CMake: make it possible to override include install location.

Needed so Gradle CMake on Android "just works".

CMakeLists.txt

@@ -165,6 +165,8 @@ endif()
 
 set(MAGNUM_DEPLOY_PREFIX "."
     CACHE STRING "Prefix where to put final application executables")
+set(MAGNUM_INCLUDE_INSTALL_PREFIX "."
+    CACHE STRING "Prefix where to put platform-independent include and other files")
 
 option(BUILD_STATIC "Build static libraries (default are shared)" OFF)
 option(BUILD_STATIC_PIC "Build static libraries and plugins with position-independent code" ON)
@@ -270,11 +272,11 @@ endif()
 include(${CORRADE_LIB_SUFFIX_MODULE})
 set(MAGNUM_BINARY_INSTALL_DIR bin)
 set(MAGNUM_LIBRARY_INSTALL_DIR lib${LIB_SUFFIX})
-set(MAGNUM_DATA_INSTALL_DIR share/magnum)
-set(MAGNUM_CMAKE_MODULE_INSTALL_DIR share/cmake/Magnum)
-set(MAGNUM_INCLUDE_INSTALL_DIR include/Magnum)
-set(MAGNUM_EXTERNAL_INCLUDE_INSTALL_DIR include/MagnumExternal)
-set(MAGNUM_PLUGINS_INCLUDE_INSTALL_DIR include/MagnumPlugins)
+set(MAGNUM_DATA_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/share/magnum)
+set(MAGNUM_CMAKE_MODULE_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/share/cmake/Magnum)
+set(MAGNUM_INCLUDE_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/include/Magnum)
+set(MAGNUM_EXTERNAL_INCLUDE_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/include/MagnumExternal)
+set(MAGNUM_PLUGINS_INCLUDE_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/include/MagnumPlugins)
 
 # Separate install dirs for debug and release plugins
 set(MAGNUM_PLUGINS_DEBUG_BINARY_INSTALL_DIR ${MAGNUM_BINARY_INSTALL_DIR}/magnum-d)

doc/building.dox

@@ -358,6 +358,13 @@ installed files. The following variables are supported:
     are installed, so you can have libraries installed to a system location and
     utilities to your webserver, for example. Defaults to ``.``. If a relative
     path is used, it's relative to `CMAKE_INSTALL_PREFIX`.
+-   `MAGNUM_INCLUDE_INSTALL_PREFIX` --- Used on @ref CORRADE_TARGET_ANDROID "Android"
+    to override location where platform-independent include files, CMake
+    scripts and other files are installed. CMake on Android by default searches
+    for binaries in <tt>&lt;ndk&gt;/platforms/android-&lt;api&gt;/arch-&lt;arch&gt;/usr</tt>
+    based on target API and platform, but looks for headers in a central
+    location at <tt>&lt;ndk&gt;/sysroot/usr</tt>. Defaults to ``.``. If a
+    relative path is used, it's relative to `CMAKE_INSTALL_PREFIX`.
 
 The library is constantly evolving and thus some APIs are deprecated and then
 later removed in favor of better ones. To preserve backwards compatibility,
@@ -834,8 +841,12 @@ use and `CMAKE_ANDROID_ARCH_ABI` to target platform ABI. Check the
 for further information.
 
 If you set `CMAKE_INSTALL_PREFIX` to `/usr` subdirectory of the particular
-Android sysroot, the package will get found automatically when compiling
-subprojects, otherwise you may need to explicitly set `CMAKE_PREFIX_PATH`.
+Android platform sysroot, the package will get found automatically when
+compiling subprojects. Gradle and other Android buildsystems expect
+platform-independent includes and other files to be stored in a central
+location, you can set `MAGNUM_INCLUDE_INSTALL_PREFIX` to `/usr` subdirectory of
+the global NDK sysroot. Another option is to explicitly set `CMAKE_PREFIX_PATH`
+to the install location in depending projects.
 
 Note that `BUILD_STATIC` is implicitly enabled, because manually loading all
 depending shared libraries using JNI would be too inconvenient. The engine is
@@ -850,8 +861,8 @@ cmake .. \
     -DCMAKE_ANDROID_NDK_TOOLCHAIN_VERSION=clang \
     -DCMAKE_ANDROID_STL_TYPE=c++_static \
     -DCMAKE_BUILD_TYPE=Release \
-    -DCMAKE_PREFIX_PATH=/opt/android-ndk/platforms/android-22/arch-arm/usr \
     -DCMAKE_INSTALL_PREFIX=/opt/android-ndk/platforms/android-22/arch-arm/usr \
+    -DMAGNUM_INCLUDE_INSTALL_PREFIX=/opt/android-ndk/sysroot/usr \
     -DTARGET_GLES2=OFF \
     -DWITH_ANDROIDAPPLICATION=ON
 cmake --build .

