StatusBar.java

public class StatusBar extends View {

    private int statusBarColor = Integer.MIN_VALUE;

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

    public StatusBar(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs);
    }

    public StatusBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context, attrs);
    }

    public StatusBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        init(context, attrs);
    }

    private void init(Context context, AttributeSet attrs) {
        if (attrs != null) {
            TypedArray a = context.getTheme().obtainStyledAttributes(attrs,
                    R.styleable.StatusBar, 0, 0);
            try {
                //get the text and colors specified using the names in attrs.xml
                statusBarColor = a.getInteger(R.styleable.StatusBar_statusBarColor, Integer.MIN_VALUE);//0 is default
            } finally {
                a.recycle();
            }
        }
    }

    @Override
    public void draw(Canvas canvas) {

        Activity host = ((Activity) getContext());

        Rect rectangle = new Rect();
        Window window = host.getWindow();
        window.getDecorView().getWindowVisibleDisplayFrame(rectangle);
        int height = rectangle.top;

        DisplayMetrics metrics = host.getResources().getDisplayMetrics();
        int width = metrics.widthPixels;

        if (statusBarColor == Integer.MIN_VALUE) {
            TypedValue typedValue = new TypedValue();
            host.getTheme().resolveAttribute(R.attr.colorPrimary, typedValue, true);
            statusBarColor = typedValue.data;
        }

        Paint paint = new Paint();
        paint.setStyle(Paint.Style.FILL);
        paint.setColor(statusBarColor);
        paint.setAntiAlias(true);

        Rect statusBar = new Rect(
                0, // Left
                0, // Top
                width, // Right
                height // Bottom
        );

        canvas.drawRect(statusBar, paint);

        super.draw(canvas);
    }
}

statusbar_attributes.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="StatusBar">
        <attr name="statusBarColor" format="color"/>
    </declare-styleable>
</resources>