@Override
    public void draw(Canvas canvas) {
        mPaint.setColor(mCurrentColor);
        int alpha = modulateAlpha(Color.alpha(mCurrentColor));
        mPaint.setAlpha(alpha);
        doDraw(canvas, mPaint);
    }
A drawable that changes it's Paint color depending on the Drawable State
<p>
Subclasses should implement {@link #doDraw(Canvas, Paint)}
</p>

@hide
app/src/main/java/com/duan/musicoco/view/discreteseekbar/internal/drawable/StateDrawable.java