I don't understand how the layer-lists work. I read the official documentation with some examples but it does not work for me like expected. I want four squares which should be padded with 1dp, but nothing is like expected. Here is a screenshot scaled by 500%:
(The wrong colors do not matter)
As you can see the size is completely wrong and the paddings are missing. I tried to set real values like width/height and right/left/top/buttom to be sure that android get the point what I want.
Here is my xml:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:top="0dp" android:left="0dp" android:bottom="0dp" android:right="0dp">
<shape android:shape="rectangle">
<size android:width="9dp"
android:height="9dp"/>
<solid android:color="#f000"/>
</shape>
</item>
<item android:top="1dp" android:left="1dp" android:bottom="5dp" android:right="5dp">
<shape android:shape="rectangle">
<size android:width="3dp"
android:height="3dp"/>
<solid android:color="#f00"/>
</shape>
</item>
<item android:top="1dp" android:left="5dp" android:bottom="5dp" android:right="1dp">
<shape android:shape="rectangle">
<size android:width="3dp"
android:height="3dp"/>
<solid android:color="#0f0"/>
</shape>
</item>
<item android:top="5dp" android:left="1dp" android:bottom="1dp" android:right="5dp">
<shape android:shape="rectangle">
<size android:width="3dp"
android:height="3dp"/>
<solid android:color="#0f0"/>
</shape>
</item>
<item android:top="5dp" android:left="5dp" android:bottom="1dp" android:right="1dp">
<shape android:shape="rectangle">
<size android:width="3dp"
android:height="3dp"/>
<solid android:color="#f00"/>
</shape>
</item>
</layer-list>
The values for left, top, right and bottom are measured from their respective edge.
So left=0dp, top=0dp, bottom=0dp & right=50dp will give you a rectangle that is (match_parent - 50dp) wide and not 50dp wide. Therefore larger values for "right" will actually give you a smaller rectangle.
The same would apply to the other value, but these would behave as expected in most cases, its just "right" that might cause confusion.