Select that the compiler and xtask should be compiled as host binaries,
not target.
This also pulls in new corrosion with better cross-compilation support.
Move those two classes into the private_api namespace, which is excluded
from the API reference documentation.
For generate code the explicit qualification of Property<T> is changed,
for the cbindgen generated item types the private_api namespace is
pulled into the cbindgen_private namespace.
A few problem:
- the horizontal and vertical property were swapped
- The implementation of the "preferred_xxx" property was not materialized properly
because the `bindings` were borrowed in the materialize_fake_properties pass
- Since the Window has a stretch factor of 0., the preferred size of the inner layout
was not taken into account when merging the LayoutInfo. I believe taking the
maximum preferred size is the right solution when merging them.
When using cmake to configure the C++ build and Qt is found, and then
build with `SIXTYFPS_NO_QT=0 cmake --build ..`, the C++ library is built
without Qt support but qt_viewer is built. Linkage then fails when it
tries to access the API in libsixtyfps_cpp.so that provides the QWidget,
as that symbol is not present.
So with newer CMake we use find_package to provide positive information
to the cargo build about where Qt is, and consequently this patch
provides negative information to disable Qt support if CMake could not
find Qt -- or it was deliberately disabled for example using
`-DCMAKE_DISABLE_FIND_PACKAGE_Qt5=1`.
cc #232
find_package(Qt5) may do a better job at finding qmake, especially if the build is invoked
through Qt Creator, which may make sure that CMAKE_PREFIX_PATH is set.
Forward the qmake path therefore the the rust build.
The item tree is intended to be initialized with pointers to the item
vtables, which are implemented using data relocation records that
resolve to the symbols exported by the sixtyfps_cpp shared library.
On windows, according to
https://docs.microsoft.com/en-us/cpp/c-language/rules-and-limitations-for-dllimport-dllexport?view=msvc-160
such data relocations are not supported, so this patch implements the
fallback through getter functions.
