Android自定义View用切图显示字符串

public class digitaltextview extends linearlayout {

  public digitaltextview(context context) {
    super(context);
    init();
  }

  public digitaltextview(context context, attributeset attrs) {
    super(context, attrs);
    init();
  }

  // 初始化
  private void init() {
    this.setorientation(linearlayout.horizontal);
  }
  /**
   * 获取调频图片
   *
   * @param index 频率值
   * @return 对应频率值的图片id
   */
  private int getfreqdrawable(int index) {
    int drawableid = -1;
    switch (index) {
      case 0:
        drawableid = r.drawable.num_0;
        break;
      case 1:
        drawableid = r.drawable.num_1;
        break;
      case 2:
        drawableid = r.drawable.num_2;
        break;
      case 3:
        drawableid = r.drawable.num_3;
        break;
      case 4:
        drawableid = r.drawable.num_4;
        break;
      case 5:
        drawableid = r.drawable.num_5;
        break;
      case 6:
        drawableid = r.drawable.num_6;
        break;
      case 7:
        drawableid = r.drawable.num_7;
        break;
      case 8:
        drawableid = r.drawable.num_8;
        break;
      case 9:
        drawableid = r.drawable.num_9;
        break;
    }
    return drawableid;
  }

  /**
   * 根据传递进来的字符，返回对应的图片资源
   *
   * @param c 传递进来的字符
   * @return 对应的图片id
   */
  private int getresourceforchar(char c) {
    if (c == '.') {
      return r.drawable.num_dot;
    } else if (c >= '0' && c <= '9') {
      return getfreqdrawable(c - '0');
    } else {
      return -1;
    }
  }

  // 创建一个imageview
  private imageview createimageview() {
    imageview imageview = new imageview(getcontext());
    layoutparams param = new layoutparams(
        linearlayout.layoutparams.wrap_content,
        linearlayout.layoutparams.wrap_content);
    imageview.setlayoutparams(param);
    return imageview;
  }


  /**
   * 更新自定义textview
   * @param text 传递进来的字符串
   */
  public void setdigitaltext(string text) {

    int startindex = getchildcount() - text.length();// 起始位置，因为imageview的数量是根据字符串的长度创建的
    if (startindex < 0)//第一次更新的时候肯定是小于0的
      startindex = 0;

    for (int i = 0; i < startindex; i++) {
      getchildat(i).setvisibility(view.gone);
    }

    //下面是根据字符串的长度，循环更换为对应的图片
    for (int i = 0; i < text.length(); i++) {
      int childid = i + startindex;
      int resid = getresourceforchar(text.charat(i));//将每个字符转换为数字

      if (resid != -1) {
        if (childid == getchildcount()) {
          addview(createimageview());//添加到linearlayout中
        }
        imageview child = ((imageview) getchildat(childid));
        child.setvisibility(view.visible);
        child.setimageresource(resid);
      }
    }
  }
}