StopWatch class (#631)

dwalton76 · web-flow · commit 2be6c87e0b07 · 2019-05-12T20:11:52.000-04:00
diff --git a/debian/changelog b/debian/changelog
@@ -1,6 +1,7 @@
 python-ev3dev2 (2.0.0~beta4) UNRELEASED; urgency=medium
 
   [Daniel Walton]
+  * StopWatch class
   * Avoid race condition due to poll(None)
   * MoveDifferential odometry support, tracks robot's (x,y) position
   * Display support via raspberry pi HDMI 
diff --git a/ev3dev2/stopwatch.py b/ev3dev2/stopwatch.py
@@ -0,0 +1,84 @@
+"""
+A StopWatch class for tracking the amount of time between events
+"""
+
+try:
+    import datetime as dt
+    micropython = False
+except ImportError:
+    import utime
+    micropython = True
+
+
+def get_ticks_ms():
+    if micropython:
+        return utime.ticks_ms()
+    else:
+        return int(dt.datetime.timestamp(dt.datetime.now()) * 1000)
+
+
+class StopWatch(object):
+
+    def __init__(self, desc=None):
+        self.desc = desc
+        self._value = 0
+        self.start_time = None
+        self.prev_update_time = None
+
+    def __str__(self):
+        if self.desc is not None:
+            return self.desc
+        else:
+            return self.__class__.__name__
+
+    def start(self):
+        assert self.start_time is None, "%s is already running" % self
+        self.start_time = get_ticks_ms()
+
+    def update(self):
+
+        if self.start_time is None:
+            return
+
+        current_time = get_ticks_ms()
+
+        if self.prev_update_time is None:
+            delta = current_time - self.start_time
+        else:
+            delta = current_time - self.prev_update_time
+
+        self._value += delta
+        self.prev_update_time = current_time
+
+    def stop(self):
+
+        if self.start_time is None:
+            return
+
+        self.update()
+        self.start_time = None
+        self.prev_update_time = None
+
+    def reset(self):
+        self.stop()
+        self._value = 0
+
+    @property
+    def value_ms(self):
+        """
+        Returns the value of the stopwatch in milliseconds
+        """
+        self.update()
+        return self._value
+
+    @property
+    def value_hms(self):
+        """
+        Returns the value of the stopwatch in HH:MM:SS.msec format
+        """
+        self.update()
+        (hours, x) = divmod(int(self._value), 3600000)
+        (mins, x) = divmod(x, 60000)
+        (secs, x) = divmod(x, 1000)
+
+        return '%02d:%02d:%02d.%03d' % (hours, mins, secs, x)
