1 files changed, 117 insertions, 0 deletions
diff --git a/app/hrm.js b/app/hrm.js
new file mode 100644
index 0000000..d3f1483
--- /dev/null
+++ b/app/hrm.js
@@ -0,0 +1,117 @@
+import document from "document";
+import { HeartRateSensor } from "heart-rate";
+import { display } from "display";
+import { me } from "appbit";
+
+
+var hrImage = document.getElementById("hrImage");
+var hrIcon = document.getElementById("hrIcon");
+var hrText = document.getElementById("hrText");
+
+var hrm = null;
+var lastMeasuredHR = 0;
+var timeOfLastMeasuredHR = 0;
+var lastHRMReading = 0;
+var hrmActive = false;
+var hrTimer = null;
+
+function getHRMReading() {
+  let timeToNextReading = 1000;   //check every second even when no HR is detected
+  
+  let now = new Date().getTime();
+  let hr = hrm.heartRate;
+  if (hrm.timestamp === lastHRMReading || !hr) {
+    if (now - timeOfLastMeasuredHR >= 3000) {
+      //more then 3 seconds no new HR reading, watch probably off wrist
+      if (hrmActive) {
+        //show as not active
+        hrmActive = false;
+        setHRIconColor();
+        showHRMValue("--");
+      }
+    }
+    else {
+      //no new reading, but less then 3 seconds ago we still had a valid reading, so keep animating at same speed
+      timeToNextReading = 60000/lastMeasuredHR;
+    }
+  } else {
+    //new reading
+    if (!hrmActive) {
+      hrmActive = true;
+      setHRIconColor();
+    }
+
+    //store last measured to use when we get no new readings next time
+    timeOfLastMeasuredHR = now;
+    lastMeasuredHR = hr;
+    showHRMValue(lastMeasuredHR);
+    timeToNextReading = 60000/lastMeasuredHR;
+  }
+  lastHRMReading = hrm.timestamp;
+  
+  //animate when active
+  if (hrmActive) {
+    hrImage.animate("enable");
+  }
+  
+  //set next reading timeout depending on HR
+  if (hrTimer) {
+    clearTimeout(hrTimer);
+    hrTimer = null;
+  }
+  hrTimer = setTimeout(getHRMReading, timeToNextReading);
+}
+
+function setHRIconColor() {
+  if (hrmActive) {
+    hrIcon.style.fill = "#FF0000";
+  }
+  else {
+    hrImage.animate("disable");
+    hrIcon.style.fill = "#CCCCCC";
+  }
+}
+
+function showHRMValue(newHRMValue) {
+  hrText.text = newHRMValue;
+}
+
+function startHRMeasurements() {
+  if (hrm) {
+    if (hrmActive) {
+      timeOfLastMeasuredHR = new Date().getTime();    //make sure the icon doesn't show as gray after the screen was off a long time
+    }
+    hrm.start();
+    getHRMReading();
+  }
+}
+
+function stopHRMeasurements() {
+  if (hrTimer) {
+    clearTimeout(hrTimer);
+    hrTimer = null;
+  }
+  if (hrm) {
+    hrm.stop();
+  }
+}
+
+export function initialize() {
+  hrText.text = '--';
+  if (me.permissions.granted("access_heart_rate")) {
+    hrm = new HeartRateSensor();
+    if (display.on) {
+      //already start measurements
+      startHRMeasurements();
+    }
+  }
+
+  //react on display on/off
+  display.onchange = function() {
+    if (display.on) {
+      startHRMeasurements();
+    } else {
+      stopHRMeasurements();
+    }
+  }
+}
+\ No newline at end of file