Angry birds like Floating menu on Android

Does anyone know how to make a floating menu like the ones in Angry Birds home screen?

Here is a picture showing the menu buttons in collapsed mode (gear, up buttons). On tapping these buttons, the actual menu would expand, showing two or more round buttons.

Any links,开发者_如何学C clues is much appreciated.

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I might be wrong but I think that the entire thing is done in OpenGL.

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I guess it's an image with a transparent background and you calculate its position based on time....

Although you could achieve it with standard widgets, maybe it would be a better idea to create a custom view and implement onDraw()

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This is done within the XML of your 'game screen.' Assuming you've done a tutorial on OpenGL-ES, you should have an xml file that holds your custom GLSurfaceView. To add overlay items like buttons and, well.. anything, just add them to this xml file. Here's an example of a game I'm working on:

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">

//This is your GLSurfaceView which will fill the whole screen
<android.opengl.GLSurfaceView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/GLSurface" />


        //This layout will overlay the game
        <LinearLayout
        android:gravity="center"
        android:weightSum="100"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

            <Button
            android:layout_weight="10"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Sel"
            />

            <SeekBar
            android:paddingLeft="30px"
            android:paddingRight="30px"
            android:layout_weight="80"
            android:gravity="center"
            android:id="@+id/RotateBar"
            android:layout_width="180px"
            android:layout_height="wrap_content"
            android:max="180"
            />

            <Button
            android:layout_weight="10"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Act"
            />

        </LinearLayout>

Obviously this is modified (I don't have buttons floating in the center of the screen :P ) but you get the idea. Here's a link to good OpenGL-ES tutorial: link