Create transparent activity

We want an activity has transparent screen, user can touch icons behind it to run them.

Copy these lines in tag values, file styles.xml.

<style name="Theme.Transparent" parent="android:Theme">

    <item name="android:windowIsTranslucent">true</item>

    <item name="android:windowBackground">@android:color/transparent</item>

    <item name="android:windowNoTitle">true</item>

    <item name="android:windowIsFloating">true</item>

    <item name="android:windowCloseOnTouchOutside">false</item>

    <item name="android:backgroundDimEnabled">false</item>

  </style>

Add to class declaration.

android:theme="@style/Theme.Transparent"

Now in class, copy to below setContentView();

WindowManager.LayoutParams wlp = getWindow().getAttributes();

          wlp.dimAmount = 0;

          wlp.flags = WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS

                     | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;

          getWindow().setAttributes(wlp);

Activity now float in center screen, to make it on top, add this to above setContentView();

WindowManager.LayoutParams wmlp = getWindow().getAttributes();

          wmlp.width = LayoutParams.WRAP_CONTENT;

          wmlp.gravity = Gravity.TOP | Gravity.CENTER;

In some phones like Samsung, screen behind still can’t touch, we should use service if need to run always on screen.