package com.dayu.baselibrary.view.datepicker;
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import android.animation.ObjectAnimator;
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import android.animation.PropertyValuesHolder;
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import android.content.Context;
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import android.graphics.Canvas;
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import android.graphics.Paint;
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import android.graphics.Paint.Align;
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import android.graphics.Paint.Style;
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import android.os.Handler;
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import android.os.Message;
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import android.text.TextUtils;
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import android.util.AttributeSet;
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import android.view.MotionEvent;
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import android.view.View;
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import java.lang.ref.WeakReference;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Timer;
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import java.util.TimerTask;
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/**
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* 说明：内容选择器，例如年月日、省市区等
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* 作者：liuwan1992
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* 添加时间：2016/9/28
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* 修改人：liuwan1992
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* 修改时间：2018/12/21
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*/
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public class PickerView extends View {
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private Context mContext;
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private Paint mPaint;
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private int mLightColor, mDarkColor;
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private float mHalfWidth, mHalfHeight, mQuarterHeight;
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private float mMinTextSize, mTextSizeRange;
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private float mTextSpacing, mHalfTextSpacing;
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private float mScrollDistance;
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private float mLastTouchY;
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private List<String> mDataList = new ArrayList<>();
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private int mSelectedIndex;
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private boolean mCanScroll = true;
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private boolean mCanScrollLoop = true;
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private OnSelectListener mOnSelectListener;
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private ObjectAnimator mScrollAnim;
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private boolean mCanShowAnim = true;
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private Timer mTimer = new Timer();
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private TimerTask mTimerTask;
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private Handler mHandler = new ScrollHandler(this);
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/**
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* 自动回滚到中间的速度
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*/
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private static final float AUTO_SCROLL_SPEED = 10;
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/**
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* 透明度：最小 120，最大 255，极差 135
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*/
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private static final int TEXT_ALPHA_MIN = 120;
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private static final int TEXT_ALPHA_RANGE = 135;
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/**
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* 选择结果回调接口
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*/
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public interface OnSelectListener {
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void onSelect(View view, String selected);
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}
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private static class ScrollTimerTask extends TimerTask {
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private WeakReference<Handler> mWeakHandler;
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private ScrollTimerTask(Handler handler) {
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mWeakHandler = new WeakReference<>(handler);
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}
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@Override
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public void run() {
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Handler handler = mWeakHandler.get();
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if (handler == null) return;
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handler.sendEmptyMessage(0);
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}
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}
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private static class ScrollHandler extends Handler {
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private WeakReference<PickerView> mWeakView;
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private ScrollHandler(PickerView view) {
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mWeakView = new WeakReference<>(view);
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}
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@Override
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public void handleMessage(Message msg) {
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PickerView view = mWeakView.get();
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if (view == null) return;
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view.keepScrolling();
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}
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}
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public PickerView(Context context, AttributeSet attrs) {
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super(context, attrs);
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mContext = context;
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initPaint();
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}
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private void initPaint() {
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mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
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mPaint.setStyle(Style.FILL);
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mPaint.setTextAlign(Align.CENTER);
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mLightColor = getContext().getResources().getColor(com.dayu.baselibrary.R.color.date_picker_text_light);
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mDarkColor = getContext().getResources().getColor(com.dayu.baselibrary.R.color.date_picker_text_dark);
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}
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@Override
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protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
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super.onMeasure(widthMeasureSpec, heightMeasureSpec);
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mHalfWidth = getMeasuredWidth() / 2f;
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int height = getMeasuredHeight();
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mHalfHeight = height / 2f;
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mQuarterHeight = height / 4f;
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float maxTextSize = height / 7f;
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mMinTextSize = maxTextSize / 2.2f;
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mTextSizeRange = maxTextSize - mMinTextSize;
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mTextSpacing = mMinTextSize * 2.8f;
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mHalfTextSpacing = mTextSpacing / 2f;
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}
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@Override
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protected void onDraw(Canvas canvas) {
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super.onDraw(canvas);
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if (mSelectedIndex >= mDataList.size()) return;
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// 绘制选中的 text
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drawText(canvas, mLightColor, mScrollDistance, mDataList.get(mSelectedIndex));
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// 绘制选中上方的 text
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for (int i = 1; i <= mSelectedIndex; i++) {
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drawText(canvas, mDarkColor, mScrollDistance - i * mTextSpacing,
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mDataList.get(mSelectedIndex - i));
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}
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// 绘制选中下方的 text
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int size = mDataList.size() - mSelectedIndex;
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for (int i = 1; i < size; i++) {
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drawText(canvas, mDarkColor, mScrollDistance + i * mTextSpacing,
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mDataList.get(mSelectedIndex + i));
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}
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}
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private void drawText(Canvas canvas, int textColor, float offsetY, String text) {
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if (TextUtils.isEmpty(text)) return;
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float scale = 1 - (float) Math.pow(offsetY / mQuarterHeight, 2);
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scale = scale < 0 ? 0 : scale;
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mPaint.setTextSize(mMinTextSize + mTextSizeRange * scale);
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mPaint.setColor(textColor);
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mPaint.setAlpha(TEXT_ALPHA_MIN + (int) (TEXT_ALPHA_RANGE * scale));
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// text 居中绘制，mHalfHeight + offsetY 是 text 的中心坐标
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Paint.FontMetrics fm = mPaint.getFontMetrics();
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float baseline = mHalfHeight + offsetY - (fm.top + fm.bottom) / 2f;
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canvas.drawText(text, mHalfWidth, baseline, mPaint);
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}
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@Override
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public boolean dispatchTouchEvent(MotionEvent event) {
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return mCanScroll && super.dispatchTouchEvent(event);
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}
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@Override
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public boolean onTouchEvent(MotionEvent event) {
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switch (event.getActionMasked()) {
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case MotionEvent.ACTION_DOWN:
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cancelTimerTask();
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mLastTouchY = event.getY();
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break;
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case MotionEvent.ACTION_MOVE:
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float offsetY = event.getY();
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mScrollDistance += offsetY - mLastTouchY;
