altosdroid: Show direction to target in recover tab

[fw/altos] / altosdroid / src / org / altusmetrum / AltosDroid / AltosDroid.java

diff --git a/altosdroid/src/org/altusmetrum/AltosDroid/AltosDroid.java b/altosdroid/src/org/altusmetrum/AltosDroid/AltosDroid.java
index 6cd9463afbc056f39e7cde3561134a943bd75933..f1da27d8a8ab6908fb61b0a15d93729e5702e823 100644 (file)
--- a/altosdroid/src/org/altusmetrum/AltosDroid/AltosDroid.java
+++ b/altosdroid/src/org/altusmetrum/AltosDroid/AltosDroid.java
@@ -990,4 +990,29 @@ public class AltosDroid extends FragmentActivity implements AltosUnitsListener {
                }
                return false;
        }
+
+       static String direction(AltosGreatCircle from_receiver,
+                            Location receiver) {
+               if (!receiver.hasBearing())
+                       return null;
+
+               float   bearing = receiver.getBearing();
+               float   heading = (float) from_receiver.bearing - bearing;
+
+               while (heading <= -180.0f)
+                       heading += 360.0f;
+               while (heading > 180.0f)
+                       heading -= 360.0f;
+
+               int iheading = (int) (heading + 0.5f);
+
+               if (-1 < iheading && iheading < 1)
+                       return "ahead";
+               else if (iheading < -179 || 179 < iheading)
+                       return "backwards";
+               else if (iheading < 0)
+                       return String.format("left %d", -iheading);
+               else
+                       return String.format("right %d", iheading);
+       }
 }