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Custom View. attrs array

I have a custom view with 4 rectangles in it. I want to make this view configurable from xml.
Is it possible to make it like:
custom:rectColor="red|cyan|blue|green" //each color correspond rectangle
with
<attr name="rectColor" format="color">
<flag name="red" value="2" />
<flag name="cyan" value="5" />
<flag name="blue" value="7" />
<flag name="green" value="9" />
</attr>
Or it must be:
<attr name="firstRectColor" format="color" />
<attr name="secondRectColor" format="color" />
<attr name="thirdRectColor" format="color" />
<attr name="fourthRectColor" format="color" />
and each view should contains:
custom:firstRectColor="red"
custom:secondRectColor="red"
custom:thirdRectColor="red"
custom:fourthRectColor="red"
And if it possible. How can I get set of color values from attributes.
Thanks

Read this documentation.. it shows you how to declare custom attributes and access them in your layout file..
http://developer.android.com/training/custom-views/create-view.html

Inheritance in custom attributes

I have an attribute eg "parent" in my attrs file
<declare-styleable name="parent">
<attr name="text" format="string" />
</declare-styleable>
Now I want another attribute set which contains the attributes in "parent" and also has other attributes
<declare-styleable name="child">
<attr name="text2" format="string" />
</declare-styleable>
Can you please let me know how to inherit parent into child

Give this a shot:
<declare-styleable name="child" parent="#declare-styleable/parent">
<attr name="text2" format="string" />
</declare-styleable>

What's the point of declare-styleable?

Suppose I am making some new views with styleable attributes. I declare them thusly (this is how the documentation says to do it:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="TriangleView">
<attr name="direction">
<enum name="NE" value="0" />
<enum name="NW" value="1" />
<enum name="SW" value="2" />
<enum name="SE" value="3" />
</attr>
</declare-styleable>
<declare-styleable name="BannerView">
<attr name="direction">
<enum name="NE" value="0" />
<enum name="NW" value="1" />
<enum name="SW" value="2" />
<enum name="SE" value="3" />
</attr>
<attr name="thickness" format="dimension" />
</declare-styleable>
</resources>
However, this won't work because all attributes are apparently in the same namespace, and I get the error Error: Attribute "direction" has already been defined.
So apparently I have to move the apparently duplicated attributes outside the <declare-styleable> like this:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<attr name="direction">
<enum name="NE" value="0" />
<enum name="NW" value="1" />
<enum name="SW" value="2" />
<enum name="SE" value="3" />
</attr>
<declare-styleable name="BannerView">
<attr name="thickness" format="dimension" />
</declare-styleable>
</resources>
But this poses two questions:
If this works, what exactly is the point of <declare-styleable>?
What if I want the attribute to behave differently in different views? For example if BannerView's direction can only be up or down.

What exactly is the point of <declare-styleable>?
<declare-stylable> tags let you declare attributes for your custom views that you can then set for those views in xml. There are really 3 parts to using the attribute:
Declare an <attr> inside of a <declare-stylable> tag.
Define a custom namespace in your xml layout pointing to your app package name (ex. app). Use the custom attribute in your layout (ex. app:direction="NW").
In your custom view, override the constructors with an AttributeSet parameter, get a TypedArray and read the custom attributes, if any, from it and then within the constructor tell the view how to use those attributes appropriately.
What if I want the attribute to behave differently in different views?
For example if BannerView's direction can only be up or down.
Try something like this:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<attr name="direction">
<enum name="NE" value="0" />
<enum name="NW" value="1" />
<enum name="SW" value="2" />
<enum name="SE" value="3" />
</attr>
<declare-styleable name="TriangleView">
<attr name="direction" />
</declare-styleable>
<declare-styleable name="BannerView">
<attr name="direction" />
<attr name="thickness" format="dimension" />
</declare-styleable>
</resources>
When you build your xml layout for TriangleView or BannerView, you can use the app:direction="NW" example for both. In the constructors with AttributeSet in TriangleView or BannerView, the attributes will have the same format as the original, but what you do with that value is dependent on your implementation of the constructors in each respective view (can be the same or different for both).
If you want attributes to be defined differenly (ie. different "format" or "enum") for different views, then you have to create different attributes with different names.

