Develop Reference

How is a bottom line added with this layer-list drawable?

I want to have a bottom line in a view. The following drawable somehow adds a bottom border:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<shape
android:shape="rectangle">
<!-- Set the border color of your layout here -->
<solid android:color="#color/red" />
</shape>
</item>
<!-- This is for border bottom but
you can change this according to your need -->
<item android:bottom="2dp" >
<shape
android:shape="rectangle">
<!-- Set the background color of your layout here -->
<solid android:color="#color/green" />
</shape>
</item>
</layer-list>
The result of this is:
Problem:
1) I don't understand how this works at all. It seems this is some trick using margins to get a red bottom border but I don't really get it.
2) I need to be able to add a bottom border but I don't want to set any specific background color for the whole view. Is that possible?

This is telling the system from where to start this item layout.
Since here we have bottom 2dp so this layout start 2dp from bottom.
Change bottom to end,start or other options for more understanding.

For 2) I need to be able to add a bottom border but I don't want to set any specific background color for the whole view. Is that possible?
replace your drawable with below code:
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item
android:left="-2dp"
android:right="-2dp"
android:top="-2dp">
<shape android:shape="rectangle">
<solid android:color="#ffffff" />
<!--Uncomment this if you wnat to set any background color to
your rectangle
<solid android:color="#ffffff" />-->
<stroke
android:width="1dp"
android:color="#color/red" />
</shape>
</item>

Custom listview selector / drawable dimensions?

Is there any way I can set my listview selector to a custom drawable that only occupies a portion of the item view? I have made a drawable rectangle and set it as the selector, but I'm having a difficult time getting it to size properly. The picture shows what I have now (1) and the desired effect (2).

Got it - initially decided to just set the selector as a drawable that only shows a border on one side, and messed around with insets to no avail (for some reason the top and bottom were not working properly). So I just made a layer list and offset the top layer to the right by a few dp.
<?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">
<solid android:color="#color/colorAccent"/>
</shape>
</item>
<item android:top="0dp" android:left="5dp" android:bottom="0dp" android:right="0dp">
<shape android:shape="rectangle">
<solid android:color="#FFFFFF"/>
</shape>
</item>
</layer-list>

Shape Drawable Size not working

I have a very simple shape that I want to set the width of:
<shape android:shape="rectangle">
<solid android:color="#color/orange"/>
<size android:width="2dp"/>
</shape>
However, when I assign this to the background of a EditText it just shows an orange background instead of a rectangle of width 2dp. Why isn't setting the size working? I want to create a transparent drawable with a orange rectangle on the left side. I also have this wrapped in a selector:
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_focused="true">
<shape android:shape="rectangle">
<solid android:color="#color/orange"/>
<size android:width="2dp" android:height="6dp"/>
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="#android:color/transparent"/>
</shape>
</item>
</selector>
I've tried adding height just to see if it would change the size. It doesn't. It's like its completely ignoring the size. WTF?

For me, setting the gravity of the item to "center" solved the issue.
For example:
<item android:id="#android:id/progress" android:gravity="center">
<clip>
<shape>
<size android:height="2dp"/>
<solid android:color="#color/my_color"/>
</shape>
</clip>
</item>

It can work with a foreground. It seems like you can't set a background's gravity. But you can on a foreground. I checked API 21, 23 and 24 (well, with the Studio design preview) and the following places a solid circle dot on the ImageView.
<shape android:shape="oval" xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#color/colorPrimary" />
<size android:height="8dp" android:width="8dp" />
</shape>
With the layout snippet
<ImageView
android:foreground="#drawable/list_new_dot"
android:foregroundGravity="right|center_vertical"
tools:src="#drawable/model_1_sm"
/>
UPDATE: While it appears to work in the layout design tool, it doesn't look the same in the emulator. UPDATE 2: Since this answer has a few votes, you might want to check what I actually used in order to show a new indicator dot:
https://gist.github.com/CapnSpellcheck/4d4638aefd085c703b9d990a21ddc1eb

Just to specify the user983447's answer - the size attribute does really mean a proportion. You should set the size for all shapes in your layer-list and it'll be used a as a proportion when scaling - like the layout_weight attribute of LinearLayout. So it's better to name it not a size but a weight
Below is a work-around how to implement top and bottom white lines without using the size attribute:
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape>
<solid android:color="#fff" />
</shape>
</item>
<item android:top="1dp" android:bottom="1dp">
<shape>
<solid android:color="#888" />
</shape>
</item>
</layer-list>

