PyQt demo app (#21625)

* build python helpers lib

* call setMainWindow from python

* put in helper lib

* linter

* move to scripts
old-commit-hash: 25e4e94691d90f1a4496a2742c63ede108593e15

selfdrive/ui/qt/python_helpers.py

@@ -0,0 +1,21 @@
+
+import os
+from cffi import FFI
+
+import sip  # pylint: disable=import-error
+
+from common.ffi_wrapper import suffix
+from common.basedir import BASEDIR
+
+
+def get_ffi():
+  lib = os.path.join(BASEDIR, "selfdrive", "ui", "qt", "libpython_helpers" + suffix())
+
+  ffi = FFI()
+  ffi.cdef("void set_main_window(void *w);")
+  return ffi, ffi.dlopen(lib)
+
+
+def set_main_window(widget):
+  ffi, lib = get_ffi()
+  lib.set_main_window(ffi.cast('void*', sip.unwrapinstance(widget)))