highgui Wayland xdg_shell

-enable using -DWITH_WAYLAND=ON
-adapted from https://github.com/pfpacket/opencv-wayland
-using xdg_shell stable protocol
-overrides HAVE_QT if HAVE_WAYLAND and WITH_WAYLAND are set

Signed-off-by: Joel Winarske <joel.winarske@gmail.com>

Co-authored-by: Ryo Munakata <afpacket@gmail.com>

modules/highgui/cmake/detect_wayland.cmake

@@ -0,0 +1,35 @@
+# --- Wayland ---
+macro(ocv_wayland_generate protocol_file output_file)
+    add_custom_command(OUTPUT ${output_file}.h
+            COMMAND ${WAYLAND_SCANNER_EXECUTABLE} client-header < ${protocol_file} > ${output_file}.h
+            DEPENDS ${protocol_file})
+    add_custom_command(OUTPUT ${output_file}.c
+            COMMAND ${WAYLAND_SCANNER_EXECUTABLE} private-code < ${protocol_file} > ${output_file}.c
+            DEPENDS ${protocol_file})
+    list(APPEND WAYLAND_PROTOCOL_SOURCES ${output_file}.h ${output_file}.c)
+endmacro()
+
+ocv_clear_vars(HAVE_WAYLAND_CLIENT HAVE_WAYLAND_CURSOR HAVE_XKBCOMMON HAVE_WAYLAND_PROTOCOLS)
+if(WITH_WAYLAND)
+    ocv_check_modules(WAYLAND_CLIENT wayland-client)
+    if(WAYLAND_CLIENT_FOUND)
+        set(HAVE_WAYLAND_CLIENT ON)
+    endif()
+    ocv_check_modules(WAYLAND_CURSOR wayland-cursor)
+    if(WAYLAND_CURSOR_FOUND)
+        set(HAVE_WAYLAND_CURSOR ON)
+    endif()
+    ocv_check_modules(XKBCOMMON xkbcommon)
+    if(XKBCOMMON_FOUND)
+        set(HAVE_XKBCOMMON ON)
+    endif()
+    ocv_check_modules(WAYLAND_PROTOCOLS wayland-protocols>=1.13)
+    if(HAVE_WAYLAND_PROTOCOLS)
+        pkg_get_variable(WAYLAND_PROTOCOLS_BASE wayland-protocols pkgdatadir)
+        find_host_program(WAYLAND_SCANNER_EXECUTABLE NAMES wayland-scanner REQUIRED)
+    endif()
+
+    if(HAVE_WAYLAND_CLIENT AND HAVE_WAYLAND_CURSOR AND HAVE_XKBCOMMON AND HAVE_WAYLAND_PROTOCOLS)
+        set(HAVE_WAYLAND TRUE)
+    endif()
+endif()

modules/highgui/cmake/init.cmake

@@ -38,6 +38,7 @@ endmacro()
 
 add_backend("gtk" WITH_GTK)
 add_backend("win32ui" WITH_WIN32UI)
+add_backend("wayland" WITH_WAYLAND)
 # TODO cocoa
 # TODO qt
 # TODO opengl