線上直播系統原始碼，滾動式內容展示控制元件實現的相關程式碼

原始碼：

public class RollView extends FrameLayout {
  private static final int DEFAULTTEXTSIZE = 16;
  private static final int DEFAULTTEXTHEIGHT = 72;
  private List<?> contents = new LinkedList<>();
  private float textSize;
  private int textColor = Color.BLACK;
  //當前顯示內容在集合中的下標
  private int curIndex = -1;
  //下一個顯示的下標
  private TextView curText;
  private TextView nextText;
  private int hSize;
  private int wSize;
  private TranslateAnimation outAnim;
  private TranslateAnimation inAnim;
  //是否執行動畫中
  private boolean isAnimationing = false;
  private onItemClickListener listener;
  private MyHandler handler = new MyHandler(this);
  public RollView(Context context) {
    this(context, null);
  }
  public RollView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
  }
  public RollView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context, attrs);
  }
  private void init(Context context, AttributeSet attrs) {
    View view = LayoutInflater.from(context).inflate(R.layout.custom_rollview_layout, this);
    curText = ((TextView) view.findViewById(R.id.curText));
    nextText = ((TextView) view.findViewById(R.id.nextText));
    TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.RollView);
    float tmpTextSize = ta.getInteger(R.styleable.RollView_rollSize, DEFAULTTEXTSIZE);
    textSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, tmpTextSize, getResources().getDisplayMetrics());
    int colorRes = ta.getResourceId(R.styleable.RollView_rollColor, -1);
    int colorRes2 = ta.getColor(R.styleable.RollView_rollColor, -1);
    curText.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        //如果是執行動畫中，就不響應點選事件
        if (isAnimationing) {
          return;
        } else {
          if (listener != null) {
            listener.onClick(curIndex);
          }
        }
      }
    });
    if (colorRes != -1) {
      textColor = colorRes;
    } else if (colorRes2 != -1) {
      textColor = colorRes2;
    }
    curText.setTextSize(textSize);
    curText.setTextColor(textColor);
    nextText.setTextSize(textSize);
    nextText.setTextColor(textColor);
    ta.recycle();
  }
  public void setListener(onItemClickListener listener) {
    this.listener = listener;
  }
  /**
  * 可以是自定義型別，只需要重新toString() 方法
  * @param contents
  */
  public void setObjContents(List<?> contents) {
    if (contents == null || contents.size() == 0) {
      return;
    }
    this.contents.clear();
    List<String> list = new LinkedList<>();
    for (Object content : contents) {
      list.add(content.toString());
    }
    setContents(list);
  }
  public void setContents(List<String> contents) {
    if (contents == null || contents.size() == 0) {
      return;
    }
    this.contents = contents;
    initData();
  }
  private void initData() {
    curIndex = 0;
    if (contents.size() > 0) {
      curText.setText(contents.get(0).toString());
    }
    if (contents.size() > 1) {
      nextText.setText(contents.get(1).toString());
    }
  }
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int wMode = MeasureSpec.getMode(widthMeasureSpec);
    int hMode = MeasureSpec.getMode(heightMeasureSpec);
    hSize = MeasureSpec.getSize(heightMeasureSpec);
    wSize = MeasureSpec.getSize(widthMeasureSpec);
    switch (hMode) {
      case MeasureSpec.EXACTLY:
        break;
      case MeasureSpec.AT_MOST:
      case MeasureSpec.UNSPECIFIED:
        hSize = DEFAULTTEXTHEIGHT;
        break;
    }
    setMeasuredDimension(wSize, hSize);
    outAnim = new TranslateAnimation(Animation.ABSOLUTE, 0, Animation.ABSOLUTE, 0, Animation.ABSOLUTE, 0, Animation.ABSOLUTE, -hSize);
    //動畫結束時，將控制元件還原到初始化狀態，必須設定這個
    outAnim.setFillEnabled(true);
    outAnim.setAnimationListener(new Animation.AnimationListener() {
      @Override
      public void onAnimationStart(Animation animation) {
        isAnimationing = true;
      }
      @Override
      public void onAnimationEnd(Animation animation) {
        isAnimationing = false;
        curIndex++;
        curIndex = curIndex % contents.size();//滾動到最後一條資料了，下一條顯示第一條資料
        int nextIndex = (curIndex + 1) % contents.size();//獲取nextText 需要顯示的下一條資料的下標
        /**
        * 這裡的含義是：動畫結束後，控制元件還原到初始化狀態，
        * curText 就需要顯示滾動後的 nextText 的內容，起到介面沒有視覺差
        * nextText 就需要顯示，下下條資料，為了下次滾動做準備
        */
        curText.setText(contents.get(curIndex).toString());
        nextText.setText(contents.get(nextIndex).toString());
        //動畫結束後，延遲3秒繼續滾動
        handler.sendEmptyMessageDelayed(0, 2000);
      }
      @Override
      public void onAnimationRepeat(Animation animation) {
      }
    });
    outAnim.setDuration(1000);
    inAnim = new TranslateAnimation(Animation.ABSOLUTE, 0, Animation.ABSOLUTE, 0, Animation.ABSOLUTE, hSize, Animation.ABSOLUTE, 0);
    inAnim.setFillEnabled(true);
    inAnim.setDuration(1000);
  }
  /**
  * 開始滾動，數量必須大於1才會滾動，每3秒滾動一次
  */
  public void startRoll() {
    if (contents.isEmpty() || contents.size() == 1) {
      return;
    }
    handler.sendEmptyMessageDelayed(0, 2000);
  }
  private void roll() {
    if (isAnimationing) {
      return;
    }
    curText.startAnimation(outAnim);
    nextText.startAnimation(inAnim);
  }
  private static class MyHandler extends Handler {
    private WeakReference<RollView> weakReference;
    public MyHandler(RollView rollView) {
      this.weakReference = new WeakReference<>(rollView);
    }
    @Override
    public void handleMessage(Message msg) {
      RollView rollView = weakReference.get();
      if (rollView == null) {
        return;
      }
      rollView.roll();
    }
  }
  public interface onItemClickListener {
    /**
    * 這裡也可以用泛型，返回當前顯示的自定義資料,為了簡單，這裡就只返回當前點選的位置
    * @param position
    */
    void onClick(int position);
  }
}