Same-named attributes in attrs.xml for custom view

I'm writing a few custom views which share some same-named attributes. In their respective <declare-styleable> section in attrs.xml I'd like to use the same names for attributes:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="MyView1">
<attr name="myattr1" format="string" />
<attr name="myattr2" format="dimension" />
...
</declare-styleable>
<declare-styleable name="MyView2">
<attr name="myattr1" format="string" />
<attr name="myattr2" format="dimension" />
...
</declare-styleable>
</resources>
I'm getting an error saying that myattr1 and myattr2 are already defined. I found that I should omit the format attribute for myattr1 and myattr2 in MyView2, but if I do that, I obtain the following error in the console:
[2010-12-13 23:53:11 - MyProject] ERROR: In <declare-styleable> MyView2, unable to find attribute
Is there a way I could accomplish this, maybe some sort of namespacing (just guessing)?

Solution: Simply extract common attributes from both views and add them directly as children of the <resources> node:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<attr name="myattr1" format="string" />
<attr name="myattr2" format="dimension" />
<declare-styleable name="MyView1">
<attr name="myattr1" />
<attr name="myattr2" />
...
</declare-styleable>
<declare-styleable name="MyView2">
<attr name="myattr1" />
<attr name="myattr2" />
...
</declare-styleable>
</resources>

I am posting this answer as the above-posted solution didn't work out for me in Android Studio. I need to share my custom attributes among my custom views so I tried the above solution in Android Studio but had no luck. So I experiment and go a way to do it. Hope it might help someone looking for the same problem.
<?xml version="1.0" encoding="utf-8"?>
<resources>
<!-- parent styleable -->
<declare-styleable name="MyView">
<attr name="myattr1" format="string" />
<attr name="myattr2" format="dimension" />
</declare-styleable>
<!-- inheriting parent styleable -->
<!-- also note "myBackgroundColor" belongs to child styleable"MyView1"-->
<declare-styleable name="MyView1" parent="MyView">
<attr name="myattr1" />
<attr name="myattr2" />
<attr name="myBackgroundColor" format="color"/>
</declare-styleable>
<!-- inheriting parent styleable -->
<!-- same way here "myfonnt" belongs to child styelable "MyView2" -->
<declare-styleable name="MyView2" parent="MyView">
<attr name="myattr1" />
<attr name="myattr2" />
<attr name="myfont" format="string"/>
...
</declare-styleable>
</resources>
This works for me completely.
We need to make a Parent styleable and then we need to inherit that parent styleable. For example, as I have done above :
Parent styleable name MyView and inherited this to my other styleable like MyView1 and MyView2 respectively.

As Priya Singhal answered, Android Studio requires the common attribute names to be defined within their own style name. They can't be at the root any more.
However, there are a couple other things to note (which is why I am also adding an answer):
The common styles don't need to be named the same thing as a view. (Thanks to this answer for pointing that out.)
You don't need to use inheritance with a parent.
Example
Here is what I did in a recent project that has two custom views that both share the same attributes. As long as the custom views still have the names for the attributes and don't include a format, I can still access them as normal from code.
<?xml version="1.0" encoding="utf-8"?>
<resources>
<!-- common attributes to all custom text based views -->
<declare-styleable name="TextAttributes">
<attr name="text" format="string"/>
<attr name="textSize" format="dimension"/>
<attr name="textColor" format="color"/>
<attr name="gravity">
<flag name="top" value="48" />
<flag name="center" value="17" />
<flag name="bottom" value="80" />
</attr>
</declare-styleable>
<!-- custom text views -->
<declare-styleable name="View1">
<attr name="text"/>
<attr name="textSize"/>
<attr name="textColor"/>
<attr name="gravity"/>
</declare-styleable>
<declare-styleable name="View2">
<attr name="text"/>
<attr name="textSize"/>
<attr name="textColor"/>
<attr name="gravity"/>
</declare-styleable>
</resources>
Streamlined example
In fact, I don't even need to put the attributes under a custom name. As long as I define them (give them a format) for at least one custom view, I can use them anywhere (without the format). So this also works (and looks cleaner):
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="View1">
<attr name="text" format="string"/>
<attr name="textSize" format="dimension"/>
<attr name="textColor" format="color"/>
<attr name="gravity">
<flag name="top" value="48" />
<flag name="center" value="17" />
<flag name="bottom" value="80" />
</attr>
</declare-styleable>
<declare-styleable name="View2">
<attr name="text"/>
<attr name="textSize"/>
<attr name="textColor"/>
<attr name="gravity"/>
</declare-styleable>
</resources>
For a large project, though, this could get messy and defining them at the top in a single location might be better (as recommended here).

