w32_common: handle media keys

This was attempted before in fc9695e63b5b, but it was reverted in
1b7ce759b1f4 because it caused conflicts with other software watching
the same keys (See #2041.) It seems like some PCs ship with OEM software
that watches the volume keys without consuming key events and this
causes them to be handled twice, once by mpv and once by the other
software.

In order to prevent conflicts like this, use the WM_APPCOMMAND message
to handle media keys. Returning TRUE from the WM_APPCOMMAND handler
should indicate to the operating system that we consumed the key event
and it should not be propogated to the shell. Also, we now only listen
for keys that are directly related to multimedia playback (eg. the
APPCOMMAND_MEDIA_* keys.) Keys like APPCOMMAND_VOLUME_* are ignored, so
they can be handled by the shell, or by other mixer software.

1 files changed, 15 insertions, 0 deletions

diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index 221f0b37dc..26edde17eb 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -354,6 +354,17 @@ static int decode_key(struct vo_w32_state *w32, UINT vkey, UINT scancode)
     return c;
 }
 
+static bool handle_appcommand(struct vo_w32_state *w32, UINT cmd)
+{
+    if (!mp_input_use_media_keys(w32->input_ctx))
+        return false;
+    int mpkey = mp_w32_appcmd_to_mpkey(cmd);
+    if (!mpkey)
+        return false;
+    mp_input_put_key(w32->input_ctx, mpkey | mod_state(w32));
+    return true;
+}
+
 static void handle_key_down(struct vo_w32_state *w32, UINT vkey, UINT scancode)
 {
     // Ignore key repeat
@@ -1020,6 +1031,10 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
                                         GET_Y_LPARAM(lParam));
         }
         break;
+    case WM_APPCOMMAND:
+        if (handle_appcommand(w32, GET_APPCOMMAND_LPARAM(lParam)))
+            return TRUE;
+        break;
     case WM_SYSKEYDOWN:
         // Open the window menu on Alt+Space. Normally DefWindowProc opens the
         // window menu in response to WM_SYSCHAR, but since mpv translates its