Android – image button with @ null background (transparent) [copy]

See the English answer > how to set image button background image for different state? I have an image button with a transparent image source, but the background color of the image button is a typical gray button color

I want to set the background = @ null, which is good

However, when I press this image button, I can't see the color indicating that I press the button

If I delete background = @ null when I press the button, please change the color that the user knows you press

I read that you can create an XML with three images, specify the time to press the button, this normal situation and when to focus. But I think there is an easier way

resolvent:

According to the above answer, use the selector drawable (for the background, not null) to set the default state to transparent color:

* selector_ with_ transparency：*

<?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/pressed" />
    <item android:drawable="@drawable/transparent" />

</selector>

Press:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >

    <solid android:color="#0077cc" />

</shape>

Transparency:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <solid android:color="#00000000"/>

</shape>

Then for imagebutton:

background = "@drawable/selector_with_transparency"