build: Add an option to use a bundled KDSingleApplication (flameshot-org#4130)

When packaging, distros like to not use bundled dependencies when
possible. This adds an option to use a bundled version of
KDSingleApplication, or a system version of the library.

I briefly explored doing the same for Qt-Color-Widgets, but it seems to
expect to be bundled in a project.

Signed-off-by: Evan Maddock <[email protected]>

Author: EbonJaeger

CMakeLists.txt

@@ -74,6 +74,7 @@ option(FLAMESHOT_DEBUG_CAPTURE "Enable mode to make debugging easier" OFF)
 option(USE_MONOCHROME_ICON "Build using monochrome icon as default" OFF)
 option(GENERATE_TS "Regenerate translation source files" OFF)
 option(USE_KDSINGLEAPPLICATION "Use KDSingleApplication library" ON)
+option(USE_BUNDLED_KDSINGLEAPPLICATION "Use a bundled version of the KDSingleApplication library" ${USE_KDSINGLEAPPLICATION})
 option(USE_LAUNCHER_ABSOLUTE_PATH "Use absolute path for the desktop launcher" ON)
 option(USE_WAYLAND_CLIPBOARD "USE KF Gui Wayland Clipboard" OFF)
 option(DISABLE_UPDATE_CHECKER "Disable check for updates" OFF)
@@ -108,19 +109,23 @@ enable_sanitizers(project_options)
 # allow for static analysis options include(cmake/StaticAnalyzers.cmake)
 
 if (USE_KDSINGLEAPPLICATION)
-  set(KDSingleApplication_EXAMPLES OFF CACHE BOOL "Don't build the examples")
-  set(KDSingleApplication_STATIC ON CACHE BOOL "Build static versions of the libraries")
+  if (USE_BUNDLED_KDSINGLEAPPLICATION)
+    set(KDSingleApplication_EXAMPLES OFF CACHE BOOL "Don't build the examples")
+    set(KDSingleApplication_STATIC ON CACHE BOOL "Build static versions of the libraries")
 
-  # Check if KDSingleApplication is available locally
-  if(EXISTS "${CMAKE_SOURCE_DIR}/external/KDSingleApplication/CMakeLists.txt")
-    add_subdirectory("${CMAKE_SOURCE_DIR}/external/KDSingleApplication")
+    # Check if KDSingleApplication is available locally
+    if(EXISTS "${CMAKE_SOURCE_DIR}/external/KDSingleApplication/CMakeLists.txt")
+      add_subdirectory("${CMAKE_SOURCE_DIR}/external/KDSingleApplication")
+    else()
+      FetchContent_Declare(
+          kdsingleApplication
+          GIT_REPOSITORY https://github.com/KDAB/KDSingleApplication.git
+          GIT_TAG v1.2.0
+      )
+      FetchContent_MakeAvailable(kdsingleApplication)
+    endif()
   else()
-    FetchContent_Declare(
-        kdsingleApplication
-        GIT_REPOSITORY https://github.com/KDAB/KDSingleApplication.git
-        GIT_TAG v1.2.0
-    )
-    FetchContent_MakeAvailable(KDSingleApplication)
+    find_package(KDSingleApplication-qt6 REQUIRED)
   endif()
 endif()
 

src/CMakeLists.txt

@@ -218,9 +218,13 @@ if (USE_KDSINGLEAPPLICATION)
   message(STATUS "KDSingleApplication is used!")
   add_compile_definitions(USE_KDSINGLEAPPLICATION=1)
 
+  if (USE_BUNDLED_KDSINGLEAPPLICATION)
+    target_include_directories(flameshot PRIVATE ${kdsingleapplication_SOURCE_DIR} ${kdsingleapplication_BINARY_DIR})
+  endif()
+
   target_link_libraries(
           flameshot
-          kdsingleapplication
+          KDAB::kdsingleapplication
   )
 endif()
 

src/main.cpp

@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: 2017-2019 Alejandro Sirgo Rica & Contributors
 
 #ifdef USE_KDSINGLEAPPLICATION
-#include "kdsingleapplication.h"
+#include <kdsingleapplication.h>
 #ifdef Q_OS_UNIX
 #include "core/signaldaemon.h"
 #include "csignal"