Display new Activity on top of previous Activity

Question

I have an Activity A which has a \"down\" button (see image above). When I pre

Answer 1

This is the xml for activities that should be on top of activity a

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#00000000" >
     <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="0"
        android:layout_weight="0.6"
        android:background="#000000" >
     //use this for your new activity contents
     </LinearLayout>
     <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="0"
        android:layout_weight="0.4"
        android:background="#00000000" >
     //this is empty
     </LinearLayout>
</LinearLayout>

Now in your manifest for activity B,C ,... etc:

    <activity
        android:label="@string/app_name"
        android:name=".ActivityB"
        android:theme="@style/Theme.Transparent"
        android:screenOrientation="portrait" >

in values/styles.xml :

<?xml version="1.0" encoding="utf-8"?>  
<resources>
    <style name="Theme.Transparent" parent="android:Theme.NoTitleBar">  
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowBackground">@drawable/theme_transparent</item>
    </style>
</resources>  

Finally in drawable/theme_transparent.xml :

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <solid android:color="#00000000" ></solid>
</shape>

Answer 2

What you need to use, are Fragments.

Fragments can be used to fill a part of the screen, while doing something else entirely in a different one. In your example you can create a main activity that contains two Fragments. One Fragment controls the "A activity" , the other one controls the "B activity" and the other ones.. By replacing the current Fragment in your "B activity" area with a different one on the press of a button, you can achieve the behavior you are looking for. At least, that's how I did it in an app of mine containing a main content area and a music player. The music player stays in place while the main content changes.

Sadly I can't provide any example code right now, but here is a tutorialthat should help you get started:

• Android User Interface Design: Working With Fragments

In case you are working with an Android version below 3.0, you can use the Compatibility package.

http://developer.android.com/sdk/compatibility-library.html

http://mobile.tutsplus.com/tutorials/android/android-compatibility-working-with-fragments/