cocoa: reintroduce async resize

After removing synchronous libdispatch calls, this looks like it doesn't
deadlock anymore. I also experimented with pthread_mutex_trylock liek wm4
suggested, but it leads to some annoying black flickering. I will fallback to
that only if some new deadlocks are discovered.

video/out/cocoa/mpvadapter.h

@@ -19,8 +19,6 @@
 #include "video/out/vo.h"
 
 @interface MpvCocoaAdapter : NSObject
-- (void)lock;
-- (void)unlock;
 - (void)setNeedsResize;
 - (void)signalMouseMovement:(NSPoint)point;
 - (void)putKeyEvent:(NSEvent*)event;
@@ -29,6 +27,7 @@
 - (void)putCommand:(char*)cmd;
 - (void)handleFilesArray:(NSArray *)files;
 - (void)didChangeWindowedScreenProfile:(NSScreen *)screen;
+- (void)performAsyncResize:(NSSize)size;
 
 - (BOOL)isInFullScreenMode;
 - (BOOL)keyboardEnabled;

video/out/cocoa/video_view.m

@@ -40,4 +40,10 @@
 {
     return [self convertRectToBacking:[self frame]];
 }
+
+
+- (void)drawRect:(NSRect)rect
+{
+    [self.adapter performAsyncResize:[self frameInPixels].size];
+}
 @end

video/out/cocoa_common.m

@@ -70,6 +70,7 @@ struct vo_cocoa_state {
     int pending_events;
 
     bool waiting_frame;
+    bool skip_swap_buffer;
     bool embedded; // wether we are embedding in another GUI
 
     IOPMAssertionID power_mgmt_assertion;
@@ -83,6 +84,8 @@ struct vo_cocoa_state {
     char *icc_wnd_profile_path;
     char *icc_fs_profile_path;
     id   fs_icc_changed_ns_observer;
+
+    void (*resize_redraw)(struct vo *vo, int w, int h);
 };
 
 static void with_cocoa_lock(struct vo *vo, void(^block)(void))
@@ -175,6 +178,13 @@ static int vo_cocoa_set_cursor_visibility(struct vo *vo, bool *visible)
     return VO_TRUE;
 }
 
+void vo_cocoa_register_resize_callback(struct vo *vo,
+                                       void (*cb)(struct vo *vo, int w, int h))
+{
+    struct vo_cocoa_state *s = vo->cocoa;
+    s->resize_redraw = cb;
+}
+
 void vo_cocoa_uninit(struct vo *vo)
 {
     with_cocoa_lock(vo, ^{
@@ -456,6 +466,26 @@ void vo_cocoa_set_current_context(struct vo *vo, bool current)
     }
 }
 
+static void vo_cocoa_resize_redraw(struct vo *vo, int width, int height)
+{
+    struct vo_cocoa_state *s = vo->cocoa;
+
+    if (!s->gl_ctx)
+        return;
+
+    if (!s->resize_redraw)
+        return;
+
+    vo_cocoa_set_current_context(vo, true);
+
+    [s->gl_ctx update];
+    s->resize_redraw(vo, width, height);
+    s->skip_swap_buffer = true;
+
+    [s->gl_ctx flushBuffer];
+    vo_cocoa_set_current_context(vo, false);
+}
+
 static void draw_changes_after_next_frame(struct vo *vo)
 {
     struct vo_cocoa_state *s = vo->cocoa;
@@ -468,7 +498,13 @@ static void draw_changes_after_next_frame(struct vo *vo)
 void vo_cocoa_swap_buffers(struct vo *vo)
 {
     struct vo_cocoa_state *s = vo->cocoa;
-    [s->gl_ctx flushBuffer];
+    if (s->skip_swap_buffer) {
+        s->skip_swap_buffer = false;
+        return;
+    } else {
+        [s->gl_ctx flushBuffer];
+    }
+
     if (s->waiting_frame) {
         s->waiting_frame = false;
         NSEnableScreenUpdates();
@@ -687,12 +723,8 @@ void *vo_cocoa_cgl_pixel_format(struct vo *vo)
 @implementation MpvCocoaAdapter
 @synthesize vout = _video_output;
 
-- (void)lock {
-    vo_cocoa_set_current_context(self.vout, true);
-}
-
-- (void)unlock {
-    vo_cocoa_set_current_context(self.vout, false);
+- (void)performAsyncResize:(NSSize)size {
+    vo_cocoa_resize_redraw(self.vout, size.width, size.height);
 }
 
 - (BOOL)keyboardEnabled {

video/out/gl_cocoa.c

@@ -149,6 +149,7 @@ void mpgl_set_backend_cocoa(MPGLContext *ctx)
     ctx->releaseGlContext = releaseGlContext_cocoa;
     ctx->swapGlBuffers = swapGlBuffers_cocoa;
     ctx->vo_init = vo_cocoa_init;
+    ctx->register_resize_callback = vo_cocoa_register_resize_callback;
     ctx->vo_uninit = vo_cocoa_uninit;
     ctx->vo_control = vo_cocoa_control;
     ctx->set_current = set_current_cocoa;

video/out/gl_video.c

@@ -2388,6 +2388,18 @@ static int validate_scaler_opt(struct mp_log *log, const m_option_t *opt,
     return handle_scaler_opt(s) ? 1 : M_OPT_INVALID;
 }
 
+// Resize and redraw the contents of the window without further configuration.
+// Intended to be used in situations where the frontend can't really be
+// involved with reconfiguring the VO properly.
+// gl_video_resize() should be called when user interaction is done.
+void gl_video_resize_redraw(struct gl_video *p, int w, int h)
+{
+    p->gl->Viewport(p->vp_x, p->vp_y, w, h);
+    p->vp_w = w;
+    p->vp_h = h;
+    gl_video_render_frame(p);
+}
+
 void gl_video_set_hwdec(struct gl_video *p, struct gl_hwdec *hwdec)
 {
     p->hwdec = hwdec;

video/out/gl_video.h

@@ -74,6 +74,7 @@ bool gl_video_set_equalizer(struct gl_video *p, const char *name, int val);
 bool gl_video_get_equalizer(struct gl_video *p, const char *name, int *val);
 
 void gl_video_set_debug(struct gl_video *p, bool enable);
+void gl_video_resize_redraw(struct gl_video *p, int w, int h);
 
 struct gl_hwdec;
 void gl_video_set_hwdec(struct gl_video *p, struct gl_hwdec *hwdec);

video/out/vo_opengl.c

@@ -203,6 +203,13 @@ static bool config_window(struct gl_priv *p, int flags)
     return mpgl_config_window(p->glctx, mpgl_caps, flags);
 }
 
+static void video_resize_redraw_callback(struct vo *vo, int w, int h)
+{
+    struct gl_priv *p = vo->priv;
+    gl_video_resize_redraw(p->renderer, w, h);
+
+}
+
 static int reconfig(struct vo *vo, struct mp_image_params *params, int flags)
 {
     struct gl_priv *p = vo->priv;
@@ -214,6 +221,10 @@ static int reconfig(struct vo *vo, struct mp_image_params *params, int flags)
         return -1;
     }
 
+    if (p->glctx->register_resize_callback) {
+        p->glctx->register_resize_callback(vo, video_resize_redraw_callback);
+    }
+
     gl_video_config(p->renderer, params);
 
     p->vo_flipped = !!(flags & VOFLAG_FLIPPING);