Thanks Lewis
I had the same problem , and your inheritance solution gave me the hint for doing it like below and it works fine.I just declared common attributes at the above and rewrite it in the body of style declaration again without formatting.
I hope it helps someone
<?xml version="1.0" encoding="utf-8"?>
<resources>
<!-- common attributes -->
<attr name="myattr1" format="string" />
<attr name="myattr2" format="dimension" />
<!-- also note "myBackgroundColor" belongs to child styleable"MyView1"-->
<declare-styleable name="MyView1" >
<attr name="myattr1" />
<attr name="myattr2" />
<attr name="myBackgroundColor" format="color"/>
</declare-styleable>
<!-- same way here "myfonnt" belongs to child styelable "MyView2" -->
<declare-styleable name="MyView2" parent="MyView">
<attr name="myattr1" />
<attr name="myattr2" />
<attr name="myfont" format="string"/>
...
</declare-styleable>

Just in case someone still stuck with this problem after tried available solution. I stuck with add subtitle attribute with string format.
My solution is remove the format.
before:
<attr name="subtitle" format="string"/>
after:
<attr name="subtitle"/>

Format attribute value "android:drawable" not valid

I'm trying to create custom attributes to my button but I dont know which format I must use to images in attributes declaration...
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="TCButton">
<attr name="Text" format="string"/>
<attr name="BackgroundImage" format="android:drawable" />
</declare-styleable>
</resources>
Error is in the format="android:drawable"...

You can use format="integer", the resource id of the drawable, and AttributeSet.getDrawable(...).
Here is an example.
Declare the attribute as integer in res/values/attrs.xml:
<resources>
<declare-styleable name="MyLayout">
<attr name="icon" format="integer" />
</declare-styleable>
</resources>
Set the attribute to a drawable id in your layout:
<se.jog.MyLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
myapp:icon="#drawable/myImage"
/>
Get the drawable from the attribute in your custom widget component class:
ImageView myIcon;
//...
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.MyLayout);
Drawable drawable = a.getDrawable(R.styleable.MyLayout_icon);
if (drawable != null)
myIcon.setBackgroundDrawable(drawable);
To see all options possible check the android src here

I think it will be better to use it as a simple reference:
<declare-styleable name="TCButton">
<attr name="customText" format="string"/>
<attr name="backgroundImage" format="reference" />
</declare-styleable>
And set it in your xml like this:
<your.package.name.TCButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
custom:customText="Some custom text"
custom:backgroundImage="#drawable/myImage"
/>
And in your class set the attributes like this:
public TCButton(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.MembershipItemView, 0, 0);
String customText;
Drawable backgroundImage;
try {
customText = a.getString(R.styleable.TCButton_customText);
backgroundImage = a.getDrawable(R.styleable.TCButton_backgroundImage);
} finally {
a.recycle();
}
if(!TextUtils.isEmpty(customText)) {
((TextView)findViewById(R.id.yourTextView)).setText(customText);
}
if(null != backgroundImage) {
((ImageView)findViewById(R.id.yourImageView)).setBackgroundDrawable(backgroundImage);
}
}
PS:
Don't forget to add this line for the root element of the layout you are using your custom view in
xmlns:custom="http://schemas.android.com/apk/res-auto"
If you don't set this, you won't be able to access your custom attributes.

From AOSP code, I found how google engineers declare ImageView#src attr.
<declare-styleable name="ImageView">
<attr name="src" format="reference|color" />
<attr name="scaleType">
<enum name="matrix" value="0" />
<enum name="fitXY" value="1" />
<enum name="fitStart" value="2" />
<enum name="fitCenter" value="3" />
<enum name="fitEnd" value="4" />
<enum name="center" value="5" />
<enum name="centerCrop" value="6" />
<enum name="centerInside" value="7" />
</attr>
<attr name="adjustViewBounds" format="boolean" />
<attr name="maxWidth" format="dimension" />
<attr name="maxHeight" format="dimension" />
<attr name="tint" format="color" />
<attr name="baselineAlignBottom" format="boolean" />
<attr name="cropToPadding" format="boolean" />
<attr name="baseline" format="dimension" />
<attr name="drawableAlpha" format="integer" />
<attr name="tintMode" />
</declare-styleable>
Above code is a sample and it can cover most case in our development.