Android矢印付きtextview文字伸縮効果

自分で作ったのかよくわからないけどネットの方法を見て自分でまとめたものです品質の良いdemoがあればシェアしてください
主に1つの方法はいくつかの変数がxmlファイルを制限して普通のTextViewを貼らないことです

public class TextViewActivity extends Activity {

	private TextView tv;

	private String status = "up";
	private String str = "Android     Linux              ，         ，          ， Google              。";
	private String str_show = "";
	private int maxlength = 50;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		tv = (TextView) findViewById(R.id.textView1);
		if (str.length() < maxlength) {
			tv.setText(str);
		} else {
			changStatus();
		}
	}

	private void changStatus() {
		tv.setText("");
		Drawable drawable = null;
		if (status.equals("down")) {
			drawable = getResources().getDrawable(R.drawable.icon_arrow_up);
			status = "up";
			str_show = str;
			tv.setMaxLines(10000);
		} else if (status.equals("up")) {
			drawable = getResources().getDrawable(R.drawable.icon_arrow_down);
			status = "down";
			tv.setMaxLines(2);
			str_show = str.substring(0, maxlength);
			str_show += "...";
		}
		String spanString = str_show;
		spanString = spanString.substring(0, spanString.length());
		drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
				drawable.getIntrinsicHeight());
		SpannableString spannable = new SpannableString(spanString.toString()
				+ "s");
		ImageSpan span = new ImageSpan(drawable, ImageSpan.ALIGN_BASELINE);
		spannable.setSpan(span, spanString.toString().length(), spanString
				.toString().length() + "s".length(),
				Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
		ClickableSpan rightClickableSpan = new ClickableSpan() {

			@Override
			public void onClick(View view) {
				changStatus();
			}
		};
		spannable.setSpan(rightClickableSpan, spanString.toString().length(),
				spanString.toString().length() + "s".length(),
				Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
		tv.setText(spannable);
		tv.setMovementMethod(new MyTouch());

	}

}