Add architecture description, make ESC quit the app

1 files changed, 40 insertions, 1 deletions

diff --git a/zmq-camera.c b/zmq-camera.c
index 61c7edd..2192165 100644
--- a/zmq-camera.c
+++ b/zmq-camera.c
@@ -34,6 +34,41 @@
 
 #include <zmq.h>
 
+/*
+ *  Overall architecture:
+ *
+ *  zmq-camera uses 3 application threads:
+ *
+ *  1) the main thread, which receives and displays video from either the
+ *     sender thread using inproc://local-camera if running in sender mode (-s)
+ *     or from a remote endpoint specified by the user if running in 
+ *     receive-only mode (-r).
+ *
+ *     the main thread also receives and handles signals and timers, 
+ *     using inproc://local-signal and periodically polls for UI events.
+ *
+ *  2) the signal handling thread, which handles all signals synchronously
+ *     using a sigwait() loop and sends a single message for each signal
+ *     received to the main thread.
+ *
+ *  3) the sender thread which does the actual video capture and sends one
+ *     message per raw video frame both to inproc://local-camera so that the
+ *     user sees what they are sending and to the remote endpoint specified.
+ *
+ *  Message formats:
+ *
+ *  inproc://local-signal
+ *
+ *  [ signo (int) ]
+ *
+ *  Video data:
+ *
+ *  [ width (uint32_t in network byte order),
+ *    height (uint32_t in network byte order),
+ *    (RGB24 pixel data) ]
+ *
+ */
+
 #define FOURCC(a,b,c,d) (unsigned int)((((unsigned int)d)<<24)+\
     (((unsigned int)c)<<16)+(((unsigned int)b)<<8)+a)
 
@@ -552,11 +587,15 @@ int main (int argc, char *argv [])
         {
             if (event.type == SDL_QUIT)
                 quit = 1;
+            if (event.type == SDL_KEYDOWN)
+                if (event.key.keysym.sym == SDLK_ESCAPE)
+                    quit = 1;
         }
     }
 
     /* TODO: Send a 'stop' message to sender thread rather than killing it
-             forcefully by terminating the main thread. */
+             forcefully by terminating the main thread. This would allow it
+             to call zmq_close() correctly and us to call zmq_term() here. */
 
     /* Cleanup */
     SDL_Quit ();