Android跑马灯MarqueeView源码解析-创新互联

跑马灯效果，大家可以去原作者浏览https://github.com/sfsheng0322/MarqueeView
下面看自定义控件的代码

public class MarqueeView extends ViewFlipper {

  private Context mContext;
  private List notices;
  private boolean isSetAnimDuration = false;
  private OnItemClickListener onItemClickListener;

  private int interval = 2000;
  private int animDuration = 500;
  private int textSize = 14;
  private int textColor = 0xffffffff;

  private int gravity = Gravity.LEFT | Gravity.CENTER_VERTICAL;
  private static final int TEXT_GRAVITY_LEFT = 0, TEXT_GRAVITY_CENTER = 1, TEXT_GRAVITY_RIGHT = 2;

  public MarqueeView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context, attrs, 0);
  }

  private void init(Context context, AttributeSet attrs, int defStyleAttr) {
    this.mContext = context;
    if (notices == null) {
      notices = new ArrayList<>();
    }

    TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.MarqueeViewStyle, defStyleAttr, 0);
    interval = typedArray.getInteger(R.styleable.MarqueeViewStyle_mvInterval, interval);
    isSetAnimDuration = typedArray.hasValue(R.styleable.MarqueeViewStyle_mvAnimDuration);
    animDuration = typedArray.getInteger(R.styleable.MarqueeViewStyle_mvAnimDuration, animDuration);
    if (typedArray.hasValue(R.styleable.MarqueeViewStyle_mvTextSize)) {
      textSize = (int) typedArray.getDimension(R.styleable.MarqueeViewStyle_mvTextSize, textSize);
      textSize = DisplayUtil.px2sp(mContext, textSize);
    }
    textColor = typedArray.getColor(R.styleable.MarqueeViewStyle_mvTextColor, textColor);
    int gravityType = typedArray.getInt(R.styleable.MarqueeViewStyle_mvGravity, TEXT_GRAVITY_LEFT);
    switch (gravityType) {
      case TEXT_GRAVITY_CENTER:
        gravity = Gravity.CENTER;
        break;
      case TEXT_GRAVITY_RIGHT:
        gravity = Gravity.RIGHT | Gravity.CENTER_VERTICAL;
        break;
    }
    typedArray.recycle();

    setFlipInterval(interval);

    Animation animIn = AnimationUtils.loadAnimation(mContext, R.anim.anim_marquee_in);
    if (isSetAnimDuration) animIn.setDuration(animDuration);
    setInAnimation(animIn);

    Animation animOut = AnimationUtils.loadAnimation(mContext, R.anim.anim_marquee_out);
    if (isSetAnimDuration) animOut.setDuration(animDuration);
    setOutAnimation(animOut);
  }

  // 根据公告字符串启动轮播
  public void startWithText(final String notice) {
    if (TextUtils.isEmpty(notice)) return;
    getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
      @Override
      public void onGlobalLayout() {
        getViewTreeObserver().removeGlobalOnLayoutListener(this);
        startWithFixedWidth(notice, getWidth());
      }
    });
  }

  // 根据公告字符串列表启动轮播
  public void startWithList(List notices) {
    setNotices(notices);
    start();
  }

  // 根据宽度和公告字符串启动轮播
  private void startWithFixedWidth(String notice, int width) {
    int noticeLength = notice.length();
    int dpW = DisplayUtil.px2dip(mContext, width);
    int limit = dpW / textSize;
    if (dpW == 0) {
      throw new RuntimeException("Please set MarqueeView width !");
    }

    if (noticeLength <= limit) {
      notices.add(notice);
    } else {
      int size = noticeLength / limit + (noticeLength % limit != 0 ? 1 : 0);
      for (int i = 0; i < size; i++) {
        int startIndex = i * limit;
        int endIndex = ((i + 1) * limit >= noticeLength ? noticeLength : (i + 1) * limit);
        notices.add(notice.substring(startIndex, endIndex));
      }
    }
    start();
  }

  // 启动轮播
  public boolean start() {
    if (notices == null || notices.size() == 0) return false;
    removeAllViews();

    for (int i = 0; i < notices.size(); i++) {
      final TextView textView = createTextView(notices.get(i), i);
      final int finalI = i;
      textView.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
          if (onItemClickListener != null) {
            onItemClickListener.onItemClick(finalI, textView);
          }
        }
      });
      addView(textView);
    }

    if (notices.size() > 1) {
      startFlipping();
    }
    return true;
  }

  // 创建ViewFlipper下的TextView
  private TextView createTextView(String text, int position) {
    TextView tv = new TextView(mContext);
    tv.setGravity(gravity);
    tv.setText(text);
    tv.setTextColor(textColor);
    tv.setTextSize(textSize);
    tv.setTag(position);
    return tv;
  }

  public int getPosition() {
    return (int) getCurrentView().getTag();
  }

  public List getNotices() {
    return notices;
  }

  public void setNotices(List notices) {
    this.notices = notices;
  }

  public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
    this.onItemClickListener = onItemClickListener;
  }

  public interface OnItemClickListener {
    void onItemClick(int position, TextView textView);
  }

}