hidapi: Add SDL_hidapi.c, allows support for multiple hidapi backends.

This is currently supported on Linux and macOS. iOS and Android are not
supported at all, Windows support could be added with some changes to the libusb
backend. The Visual Studio and Xcode projects do not use this feature.

Based on Valve Software's hid.cpp, written in collaboration with Andrew Eikum.

CMakeLists.txt

@@ -156,11 +156,10 @@ if(UNIX OR MINGW OR MSYS)
 endif()
 
 # The hidraw support doesn't catch Xbox, PS4 and Nintendo controllers,
-#  so we'll just use libusb when it's available. Except that libusb
+#  so we'll just use libusb when it's available. libusb does not support iOS,
-#  requires root permissions to open devices, so that's not generally
+#  so we default to yes on iOS.
-#  useful, and we'll disable this by default on Unix. Windows and macOS
+#  TODO: Windows can support libusb, the hid.c file just depends on Unix APIs
-#  can use it without root access, though, so enable by default there.
+if(WINDOWS OR IOS OR ANDROID)
-if(WINDOWS OR APPLE OR ANDROID)
   set(HIDAPI_SKIP_LIBUSB TRUE)
 else()
   set(HIDAPI_SKIP_LIBUSB FALSE)
@@ -169,6 +168,14 @@ if (HIDAPI_SKIP_LIBUSB)
   set(OPT_DEF_HIDAPI ON)
 endif()
 
+# On the other hand, *BSD specifically uses libusb only, so we make a special
+#  case just for them.
+if(FREEBSD OR NETBSD OR OPENBSD OR BSDI)
+  set(HIDAPI_ONLY_LIBUSB TRUE)
+else()
+  set(HIDAPI_ONLY_LIBUSB FALSE)
+endif()
+
 # Compiler info
 if(CMAKE_COMPILER_IS_GNUCC)
   set(USE_GCC TRUE)
@@ -1376,6 +1383,7 @@ elseif(WINDOWS)
 
   if(SDL_JOYSTICK)
     CheckHIDAPI()
+    # TODO: Remove this hid.c block when SDL_hidapi.c is supported on Windows!
     if(HAVE_HIDAPI)
       set(SOURCE_FILES ${SOURCE_FILES} ${SDL2_SOURCE_DIR}/src/hidapi/windows/hid.c)
     endif()
@@ -1466,8 +1474,6 @@ elseif(APPLE)
     if(HAVE_HIDAPI)
       if(IOS)
         set(SOURCE_FILES ${SOURCE_FILES} ${SDL2_SOURCE_DIR}/src/hidapi/ios/hid.m)
-      else()
-        set(SOURCE_FILES ${SOURCE_FILES} ${SDL2_SOURCE_DIR}/src/hidapi/mac/hid.c)
       endif()
     endif()
     set(SDL_JOYSTICK_IOKIT 1)

cmake/sdlchecks.cmake

@@ -1088,8 +1088,15 @@ macro(CheckHIDAPI)
       set(SOURCE_FILES ${SOURCE_FILES} ${HIDAPI_SOURCES})
       set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${LIBUSB_CFLAGS} -I${SDL2_SOURCE_DIR}/src/hidapi/hidapi")
       if(NOT HIDAPI_SKIP_LIBUSB)
+        if(HIDAPI_ONLY_LIBUSB)
           set(SOURCE_FILES ${SOURCE_FILES} ${SDL2_SOURCE_DIR}/src/hidapi/libusb/hid.c)
           list(APPEND EXTRA_LIBS ${LIBUSB_LIBS})
+        else()
+          set(SOURCE_FILES ${SOURCE_FILES} ${SDL2_SOURCE_DIR}/src/hidapi/SDL_hidapi.c)
+          # libusb is loaded dynamically, so don't add it to EXTRA_LIBS
+          FindLibraryAndSONAME("usb-1.0")
+          set(SDL_LIBUSB_DYNAMIC "\"${USB_LIB_SONAME}\"")
+        endif()
       endif()
     endif()
   endif()

configure

@@ -24106,16 +24106,24 @@ CheckHIDAPI()
     # The hidraw support doesn't catch Xbox, PS4 and Nintendo controllers,
     # so we'll just use libusb when it's available.
     #
-    # Except that libusb requires root permissions to open devices, so that's not generally useful, and we'll disable this by default.
+    # libusb does not support iOS, so we default to yes on iOS.
-    #
+    # TODO: Windows can support libusb, the hid.c file just depends on Unix APIs
-    #  On macOS and Windows, where you don't need libusb or root, we default to yes.
     skiplibusb=no
     case "$host" in
-        *-*-cygwin* | *-*-mingw32* | *-*-darwin* )
+        *-*-cygwin* | *-*-mingw32* | arm*-apple-darwin* | *-ios-* )
             skiplibusb=yes
             ;;
     esac
 