doc/cmake.dox

@@ -62,6 +62,9 @@ This module tries to find base Magnum library and then defines:
 -   `MAGNUM_DEPLOY_PREFIX` --- Prefix where to put final application
     executables, defaults to `.`. If a relative path is used, it's relative to
     `CMAKE_INSTALL_PREFIX`.
+-   `MAGNUM_INCLUDE_INSTALL_PREFIX` --- Prefix where to put
+    platform-independent include and other files, defaults to `.`. If a
+    relative path is used, it's relative to `CMAKE_INSTALL_PREFIX`.
 -   `MAGNUM_PLUGINS_DEBUG_DIR` --- Base directory with dynamic plugins for debug
     builds, defaults to `magnum-d/` subdirectory of dir where Magnum library
     was found

modules/FindMagnum.cmake

@@ -13,6 +13,9 @@
 #  MAGNUM_DEPLOY_PREFIX         - Prefix where to put final application
 #   executables, defaults to ``.``. If a relative path is used, it's relative
 #   to :variable:`CMAKE_INSTALL_PREFIX`.
+#  MAGNUM_INCLUDE_INSTALL_PREFIX - Prefix where to put platform-independent
+#   include and other files, defaults to ``.``. If a relative path is used,
+#   it's relative to :variable:`CMAKE_INSTALL_PREFIX`.
 #  MAGNUM_PLUGINS_DEBUG_DIR     - Base directory with dynamic plugins for
 #   debug builds, defaults to magnum-d/ subdirectory of dir where Magnum
 #   library was found
@@ -787,11 +790,13 @@ endif()
 # Installation and deploy dirs
 set(MAGNUM_DEPLOY_PREFIX "."
     CACHE STRING "Prefix where to put final application executables")
+set(MAGNUM_INCLUDE_INSTALL_PREFIX "."
+    CACHE STRING "Prefix where to put platform-independent include and other files")
 
 include(${CORRADE_LIB_SUFFIX_MODULE})
 set(MAGNUM_BINARY_INSTALL_DIR bin)
 set(MAGNUM_LIBRARY_INSTALL_DIR lib${LIB_SUFFIX})
-set(MAGNUM_DATA_INSTALL_DIR share/magnum)
+set(MAGNUM_DATA_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/share/magnum)
 set(MAGNUM_PLUGINS_DEBUG_BINARY_INSTALL_DIR ${MAGNUM_BINARY_INSTALL_DIR}/magnum-d)
 set(MAGNUM_PLUGINS_DEBUG_LIBRARY_INSTALL_DIR ${MAGNUM_LIBRARY_INSTALL_DIR}/magnum-d)
 set(MAGNUM_PLUGINS_RELEASE_BINARY_INSTALL_DIR ${MAGNUM_BINARY_INSTALL_DIR}/magnum)
@@ -814,8 +819,8 @@ set(MAGNUM_PLUGINS_AUDIOIMPORTER_DEBUG_BINARY_INSTALL_DIR ${MAGNUM_PLUGINS_DEBUG
 set(MAGNUM_PLUGINS_AUDIOIMPORTER_DEBUG_LIBRARY_INSTALL_DIR ${MAGNUM_PLUGINS_DEBUG_LIBRARY_INSTALL_DIR}/audioimporters)
 set(MAGNUM_PLUGINS_AUDIOIMPORTER_RELEASE_BINARY_INSTALL_DIR ${MAGNUM_PLUGINS_RELEASE_BINARY_INSTALL_DIR}/audioimporters)
 set(MAGNUM_PLUGINS_AUDIOIMPORTER_RELEASE_LIBRARY_INSTALL_DIR ${MAGNUM_PLUGINS_RELEASE_LIBRARY_INSTALL_DIR}/audioimporters)
-set(MAGNUM_INCLUDE_INSTALL_DIR include/Magnum)
-set(MAGNUM_PLUGINS_INCLUDE_INSTALL_DIR include/MagnumPlugins)
+set(MAGNUM_INCLUDE_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/include/Magnum)
+set(MAGNUM_PLUGINS_INCLUDE_INSTALL_DIR ${MAGNUM_INCLUDE_INSTALL_PREFIX}/include/MagnumPlugins)
 
 # Get base plugin directory from main library location. This is *not* PATH,
 # because CMake always converts the path to an absolute location internally,

package/archlinux/PKGBUILD-android-arm64

@@ -31,6 +31,7 @@ build() {
     cmake .. \
         -DCMAKE_BUILD_TYPE=Release \
         -DCMAKE_INSTALL_PREFIX=/opt/android-ndk/platforms/android-22/arch-arm64/usr \
+        -DMAGNUM_INCLUDE_INSTALL_PREFIX=/opt/android-ndk/sysroot/usr \
         -DWITH_MAGNUMFONT=ON \
         -DWITH_OBJIMPORTER=ON \
         -DWITH_TGAIMAGECONVERTER=ON \