Android跑马灯MarqueeView源码解析

概述跑马灯效果，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

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<String> 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<String> 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<String> getNotices() {    return notices;  }  public voID setNotices(List<String> notices) {    this.notices = notices;  }  public voID setonItemClickListener(OnItemClickListener onItemClickListener) {    this.onItemClickListener = onItemClickListener;  }  public interface OnItemClickListener {    voID onItemClick(int position,TextVIEw textVIEw);  }}

跑马灯vIEw是继承VIEwFlipper，可以看到他的结构体

其实VIEwFlipper工作机制很简单，如上图，就是将添加到VIEwFlipper中的子VIEw按照顺序定时的显示是其中一个子VIEw，其他的子VIEw设置为Gone状态

private Context mContext;  private List<String> 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_RIGHT = 2;

看出vIEw的一些属性，上下文，集合，是否动画延迟，点击事件，跑马灯的时间间隔，动画延迟时间，字体大小颜色，设置位置在靠左垂直中间对齐，文字的位置常量。

修改MarqueeVIEw的构造方法，我们可以在右键generate快速生成。

<declare-styleable name="MarqueeVIEwStyle">    <attr name="mvInterval" format="integer|reference"/>    <attr name="mvAnimDuration" format="integer|reference"/>    <attr name="mvTextSize" format="dimension|reference"/>    <attr name="mvTextcolor" format="color|reference"/>    <attr name="mvGravity">      <enum name="left" value="0"/>      <enum name="center" value="1"/>      <enum name="right" value="2"/>    </attr>  </declare-styleable>

TypedArray typedArray = getContext().obtainStyledAttributes(attrs,0);

首先获取属性集合，获取一个mv的间隔，默认值2000

 isSetAnimDuration = typedArray.hasValue(R.styleable.MarqueeVIEwStyle_mvAnimDuration);

是否设置动画时间的延迟

if (typedArray.hasValue(R.styleable.MarqueeVIEwStyle_mvTextSize)) {      textSize = (int) typedArray.getDimension(R.styleable.MarqueeVIEwStyle_mvTextSize,textSize);    }

假如设置有自定义文字大小，就获取然后px转成sp
获取控件位置，自由设置
在后面要回收

typedArray.recycle();

setFlipInterval(interval);设置滚屏间隔，单位毫秒

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

一进一出的动画效果

// 根据公告字符串启动轮播
public voID startWithText(final String notice)
暴露个公共方法，里面有测量vIEw的getVIEwTreeObserver方法，里面内部类调用了startWithFixeDWIDth(notice,getWIDth());方法

 // 根据宽度和公告字符串启动轮播  private voID startWithFixeDWIDth(String notice,endindex));      }    }    start();  }

转换得到一个dp的宽度，限制字数长度大小。假如字符串小于直接add。假如过长取余得到行数。然后循环，获取那行的头尾，末尾假如2行字数还是比总体长度大就取总体长度，假如小于总体长度，就取那行的末尾下表。
然后开始播放

 // 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),textVIEw);          }        }      });      addVIEw(textVIEw);    }    if (notices.size() > 1) {      startFlipPing();    }    return true;  }

创建部署每行的tv

 // 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;  }

然后将所有的textvIEw add起来，然后开始播放。后面就是做个点击回调，然后set get这个公告的集合。
最后不要忘了在布局顶层加入

xmlns:app="http://schemas.androID.com/apk/res-auto"

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持编程小技巧。

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