options: add option to disable using right Alt key as Alt Gr

mpv was hardcoded to always consider the right Alt key as Alt Gr, but there
are parituclar combinations of platforms and keyboard layouts where it's more
convenient to treat the right Alt as a keyboard modifier just like the left
one.

Fixes #388

9 files changed, 40 insertions, 6 deletions

diff --git a/DOCS/man/en/input.rst b/DOCS/man/en/input.rst
index 7d62784b97..ac93d01105 100644
--- a/DOCS/man/en/input.rst
+++ b/DOCS/man/en/input.rst
@@ -31,6 +31,10 @@ General Input Command Syntax
 
 ``[Shift+][Ctrl+][Alt+][Meta+]<key> [{<section>}] [<prefixes>] <command> (<argument>)* [; <command>]``
 
+Note that by default, the right Alt key can be used to create special
+characters, and thus does not register as a modifier. The option
+``--no-right-alt-gr`` changes this behavior.
+
 Newlines always start a new binding. ``#`` starts a comment (outside of quoted
 string arguments). To bind commands to the ``#`` key, ``SHARP`` can be used.
 
diff --git a/DOCS/man/en/options.rst b/DOCS/man/en/options.rst
index fec8aa0575..15cba5e460 100644
--- a/DOCS/man/en/options.rst
+++ b/DOCS/man/en/options.rst
@@ -1823,6 +1823,11 @@ OPTIONS
         - ``--reset-on-next-file=""``
           Do not reset pause mode.
 
+``--right-alt-gr``, ``--no-right-alt-gr``
+    (Cocoa and Windows only)
+    Use the right Alt key as Alt Gr to produce special characters. If disabled,
+    count the right Alt as an Alt modifier key. Enabled by default.
+
 ``--rtsp-transport=<lavf|udp|tcp|http>``
     Select RTSP transport method (default: tcp). This selects the underlying
     network transport when playing ``rtsp://...`` URLs. The value ``lavf``
diff --git a/mpvcore/input/input.c b/mpvcore/input/input.c
index c1711a94d8..8b31352f72 100644
--- a/mpvcore/input/input.c
+++ b/mpvcore/input/input.c
@@ -550,6 +550,7 @@ struct input_ctx {
     pthread_mutex_t mutex;
     struct mp_log *log;
 
+    bool using_alt_gr;
     bool using_ar;
     bool using_cocoa_media_keys;
 
@@ -635,6 +636,7 @@ const m_option_t mp_input_opts[] = {
     OPT_FLAG("joystick", input.use_joystick, CONF_GLOBAL),
     OPT_FLAG("lirc", input.use_lirc, CONF_GLOBAL),
     OPT_FLAG("lircc", input.use_lircc, CONF_GLOBAL),
+    OPT_FLAG("right-alt-gr", input.use_alt_gr, CONF_GLOBAL),
 #if HAVE_COCOA
     OPT_FLAG("ar", input.use_ar, CONF_GLOBAL),
     OPT_FLAG("media-keys", input.use_media_keys, CONF_GLOBAL),
@@ -2387,6 +2389,10 @@ struct input_ctx *mp_input_init(struct mpv_global *global)
     }
 #endif
 
+    if (input_conf->use_alt_gr) {
+        ictx->using_alt_gr = true;
+    }
+
 #if HAVE_COCOA
     if (input_conf->use_ar) {
         cocoa_init_apple_remote();
@@ -2528,3 +2534,8 @@ unsigned int mp_input_get_mouse_event_counter(struct input_ctx *ictx)
     input_unlock(ictx);
     return ret;
 }
+
+bool mp_input_use_alt_gr(struct input_ctx *ictx)
+{
+    return ictx->using_alt_gr;
+}
diff --git a/mpvcore/input/input.h b/mpvcore/input/input.h
index 9e897abbbb..2465fe6010 100644
--- a/mpvcore/input/input.h
+++ b/mpvcore/input/input.h
@@ -287,6 +287,10 @@ void mp_input_wakeup(struct input_ctx *ictx);
 // Interruptible usleep:  (used by demux)
 int mp_input_check_interrupt(struct input_ctx *ictx, int time);
 
+// If this returns true, use Right Alt key as Alt Gr to produce special
+// characters. If false, count Right Alt as the modifier Alt key.
+bool mp_input_use_alt_gr(struct input_ctx *ictx);
+
 extern int async_quit_request;
 
