cocoa: don't accidentally drop initial screen drawing

With --idle --force-window, or when started from the bundle, the cocoa
code dropped the first frame. This resulted in a black frame on start
sometimes.

The reason was that the live resizing/redrawing code was invoked, which
simply set skip_swap_buffer to false, blocking redrawing whatever was
going to be rendered next. Normally this is done so that the following
works:

1. vo_opengl draw a frame, releases GL lock
2. live resizing kicks in, redraw the frame
3. vo_opengl wants to call SwapBuffers, drawing a stale buffer
   overwritten by the live resizing code

This is solved by setting skip_swap_buffer in 2., and querying it in 3.

Fix this by resetting the skip_swap_buffer at a known good point: when
vo_opengl starts drawing a new frame.

The start_frame function returns bool, so that it can be merged with
is_active in a following commit.

1 files changed, 1 insertions, 0 deletions

diff --git a/video/out/cocoa_common.h b/video/out/cocoa_common.h
index 30792a674e..e2bed88d08 100644
--- a/video/out/cocoa_common.h
+++ b/video/out/cocoa_common.h
@@ -30,6 +30,7 @@ void vo_cocoa_uninit(struct vo *vo);
 int vo_cocoa_config_window(struct vo *vo, uint32_t flags, void *gl_ctx);
 
 void vo_cocoa_set_current_context(struct vo *vo, bool current);
+bool vo_cocoa_start_frame(struct vo *vo);
 void vo_cocoa_swap_buffers(struct vo *vo);
 int vo_cocoa_check_events(struct vo *vo);
 int vo_cocoa_control(struct vo *vo, int *events, int request, void *arg);