Update the GTK icon cache when installing.

Despite the name this is also used by Qt, and considerably speeds up
icon lookup.

REVIEW: 125195

CMakeLists.txt

@@ -11,13 +11,14 @@ if(USE_KDE4)
   add_subdirectory(kstyle)
 else()
   find_package(ECM 0.0.9 REQUIRED NO_MODULE)
-  set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR})
+  set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR} ${CMAKE_SOURCE_DIR}/cmake)
 
   include(ECMInstallIcons)
   include(KDEInstallDirs)
   include(KDECMakeSettings)
   include(KDECompilerSettings)
   include(GenerateExportHeader)
+  include(GtkUpdateIconCache)
 
   add_subdirectory(cursors)
   add_subdirectory(icons)

cmake/GtkUpdateIconCache.cmake

@@ -0,0 +1,21 @@
+# Copyright 2015 Volker Krause <vkrause@kde.org>
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file COPYING-CMAKE-SCRIPTS for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+
+find_program(GTK_UPDATE_ICON_CACHE_EXECUTABLE NAMES gtk-update-icon-cache)
+
+macro(gtk_update_icon_cache _dir)
+    if (GTK_UPDATE_ICON_CACHE_EXECUTABLE)
+        install(CODE "
+            set(DESTDIR_VALUE \"\$ENV{DESTDIR}\")
+            if (NOT DESTDIR_VALUE)
+                execute_process(COMMAND ${GTK_UPDATE_ICON_CACHE_EXECUTABLE} -q -i . WORKING_DIRECTORY ${_dir})
+            endif()
+        ")
+    endif()
+endmacro()

icons-dark/CMakeLists.txt

@@ -18,4 +18,4 @@ set(BREEZE_INSTALL_DIR ${ICON_INSTALL_DIR}/breeze-dark)
 install( DIRECTORY ${breeze_icon_dark_dirs} DESTINATION ${BREEZE_INSTALL_DIR} PATTERN "*.sh" EXCLUDE )
 install( FILES index.theme DESTINATION ${BREEZE_INSTALL_DIR})
 
-
+gtk_update_icon_cache(${BREEZE_INSTALL_DIR})

icons/CMakeLists.txt

@@ -18,4 +18,4 @@ set(BREEZE_INSTALL_DIR ${ICON_INSTALL_DIR}/breeze)
 install( DIRECTORY ${breeze_icon_dirs} DESTINATION ${BREEZE_INSTALL_DIR} PATTERN "*.sh" EXCLUDE )
 install( FILES index.theme DESTINATION ${BREEZE_INSTALL_DIR})
 
-
+gtk_update_icon_cache(${BREEZE_INSTALL_DIR})