Android实现自定义的弹幕效果

一、效果图

先来看看效果图吧~~

二、实现原理方案

1、自定义ViewGroup-XCDanmuView，继承RelativeLayout来实现，当然也可以继承其他三大布局类哈

2、初始化若干个TextView（弹幕的item View，这里以TextView 为例，当然也可以其他了~），然后通过addView添加到自定义View中

3、通过addView添加到XCDanmuView中，位置在坐标，为了实现 从屏幕外移动进来的效果

我们还需要修改添加进来TextView的位置，以从右向左移动方向来说，addView后必须将该TextView的位置设置到右边的屏幕外

这样我们采用的方法，是在onLayout（）方法中对childView进行layout重新布局设置位置

4、随机冲左侧或右侧出来弹幕itemView，移动采用属性动画来实现平移，从屏幕的一端移动到另一端，当动画结束后，就将

该child从XCDanmuView中remove掉。并重新new 一个弹幕itemView ，并addView到XCDanmuView中，并开始动画移动

5、本自定义弹幕View支持从左到右和从右到左两个方向，支持自定义设置屏幕弹幕最多显示个数。

三、自定义弹幕效果XCDanmuView的具体实现

1、初始化需要用到的数据变量

private int mWidth;
  private int mScreenWidth;
  private List<View> mChildList;
  private boolean mIsWorking = false;
  private Context mContext;
  private int mMaxShowNum = 15;
  private int mRowNum = 4;
  private int[] mSpeeds = {
      3000,4000,5000,6000
  };
  private int mDelayDuration = 500;
  private int[] mBgResIds = {
      R.drawable.bg_danmu0,
      R.drawable.bg_danmu1,
      R.drawable.bg_danmu2,
      R.drawable.bg_danmu3
  };
  private int[] mRowPos = {
      150,140,160,150
  };
  private Random mRandom;
  private String[] mStrContents;
  public static enum XCDirection{
    FROM_RIGHT_TO_LEFT,
    FORM_LEFT_TO_RIGHT
  }
  public enum XCAction{
    SHOW,HIDE
  }
  private XCDirection mDirection = XCDirection.FROM_RIGHT_TO_LEFT;
　　private void init() {
  mScreenWidth = getScreenWidth();
  mChildList = new ArrayList<>();
  mRandom = new Random();
}

2、初始化若干个弹幕item view

public void initDanmuItemViews(String[] strContents){
    mStrContents = strContents;
    for(int i = 0; i < mMaxShowNum; i ++){
      int index = mRandom.nextInt(100) % strContents.length;
      createDanmuView(i,strContents[index],false);
    }
  }

3、创建弹幕item view 并addView到XCDanmuView中

public void createDanmuView(int index,String content,boolean reset){
    final TextView textView = new TextView(mContext);
    textView.setTextColor(Color.WHITE);
    int r = mRandom.nextInt(100) % mRowNum;
    textView.setBackgroundResource(mBgResIds[r]);
    textView.setText(content +"_"+ (index+1));
    RelativeLayout.LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT,
        RelativeLayout.LayoutParams.WRAP_CONTENT);
    int row = mRandom.nextInt(100) % mRowNum;
    while(row == lastRow){
      row = mRandom.nextInt(100)% mRowNum;
    }
    int pos = mRandom.nextInt(100)% mRowNum;
    lp.topMargin = row * mRowPos[pos];
    lastRow = row;
    textView.setLayoutParams(lp);
    textView.setPadding(40, 2, 40, 2);
    this.addView(textView);
    if(reset){
      mChildList.set(index,textView);
    }else{
      mChildList.add(index,textView);
    }
    textView.setClickable(true);
    textView.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View view) {
        Toast toast = Toast.makeText(mContext, textView.getText(), Toast.LENGTH_SHORT);
        toast.setGravity(Gravity.TOP,0,50);
        toast.show();
      }
    });
  }

4、重新设置childView的初始位置到屏幕之外

@Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);
    int childCount = this.getChildCount();
    for(int i=0;i<childCount;i++){
      View view = getChildAt(i);
      RelativeLayout.LayoutParams lp = (LayoutParams) view.getLayoutParams();
      if(lp.leftMargin <= 0){
        if(mDirection == XCDirection.FORM_LEFT_TO_RIGHT){
          view.layout(-view.getMeasuredWidth(), lp.topMargin,
              0,lp.topMargin + view.getMeasuredHeight());
        }else{
          view.layout(mScreenWidth,lp.topMargin,mScreenWidth+view.getMeasuredWidth(),
              lp.topMargin+view.getMeasuredHeight());
        }

