package com.pickerscrollview.views;  import java.util.ArrayList; import java.util.List; import java.util.Timer; import java.util.TimerTask;  import android.annotation.SuppressLint; import android.content.Context; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Paint.Align; import android.graphics.Paint.FontMetricsInt; import android.graphics.Paint.Style; import android.os.Handler; import android.os.Message; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View;  import com.pickerscrollview.bean.Pickers;  /**  * 自定義滾動選擇器  *  * @author zengtao 2015年5月20日 下午7:36:03  *  */ @SuppressLint({ "HandlerLeak", "ClickableViewAccessibility" }) public class PickerScrollView extends View {    public static final String TAG = "PickerView";   /**    * text之間間距和minTextSize之比    */   public static final float MARGIN_ALPHA = 2.8f;   /**    * 自動回滾到中間的速度    */   public static final float SPEED = 2;    private List<Pickers> mDataList;   /**    * 選中的位置，這個位置是mDataList的中心位置，一直不變    */   private int mCurrentSelected;   private Paint mPaint;    private float mMaxTextSize = 20;   private float mMinTextSize = 10;    private float mMaxTextAlpha = 255;   private float mMinTextAlpha = 120;    private int mColorText = 0x333333;    private int mViewHeight;   private int mViewWidth;    private float mLastDownY;   /**    * 滑動的距離    */   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         // 這里mMoveLen / Math.abs(mMoveLen)是為了保有mMoveLen的正負號，以實現(xiàn)上滾或下滾         mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED;       invalidate();     }    };    public PickerScrollView(Context context) {     super(context);     init();   }    public PickerScrollView(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<Pickers> datas) {     mDataList = datas;     mCurrentSelected = datas.size() / 2;     invalidate();   }    /**    * 選擇選中的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();   }    /**    * 選擇選中的內(nèi)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() {     Pickers head = mDataList.get(0);     mDataList.remove(0);     mDataList.add(head);   }    private void moveTailToHead() {     Pickers tail = mDataList.get(mDataList.size() - 1);     mDataList.remove(mDataList.size() - 1);     mDataList.add(0, tail);   }    @Override   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {     super.onMeasure(widthMeasureSpec, heightMeasureSpec);     mViewHeight = getMeasuredHeight();     mViewWidth = getMeasuredWidth();     // 按照View的高度計算字體大小     mMaxTextSize = mViewHeight / 8.0f;     mMinTextSize = mMaxTextSize / 2f;     isInit = true;     invalidate();   }    private void init() {     timer = new Timer();     mDataList = new ArrayList<Pickers>();     mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);     mPaint.setStyle(Style.FILL);     mPaint.setTextAlign(Align.CENTER);     mPaint.setColor(mColorText);   }    @Override   protected void onDraw(Canvas canvas) {     super.onDraw(canvas);     // 根據(jù)index繪制view     if (isInit)       drawData(canvas);   }    private void drawData(Canvas canvas) {     // 先繪制選中的text再往上往下繪制其余的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居中繪制，注意baseline的計算才能達到居中，y值是text中心坐標     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));      int indexs = mCurrentSelected;     String textData = mDataList.get(indexs).getShowConetnt();     canvas.drawText(textData, x, baseline, mPaint);      // 繪制上方data     for (int i = 1; (mCurrentSelected - i) >= 0; i++) {       drawOtherText(canvas, i, -1);     }     // 繪制下方data     for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++) {       drawOtherText(canvas, i, 1);     }   }    /**    * @param canvas    * @param position    *      距離mCurrentSelected的差值    * @param type    *      1表示向下繪制，-1表示向上繪制    */   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));      int indexs = mCurrentSelected + type * position;     String textData = mDataList.get(indexs).getShowConetnt();     canvas.drawText(textData, (float) (mViewWidth / 2.0), baseline, mPaint);   }    /**    * 拋物線    *    * @param zero    *      零點坐標    * @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;   }    @Override   public 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) {       // 往下滑超過離開距離       moveTailToHead();       mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;     } else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2) {       // 往上滑超過離開距離       moveHeadToTail();       mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;     }      mLastDownY = event.getY();     invalidate();   }    private void doUp(MotionEvent event) {     // 抬起手后mCurrentSelected的位置由當前位置move到中間選中位置     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(Pickers pickers);   } } 

package com.pickerscrollview.bean;  import java.io.Serializable;  /**  *  * @author zengtao 2015年5月20日下午7:18:14  *  */ public class Pickers implements Serializable {    private static final long serialVersionUID = 1L;    private String showConetnt;   private String showId;    public String getShowConetnt() {     return showConetnt;   }    public String getShowId() {     return showId;   }    public Pickers(String showConetnt, String showId) {     super();     this.showConetnt = showConetnt;     this.showId = showId;   }    public Pickers() {     super();   }  } 

package com.pickerscrollview.ui;  import java.util.ArrayList; import java.util.List;  import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.RelativeLayout;  import com.pickerscrollview.bean.Pickers; import com.pickerscrollview.views.PickerScrollView; import com.pickerscrollview.views.PickerScrollView.onSelectListener;  /**  * 主界面  *  * @author zengtao 2015年5月20日 下午7:36:03  *  */ public class MainActivity extends Activity {    private Button bt_scrollchoose; // 滾動選擇器按鈕   private PickerScrollView pickerscrlllview; // 滾動選擇器   private List<Pickers> list; // 滾動選擇器數(shù)據(jù)   private String[] id;   private String[] name;    private Button bt_yes; // 確定按鈕   private RelativeLayout picker_rel; // 選擇器布局    @Override   protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      initView();     initLinstener();     initData();   }    /**    * 初始化    */   private void initView() {     bt_scrollchoose = (Button) findViewById(R.id.bt_scrollchoose);     picker_rel = (RelativeLayout) findViewById(R.id.picker_rel);     pickerscrlllview = (PickerScrollView) findViewById(R.id.pickerscrlllview);     bt_yes = (Button) findViewById(R.id.picker_yes);   }    /**    * 設置監(jiān)聽事件    */   private void initLinstener() {     bt_scrollchoose.setOnClickListener(onClickListener);     pickerscrlllview.setOnSelectListener(pickerListener);     bt_yes.setOnClickListener(onClickListener);   }    /**    * 初始化數(shù)據(jù)    */   private void initData() {     list = new ArrayList<Pickers>();     id = new String[] { "1", "2", "3", "4", "5", "6" };     name = new String[] { "中國銀行", "農(nóng)業(yè)銀行", "招商銀行", "工商銀行", "建設銀行", "民生銀行" };     for (int i = 0; i < name.length; i++) {       list.add(new Pickers(name[i], id[i]));     }     // 設置數(shù)據(jù)，默認選擇第一條     pickerscrlllview.setData(list);     pickerscrlllview.setSelected(0);   }    // 滾動選擇器選中事件   onSelectListener pickerListener = new onSelectListener() {      @Override     public void onSelect(Pickers pickers) {       System.out.println("選擇：" + pickers.getShowId() + "--銀行："           + pickers.getShowConetnt());     }   };    // 點擊監(jiān)聽事件   OnClickListener onClickListener = new OnClickListener() {      @Override     public void onClick(View v) {       if (v == bt_scrollchoose) {         picker_rel.setVisibility(View.VISIBLE);       } else if (v == bt_yes) {         picker_rel.setVisibility(View.GONE);       }     }   }; }