Develop Reference

Android XML How to set background gradient inside a custom shape button

I am creating a button shape look like WWTBAM game show:
I have created the shape for it but don't know how to put the gradient in it.
This is my styles.xml file I created:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="ButtonShapeArrow">
<item name="cornerFamily">cut</item>
<item name="cornerSize">50%</item>
</style>
</resources>
And button in layout_main.xml:
<com.google.android.material.button.MaterialButton
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Start"
app:shapeAppearance="#style/ButtonShapeArrow"/>
How do I set gradient for that button?

Create a custom background, you can change angle to change to position of the gradient
bg_gradient.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<gradient
android:angle="270"
android:endColor="#android:color/transparent"
android:startColor="#802BC0E4" />
</shape>

Add full active drop-shadow from figma for any icon

I want add drop-shadow in drawables for use them on any android icons (navbars, custom views, buttons). Then should get something like this. Trying with ninepatch and layer-list or just png. It works, but there is a problem: due to the shadow, paddings of drawable increases, as a result, main picture becomes smaller. And it becomes impossible to use such a layers-list in selector with other images for example. What can do about it?

Okay, I just used shadow png bitmap as background for vector image like this:
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#drawable/ic_vector_active_with_sunshine" android:state_checked="true" />
<item android:drawable="#drawable/ic_vector_inactive" android:state_checked="false" />
</selector>
Where ic_vector_active_with_sunshine:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#drawable/drop_shadow" />
<item android:drawable="#drawable/ic_vector" />
</layer-list>

centered element in background doesn't match centered element in foreground

I'm working on an Android application where I want to create a windowBackground with a centered element and a layout also with a centered element. I want these elements to be in the exact same position, with the layout overlapping the background. The problem I'm having is that the layout and the background seem to be calculating center differently (see image). Why is this happening, and what can I do to line the elements up?
This is what I see right now. The red box is created by the background and the green box is created by the foreground. Screenshot was created with a Nexus 5X API 26 emulator.
Foreground layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<View
android:background="#color/foreground_box"
android:layout_width="10dp"
android:layout_height="10dp"
android:layout_centerInParent="true" />
</RelativeLayout>
Background Drawable (applied via android:windowBackground in my theme)
<?xml version="1.0" encoding="UTF-8" ?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#color/background" />
<item android:gravity="center">
<shape
android:gravity="center"
android:shape="rectangle">
<solid android:color="#color/background_box" />
<size android:width="10dp"
android:height="10dp" />
</shape>
</item>
</layer-list>
For clarity, my colors file is
<?xml version="1.0" encoding="utf-8"?>
<resources>
...
<color name="background">#ffffff</color>
<color name="background_box">#AAFF0000</color>
<color name="foreground_box">#AA00FF00</color>
</resources>
Full source for this sample project is available at https://github.com/HofmaDresu/AndroidCenteredTest

The reason windowBackground includes both the heights 1) statusBar and 2) actionBar
Modify below line in your background.xml
<item android:gravity="center" android:top="80dp"> // 56 actionBarSize + 24 statusBarHeight
You may need to manage this programatically as statusBarHeight and actionBarSize varies based on device API/resolution.
Here is the result. For testing, have resized background size bit bigger so that overlapping between views and background become visible.

It is probably because of the extra space taken up by the ActionBar in the foreground.
To fix this, you can add a margin to your View in the foreground layout as:
android:layout_marginBottom="?android:attr/actionBarSize"

After test it in AS, I can say you that the right code for you background_drawable is this:
<?xml version="1.0" encoding="UTF-8" ?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#color/background" />
<item android:gravity="center" android:bottom="48dp">
<shape
android:gravity="center"
android:shape="rectangle">
<solid android:color="#color/background_box" />
<size
android:width="10dp"
android:height="10dp" />
</shape>
</item>
using android:top, the red square go more down than center. Need to use android:bottom instead to center background. By my tests results that 48dp is the right value.

How to deal with scaling and transparency of a bitmap as android:windowBackground

I am trying to set a global background image for my android application. The image is a PNG file with transparency. I set it in the following way:
<style name="MyAppTheme" parent="#style/Theme.AppCompat">
<item name="android:windowBackground">#drawable/background_main</item>
</style>
And drawable/background_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<bitmap
xmlns:android="http://schemas.android.com/apk/res/android"
android:src="#drawable/background_main_bitmap"
android:gravity="bottom|center_horizontal" />
My PNG file should sit at the bottom of the screen always, being scaled to match the screen size always. With the above code, however, I am facing two problems.
The transparent background of the PNG file is black while I want it to be white.
The PNG file is larger than the screen width and hence, I can only see a portion of it. It is not scaled to match the width of the screen.
How can I accomplish these two things, possibly without havin to write Java code? (Although it would be better than nothing...)

Problem #1 can be solved with a layer-list in drawable/background_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="rectangle">
<solid android:color="#ffffff"/>
</shape>
</item>
<item>
<bitmap
xmlns:android="http://schemas.android.com/apk/res/android"
android:src="#drawable/background_main_bitmap"
android:gravity="bottom|center_horizontal|fill_horizontal" />
</item>
</layer-list>
Problem #2 remains though...

just change the property of android:gravity like following:
<?xml version="1.0" encoding="utf-8"?>
<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
android:src="#drawable/flush"
android:gravity="fill_horizontal|fill_vertical"/>

Actually, using layer-list may give you expected scaling:
All drawable items are scaled to fit the size of the containing View, by default. Thus, placing your images in a layer list at different positions might increase the size of the View and some images scale as appropriate. To avoid scaling items in the list, use a <bitmap> element inside the <item> element to specify the drawable and define the gravity to something that does not scale, such as "center"
Thus, the following drawable will suit your request:
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="#android:color/white" />
<item android:drawable="#drawable/background_main_bitmap" />
</layer-list>

Creating a Custom Compound Button Bar

I have to create a custom compound button bar control in Android like the one here. To create a button bar like this, I am thinking of extending a LinearLayout and add my buttons to it. The buttons have a black background but with a gradient fill; I am not keen on using PNGs since the color of the buttons can change at runtime.
How can I get similar effect in Android?
Thanks.

u have to use imageview as button.
set two image view you can change color the button
use xml file to src of that imageview like
<?xml version="1.0" encoding="UTF-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="false"
android:drawable="#drawable/back_normal" />
<item android:state_pressed="true"
android:drawable="#drawable/back_pressed" />
</selector>
for gredient style.
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient android:angle="90" android:startColor="#663300"
android:centerColor="#330000"
android:endColor="#330000"/>
</shape>
thats it.