cocoa-cb: remove pre-allocation and initialise only when used

cocoa-cb was always pre-allocated in the Application itself because
libmpv needs to be set up before usage, an opengl context has to be set
and because it was decided mac specific code should be kept out of
libmpv.

this means that a completely working libmpv and opengl renderer was set
up even if it wasn't used. leading to unnecessary log message, resources
being used or reserved on the system that might not be used, triggering
of dedicated GPU unnecessarily and many other things.

even if not optimal, this wasn't the biggest problem since we only had
that one working vo on macOS. though now that we have a vulkan
gpu(-next) backend on macOS that was made the default, we always have
that dangling cocoa-cb instance, which is completely unnecessary.

move the cocoa-cb initialisation into libmpv preinit function and only
init cocoa-cb when we are a standalone App and cocoa-cb support is build
into.

osdep/macosx_application.m

@@ -183,10 +183,12 @@ static const char macosx_icon[] =
     }
 }
 
-- (void)setMpvHandle:(struct mpv_handle *)ctx
+- (void)initCocoaCb:(struct mpv_handle *)ctx
 {
 #if HAVE_MACOS_COCOA_CB
-    [NSApp setCocoaCB:[[CocoaCB alloc] init:ctx]];
+    if (!_cocoa_cb) {
+        [NSApp setCocoaCB:[[CocoaCB alloc] init:ctx]];
+    }
 #endif
 }
 

osdep/macosx_application_objc.h

@@ -30,7 +30,7 @@ struct mpv_handle;
 - (void)queueCommand:(char *)cmd;
 - (void)stopMPV:(char *)cmd;
 - (void)openFiles:(NSArray *)filenames;
-- (void)setMpvHandle:(struct mpv_handle *)ctx;
+- (void)initCocoaCb:(struct mpv_handle *)ctx;
 + (const struct m_sub_options *)getMacOSConf;
 + (const struct m_sub_options *)getVoSubConf;
 

osdep/macosx_events.h

@@ -32,5 +32,6 @@ void cocoa_uninit_media_keys(void);
 
 void cocoa_set_input_context(struct input_ctx *input_context);
 void cocoa_set_mpv_handle(struct mpv_handle *ctx);
+void cocoa_init_cocoa_cb(void);
 
 #endif

osdep/macosx_events.m

@@ -52,6 +52,7 @@
 
 - (NSEvent *)handleKey:(NSEvent *)event;
 - (BOOL)setMpvHandle:(struct mpv_handle *)ctx;
+- (void)initCocoaCb;
 - (void)readEvents;
 - (void)startMediaKeys;
 - (void)stopMediaKeys;
@@ -166,6 +167,11 @@ void cocoa_set_mpv_handle(struct mpv_handle *ctx)
     }
 }
 
+void cocoa_init_cocoa_cb(void)
+{
+    [[EventsResponder sharedInstance] initCocoaCb];
+}
+
 @implementation EventsResponder
 
 @synthesize remoteCommandCenter = _remoteCommandCenter;
@@ -252,14 +258,20 @@ void cocoa_set_mpv_handle(struct mpv_handle *ctx)
 - (BOOL)setMpvHandle:(struct mpv_handle *)ctx
 {
     if (_is_application) {
-        dispatch_sync(dispatch_get_main_queue(), ^{
-            _ctx = ctx;
-            [NSApp setMpvHandle:ctx];
-        });
+        _ctx = ctx;
         return YES;
-    } else {
-        mpv_destroy(ctx);
-        return NO;
+    }
+
+    mpv_destroy(ctx);
+    return NO;
+}
+
+- (void)initCocoaCb
+{
+    if (_is_application) {
+        dispatch_sync(dispatch_get_main_queue(), ^{
+            [NSApp initCocoaCb:_ctx];
+        });
     }
 }
 

video/out/vo_libmpv.c

@@ -27,6 +27,10 @@
 
 #include "libmpv.h"
 
+#if HAVE_MACOS_COCOA_CB
+#include "osdep/macosx_events.h"
+#endif
+
 /*
  * mpv_render_context is managed by the host application - the host application
  * can access it any time, even if the VO is destroyed (or not created yet).
@@ -705,7 +709,9 @@ static void uninit(struct vo *vo)
 
 static int preinit(struct vo *vo)
 {
-#if !HAVE_MACOS_COCOA_CB
+#if HAVE_MACOS_COCOA_CB
+    cocoa_init_cocoa_cb();
+#else
     if (vo->probing)
         return -1;
 #endif