Barber is your personal custom view stylist.

• Simply annotate your fields using the @StyledAttr or @AndroidAttr annotations
• Call the appropriate Barber.style(this...) variant
• Let Barber take care of all the boilerplate for you.
• Profit

This library is heavily influenced by Jake Wharton's Butterknife library, and was actually suggested to me by the man himself.

Barber has two main annotations that you use: @StyledAttr and @AndroidAttr. These can be used on fields or methods (e.g. setters). StyledAttr is used for retrieving custom attrs for custom views. @AndroidAttr is used for retrieving values for attributes in the android namespace.

The Barber class has 3 overloaded style() methods, so you can call the appropriate one from whichever constructor you prefer.

Annotated fields or methods cannot be private, and must at least be package accessible. This is because Barber will generate a **$$Barbershop class in the same package as the target class.

Declare your styled attributes in your attrs.xml, like you normally would. For example:

<declare-styleable name="BarberView">
    <attr name="stripeColor" format="color" />
    <attr name="stripeCount" format="integer" />
    <attr name="animated" format="boolean" />
    <attr name="toggleAnimation" format="reference" />
</declare-styleable>

public class BarberView extends FrameLayout {

    @StyledAttr(value = R.styleable.BarberView_stripeColor, kind = Kind.COLOR)
    public int stripeColor;

    @StyledAttr(R.styleable.BarberView_stripeCount)
    public int stripeCount;

    @StyledAttr(R.styleable.BarberView_animated)
    public boolean isAnimated;

    public BarberView(Context context) {
        super(context);
    }

    public BarberView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public BarberView(Context context, AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public BarberView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        Barber.style(this, attrs, R.styleable.BarberView, defStyleAttr, defStyleRes);
    }

    @StyledAttr(R.styleable.BarberView_toggleAnimation)
    public void setToggleAnimationDrawable(Drawable toggleAnimation) {
        // Do something with it
    }
}

By default, Barber will resolve which TypedArray method to use based on the type of the target. That is, if you declare it on an int, then Barber will generate code that calls typedArray.getInt(...).

@StyledAttr(R.styleable.BarberView_stripeCount)
public int stripeCount;

"But wait, sometimes my int is a color!".

If you have a special case, such as colors, then you can specify the kind member of the annotation with the appropriate Kind enum to let Barber know.

@StyledAttr(value = R.styleable.BarberView_stripeColor, kind = Kind.COLOR)
public int stripeColor;

The color example above tells Barber it should use TypedArray's getColor(...) method. This works for other types as well!

@StyledAttr(value = R.styleable.TestView_testDimension, kind = Kind.DIMEN)
public float testDimension;

@StyledAttr(value = R.styleable.TestView_testDimensionPixelSize, kind = Kind.DIMEN_PIXEL_SIZE)
public int testDimensionPixelSize;

And, if you're one of the 10 people that use fraction attributes, you'll be happy to know that those are supported as well.

@StyledAttr(
        value = R.styleable.TestView_testFractionBase,
        kind = Kind.FRACTION,
        base = 2,
        pbase = 2
)
public float testFractionBase;

See the Kind enum for a full list of supported types.

If you want to retrieve the value of an Android attribute, you can use @AndroidAttr to retrieve its value

@AndroidAttr("textAllCaps")
public boolean textAllCaps;

Like StyledAttr, the default behavior is to return the type of the field/param. These are also subject to the same approach as @StyledAttr regarding special return types. See the AttrSetKind enum for a full list of supported types.

@AndroidAttr(value = "textColor", kind = AttrSetKind.RESOURCE)
public int textColor;

Right now it's just limited to the API of AttributeSet, but I may look into adding a more flexible API layer on top of this for coercing the returned data if people express an interest.

If you want to require an attribute to be specified (beyond just checking if the value is still the default), you can use the @Required annotation as well.

@Required
@StyledAttr(R.styleable.RequiredTestView_requiredString)
public String requiredString;

Now, if a view is inflated without specifying this attribute, its generated $$Barbershop class will throw an IllegalStateException looking like this:

Missing required attribute 'requiredString' while styling 'io.sweers.barber.sample.testing.RequiredTestView'

NOTE: Due to how AttributeSet's interface works, @Required is not compatible with @AndroidAttr annotations.

Due to limitations of how annotations work, you cannot specify a default value in the annotation. For @StyledAttr fields however, Barber will not override any existing values on a field if there is no value at that index. So if you want a default value, initialize the field to it. This is because we can check if the TypedArray contains a value without retrieving it. Unfortunately, annotated setters and fields annotated with @AndroidAttr are out of luck here.

buildscript {
    repositories {
        jcenter() // Also available in maven central
    }
    dependencies {
        classpath 'com.neenbedankt.gradle.plugins:android-apt:1.4'
    }
}

apply plugin: 'com.neenbedankt.android-apt'

dependencies {
    apt 'io.sweers.barber:barber-compiler:1.2.1'
    compile 'io.sweers.barber:barber-api:1.2.1'
}

The api module comes in the form of an AAR. If you want the api sources available in your IDE, consider using this handy gradle plugin.

If you use Proguard, add the following lines to your rules

-keep class **$$Barbershop { *; }
-keep class io.sweers.barber.** { *; }
-keepclasseswithmembers class * {
    @io.sweers.barber.* <fields>;
}
-keepclasseswithmembers class * {
    @io.sweers.barber.* <methods>;
}

Copyright 2015 Henri Z. Sweers

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.