sddm: Provide a configuration for SDDM Wayland sessions

It will simplify the deployments of SDDM and wayland together for
Plasma-based systems.

CMakeLists.txt

@@ -7,6 +7,7 @@ set(PROJECT_VERSION_MAJOR 5)
 set(QT_MIN_VERSION "5.15.0")
 set(KF5_MIN_VERSION "5.82")
 set(INSTALL_SDDM_THEME TRUE)
+option(INSTALL_SDDM_WAYLAND_SESSION OFF)
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -202,7 +203,12 @@ if (INSTALL_SDDM_THEME)
     PATTERN "theme.conf.cmake" EXCLUDE)
     install(FILES ${CMAKE_CURRENT_BINARY_DIR}/sddm-theme/theme.conf DESTINATION ${KDE_INSTALL_FULL_DATADIR}/sddm/themes/breeze)
     install(DIRECTORY lookandfeel/contents/components DESTINATION ${KDE_INSTALL_FULL_DATADIR}/sddm/themes/breeze PATTERN "README.txt" EXCLUDE)
+endif()
 
+if (INSTALL_SDDM_WAYLAND_SESSION)
+    install(FILES sddm-wayland-session/plasma-wayland.conf DESTINATION /etc/sddm.conf.d)
+else()
+    message(STATUS "INSTALL_SDDM_WAYLAND_SESSION is disabled. As soon as it's installed, SDDM will default to use Wayland and KWin for its greeter session (BETA, do not deploy to final users yet).")
 endif()
 
 add_definitions(-DQT_NO_URL_CAST_FROM_STRING)

sddm-wayland-session/plasma-wayland.conf

@@ -0,0 +1,7 @@
+[General]
+DisplayServer=wayland
+GreeterEnvironment=QT_WAYLAND_SHELL_INTEGRATION=layer-shell
+InputMethod=
+
+[Wayland]
+CompositorCommand=kwin_wayland --no-lockscreen --inputmethod maliit-keyboard