+    # On the other hand, *BSD specifically uses libusb only, so we make a
+    # special case just for them.
+    onlylibusb=no
+    case "$host" in
+        *-*-*bsd* )
+            onlylibusb=yes
+            ;;
+    esac
+
     # Check whether --enable-hidapi was given.
 if test "${enable_hidapi+set}" = set; then :
   enableval=$enable_hidapi;
@@ -24224,9 +24232,35 @@ $as_echo "#define SDL_JOYSTICK_HIDAPI 1" >>confdefs.h
             SOURCES="$SOURCES $srcdir/src/joystick/hidapi/*.c"
 
             if test x$skiplibusb = xno; then
-                SOURCES="$SOURCES $srcdir/src/hidapi/libusb/hid.c"
                 EXTRA_CFLAGS="$EXTRA_CFLAGS $LIBUSB_CFLAGS"
+                if test x$onlylibusb = xyes; then
+                    SOURCES="$SOURCES $srcdir/src/hidapi/libusb/hid.c"
                     EXTRA_LDFLAGS="$EXTRA_LDFLAGS $LIBUSB_LIBS"
+                else
+                    if test x$have_loadso != xyes; then
+                        { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: You must have SDL_LoadObject() support for dynamic libusb loading" >&5
+$as_echo "$as_me: WARNING: You must have SDL_LoadObject() support for dynamic libusb loading" >&2;}
+                    fi
+                    SOURCES="$SOURCES $srcdir/src/hidapi/SDL_hidapi.c"
+                    # libusb is loaded dynamically, so don't add it to LDFLAGS
+                    libusb_lib=""
+                    case "$host" in
+                        *-*-darwin* )
+                            libusb_lib="libusb-1.0.0.dylib"
+                            ;;
+                        *-*-cygwin* | *-*-mingw32* )
+                            libusb_lib="libusb-1.0.dll"
+                            ;;
+                    esac
+                    if test x$libusb_lib = x; then
+                        libusb_lib=`find_lib "libusb-1.0.so.*" "" | sed 's/.*\/\(.*\)/\1/; q'`
+                    fi
+
+cat >>confdefs.h <<_ACEOF
+#define SDL_LIBUSB_DYNAMIC "$libusb_lib"
+_ACEOF
+
+                fi
             fi
         fi
 
@@ -24732,6 +24766,7 @@ $as_echo "#define SDL_JOYSTICK_WINMM 1" >>confdefs.h
             fi
             SOURCES="$SOURCES $srcdir/src/joystick/windows/*.c"
             have_joystick=yes
+            # TODO: Remove this block once SDL_hidapi.c supports Windows!
             if test x$hidapi_support = xyes; then
                 SOURCES="$SOURCES $srcdir/src/hidapi/windows/hid.c"
             fi
@@ -25077,9 +25112,6 @@ $as_echo "#define SDL_JOYSTICK_IOKIT 1" >>confdefs.h
 
             SOURCES="$SOURCES $srcdir/src/joystick/darwin/*.c"
             have_joystick=yes
-            if test x$hidapi_support = xyes; then
-                SOURCES="$SOURCES $srcdir/src/hidapi/mac/hid.c"
-            fi
         fi
         # Set up files for the haptic library
         if test x$enable_haptic = xyes; then

configure.ac

@@ -3198,16 +3198,24 @@ CheckHIDAPI()
     # The hidraw support doesn't catch Xbox, PS4 and Nintendo controllers,
     # so we'll just use libusb when it's available.
     #
-    # Except that libusb requires root permissions to open devices, so that's not generally useful, and we'll disable this by default.
+    # libusb does not support iOS, so we default to yes on iOS.
-    #
+    # TODO: Windows can support libusb, the hid.c file just depends on Unix APIs
-    #  On macOS and Windows, where you don't need libusb or root, we default to yes.
     skiplibusb=no
     case "$host" in
-        *-*-cygwin* | *-*-mingw32* | *-*-darwin* )
+        *-*-cygwin* | *-*-mingw32* | arm*-apple-darwin* | *-ios-* )
             skiplibusb=yes
             ;;
     esac
 
