How to put semi transparent buttons over an image in layout?

What I am trying to do is put few buttons, made from PNG image, that has opa开发者_运维技巧que border and semi transparent other area, over an image that will be controlled (zoomed, panned).

Something like that:

What is the best way to achieve this? What layout and what views should be used? Maybe there is similar tutorial to such app design.

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I guess I'd use a relative layout and skinned buttons. The only issue you'll have with skinned buttons is that you'll need to be sure you are using 32bit pngs (with a transparency layer) as your button skins.

Here's a code chunk for doing button skins - they get set as the background of the button object and you place them in the drawable folder along side your images.

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"
      android:drawable="@drawable/btn_back_down" /> <!-- pressed -->
    <!-- item android:state_focused="true"
      android:drawable="@drawable/button_focused" /--> <!-- focused -->
    <item android:drawable="@drawable/btn_back_up" /> <!-- default -->
</selector>