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diff --git a/docs/html/training/backward-compatible-ui/using-component.jd b/docs/html/training/backward-compatible-ui/using-component.jd new file mode 100644 index 0000000..4bf7fa0 --- /dev/null +++ b/docs/html/training/backward-compatible-ui/using-component.jd @@ -0,0 +1,143 @@ +page.title=Using the Version-Aware Component +parent.title=Creating Backward-Compatible UIs +parent.link=index.html + +trainingnavtop=true +previous.title=Creating an Implementation with Older APIs +previous.link=older-implementation.html + +@jd:body + +<div id="tb-wrapper"> +<div id="tb"> + +<h2>This lesson teaches you to:</h2> +<ol> + <li><a href="#switching-logic">Add the Switching Logic</a></li> + <li><a href="#layout">Create a Version-Aware Activity Layout</a></li> + <li><a href="#use-tabhelper">Use TabHelper in Your Activity</a></li> +</ol> + +<h2>Try it out</h2> + +<div class="download-box"> +<a href="http://developer.android.com/shareables/training/TabCompat.zip" + class="button">Download the sample app</a> +<p class="filename">TabCompat.zip</p> +</div> + +</div> +</div> + +<p>Now that you have two implementations of <code>TabHelper</code> and <code>CompatTab</code>—one for Android 3.0 and later and one for earlier versions of the platform—it's time to do something with these implementations. This lesson discusses creating the logic for switching between these implementations, creating version-aware layouts, and finally using the backward-compatible UI component.</p> + +<h2 id="switching-logic">Add the Switching Logic</h2> + +<p>The <code>TabHelper</code> abstract class acts as a <a href="http://en.wikipedia.org/wiki/Factory_(software_concept)">factory</a> for creating version-appropriate <code>TabHelper</code> and <code>CompatTab</code> instances, based on the current device's platform version:</p> + +<pre> +public abstract class TabHelper { + ... + // Usage is TabHelper.createInstance(activity) + public static TabHelper createInstance(FragmentActivity activity) { + if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { + return new TabHelperHoneycomb(activity); + } else { + return new TabHelperEclair(activity); + } + } + + // Usage is mTabHelper.newTab("tag") + public CompatTab newTab(String tag) { + if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { + return new CompatTabHoneycomb(mActivity, tag); + } else { + return new CompatTabEclair(mActivity, tag); + } + } + ... +} +</pre> + +<h2 id="layout">Create a Version-Aware Activity Layout</h2> + +<p>The next step is to provide layouts for your activity that can support the two tab implementations. For the older implementation (<code>TabHelperEclair</code>), you need to ensure that your activity layout contains a {@link android.widget.TabWidget} and {@link android.widget.TabHost}, along with a container for tab contents:</p> + +<p><strong>res/layout/main.xml:</strong></p> + +<pre> +<!-- This layout is for API level 5-10 only. --> +<TabHost xmlns:android="http://schemas.android.com/apk/res/android" + android:id="@android:id/tabhost" + android:layout_width="match_parent" + android:layout_height="match_parent"> + + <LinearLayout + android:orientation="vertical" + android:layout_width="match_parent" + android:layout_height="match_parent" + android:padding="5dp"> + + <TabWidget + android:id="@android:id/tabs" + android:layout_width="match_parent" + android:layout_height="wrap_content" /> + + <FrameLayout + android:id="@android:id/tabcontent" + android:layout_width="match_parent" + android:layout_height="0dp" + android:layout_weight="1" /> + + </LinearLayout> +</TabHost> +</pre> + +<p>For the <code>TabHelperHoneycomb</code> implementation, all you need is a {@link android.widget.FrameLayout} to contain the tab contents, since the tab indicators are provided by the {@link android.app.ActionBar}:</p> + +<p><strong>res/layout-v11/main.xml:</strong></p> + +<pre> +<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" + android:id="@android:id/tabcontent" + android:layout_width="match_parent" + android:layout_height="match_parent" /> +</pre> + +<p>At runtime, Android will decide which version of the <code>main.xml</code> layout to inflate depending on the platform version. This is the same logic shown in the previous section to determine which <code>TabHelper</code> implementation to use.</p> + +<h2 id="use-tabhelper">Use TabHelper in Your Activity</h2> + +<p>In your activity's {@link android.app.Activity#onCreate onCreate()} method, you can obtain a <code>TabHelper</code> object and add tabs with the following code:</p> + +<pre> +{@literal @}Override +public void onCreate(Bundle savedInstanceState) { + setContentView(R.layout.main); + + TabHelper tabHelper = TabHelper.createInstance(this); + tabHelper.setUp(); + + CompatTab photosTab = tabHelper + .newTab("photos") + .setText(R.string.tab_photos); + tabHelper.addTab(photosTab); + + CompatTab videosTab = tabHelper + .newTab("videos") + .setText(R.string.tab_videos); + tabHelper.addTab(videosTab); +} +</pre> + +<p>When running the application, this code inflates the correct activity layout and instantiates either a <code>TabHelperHoneycomb</code> or <code>TabHelperEclair</code> object. The concrete class that's actually used is opaque to the activity, since they share the common <code>TabHelper</code> interface.</p> + +<p>Below are two screenshots of this implementation running on an Android 2.3 and Android 4.0 device.</p> + +<img src="{@docRoot}images/training/backward-compatible-ui-gb.png" + alt="Example screenshot of tabs running on an Android 2.3 device (using TabHelperEclair)." width="200"> + +<img src="{@docRoot}images/training/backward-compatible-ui-ics.png" + alt="Example screenshots of tabs running on an Android 4.0 device (using TabHelperHoneycomb)." width="200"> + +<p class="img-caption"><strong>Figure 1.</strong> Example screenshots of backward-compatible tabs running on an Android 2.3 device (using <code>TabHelperEclair</code>) and an Android 4.0 device (using <code>TabHelperHoneycomb</code>).</p> |