with
an event loop can only be set on one thread. So the test backend can't
implement new_event_loop_proxy()
When using box shadows in repeaters, we end up creating multiple
distinct textures of the drop shadow. That's a waste of precious texture
memory if they have the same properties.
Instead, when creating box shadows in a frame, see if they can be
re-used across images. The texture still persistent in the image_cache,
via the explicitly shared skia_safe::Image and Rc<Texture>.
This works well when rendering repeated elements new top-down, but it's
not perfect. For example if a bunch of repeated elements are in a
flickable, only a portion of them are visible and the view is scroll up,
then the top-down rendering will not find a cache hit for the newly
visible element with drop shadows. Yet this is simple enough to help
with sharing in many cases.
Since the new version also depends on the ctirical-section 1.0 crate
we need to enable the relevant API in the cortex-m crate because the
rp2040-hal doesn't have it yet
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.
For hide() we don't really need Rc<Self>, and for show() we had Rc<Self> because
for example for winit we need a Weak<Self> for the thread-local mapping of
window id to window.
However that can be encapsulated in the PlatformWindow impl using Rc::new_cyclic,
there's no need to expose this in the trait.
Move the self_weak of WindowInner into the impl of PlatformWindow. Most implementations already have it anyway.
While right now the method returns a `WindowRc`, at the end of the series
it should return a `&Window`.
From that `&Window` we can get to `&WindowInner` and all receivers there
are `&self`.
