Develop Reference

Align XML drawable background to bottom of view

I am trying to provide a simple solid-color underline to a TextView header. I want this to be reusable and to work with any view in the future, regardless of height. I am trying to favor a background drawable so I can simply apply it to view. I can draw a line without any problem:
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:shape="line"
>
<stroke
android:color="#8a9299"
android:width="1dp"
/>
</shape>
This line is, however, centered in the background of the view. I see a bunch of online tutorials that use layers to draw a background-colored rectangle and then "peek" another rectangle from behind, however I don't know what background color this header element type will be used on, and transparent rectangle backgrounds show the color rectangle below. Is there any way to stick to a line but give it a bottom gravity inside the view it is applied to?

This can be achieved using gradientDrawable. Here you go:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<gradient
android:angle="90"
android:startColor="#000000"
android:centerColor="#android:color/transparent"
android:centerX="0.1" />
</shape>
Increase/Decrease centerX to increase/decrease width of your underline. Change startColor to change the color of the underline.
Explanation:
angle is the angle of the gradient. 0 is left to right. 90 is bottom to top.
startColor is the start color of the gradient. Our angle is 90 so the gradient starts from bottom (and so it appears like an underline)
centerColor is the centerColor which is transparent.
centerX is the X position of the gradient as a fraction of the width. Keep it small (<0.1) for a good looking underline. Anything above 0.1 looks bad (nobody is stopping you though!).

Android Shape Inverse Rectangle

Is there any xml that i can use to perform something like this ?
I want to have an single ImageView where i show my picture. The picture is "fillparent" that it goes on the whole screen. But i only want to see the pink part normal and all outside the lines i want something like an "alpha = 0.5" or just that it is a little bit less seen than the main.
<?xml version="1.0" encoding="UTF-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:top="120px" android:right="120px" android:bottom="120px" android:left="120px">
<shape android:shape="rectangle">
<solid android:color="#9fffffff" />
</shape>
</item>
I want to put an xml as foreground to perform this. With an shape of an rectangle and an alpha of 0.5 it works exactly the opposite side. Now i just need something like an inverse rectangle or something.
Thanks for your time.

Shadow round corners Android

how can i make a shadow for round corners? I tried it with views for the bottom, right an the corner, but that works not really :D
I tried this xml for the corner:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
android:startColor="#404040"
android:centerColor="#DBDBDB"
android:endColor="#color/shadow_end"
android:angle="315"
>
</gradient>
<corners
android:bottomRightRadius="5dp"
android:bottomLeftRadius="0dp"
android:topLeftRadius="0dp"
android:topRightRadius="0dp"/>
</shape>
Is it good to use views for shadows? What you are using?
Thanks for help :)

You can simply draw a 9-patch image with Photoshop drawing the shadows and put it into the drawable folders and set this in your View in xml:
android:background="#drawable/your_9patch_image"
I always do it by using Photoshop. For more details see this: Draw 9-patch
Or you can check in the default Android Studio drawables and see if there's one that you like. Check my answer here: my answer

Dynamic radial circle in the middle of the screen

Why is it so difficult to make this little thing work? : /
I want to create something like android's lock screen.
I have an XML:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval" >
<stroke
android:width="#dimen/dp_5"
android:color="#color/black" />
<gradient
android:type="radial"
android:startColor="#color/green"
android:endColor="#color/red"
android:gradientRadius="#dimen/dp_50" />
</shape>
This circle is a background of a TextView, so the following happens:
1. wrap_content creates a little circle in the center of the screen
2. fill_parent creates an elipse taking the whole screen, instead of a circle
In addition I would like to change the startColor and endColor programmatically - Didn't find any documentations\threads which solved this SIMPLE issue.

Radial gradient in XML with parent size

Im trying to achieve a component to make custom shadows to buttons or other components, i know that it will be easier with a 9patch or a png with the shadow, but i want to change it color and size programmatically also in its states (pressed,etc), so i decided to try with 9 images, all in XML so the shadow shades start its gradient from the side of the component.
<!-- Left Shadow layer -->
<item>
<shape android:shape="rectangle" >
<gradient
android:angle="0"
android:endColor="#FFFF0000"
android:startColor="#00FF0000" />
</shape>
</item>
It looks good, the problem is on the corners and with the android:gradientRadius parameter now its set to a fixed size, but in the contextual help is said that can be set in a percentage of the base size 10% or parent size 10%p, what i want its to set a 100%p radius so the gradient will always go from the main color and disappear in the edge of the square.
-- EDIT --
The android doc about gradientRadius gradientRadius
<shape android:shape="rectangle" >
<gradient
android:endColor="#00FF0000"
android:startColor="#FFFF0000"
android:gradientRadius="18"
android:centerX="100%"
android:centerY="100%"
android:type="radial" />
</shape>
And thats where im now :( i do not know how can i set this size to fit its parent view.
Any help will be appreciated, when im finished with the component i will put the code in an answer :) so typical buttons can have customizable shadows in xml.
An image of the deserved component.
--Edit--
Im still interested in this :) no one has a clue?

I think you should give up with xml and implement drawable in code.
When you extend Drawable class you can get size as rectangle with getBounds(). Also you can dynamicaly recalculate in onBoundsChange method.
You can also easily construct gradients and use them in Paint object (setShader method)