 #endif /* MPLAYER_INPUT_H */
diff --git a/mpvcore/options.c b/mpvcore/options.c
index c8112b496d..08b1f10fe2 100644
--- a/mpvcore/options.c
+++ b/mpvcore/options.c
@@ -873,6 +873,7 @@ const struct MPOpts mp_default_opts = {
         .use_joystick = 1,
         .use_lirc = 1,
         .use_lircc = 1,
+        .use_alt_gr = 1,
 #if HAVE_COCOA
         .use_ar = 1,
         .use_media_keys = 1,
diff --git a/mpvcore/options.h b/mpvcore/options.h
index 3a4333f891..cb700cb775 100644
--- a/mpvcore/options.h
+++ b/mpvcore/options.h
@@ -251,6 +251,7 @@ typedef struct MPOpts {
         int use_joystick;
         int use_lirc;
         int use_lircc;
+        int use_alt_gr;
         int use_ar;
         int use_media_keys;
         int default_bindings;
diff --git a/osdep/macosx_events.m b/osdep/macosx_events.m
index ef67647f61..4831904aa7 100644
--- a/osdep/macosx_events.m
+++ b/osdep/macosx_events.m
@@ -174,6 +174,11 @@ void cocoa_put_key_with_modifiers(int keycode, int modifiers)
     HIDRemote *_remote;
 }
 
+- (BOOL)useAltGr
+{
+    return mp_input_use_alt_gr(mpv_shared_app().inputContext);
+}
+
 - (void)startAppleRemote
 {
     dispatch_async(dispatch_get_main_queue(), ^{
@@ -287,7 +292,8 @@ void cocoa_put_key_with_modifiers(int keycode, int modifiers)
         mask |= MP_KEY_MODIFIER_SHIFT;
     if (cocoaModifiers & NSControlKeyMask)
         mask |= MP_KEY_MODIFIER_CTRL;
-    if (LeftAltPressed(cocoaModifiers))
+    if (LeftAltPressed(cocoaModifiers) ||
+        RightAltPressed(cocoaModifiers) && ![self useAltGr])
         mask |= MP_KEY_MODIFIER_ALT;
     if (cocoaModifiers & NSCommandKeyMask)
         mask |= MP_KEY_MODIFIER_META;
@@ -333,7 +339,7 @@ void cocoa_put_key_with_modifiers(int keycode, int modifiers)
 
     NSString *chars;
 
-    if (RightAltPressed([event modifierFlags]))
+    if ([self useAltGr] && RightAltPressed([event modifierFlags]))
         chars = [event characters];
     else
         chars = [event charactersIgnoringModifiers];
diff --git a/video/out/vo_sdl.c b/video/out/vo_sdl.c
index 6fe62b187b..86643788b9 100644
--- a/video/out/vo_sdl.c
+++ b/video/out/vo_sdl.c
@@ -495,11 +495,13 @@ static void check_events(struct vo *vo)
         case SDL_TEXTINPUT: {
             int sdl_mod = SDL_GetModState();
             int mpv_mod = 0;
-            // we ignore KMOD_LSHIFT, KMOD_RSHIFT and KMOD_RALT because
-            // these are already factored into ev.text.text
+            // we ignore KMOD_LSHIFT, KMOD_RSHIFT and KMOD_RALT (if
+            // mp_input_use_alt_gr() is true) because these are already
+            // factored into ev.text.text
             if (sdl_mod & (KMOD_LCTRL | KMOD_RCTRL))
                 mpv_mod |= MP_KEY_MODIFIER_CTRL;
-            if (sdl_mod & KMOD_LALT)
+            if ((sdl_mod & KMOD_LALT) ||
+                (sdl_mod & KMOD_RALT) && !mp_input_use_alt_gr(vo->input_ctx))
                 mpv_mod |= MP_KEY_MODIFIER_ALT;
             if (sdl_mod & (KMOD_LGUI | KMOD_RGUI))
                 mpv_mod |= MP_KEY_MODIFIER_META;
diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index f5b2729956..6c5ebe1703 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -203,7 +203,7 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
             // Windows enables Ctrl+Alt when AltGr (VK_RMENU) is pressed.
             // E.g. AltGr+9 on a German keyboard would yield Ctrl+Alt+[
             // Warning: wine handles this differently. Don't test this on wine!
-            if (key_state(vo, VK_RMENU))
+            if (key_state(vo, VK_RMENU) && mp_input_use_alt_gr(vo->input_ctx))
                 mods &= ~(MP_KEY_MODIFIER_CTRL | MP_KEY_MODIFIER_ALT);
             // Apparently Ctrl+A to Ctrl+Z is special cased, and produces
             // character codes from 1-26. Work it around.