API: expose setting for e.g. RepeaterBook

AndroidManifest.xml

@@ -145,6 +145,7 @@
 		<action android:name="org.aprsdroid.app.ONCE" />
 		<action android:name="org.aprsdroid.app.SEND_PACKET" />
 		<action android:name="org.aprsdroid.app.SERVICE_STOP" />
+		<action android:name="org.aprsdroid.app.FREQUENCY" />
 	    </intent-filter>
 	</service>
 	<!-- start the service if applicable on boot -->

doc/API.mdwn

@@ -22,6 +22,8 @@ Intents ("actions"):
  * `ONCE` - send one position packet and stop
  * `SERVICE_STOP` - stop APRSdroid's tracking service
  * `SEND_PACKET` - send a (raw) APRS packet
+ * `FREQUENCY` - change the frequency announced in position packets (requires
+   APRSdroid 1.4.1)
 
 All uppercase strings mentioned in this document are suffixes to
 `"org.aprsdroid.app."` and need to be concatenated for the effective
@@ -196,6 +198,29 @@ Example for sending a raw status packet:
 	i.putExtra("data", ">third-party APRS status app");
 	startService(i);
 
+### FREQUENCY (APRSdroid 1.4.1)
+
+Update the [frequency field](http://www.aprs.org/info/freqspec.txt) in the
+position reports sent by APRSdroid. If the APRSdroid service is running, this
+will immediately generate a position packet with the new frequency.
+
+Intent extras:
+
+ * `frequency` (String): the new frequency value, e.g. "438.750MHz", "145.500"
+   or "" to disable, decimal separator must be a dot (".")
+
+Example for updating the frequency:
+
+	// send raw status packet
+	Intent i = new Intent("org.aprsdroid.app.FREQUENCY").setPackage("org.aprsdroid.app");
+	i.putExtra("frequency", "438.750");
+	startService(i);
+
+Invocation from the adb shell:
+
+	am startservice -a org.aprsdroid.app.FREQUENCY -e frequency "438.750"
+
+
 ## (In-)Security
 
 Currently, APRSdroid exposes the following personal information via

src/AprsService.scala

@@ -16,6 +16,7 @@ object AprsService {
 	val SERVICE = PACKAGE + ".SERVICE"
 	val SERVICE_ONCE = PACKAGE + ".ONCE"
 	val SERVICE_SEND_PACKET = PACKAGE + ".SEND_PACKET"
+	val SERVICE_FREQUENCY = PACKAGE + ".FREQUENCY"
 	val SERVICE_STOP = PACKAGE + ".SERVICE_STOP"
 	// event intents
 	val SERVICE_STARTED = PACKAGE + ".SERVICE_STARTED"
@@ -122,8 +123,23 @@ class AprsService extends Service {
 				data_field)
 			sendPacket(p)
 			return
+		} else
+		if (i.getAction() == SERVICE_FREQUENCY) {
+			val data_field = i.getStringExtra("frequency")
+			if (data_field == null) {
+				Log.d(TAG, "FREQUENCY ignored, 'frequency' extra is empty.")
+				return
+			}
+                        val freq_cleaned = data_field.replace("MHz", "").trim
+                        val freq = try { freq_cleaned.toFloat; freq_cleaned } catch { case _ : Throwable => "" }
+                        if (prefs.getString("frequency", null) != freq) {
+                                prefs.set("frequency", freq)
+                                if (!running) return
+                                // XXX: fall through into SERVICE_ONCE
+			} else return
 		}
 
+
 		// display notification (even though we are not actually started yet,
 		// but we need this to prevent error message reordering)
 		val toastString = if (i.getAction() == SERVICE_ONCE) {

src/PrefsWrapper.scala

@@ -41,6 +41,10 @@ class PrefsWrapper(val context : Context) {
 		prefs.edit().putBoolean(name, new_val).commit()
 		new_val
 	}
+	def set(name : String, new_val : String) = {
+		prefs.edit().putString(name, new_val).commit()
+		new_val
+	}
 	def getShowObjects() = prefs.getBoolean("show_objects", true)
 	def getShowSatellite() = prefs.getBoolean("show_satellite", false)