android:TimePicker仿照IOS时间选择器,可自定义选择器

背景:
项目要求写一个选择器:不仅仅是单纯的时间,还包括自定义部分.
搜了很久,搜出来只用一个自定义view.java类,再简单封装下的选择器:
贴下源码:
public class PickerView extends View{public static final String TAG = "PickerView";/** * text之间间距和minTextSize之比 */public static final float MARGIN_ALPHA = 2.8f;/** * 自动回滚到中间的速度 */public static final float SPEED = 2;private List mDataList;/** * 选中的位置，这个位置是mDataList的中心位置，一直不变 */private int mCurrentSelected;private Paint mPaint;private float mMaxTextSize = 80;private float mMinTextSize = 40;private float mMaxTextAlpha = 255;private float mMinTextAlpha = 120;private int mColorText = 0x333333;private int mViewHeight;private int mViewWidth;private float mLastDownY;/** * 滑动的距离 */private float mMoveLen = 0;private boolean isInit = false;private onSelectListener mSelectListener;private Timer timer;private MyTimerTask mTask;Handler updateHandler = new Handler(){    @Override    public void handleMessage(Message msg)    {        if (Math.abs(mMoveLen) < SPEED)        {            mMoveLen = 0;            if (mTask != null)            {                mTask.cancel();                mTask = null;                performSelect();            }        } else            // 这里mMoveLen / Math.abs(mMoveLen)是为了保有mMoveLen的正负号，以实现上滚或下滚            mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED;        invalidate();    }};public PickerView(Context context){    super(context);    init();}public PickerView(Context context, AttributeSet attrs){    super(context, attrs);    init();}public void setOnSelectListener(onSelectListener listener){    mSelectListener = listener;}private void performSelect(){    if (mSelectListener != null)        mSelectListener.onSelect(mDataList.get(mCurrentSelected));}public void setData(List datas){    mDataList = datas;    mCurrentSelected = datas.size() / 2;    invalidate();}/** * 选择选中的item的index *  * @param selected */public void setSelected(int selected){    mCurrentSelected = selected;    int distance = mDataList.size() / 2 - mCurrentSelected;    if (distance < 0)        for (int i = 0; i < -distance; i++)        {            moveHeadToTail();            mCurrentSelected--;        }    else if (distance > 0)        for (int i = 0; i < distance; i++)        {            moveTailToHead();            mCurrentSelected++;        }    invalidate();}/** * 选择选中的内容 *  * @param mSelectItem */public void setSelected(String mSelectItem){    for (int i = 0; i < mDataList.size(); i++)        if (mDataList.get(i).equals(mSelectItem))        {            setSelected(i);            break;        }}private void moveHeadToTail(){    String head = mDataList.get(0);    mDataList.remove(0);    mDataList.add(head);}private void moveTailToHead(){    String tail = mDataList.get(mDataList.size() - 1);    mDataList.remove(mDataList.size() - 1);    mDataList.add(0, tail);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){    super.onMeasure(widthMeasureSpec, heightMeasureSpec);    mViewHeight = getMeasuredHeight();    mViewWidth = getMeasuredWidth();    // 按照View的高度计算字体大小    mMaxTextSize = mViewHeight / 4.0f;    mMinTextSize = mMaxTextSize / 2f;    isInit = true;    invalidate();}private void init(){    timer = new Timer();    mDataList = new ArrayList();    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);    mPaint.setStyle(Style.FILL);    mPaint.setTextAlign(Align.CENTER);    mPaint.setColor(mColorText);}@Overrideprotected void onDraw(Canvas canvas){    super.onDraw(canvas);    // 根据index绘制view    if (isInit)        drawData(canvas);}private void drawData(Canvas canvas){    // 先绘制选中的text再往上往下绘制其余的text    float scale = parabola(mViewHeight / 4.0f, mMoveLen);    float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;    mPaint.setTextSize(size);    mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));    // text居中绘制，注意baseline的计算才能达到居中，y值是text中心坐标    float x = (float) (mViewWidth / 2.0);    float y = (float) (mViewHeight / 2.0 + mMoveLen);    FontMetricsInt fmi = mPaint.getFontMetricsInt();    float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));    canvas.drawText(mDataList.get(mCurrentSelected), x, baseline, mPaint);    // 绘制上方data    for (int i = 1; (mCurrentSelected - i) >= 0; i++)    {        drawOtherText(canvas, i, -1);    }    // 绘制下方data    for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++)    {        drawOtherText(canvas, i, 1);    }}/** * @param canvas * @param position *            距离mCurrentSelected的差值 * @param type *            1表示向下绘制，-1表示向上绘制 */private void drawOtherText(Canvas canvas, int position, int type){    float d = (float) (MARGIN_ALPHA * mMinTextSize * position + type            * mMoveLen);    float scale = parabola(mViewHeight / 4.0f, d);    float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;    mPaint.setTextSize(size);    mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));    float y = (float) (mViewHeight / 2.0 + type * d);    FontMetricsInt fmi = mPaint.getFontMetricsInt();    float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));    canvas.drawText(mDataList.get(mCurrentSelected + type * position),            (float) (mViewWidth / 2.0), baseline, mPaint);}/** * 抛物线 *  * @param zero *            零点坐标 * @param x *            偏移量 * @return scale */private float parabola(float zero, float x){    float f = (float) (1 - Math.pow(x / zero, 2));    return f < 0 ? 0 : f;}@Overridepublic boolean onTouchEvent(MotionEvent event){    switch (event.getActionMasked())    {    case MotionEvent.ACTION_DOWN:        doDown(event);        break;    case MotionEvent.ACTION_MOVE:        doMove(event);        break;    case MotionEvent.ACTION_UP:        doUp(event);        break;    }    return true;}private void doDown(MotionEvent event){    if (mTask != null)    {        mTask.cancel();        mTask = null;    }    mLastDownY = event.getY();}private void doMove(MotionEvent event){    mMoveLen += (event.getY() - mLastDownY);    if (mMoveLen > MARGIN_ALPHA * mMinTextSize / 2)    {        // 往下滑超过离开距离        moveTailToHead();        mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;    } else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2)    {        // 往上滑超过离开距离        moveHeadToTail();        mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;    }    mLastDownY = event.getY();    invalidate();}private void doUp(MotionEvent event){    // 抬起手后mCurrentSelected的位置由当前位置move到中间选中位置    if (Math.abs(mMoveLen) < 0.0001)    {        mMoveLen = 0;        return;    }    if (mTask != null)    {        mTask.cancel();        mTask = null;    }    mTask = new MyTimerTask(updateHandler);    timer.schedule(mTask, 0, 10);}class MyTimerTask extends TimerTask{    Handler handler;    public MyTimerTask(Handler handler)    {        this.handler = handler;    }    @Override    public void run()    {        handler.sendMessage(handler.obtainMessage());    }}public interface onSelectListener{    void onSelect(String text);}
}
`
这里定义的就是可以滚动的view,直接放入xml文件中即可

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