android仿天天动听歌曲自动滚动view

package com.goach.lib; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Typeface; import android.os.Handler; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.ViewConfiguration; import android.widget.TextView; import java.util.ArrayList; import java.util.List; public class VerticalScrollTextView extends TextView implements Runnable{ //绘制歌词画笔 private Paint mContentPaint; //绘制基线画笔 private Paint mLinePaint; //绘制滑动进度背景画笔 private Paint mRectPaint; //歌词数据 private List<Sentence> mDataList; //行数 private int index = 0 ; //当前view的宽 private float mX; //当前view的高 private float mY; //当前view垂直方向中线 private float middleY; //行与行之间的间距 private final static int DY = 80 ; //歌词文字大小 private int mTextSize = 35; //歌词中间字体的大小 private int mBigTextSize = 45; //当前是否按下 private boolean isTouch = false ; //上一次触摸view的y轴坐标 private float mLastY; //是否正在滑动 private boolean isMoving; //记录上一次滑动的时间 private long lastMoveTime; //滑动速度追踪类 private VelocityTracker mVelocityTracker; //滑动最大速度 private int mMaximumVelocity; //歌词是否为空 private boolean isEmpty; public VerticalScrollTextView(Context context) { this(context,null); } public VerticalScrollTextView(Context context, AttributeSet attrs) { this(context, attrs,0); } public VerticalScrollTextView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); //获取最大的滑动速度值 mMaximumVelocity = ViewConfiguration.get(context) .getScaledMaximumFlingVelocity(); init(); } private void init(){ setFocusable(true); setClickable(true); //歌词为空设置默认值 if(mDataList==null){ mDataList = new ArrayList<>(); Sentence sentence = new Sentence(0,"没有获取到歌词",0); mDataList.add(sentence); isEmpty = true ; } //初始化歌词画笔 mContentPaint = new Paint(); mContentPaint.setTextSize(mTextSize); mContentPaint.setAntiAlias(true); mContentPaint.setColor(Color.parseColor("#e5e2e2")); //设置为serif字体 mContentPaint.setTypeface(Typeface.SERIF); //设置字体为居中 mContentPaint.setTextAlign(Paint.Align.CENTER); //初始化基线画笔 mLinePaint = new Paint(); mLinePaint.setAntiAlias(true); mLinePaint.setStrokeWidth(1); mLinePaint.setColor(Color.WHITE); //进度背景颜色画笔 mRectPaint = new Paint(); mLinePaint.setAntiAlias(true); mRectPaint.setColor(Color.parseColor("#66666666")); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //如果当前进度为-1，直接返回，不用绘制 if (index == -1) return; Sentence sentence = mDataList.get(index); //绘制中间行的歌词,设置为高亮白色，大字体 mContentPaint.setColor(Color.WHITE); mContentPaint.setTextSize(mBigTextSize); canvas.drawText(sentence.getName(), mX/2, middleY, mContentPaint); //当前为歌词不为空并且按下的情况下，绘制基线和进度 if(!isEmpty&&isTouch){ //获取中间行字体最高的位置 float baseLine = middleY-Math.abs(mContentPaint.ascent()); //绘制进度背景 canvas.drawRect(10.0f,baseLine-70,150.0f,baseLine,mRectPaint); //绘制基线 canvas.drawLine(10.0f,baseLine,mX-10,baseLine,mLinePaint); //设置进度字体大小 mContentPaint.setTextSize(mTextSize); //绘制进度字体 canvas.drawText(String.valueOf(index),85,baseLine-35,mContentPaint); } //初始化isEmpty isEmpty = false ; //初始化歌词内容画笔 mContentPaint.setColor(Color.parseColor("#e5e2e2")); mContentPaint.setTextSize(mTextSize); //暂时保存中间线位置，来绘制中间线以上的行数字体 float tempY = middleY; //绘制中间线以上的歌词 for (int i = index - 1; i >= 0; i--) { tempY = tempY - DY; if (tempY < 0) { break; } Sentence preSentence = mDataList.get(i); canvas.drawText(preSentence.getName(), mX/2, tempY, mContentPaint); } tempY = middleY; //绘制中间线以下的歌词 for (int i = index + 1; i < mDataList.size(); i++) { tempY = tempY + DY; if (tempY > mY) { break; } Sentence nexeSentence = mDataList.get(i); canvas.drawText(nexeSentence.getName(), mX/2, tempY, mContentPaint); } //初始化isMoving，到这里表示滑动结束 isMoving = false ; } protected void onSizeChanged(int w, int h, int ow, int oh) { super.onSizeChanged(w, h, ow, oh); //获取view的宽和高 mX = w; mY = h; middleY = h * 0.5f; } public long updateIndex(int index) { if (index == -1) return -1; this.index=index; return index; } public List<Sentence> getDataList() { return mDataList; } public void setDataList(List<Sentence> mDataList){ this.mDataList = mDataList ; } public void updateUI(){ new Thread(this).start(); } @Override public boolean onTouchEvent(MotionEvent event) { int action = event.getAction(); switch (action){ case MotionEvent.ACTION_DOWN: isTouch =true; mLastY = event.getY(); break; case MotionEvent.ACTION_MOVE: //创建速度追踪器 initVelocityTrackerIfNotExists(); mVelocityTracker.addMovement(event); mVelocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); //获取当前速度。默认为100 float velocity = mVelocityTracker.getYVelocity()==0?100:mVelocityTracker.getYVelocity(); long currentTime = System.currentTimeMillis(); //设置一个固定值和速度结合决定滑动更新的快慢 if(!isMoving&&currentTime-lastMoveTime>20000/Math.abs(velocity)){ isMoving = true ; lastMoveTime = System.currentTimeMillis(); float currentY = event.getY(); float mMoveY = currentY - mLastY; //向上滑动-1向下滑动+1 int newIndex = mMoveY>0?index - 1:index+1; //循环滚动 newIndex=newIndex<0?mDataList.size()-1:newIndex>=mDataList.size()?0:newIndex; updateIndex(newIndex); invalidate(); mLastY = currentY; } break; case MotionEvent.ACTION_UP: isTouch = false ; recycleVelocityTracker(); break; } return super.onTouchEvent(event); } @Override public void run() { //自