Allow disabling X11 desktop capturing independently.

Squashed commit of the following:

commit 253b09a07520a3cecb3b88b2b7e8889ab3d9158d
Author: Hilton Chain <hako@ultrarare.space>
Date:   Fri Sep 9 22:13:15 2022 +0800

    Adapt the patch with cmake_dependent_option.

commit f6631bb43f353c9eafe1b1aba093e116518aa12a
Author: Esteve Varela Colominas <esteve.varela@gmail.com>
Date:   Sun, 27 Jun 2021 23:57:04 +0200

    Add -DTG_OWT_USE_X11

    Allows disabling X11 desktop capturing independently of pipewire support, for
    the few people that run wayland without any X11 support whatsoever.

    This setup is untested, but supported by the GNI build system, see:
    * src/modules/desktop_capture/BUILD.gn (option rtc_use_x11_extensions)

    Toggling the WEBRTC_USE_X11 define also affects some files under
    src/modules/audio_device, but that falls under "X11 support", regardless...

    Use cmake_dependent_option to better declare variables that relate on other variables

CMakeLists.txt

@@ -24,6 +24,7 @@ endif()
 
 option(BUILD_SHARED_LIBS "Builds shared libraries instead of static." OFF)
 option(TG_OWT_USE_PROTOBUF "Use protobuf to generate additional headers. Useful for packaged build." ${BUILD_SHARED_LIBS})
+cmake_dependent_option(TG_OWT_USE_X11 "Use X11 for desktop capture." ON "UNIX; NOT APPLE" OFF)
 cmake_dependent_option(TG_OWT_USE_PIPEWIRE "Use pipewire for desktop capture." ON "UNIX; NOT APPLE" OFF)
 cmake_dependent_option(TG_OWT_DLOPEN_PIPEWIRE "dlopen pipewire for desktop capture." ${not_packaged_build} TG_OWT_USE_PIPEWIRE OFF)
 option(TG_OWT_BUILD_AUDIO_BACKENDS "Build webrtc audio backends." OFF)
@@ -188,7 +189,7 @@ endif()
 include(cmake/libwebrtcbuild.cmake)
 target_link_libraries(tg_owt PUBLIC tg_owt::libwebrtcbuild)
 
-if (UNIX AND NOT APPLE)
+if (TG_OWT_USE_X11)
     link_x11(tg_owt)
 endif()
 
@@ -2369,6 +2370,39 @@ if (NOT TG_OWT_USE_PROTOBUF)
     )
 endif()
 
+if (NOT TG_OWT_USE_X11)
+    remove_target_sources(tg_owt ${webrtc_loc}
+        # src/modules/desktop_capture/BUILD.gn (rtc_use_x11_extensions)
+        modules/desktop_capture/linux/x11/mouse_cursor_monitor_x11.cc
+        modules/desktop_capture/linux/x11/mouse_cursor_monitor_x11.h
+        modules/desktop_capture/linux/x11/screen_capturer_x11.cc
+        modules/desktop_capture/linux/x11/screen_capturer_x11.h
+        modules/desktop_capture/linux/x11/shared_x_display.cc
+        modules/desktop_capture/linux/x11/shared_x_display.h
+        modules/desktop_capture/linux/x11/window_capturer_x11.cc
+        modules/desktop_capture/linux/x11/window_capturer_x11.h
+        modules/desktop_capture/linux/x11/window_finder_x11.cc
+        modules/desktop_capture/linux/x11/window_finder_x11.h
+        modules/desktop_capture/linux/x11/window_list_utils.cc
+        modules/desktop_capture/linux/x11/window_list_utils.h
+        modules/desktop_capture/linux/x11/x_atom_cache.cc
+        modules/desktop_capture/linux/x11/x_atom_cache.h
+        modules/desktop_capture/linux/x11/x_error_trap.cc
+        modules/desktop_capture/linux/x11/x_error_trap.h
+        modules/desktop_capture/linux/x11/x_server_pixel_buffer.cc
+        modules/desktop_capture/linux/x11/x_server_pixel_buffer.h
+        modules/desktop_capture/linux/x11/x_window_property.cc
+        modules/desktop_capture/linux/x11/x_window_property.h
+
+        # screen_drawer_linux.cc depends on x11, rest are revdeps
+        modules/desktop_capture/screen_drawer.cc
+        modules/desktop_capture/screen_drawer.h
+        modules/desktop_capture/screen_drawer_linux.cc
+        modules/desktop_capture/screen_drawer_lock_posix.cc
+        modules/desktop_capture/screen_drawer_lock_posix.h
+    )
+endif()
+
 if (NOT TG_OWT_USE_PIPEWIRE)
     remove_target_sources(tg_owt ${webrtc_loc}
         modules/desktop_capture/linux/wayland/base_capturer_pipewire.cc

cmake/libwebrtcbuild.cmake

@@ -29,6 +29,13 @@ INTERFACE
     BWE_TEST_LOGGING_COMPILE_TIME_ENABLE=0
 )
 
+if (TG_OWT_USE_X11)
+    target_compile_definitions(libwebrtcbuild
+    INTERFACE
+        WEBRTC_USE_X11
+    )
+endif()
+
 if (TG_OWT_USE_PIPEWIRE)
     target_compile_definitions(libwebrtcbuild
     INTERFACE
@@ -65,11 +72,6 @@ else()
         INTERFACE
             WEBRTC_MAC
         )
-    else()
-        target_compile_definitions(libwebrtcbuild
-        INTERFACE
-            WEBRTC_USE_X11
-        )
     endif()
 
     if (CMAKE_SYSTEM_NAME STREQUAL "Linux")