How do I create a transparent Activity on Android?

Question

I want to create a transparent Activity on top of another activity.

How can I achieve this?

Answer 1

In my case, i have to set the theme on the runtime in java based on some conditions. So I created one theme in style (similar to other answers):

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <style name="Theme.Transparent" parent="android:Theme">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">false</item>
  </style>
</resources>

Then in Java I applied it to my activity:

@Override
protected void onCreate(Bundle savedInstanceState) {

    String email = getIntent().getStringExtra(AppConstants.REGISTER_EMAIL_INTENT_KEY);
    if (email != null && !email.isEmpty()) {
        // We have the valid email ID, no need to take it from user,
        // prepare transparent activity just to perform bg tasks required for login
        setTheme(R.style.Theme_Transparent);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

    } else
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_dummy);
}

Remember one Important point here: You must call the setTheme() function before super.onCreate(savedInstanceState);. I missed this point and stucked for 2 hours, thinking why my theme is not reflected at run time.

Answer 2

I wanted to add to this a little bit as I am a new Android developer as well. The accepted answer is great, but I did run into some trouble. I wasn't sure how to add in the color to the colors.xml file. Here is how it should be done:

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
     <color name="class_zero_background">#7f040000</color>
     <color name="transparent">#00000000</color>
</resources>

In my original colors.xml file I had the tag "drawable":

<drawable name="class_zero_background">#7f040000</drawable>

And so I did that for the color as well, but I didn't understand that the "@color/" reference meant look for the tag "color" in the XML. I thought that I should mention this as well to help anyone else out.

Answer 3

In the onCreate function, below the setContentView, add this line:

getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

Answer 4

Add the following style in your res/values/styles.xml file (if you don’t have one, create it.) Here’s a complete file:

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <style name="Theme.Transparent" parent="android:Theme">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">false</item>
  </style>
</resources>

(The value @color/transparent is the color value #00000000 which I put in the res/values/color.xml file. You can also use @android:color/transparent in later Android versions.)

Then apply the style to your activity, for example:

<activity android:name=".SampleActivity" android:theme="@style/Theme.Transparent">
...
</activity>

Answer 5

For dialog activity I use this:

getWindow().getDecorView().setBackgroundResource(android.R.color.transparent);

But you also need to set your main View in the activity to invisible. Otherwise the background will be invisible while all views in it will be visible.

Answer 6

The easiest way that I have found is to set the activity's theme in the AndroidManifest to android:theme="@android:style/Theme.Holo.Dialog".

Then in the activity's onCreate method, call getWindow().setBackgroundDrawable(new ColorDrawable(0));.