I found the layer-list to be very devious for a first time Androider because of the following. At first glance most would think item top,bottom,right,left attributes are FROM the top,bottom,right,left. Where a value of the following:
<item android:top="10dp">
Would net you a starting point 10dp from the top of the respective container. This is not the case. Think of it as OFF OF the top,bottom,right,left. <item android:top="10dp"> will still net you a starting point 10dp OFF OF the top, but what happens when you want to set the bottom?
<item android:bottom="20dp">
This will not get you a bottom at 20dp from the TOP, rather a bottom of 20dp OFF OF the BOTTOM of the container.
So, for example with a 100dp container, if you wanted a rectangle with a top edge starting at 20dp and a bottom edge at 40dp:
<item android:top="20" android:bottom="60dp">

The size of a shape will be ignored when you use it as a background of a View. It will work when you show it via an ImageView:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#FF7700" />
<size android:width="20dp" android:height="20dp"/>
</shape>
In your layout XML:
<!-- will have the size of 20dp x 20dp -->
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/my_shape"
/>

I had similar problem.
Documentation ( http://developer.android.com/guide/topics/resources/drawable-resource.html#Shape ) says:
<size>
The size of the shape.
(...)
Note: The shape scales to the size of the container View proportionate to the dimensions defined here, by default. When you use the shape in an ImageView, you can restrict scaling by setting the android:scaleType to "center".
If I understand correctly, it means that "size" tag is not for setting size but for setting proportions.

shape's size attribute will provide the value for drawable.getIntrinsicWidth & getIntrinsicHeight.
if the drawable's container(e.g. ImageView, TextView) has the layout param WRAP_CONTENT, then the container dimension will change if the drawable drawingState change.
but there are a bug in android framework in ImageView drawingState implementation
ImageView only update/resize its dimension by the drawable dimension on state_selected but don't on state_activated

used this.
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<stroke
android:color="#color/lgray"
android:width="1dip" />
<corners
android:bottomLeftRadius="0dip"
android:bottomRightRadius="0.1dip"
android:topLeftRadius="0dip"
android:topRightRadius="0.1dip" />
<solid android:color="#color/White" />
</shape>
put this rectangle.xml to drawable.and set your view background.

Set width of Android Drawable item?

What I wanted was while background with red part on the left. Something like this.
I tried many things (is there any WYSIWIG editor? I think I ran this hundreds of times.) Specifying width like in the following article did not work.
how to specify width and height of a drawable item
The following article only tells me that I cannot use percentage, now how to apply width.
Android Drawable: Specifying shape width in percent in the XML file?
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape>
<solid
android:color="#FFFFFFFF"/>
</shape>
</item>
<item>
<shape android:shape="rectangle">
<solid android:color="#55FF0000" />
<size android:width="100px" />
</shape>
</item>
</layer-list>

Rather than specify the size of the red box, you would define a red layer and then set the left margin of the white layer equal to the amount of red to show.
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape>
<solid android:color="#55FF0000" />
</shape>
</item>
<item android:left="100px">
<shape android:shape="rectangle">
<solid android:color="#FFFFFFFF"/>
</shape>
</item>
</layer-list>
If you know the desired negative space, you could even swap the two and set the right margin of the red (now top) layer to the amount of white that should be visible.

android layer-list header and footer

I am trying to create a background drawable for a linearlayout that has multiple gradients.
E.g. I want to have a gradient at the top and bottom, and a solid color in the middle. So basically a header and footer.
I am trying to use a layer-list like this:
<?xml version="1.0" encoding="utf-8"?>
<layer-list
xmlns:android="http://schemas.android.com/apk/res/android">
<!--Red-->
<item>
<shape
xmlns:android="http://schemas.android.com/apk/res/android">
<solid
android:color="#ff0000" />
</shape>
</item>
<!-- Green -->
<!-- Offsets from the top and bottom -->
<item
android:top="20dp"
android:bottom="20dp">
<shape
xmlns:android="http://schemas.android.com/apk/res/android">
<solid
android:color="#00ff00" />
</shape>
</item>
<item
android:top="80dp">
<!--Blue -->
<shape
xmlns:android="http://schemas.android.com/apk/res/android">
<solid
android:color="#0000ff" />
</shape>
</item>
</layer-list>
The problem is, I am unsure of the max value of density independant pixels. For this to work, the bottom item offest would need to be (max dp value-20). I have tried to assume the max is 100, and also assume the max is 160 (from the documentation), but neither of these work.
Any ideas?