RxImageView.java

public class RxImageView extends ImageView {

    // region Member Variables
    private PublishSubject<Boolean> publishSubject = PublishSubject.create();
    // endregion

    // region Constructors
    public RxImageView(Context context) {
        super(context);
    }

    public RxImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public RxImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
    // endregion

    @Override
    public void setImageBitmap(Bitmap bm) {
        super.setImageBitmap(bm);
        if(publishSubject != null)
            publishSubject.onNext(true);
    }

    @Override
    public void setImageResource(@DrawableRes int resId) {
        super.setImageResource(resId);
        if(publishSubject != null)
            publishSubject.onNext(true);
    }

    @Override
    public void setImageDrawable(Drawable drawable) {
        super.setImageDrawable(drawable);
        Drawable resDrawable = ContextCompat.getDrawable(getContext(), R.drawable.ic_placholder);

        if (!(drawable.getConstantState().equals(resDrawable.getConstantState()))){
            if(publishSubject != null)
                publishSubject.onNext(true);
        }
    }

    // region Helper Methods

    public PublishSubject<Boolean> getPublishSubject() {
        return publishSubject;
    }
    // endregion
}