Objectives
Extend the location facility to track location in real time.
Exercise Solution 1
This is the revised view we are seeking:
activity_placemark layout to include lat/lng and remove the Set Location button:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="org.wit.placemark.views.placemark.PlacemarkView">
<android.support.design.widget.AppBarLayout
android:id="@+id/appBarLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/colorAccent"
android:fitsSystemWindows="true"
app:elevation="0dip"
app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbarAdd"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:titleTextColor="@color/colorPrimary" />
</android.support.design.widget.AppBarLayout>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="600dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<EditText
android:id="@+id/placemarkTitle"
android:layout_width="239dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:ems="10"
android:hint="@string/hint_placemarkTitle"
android:inputType="text"
app:layout_constraintBaseline_toBaselineOf="@+id/textView"
app:layout_constraintStart_toStartOf="parent" />
<EditText
android:id="@+id/description"
android:layout_width="239dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:ems="10"
android:hint="@string/hint_placemarkDescription"
android:inputType="textPersonName"
app:layout_constraintBaseline_toBaselineOf="@+id/textView2"
app:layout_constraintStart_toStartOf="parent" />
<Button
android:id="@+id/chooseImage"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginEnd="8dp"
android:text="@string/button_addImage"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/description" />
<ImageView
android:id="@+id/placemarkImage"
android:layout_width="0dp"
android:layout_height="139dp"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/chooseImage"
app:srcCompat="@drawable/ic_launcher_background" />
<com.google.android.gms.maps.MapView
android:id="@+id/mapView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/placemarkImage" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="Lat:"
app:layout_constraintBaseline_toBaselineOf="@+id/lat"
app:layout_constraintStart_toEndOf="@+id/placemarkTitle" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="Lng:"
app:layout_constraintBaseline_toBaselineOf="@+id/lng"
app:layout_constraintStart_toEndOf="@+id/description" />
<TextView
android:id="@+id/lat"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="72dp"
android:layout_marginEnd="8dp"
android:text="00.000000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/textView"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/lng"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="8dp"
android:text="00.000000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/textView2"
app:layout_constraintTop_toBottomOf="@+id/lat" />
</android.support.constraint.ConstraintLayout>
</android.support.constraint.ConstraintLayout>PlacemarkView
In PlacemarkView, display the lat/lng:
PlacemarkView
override fun showPlacemark(placemark: PlacemarkModel) {
placemarkTitle.setText(placemark.title)
description.setText(placemark.description)
placemarkImage.setImageBitmap(readImageFromPath(this, placemark.image))
if (placemark.image != null) {
chooseImage.setText(R.string.change_placemark_image)
}
lat.setText("%.6f".format(placemark.lat))
lng.setText("%.6f".format(placemark.lng))
}Also in PlacemarkView - remove references to the setLocation button:
// placemarkLocation.setOnClickListener { presenter.doSetLocation() }Instead, set an onClikcListener on the GoogleMap object:
mapView.getMapAsync {
presenter.doConfigureMap(it)
it.setOnMapClickListener { presenter.doSetLocation() }
}Live Location Updates
First, we need a new helper function:
LocationHelper
@SuppressLint("RestrictedApi")
fun createDefaultLocationRequest() : LocationRequest {
val locationRequest = LocationRequest().apply {
interval = 10000
fastestInterval = 5000
priority = LocationRequest.PRIORITY_HIGH_ACCURACY
}
return locationRequest
}In PlacemarkPresenter, use this helper to initialise a new attribute:
val locationRequest = createDefaultLocationRequest()Now introduce a new method, also in the presenter:
PlacemarkPresenter
@SuppressLint("MissingPermission")
fun doResartLocationUpdates() {
var locationCallback = object : LocationCallback() {
override fun onLocationResult(locationResult: LocationResult?) {
if (locationResult != null && locationResult.locations != null) {
val l = locationResult.locations.last()
locationUpdate(l.latitude, l.longitude)
}
}
}
if (!edit) {
locationService.requestLocationUpdates(locationRequest, locationCallback, null)
}
}This method, when invoked, does 12 things:
- defines a callback - to be triggered when we turn location updates
- checks to see if we are in edit mode - if not, it is assumed we would like live location updates to commence.
Finally, we need to be careful how we start these location updates. The safest place is from the PresenterView:
PlacemarkView
override fun onResume() {
super.onResume()
mapView.onResume()
presenter.doResartLocationUpdates()
}Here, in onResumne(), we ask for location updates to start (or restart if the view has been removed). We are assuming that location updates will be automatically terminated if the view is destroyed.
Run the app now in the simulator - and modify the lat/log values, then pressing Send. The location should change reasonably promptly in the view.
Exercises
Placemark application so far:
This is a revised EditLocation view:
In this version, as you drag the marker around the lat/long is updated as the marker is moved. Try to implement this now.
One strategy might be to replace the existing view completely with a version that loads a new layout. This layout can be designed in the layout editor, and contain the MapView + the lat/lng text views.
To kick start this process, you could copy the PlacemarkMapView class + layout. You should be able to keep the same presenter.