Migrate clip module from aseprite to laf

.gitmodules

@@ -1,3 +1,6 @@
+[submodule "clip"]
+	path = clip
+	url = https://github.com/aseprite/clip.git
 [submodule "third_party/googletest"]
 	path = third_party/googletest
 	url = https://github.com/aseprite/googletest.git

CMakeLists.txt

@@ -30,6 +30,7 @@ endif()
 
 option(LAF_WITH_EXAMPLES "Enable LAF examples" ON)
 option(LAF_WITH_TESTS "Enable LAF tests" ON)
+option(LAF_WITH_CLIP "Enable clip module (required for future drag-and-drop feature)" ON)
 set(LAF_BACKEND ${LAF_DEFAULT_BACKEND} CACHE STRING "Select laf backend")
 set_property(CACHE LAF_BACKEND PROPERTY STRINGS "none" "skia")
 
@@ -51,6 +52,16 @@ else()
   endif()
 endif()
 
+if(LAF_WITH_CLIP)
+  # Disable clip examples and tests
+  set(CLIP_EXAMPLES OFF CACHE BOOL "Compile clip examples")
+  set(CLIP_TESTS OFF CACHE BOOL "Compile clip tests")
+  if(PNG_LIBRARY)
+    set(CLIP_X11_PNG_LIBRARY "${PNG_LIBRARY}")
+  endif()
+  add_subdirectory(clip)
+endif()
+
 add_subdirectory(third_party)
 add_subdirectory(base)
 add_subdirectory(gfx)

os/CMakeLists.txt

@@ -89,6 +89,11 @@ endif()
 
 add_library(laf-os ${LAF_OS_SOURCES})
 target_link_libraries(laf-os laf-gfx laf-base)
+if(LAF_WITH_CLIP)
+  target_link_libraries(laf-os clip)
+  target_compile_definitions(laf-os PUBLIC
+    LAF_WITH_CLIP)
+endif()
 if(FREETYPE_LIBRARIES AND HARFBUZZ_LIBRARIES)
   target_link_libraries(laf-os laf-ft)
   target_compile_definitions(laf-os PRIVATE