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, 6 insertions, 0 deletions

diff --git a/video/out/gl_cocoa.c b/video/out/gl_cocoa.c
index fd12ef4621..014bf38204 100644
--- a/video/out/gl_cocoa.c
+++ b/video/out/gl_cocoa.c
@@ -153,6 +153,11 @@ static void releaseGlContext_cocoa(MPGLContext *ctx)
     CGLReleaseContext(p->ctx);
 }
 
+static bool start_frame_cocoa(MPGLContext *ctx)
+{
+    return vo_cocoa_start_frame(ctx->vo);
+}
+
 static void swapGlBuffers_cocoa(MPGLContext *ctx)
 {
     vo_cocoa_swap_buffers(ctx->vo);
@@ -169,6 +174,7 @@ void mpgl_set_backend_cocoa(MPGLContext *ctx)
     ctx->config_window = config_window_cocoa;
     ctx->releaseGlContext = releaseGlContext_cocoa;
     ctx->swapGlBuffers = swapGlBuffers_cocoa;
+    ctx->start_frame = start_frame_cocoa;
     ctx->vo_init = vo_cocoa_init;
     ctx->register_resize_callback = vo_cocoa_register_resize_callback;
     ctx->vo_uninit = vo_cocoa_uninit;