      }else{
        continue;
      }
    }
  }

5、弹幕item view的移动效果

private Handler mHandler = new Handler() {
    @Override
    public void handleMessage(final Message msg) {
      super.handleMessage(msg);
      final int pos = msg.what;
      ViewPropertyAnimator animator;
      if(mDirection == XCDirection.FROM_RIGHT_TO_LEFT){
        animator = mChildList.get(msg.what).animate()
            .translationXBy(-(mScreenWidth + mChildList.get(msg.what).getWidth()));
      }else{
        animator = mChildList.get(msg.what).animate()
            .translationXBy(mScreenWidth + mChildList.get(msg.what).getWidth());
      }

      Random random = new Random(System.currentTimeMillis());
      int index = random.nextInt(100) % mSpeeds.length;
      animator.setDuration(mSpeeds[index]);
      animator.setInterpolator(new LinearInterpolator());
      animator.setListener(new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animator) {

        }

        @Override
        public void onAnimationEnd(Animator animator) {
          XCDanmuView.this.removeView(mChildList.get(pos));
          int index = mRandom.nextInt(100) % mStrContents.length;
          createDanmuView(pos, mStrContents[index], true);
          mHandler.sendEmptyMessageDelayed(pos, mDelayDuration);
          Log.v("czm", "size=" + mChildList.size());
        }

        @Override
        public void onAnimationCancel(Animator animator) {

        }

        @Override
        public void onAnimationRepeat(Animator animator) {

        }
      });
      animator.start();
    }
  };

 6、开启弹幕效果和关闭弹幕效果以及对于的动画效果

boolean isFirst = true;
  public void start(){
    switchAnimation(XCAction.SHOW);
    if(isFirst){
      for(int i =0;i< mChildList.size();i++){
        mHandler.sendEmptyMessageDelayed(i,i * mDelayDuration);
      }
      isFirst = false;
    }

    mIsWorking = true;
  }
  public void hide(){
    switchAnimation(XCAction.HIDE);
    mIsWorking =false;
  }
  public void stop(){
    this.setVisibility(View.GONE);
    for(int i =0;i< mChildList.size();i++){
      mChildList.get(i).clearAnimation();
      mHandler.removeMessages(i);
    }
    mIsWorking =false;
  }
private void switchAnimation(final XCAction action){
    AlphaAnimation animation;
    if(action == XCAction.HIDE){
      animation = new AlphaAnimation(1.0f,0.0f);
      animation.setDuration(400);
    }else{
      animation = new AlphaAnimation(0.0f,1.0f);
      animation.setDuration(1000);
    }
    XCDanmuView.this.startAnimation(animation);
    animation.setAnimationListener(new Animation.AnimationListener() {
      @Override
      public void onAnimationStart(Animation animation) {

      }
      @Override
      public void onAnimationEnd(Animation animation) {
        if(action == XCAction.HIDE){
          XCDanmuView.this.setVisibility(View.GONE);
        }else{
          XCDanmuView.this.setVisibility(View.VISIBLE);
        }
      }
      @Override
      public void onAnimationRepeat(Animation animation) {

      }
    });
  }

四、如何使用该自定义侧滑View控件

使用该自定义View非常简单，控件默认效果从右向左，如果需要修改方向为从左到右，只需设置下方向即可

public class MainActivity extends Activity {

  private XCDanmuView mDanmuView;
  private List<View> mViewList;
  private String[] mStrItems = {
      "搜狗","百度",
      "腾讯","360",
      "阿里巴巴","搜狐",
      "网易","新浪",
      "搜狗-上网从搜狗开始","百度一下,你就知道",
      "必应搜索-有求必应","好搜-用好搜，特顺手",
      "Android-谷歌","IOS-苹果",
      "Windows-微软","Linux"
  };
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initDanmuView();
    initListener();
  }

  private void initListener() {
    findViewById(R.id.btn).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View view) {
        if (mDanmuView.isWorking()) {
          mDanmuView.hide();
          ((Button) view).setText("开启弹幕");
        } else {
          mDanmuView.start();
          ((Button) view).setText("关闭弹幕");
        }
      }
    });
  }

  private void initDanmuView() {
    mDanmuView = (XCDanmuView)findViewById(R.id.danmu);
    mDanmuView.initDanmuItemViews(mStrItems);
  }

}

五、总结

以上就是在Android中实现自定义弹幕效果的全部内容个，希望本文的内容对大家开发Android的时候能有所帮助。如果有疑问可以留言交流。