Android实现文字动态高亮读取进度效果

/**
 * 简要功能描述
 * 

 * <详细功能描述>
 *
 * @author : liuxs
 * @date : 2021/3/18
 */
public interface ISubtitleView {

    /**
     * 获取当前的带时间文字歌词实体类
     * @return
     */
    List getSubtitleItemList();

    /**
     * 设置带时间文字歌词实体类
     * @param linesTextList
     */
    void setSubtitleItemList(List linesTextList);

    /**
     * just like {@link #setSubtitleItemList(List)} , only call one of them
     * @param duration
     */
    void setDuration(long duration);

    /**
     * 更新pts会刷新文字进度
     * @param pts
     */
    void updatePts(long pts);

    /**
     * 复位
     */
    void reset();
}
EMSubtitleView类的代码如下：

/**
 * 歌词文字效果的基础view
 * 

 * <详细功能描述>
 *
 * @author : liuxs
 * @date : 2021/3/17
 */
public class EMSubtitleView extends android.support.v7.widget.AppCompatTextView  implements ISubtitleView{

    private int mMeasuredWidth;
    private int mMeasuredHeight;
    private List mSubtitleItemList;
    private List mLinesTextList;
    private Paint mNormalPaint;
    private Paint mHLPaint;
    private long mPts = 0;
    private int mCurHLLine;
    private float mReadSubtitleCount;
    private Rect mLastHLRect;
    private int mHLTextColor;
    private long mDuration;
    private boolean mIsPlain = false;

    public EMSubtitleView(Context context) {
        this(context , null);
    }

    public EMSubtitleView(Context context, AttributeSet attrs) {
        this(context, attrs , 0);
    }

    public EMSubtitleView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mSubtitleItemList = new ArrayList<>();
        mLinesTextList = null;
        mLastHLRect = new Rect();
        mNormalPaint = null;
        initAttrs(attrs , defStyleAttr);

    }
    private void initAttrs(AttributeSet attrs , int defStyleAttr) {
        TypedArray ta = getContext().obtainStyledAttributes(attrs , R.styleable.EMSubtitleView , defStyleAttr , R.style.EMSubtitleViewDefaultTheme);
        for(int i = 0 ; i = 0){
            int curLineTextCount = 0;
            for(int i = 0 ; i  i){
                    canvas.drawText( entity.lineText , entity.left , entity.baseLine , mHLPaint);
                }else if(mCurHLLine == i && mReadSubtitleCount > 0 ){
                    canvas.save();
                    mLastHLRect.set(entity.left , entity.top , entity.left + (int) (mHLPaint.measureText(entity.lineText)*1.0f/entity.lineText.length()*(mReadSubtitleCount-curLineTextCount)), entity.bottom);
                    canvas.clipRect(mLastHLRect );
                    canvas.drawText( entity.lineText , entity.left , entity.baseLine , mHLPaint);
                    canvas.restore();
                    //遮挡的话需要滚动
                    if(entity.baseLine > getHeight()){
                        if(getScrollY() != entity.bottom - getHeight() + 1){
                            setScrollY( entity.bottom - getHeight() + 1/*- pts/40000 * mMeasuredHeight*/);
                        }
                    }
                    break;
                }
                curLineTextCount += entity.lineText.length();
            }
        }
    }

    private void calculateReadLineAndWordsCount() {
        float curSubtitleCount = 0;
        for(SubtitleItem subtitleItem :  mSubtitleItemList){
            //文字之间不可以有空隙，否则mCurHLLine可能一直为-1；
            if(mPts >= subtitleItem.getStartTime() && mPts  curSubtitleCount){
                        mCurHLLine = i;
                        break;
                    }
                }
                break;
            }
            curSubtitleCount += subtitleItem.getWords().length();
        }
        mReadSubtitleCount = curSubtitleCount;
    }

    private void fillLinesEntityListJustOnce() {
        if(mLinesTextList != null){
            return;
        }
        mLinesTextList = new ArrayList<>();
        Layout layout = getLayout();
        int line=getLayout().getLineCount();
        String text=layout.getText().toString();
        for(int i=0;i getSubtitleItemList() {
        return mSubtitleItemList;
    }

    /**
     * 设置带时间文字歌词实体类
     * @param linesTextList
     */
    public void setSubtitleItemList(List linesTextList) {
        if(mSubtitleItemList != null){
            mSubtitleItemList.clear();
            mSubtitleItemList.addAll(linesTextList);
        }else{
            this.mSubtitleItemList = linesTextList;
        }
    }

    /**
     * must first call setText,then call here
     * @param duration
     */
    public void setDuration(long duration){
        setDuration( duration , false);
    }

    private void setDuration(long duration , boolean force){
        if((duration > 0 && mDuration != duration) || force){
            mDuration = duration;
            if(mSubtitleItemList != null){
                mSubtitleItemList.clear();
            }else{
                this.mSubtitleItemList = new ArrayList<>();
            }
            mSubtitleItemList.add(new SubtitleItem(getText().toString() , 0 , duration));
        }
    }

    /**
     * 更新pts会刷新文字进度
     * @param pts
     */
    public void updatePts(long pts){
        mPts = pts;
        postInvalidate();
    }

    /**
     * 复位
     */
    public void reset(){
        mPts = 0;
        mCurHLLine = 0;
        mReadSubtitleCount = 0;
        mLinesTextList = null;
        mNormalPaint = null;
        setScrollY(0);
        postInvalidate();

    }

    static class LineEntity{
       String lineText;
       int top;
       int bottom;
       int ascent;
       int descent;
       int baseLine;
       int left;


        public LineEntity(String lineText, int top, int bottom, int ascent, int descent, int baseLine, int left) {
            this.lineText = lineText;
            this.top = top;
            this.bottom = bottom;
            this.ascent = ascent;
            this.descent = descent;
            this.baseLine = baseLine;
            this.left = left;
        }

    }
}