如何使背景透明？

Question

I am creating a background for a Textview object like this in XML:

<selector xmlns:android="http://schemas.android.com/apk/res/android">
 <item android:state_enabled="true">
      <shape android:padding="50dp"
          android:shape="rectangle">
        <gradient android:startColor="@color/sendDarkColor"    android:endColor="@color/sendDarkColor" android:angle="90"/>
        <stroke android:width="1dip" android:color="#FFFFFF"/>
        <corners android:bottomLeftRadius="0dp" android:bottomRightRadius="0dp" android:topLeftRadius="0dp" android:topRightRadius="0dp" />
    </shape>
</item>

<item android:drawable="@android:color/transparent" />

sendDarkColor is just black. But I want this black to be transparent. Similar to this: http://i.imgur.com/wzSeJTS.png

This xml is later is set to a Textview as mentioned. I want it be a little transparent. How can I achieve this?

Answer 1

The color structure is like this AARRGGBB where AA is the alpha color in hexadecimal notation. For example, value for 50% transparency is #7FFFFFFF

Answer 2

To have black transparent color use:

android:background="#50000000"

or just use the color "#50000000" wherever you place a BG. The first two numbers after "#" , sets the opacity/transparency of the color. Hope this helps. Write if you don't understand something.