Android跑马灯MarqueeView源码解析

2019-12-12 03:53:07

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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_CENTER = 1, 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, R.styleable.MarqueeViewStyle, defStyleAttr, 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);      textSize = DisplayUtil.px2sp(mContext, 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_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);

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, 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();  }

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), 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武林网。

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