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diff --git a/docs/html/guide/tutorials/views/hello-mapview.jd b/docs/html/guide/tutorials/views/hello-mapview.jd new file mode 100644 index 0000000..976b8ab --- /dev/null +++ b/docs/html/guide/tutorials/views/hello-mapview.jd @@ -0,0 +1,247 @@ +page.title=Hello, MapView +parent.title=Hello, Views +parent.link=index.html +@jd:body + +<p>A MapView allows you to create your own map-viewing Activity. +First, we'll create a simple Activity that can view and navigate a map. Then we will add some overlay items.</p> + +<ol> + <li>Start a new project/Activity called HelloMapView. + + <li>Because we're using the Google Maps library, + which is not a part of the standard Android library, we need to + declare it in the Android Manifest. Open the AndroidManifest.xml + file and add the following as a child of the <code><application></code> element: + + <pre><uses-library android:name="com.google.android.maps" /></pre> + </li> + <li>We also need access to the internet in order to retrieve the Google Maps tiles, + so the application must request the {@link android.Manifest.permission#INTERNET INTERNET} permissions. + In the manifest file, add the following as a child of the <code><manifest></code> element: + <pre><uses-permission android:name="android.permission.INTERNET" /></pre> + </li> + <li>Now open the main layout file for your project. Define a layout with a com.google.android.maps.MapView + inside a android.widget.RelativeLayout: + +<pre> +<?xml version="1.0" encoding="utf-8"?> +<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" + android:id="@+id/mainlayout" + android:orientation="vertical" + android:layout_width="fill_parent" + android:layout_height="fill_parent" > + + <com.google.android.maps.MapView + android:id="@+id/mapview" + android:layout_width="fill_parent" + android:layout_height="fill_parent" + android:clickable="true" + android:apiKey="<em>Your Maps API Key</em>" + /> + +</RelativeLayout> +</pre> + <p>The <code>clickable</code> attribute defines whether you want to allow user-interaction with the map. + In this case, we set it "true" so that the user can navigate.</p> + + <p>The <code>apiKey</code> attribute holds the Google Maps API Key that proves your application and signer + certificate has been registered with the Google Maps service. Because MapView uses Google Maps data, this key is required + in order to receive the map data, even while you are developing. Registration is free and it only takes a couple + minutes to register your certificate and receive a Maps API Key. For instructions on getting a key, read + <a href="{@docRoot}guide/topics/location/geo/mapkey.html">Obtaining a Maps API Key</a>. + (For the purpose of this tutorial, you should register with the fingerprint of the SDK debug certificate.) + Once you've acquired the Maps API Key, insert it for the <code>apiKey</code> value.</p></li> + + <li>Now open the HelloMapView.java file. For this Activity, we're going to extend the special sub-class of + Activity called MapActivity, so change the class declaration to extend + MapActicity, instead of Activity:</p> + + <pre>public class HelloMapView extends MapActivity {</pre> + + <li>The <code>isRouteDisplayed()</code> method is required, so add it inside the class: +<pre> +@Override +protected boolean isRouteDisplayed() { + return false; +} +</pre> +<p>You can actually run this now, but all it does is allow you to pan around the map.</p> +<p>Android provides a handy {@link android.widget.ZoomControls} widget for zooming in and out of a View. +MapView can automatically hook one for us by requesting it with the <code>getZoomControls()</code> +method. Let's do this.</p> + +<li>Go back to the layout file. We need a new ViewGroup element, in which we'll + place the ZoomControls. Just below the MapView element (but inside the RelativeLayout), add this element: +<pre> +<LinearLayout + android:id="@+id/zoomview" + android:layout_width="wrap_content" + android:layout_height="wrap_content" + android:layout_alignBottom="@id/mapview" + android:layout_centerHorizontal="true" +/></pre> + + <p>It doesn't really matter what kind of ViewGroup we use, because we just want a + container that we can position within our root RelativeLayout.</p> + + <p>The last two attributes are available only to an element that's a child of a + RelativeLayout. <code>layout_alignBottom</code> aligns the bottom of this element to the bottom of + the element identified with a resource tag (which must be a sibling to this element). + <code>layout_centerHorizontal</code> centers this on the horizontal plane.</p></li> + + <li>Now go back to the HelloMapView class. We'll now retrieve the ZoomControls object from + the MapView and add it to our new layout element. First, at the top of the HelloMapView, + instantiate handles for the MapView and LinearLayout, plus a ZoomControl object: +<pre> +LinearLayout linearLayout; +MapView mapView; +ZoomControls mZoom;</pre></li> + + <li>Then initialize each of these in <code>onCreate()</code>. We'll capture the LinearLayout and + MapView through their layout resources. Then get the ZoomControls from the MapView:: +<pre> +linearLayout = (LinearLayout) findViewById(R.id.zoomview); +mapView = (MapView) findViewById(R.id.mapview); +mZoom = (ZoomControls) mapView.getZoomControls();</pre> + + <p>By using the ZoomControls object provided by MapView, we don't have to do any of the work + required to actually perform the zoom operations. The ZoomControls widget that MapView + returns for us is already hooked into the MapView and works as soon as we add it to the + layout. The controls will appear whenever the user touches the map, then dissapear after + a few moments of inactivity.