​自定義的佈局：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/textContent"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">
  <TextView
    android:id="@+id/nextText"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center_vertical"
    android:background="@color/white"
    android:gravity="center_vertical"
    android:maxLines="1"
    android:text="nextText"
    android:textColor="@color/black"
    android:textSize="@dimen/sp_16" />
  <TextView
    android:id="@+id/curText"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center_vertical"
    android:background="@color/white"
    android:gravity="center_vertical"
    android:maxLines="1"
    android:text="curText"
    android:textColor="@color/black"
    android:textSize="@dimen/sp_16" />
</FrameLayout>

自定義屬性：

<declare-styleable name="RollView">
    <attr name="rollSize" format="integer" />
    <attr name="rollColor" format="reference|color" />
  </declare-styleable>

使用：

<RollView
  android:id="@+id/rollView"
  android:layout_width="match_parent"
  android:layout_height="@dimen/dp_56"
  android:background="@color/white"
  android:paddingLeft="@dimen/dp_20"
  app:rollSize="20" />

程式碼：

List<String> contents = new LinkedList<>();
contents.add("lingtao");
contents.add("lingtao1");
contents.add("lingtao2");
contents.add("lingtao3");
rollView.setContents(contents);
rollView.setListener(new RollView.onItemClickListener() {
  @Override
  public void onClick(int position) {
    LogUtils.d("TestActivity_log", "onClick: " + contents.get(position));
  }
});
rollView.startRoll();

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