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if (mScrollDistance > mHalfTextSpacing) {
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if (!mCanScrollLoop) {
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if (mSelectedIndex == 0) {
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mLastTouchY = offsetY;
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invalidate();
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break;
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} else {
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mSelectedIndex--;
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}
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} else {
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// 往下滑超过离开距离，将末尾元素移到首位
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moveTailToHead();
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}
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mScrollDistance -= mTextSpacing;
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} else if (mScrollDistance < -mHalfTextSpacing) {
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if (!mCanScrollLoop) {
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if (mSelectedIndex == mDataList.size() - 1) {
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mLastTouchY = offsetY;
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invalidate();
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break;
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} else {
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mSelectedIndex++;
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}
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} else {
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// 往上滑超过离开距离，将首位元素移到末尾
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moveHeadToTail();
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}
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mScrollDistance += mTextSpacing;
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}
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mLastTouchY = offsetY;
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invalidate();
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break;
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case MotionEvent.ACTION_UP:
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// 抬起手后 mSelectedIndex 由当前位置滚动到中间选中位置
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if (Math.abs(mScrollDistance) < 0.01) {
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mScrollDistance = 0;
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break;
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}
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cancelTimerTask();
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mTimerTask = new ScrollTimerTask(mHandler);
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mTimer.schedule(mTimerTask, 0, 10);
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break;
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}
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return true;
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}
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private void cancelTimerTask() {
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if (mTimerTask != null) {
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mTimerTask.cancel();
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mTimerTask = null;
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}
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if (mTimer != null) {
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mTimer.purge();
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}
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}
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private void moveTailToHead() {
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if (!mCanScrollLoop || mDataList.isEmpty()) return;
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String tail = mDataList.get(mDataList.size() - 1);
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mDataList.remove(mDataList.size() - 1);
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mDataList.add(0, tail);
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}
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private void moveHeadToTail() {
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if (!mCanScrollLoop || mDataList.isEmpty()) return;
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String head = mDataList.get(0);
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mDataList.remove(0);
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mDataList.add(head);
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}
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private void keepScrolling() {
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if (Math.abs(mScrollDistance) < AUTO_SCROLL_SPEED) {
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mScrollDistance = 0;
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if (mTimerTask != null) {
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cancelTimerTask();
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if (mOnSelectListener != null && mSelectedIndex < mDataList.size()) {
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mOnSelectListener.onSelect(this, mDataList.get(mSelectedIndex));
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}
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}
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} else if (mScrollDistance > 0) {
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// 向下滚动
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mScrollDistance -= AUTO_SCROLL_SPEED;
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} else {
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// 向上滚动
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mScrollDistance += AUTO_SCROLL_SPEED;
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}
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invalidate();
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}
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/**
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* 设置数据
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*/
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public void setDataList(List<String> list) {
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if (list == null || list.isEmpty()) return;
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mDataList = list;
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// 重置 mSelectedIndex，防止溢出
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mSelectedIndex = 0;
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invalidate();
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}
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/**
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* 选择选中项
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*/
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public void setSelected(int index) {
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if (index >= mDataList.size()) return;
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mSelectedIndex = index;
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if (mCanScrollLoop) {
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// 可循环滚动时，mSelectedIndex 值固定为 mDataList / 2
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int position = mDataList.size() / 2 - mSelectedIndex;
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if (position < 0) {
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for (int i = 0; i < -position; i++) {
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moveHeadToTail();
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mSelectedIndex--;
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}
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} else if (position > 0) {
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for (int i = 0; i < position; i++) {
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moveTailToHead();
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mSelectedIndex++;
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}
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}
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}
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invalidate();
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}
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/**
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* 设置选择结果监听
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*/
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public void setOnSelectListener(OnSelectListener listener) {
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mOnSelectListener = listener;
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}
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/**
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* 是否允许滚动
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*/
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public void setCanScroll(boolean canScroll) {
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mCanScroll = canScroll;
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}
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/**
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* 是否允许循环滚动
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*/
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public void setCanScrollLoop(boolean canLoop) {
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mCanScrollLoop = canLoop;
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}
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/**
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* 执行滚动动画
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*/
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public void startAnim() {
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if (!mCanShowAnim) return;
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if (mScrollAnim == null) {
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PropertyValuesHolder alpha = PropertyValuesHolder.ofFloat("alpha", 1f, 0f, 1f);
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PropertyValuesHolder scaleX = PropertyValuesHolder.ofFloat("scaleX", 1f, 1.3f, 1f);
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PropertyValuesHolder scaleY = PropertyValuesHolder.ofFloat("scaleY", 1f, 1.3f, 1f);
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mScrollAnim = ObjectAnimator.ofPropertyValuesHolder(this, alpha, scaleX, scaleY).setDuration(200);
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}
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if (!mScrollAnim.isRunning()) {
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mScrollAnim.start();
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}
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}
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/**
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* 是否允许滚动动画
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*/
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public void setCanShowAnim(boolean canShowAnim) {
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mCanShowAnim = canShowAnim;
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}
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/**
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* 销毁资源
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*/
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public void onDestroy() {
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mOnSelectListener = null;
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mHandler.removeCallbacksAndMessages(null);
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if (mScrollAnim != null && mScrollAnim.isRunning()) {
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mScrollAnim.cancel();
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}
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cancelTimerTask();
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if (mTimer != null) {
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mTimer.cancel();
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mTimer = null;
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}
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}
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}
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