</p></li> + + <li>Now just plug our ZoomControls into the LinearLayout we added: + + <pre>linearLayout.addView(mZoom);</pre></li> + + <li>Run it.</li> +</ol> + +<hr/> + +<p>So, we now have full interaction controls. All well and good, but what we really want our map +for is custom markers and layovers. Let's add some Overlay +objects to our map. To do this, we're going to +implement the ItemizedOverlay +class, which can manage a whole set of Overlay items for us.</p> + +<ol> + <li>Create a new Java class named HelloItemizedOverlay that implements ItemizedOverlay. + + <p>When using Eclipse, right-click the package name in the Eclipse Package Explorer, and select New > Class. Fill-in + the Name field as <em>HelloItemizedOverlay</em>. For the Superclass, enter + <em>com.google.android.maps.ItemizedOverlay</em>. Click the checkbox for <em>Constructors from + superclass</em>. Click Finish.</p></li> + + <li> First thing, we need an OverlayItem ArrayList, in which we'll put each of the OverlayItem + objects we want on our map. Add this at the top of the HelloItemizedOverlay class: + + <pre>private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>();</pre></li> + + <li>All the constructor does is define the default marker to be used on each of the OverlayItems. + In order for the Drawable to actually get drawn, it must have its bounds defined. And we want the + center-point at the bottom of the image to be the point at which it's attached to the map + coordinates. We handle all this with the boundCenterBottom() method. Wrap this around our + defaultMarker, so the super constructor call looks like this: + + <pre>super(boundCenterBottom(defaultMarker));</pre></li> + + <li>In order to add new OverlayItems to our ArrayList, we need a new public method. We'll handle + this with the following method: + +<pre> +public void addOverlay(OverlayItem overlay) { + mOverlays.add(overlay); + populate(); +}</pre> + + <p>Each time we add a new OverlayItem, we must call <code>populate()</code>, which will read each of out + OverlayItems and prepare them to be drawn.</p></li> + + <li>In order for the <code>populate()</code> method to read each OverlayItem, it will make a request to + <code>createItem(int)</code>. We must define this method to properly read from our ArrayList. Replace the + existing contents of the createItem method with a <code>get()</code> call to our ArrayList: + +<pre> +@Override +protected OverlayItem createItem(int i) { + return mOverlays.get(i); +} +</pre></li> + + <li>We're also required to override the <code>size()</code> method. Replace the existing contents of the + method with a size request to our ArrayList: + + <pre>return mOverlays.size();</pre></li> +</ol> + + +<p>That's it for the HelloItemizedOverlay class. We're now ready to use it.</p> + +<hr/> +<p>Go back to the HelloMapView +class. We'll start by creating one OverlayItem, adding to an instance of our HelloItemizedOverlay, +and then adding this to the MapView.</p> + +<img src="images/androidmarker.png" align="right" /> +<p>First, we need the image that we'll use for our map overlay. Here, we'll use the Android on the +right as our marker. Drag this image (or your own) to the res/drawable/ directory of your project workspace.</p> + +<p>Now we're ready to work in the HelloMapView:</p> + +<ol> + <li>First we need some more types. Add the following at the top of the HelloMapView class: + +<pre> +List<Overlay> mapOverlays; +Drawable drawable; +HelloItemizedOverlay itemizedOverlay;</pre></li> + + <li>Now pick up where we left off in the <code>onCreate()</code> method. Instantiate the + new fields: + +<pre> +mapOverlays = mapView.getOverlays(); +drawable = this.getResources().getDrawable(R.drawable.androidmarker); +itemizedoverlay = new HelloItemizedOverlay(drawable);</pre> + + <p>All overlay elements on a map are held by the MapView, so when we want to add some, we must + first retrieve the List with <code>getOverlays()</code> methods. We instantiate the Drawable, which will + be used as our map marker, by using our Context resources to get the Drawable we placed in + the res/drawable/ directory (androidmarker.png). Our HelloItemizedOverlay takes the Drawable in order to set the + default marker.</p></li> + + <li>Now let's make our first OverlayItem by creating a GeoPoint + that defines our map coordinates, then pass it to a new OverlayItem: + +<pre> +GeoPoint point = new GeoPoint(19240000,-99120000); +OverlayItem overlayitem = new OverlayItem(point, "", "");</pre> + + <p>GeoPoint coordinates are based in microdegrees (degrees * 1e6). The OverlayItem takes this + GeoPoint and two strings. Here, we won't concern ourselves with the strings, which can display + text when we click our marker, because we haven't yet written the click handler for the OverlayItem.</p></li> + + <li>All that's left is for us to add this OverlayItem to our collection in the HelloItemizedOverlay, + and add this to the List of Overlay objects retrieved from the MapView: + +<pre> +itemizedoverlay.addOverlay(overlayitem); +mapOverlays.add(itemizedoverlay);</pre></li> + + <li>Run it!</li> +</ol> + +<p>We've sent our droid to Mexico City. Hola, Mundo!</p> +<p>You should see the following:</p> +<img src="images/hello-mapview.png" width="150px" /> + +<p>Because we created our ItemizedOverlay class with an ArrayList, we can continue adding new +OverlayItems. Try adding another one. Before the <code>addOverlay()</code> method is called, add these lines:</p> +<pre> +GeoPoint point2 = new GeoPoint(35410000, 139460000); +OverlayItem overlayitem2 = new OverlayItem(point2, "", ""); +</pre> +<p>Run it again... We've sent a new droid to Tokyo. Sekai, konichiwa!</p> + |