BaseButton.java

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.*;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.StateListDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.util.AttributeSet;
import android.widget.Button;

/**
 * User: msk
 * Date: 13/01/2015
 */
public class BaseButton extends Button {
    private final float defaultRadius = 0.0f;

    private int defaultPrimaryColor;

    public BaseButton(Context context) {
        this(context, null);
    }

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

    public BaseButton(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        defaultPrimaryColor = getResources().getColor(R.color.colorPrimary);

        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.BaseButton);
        int primaryColor = typedArray.getColor(R.styleable.BaseButton_normalStateColor, defaultPrimaryColor);
        float radius = typedArray.getDimension(R.styleable.BaseButton_cornerRadius, defaultRadius);

        int pressedStateColor = primaryColor & 0x00ffffff | 0xdf000000;
        ShapeDrawable shapeSelected = new ShapeDrawable(new RectShape());
        shapeSelected.getPaint().setColor(pressedStateColor);
        shapeSelected.getPaint().setPathEffect(new CornerPathEffect(radius));
        shapeSelected.getPaint().setAntiAlias(true);
        shapeSelected.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
        shapeSelected.getPaint().setStrokeWidth(1);


        ShapeDrawable darkenSelected = new ShapeDrawable(new RectShape());
        darkenSelected.getPaint().setColor(Color.BLACK);
        darkenSelected.getPaint().setPathEffect(new CornerPathEffect(radius));
        darkenSelected.getPaint().setAntiAlias(true);
        darkenSelected.getPaint().setXfermode(new PorterDuffXfermode(PorterDuff.Mode.OVERLAY));
        darkenSelected.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
        darkenSelected.getPaint().setStrokeWidth(1);


        LayerDrawable layerDrawable = new LayerDrawable(new Drawable[]{darkenSelected, shapeSelected});

        ShapeDrawable shapeNormal = new ShapeDrawable(new RectShape());
        shapeNormal.getPaint().setAntiAlias(true);
        shapeNormal.getPaint().setColor(primaryColor);
        shapeNormal.getPaint().setPathEffect(new CornerPathEffect(radius));
        shapeNormal.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
        shapeNormal.getPaint().setStrokeWidth(1);

        StateListDrawable states = new StateListDrawable();
        Resources res = getResources();
        states.addState(new int[]{android.R.attr.state_pressed}, layerDrawable);
        states.addState(new int[]{android.R.attr.state_focused}, layerDrawable);
        states.addState(new int[]{}, shapeNormal);

        setBackground(states);
        typedArray.recycle();
    }
}

usage.xml

<com.youapp.BaseButton
                android:id="@+id/btn"
                android:layout_width="match_parent"
                android:layout_height="48dp"
                android:layout_marginTop="24dp"
                app:cornerRadius="2dp"
                app:normalStateColor="@color/colorPrimary"/>