+    # On the other hand, *BSD specifically uses libusb only, so we make a
+    # special case just for them.
+    onlylibusb=no
+    case "$host" in
+        *-*-*bsd* )
+            onlylibusb=yes
+            ;;
+    esac
+
     AC_ARG_ENABLE(hidapi,
 AS_HELP_STRING([--enable-hidapi], [use HIDAPI for low level joystick drivers [[default=maybe]]]),
                   , enable_hidapi=maybe)
@@ -3237,9 +3245,30 @@ AS_HELP_STRING([--enable-hidapi], [use HIDAPI for low level joystick drivers [[d
             SOURCES="$SOURCES $srcdir/src/joystick/hidapi/*.c"
 
             if test x$skiplibusb = xno; then
-                SOURCES="$SOURCES $srcdir/src/hidapi/libusb/hid.c"
                 EXTRA_CFLAGS="$EXTRA_CFLAGS $LIBUSB_CFLAGS"
+                if test x$onlylibusb = xyes; then
+                    SOURCES="$SOURCES $srcdir/src/hidapi/libusb/hid.c"
                     EXTRA_LDFLAGS="$EXTRA_LDFLAGS $LIBUSB_LIBS"
+                else
+                    if test x$have_loadso != xyes; then
+                        AC_MSG_WARN([You must have SDL_LoadObject() support for dynamic libusb loading])
+                    fi
+                    SOURCES="$SOURCES $srcdir/src/hidapi/SDL_hidapi.c"
+                    # libusb is loaded dynamically, so don't add it to LDFLAGS
+                    libusb_lib=""
+                    case "$host" in
+                        *-*-darwin* )
+                            libusb_lib="libusb-1.0.0.dylib"
+                            ;;
+                        *-*-cygwin* | *-*-mingw32* )
+                            libusb_lib="libusb-1.0.dll"
+                            ;;
+                    esac
+                    if test x$libusb_lib = x; then
+                        libusb_lib=[`find_lib "libusb-1.0.so.*" "" | sed 's/.*\/\(.*\)/\1/; q'`]
+                    fi
+                    AC_DEFINE_UNQUOTED(SDL_LIBUSB_DYNAMIC, "$libusb_lib", [ ])
+                fi
             fi
         fi
 
@@ -3599,6 +3628,7 @@ AS_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
             fi
             SOURCES="$SOURCES $srcdir/src/joystick/windows/*.c"
             have_joystick=yes
+            # TODO: Remove this block once SDL_hidapi.c supports Windows!
             if test x$hidapi_support = xyes; then
                 SOURCES="$SOURCES $srcdir/src/hidapi/windows/hid.c"
             fi
@@ -3842,9 +3872,6 @@ AS_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
             AC_DEFINE(SDL_JOYSTICK_IOKIT, 1, [ ])
             SOURCES="$SOURCES $srcdir/src/joystick/darwin/*.c"
             have_joystick=yes
-            if test x$hidapi_support = xyes; then
-                SOURCES="$SOURCES $srcdir/src/hidapi/mac/hid.c"
-            fi
         fi
         # Set up files for the haptic library
         if test x$enable_haptic = xyes; then

include/SDL_config.h.cmake

@@ -294,6 +294,7 @@
 #cmakedefine SDL_HAPTIC_DINPUT @SDL_HAPTIC_DINPUT@
 #cmakedefine SDL_HAPTIC_XINPUT @SDL_HAPTIC_XINPUT@
 #cmakedefine SDL_HAPTIC_ANDROID @SDL_HAPTIC_ANDROID@
+#cmakedefine SDL_LIBUSB_DYNAMIC @SDL_LIBUSB_DYNAMIC@
 
 /* Enable various sensor drivers */
 #cmakedefine SDL_SENSOR_ANDROID @SDL_SENSOR_ANDROID@

include/SDL_config.h.in

@@ -412,6 +412,9 @@
 /* Enable dynamic udev support */
 #undef SDL_UDEV_DYNAMIC
 
+/* Enable dynamic libusb support */
+#undef SDL_LIBUSB_DYNAMIC
+
 /* Enable dynamic libsamplerate support */
 #undef SDL_LIBSAMPLERATE_DYNAMIC