limit frame rate to 60 frames per second (#100)

* limit frame rate to 60 frames per second

Note that the average frame rate we observe seems to be a little less than 60 frames per second. One may want to tune the max_frames_per_second accordingly.

* update example screenshot

README.md

@@ -32,7 +32,7 @@ julia --project=. example.jl
 
 This will open a window and you can interact with the widgets present in it. Here is a screenshot
 
-<img src="https://user-images.githubusercontent.com/32610387/213902028-ede69c75-f36c-4df2-9d8b-4db107aabe13.png">
+<img src="https://user-images.githubusercontent.com/32610387/216698734-400e1dcb-ff51-4a53-b6e3-87d5f7b60570.png">
 
 # References:
 

examples/example.jl

@@ -150,6 +150,9 @@ function start()
 
     sliding_window_size = 30
 
+    max_frames_per_second = 60
+    min_seconds_per_frame = 1 / max_frames_per_second
+
     frame_time_stamp_buffer = DS.CircularBuffer{typeof(time_ns())}(sliding_window_size)
     push!(frame_time_stamp_buffer, time_ns())
 
@@ -399,6 +402,8 @@ function start()
 
         i = i + 1
 
+        sleep(max(0.0, min_seconds_per_frame - (time_ns() - last(frame_time_stamp_buffer)) / 1e9))
+
         push!(frame_time_stamp_buffer, time_ns())
     end