android 自定义View 滚动选择器PickerView

android 自定义View 滚动选择器PickerView_第1张图片

1:自定义View

package com.arch.datetimepicker;import android.content.Context;import android.graphics.Canvas;import android.graphics.Paint;import android.os.Handler;import android.os.Message;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import java.util.ArrayList;import java.util.List;import java.util.Timer;import java.util.TimerTask;public class PickerView extends View {    public static final String TAG = "PickerView";    /**     * Text spacing and minTextSize ratio     */    //public static final float MARGIN_ALPHA = 2.0f;    /**     * Automatic rollback to intermediate speed     */    public static final float SPEED = 20;    private List mDataList;    /**     * Selected location, this position is the center of mDataList, has been unchanged     */    private int mCurrentSelected;    private Paint mPaint;    private float mMaxTextSize = 15;    private float mMinTextSize = 10;    private float mMaxTextAlpha = 255;    private float mMinTextAlpha = 255;    private int mColorText = 0x333333;    private int mViewHeight;    private int mViewWidth;    private float mLastDownY;    private int textSizeUp ;    private int textSizeDown;    private float MARGIN_ALPHA;    /**     * Sliding distance     */    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                // Here mMoveLen / Math.abs (mMoveLen) is to maintain the mMoveLen positive and negative numbers, in order to achieve roll or roll                mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED;            invalidate();        }    };    public void setPaintTextSizeDivide(int upSize ,int downSize,float divide){        textSizeUp = upSize;        textSizeDown = downSize;        MARGIN_ALPHA = divide;    }    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();    }    /**     * Select the selected item 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();    }    /**     * Select selected content     *     * @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);    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        mViewHeight = getMeasuredHeight();        mViewWidth = getMeasuredWidth();        // Font size according to View height        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(Paint.Style.FILL);        mPaint.setTextAlign(Paint.Align.CENTER);        mPaint.setColor(mColorText);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        // draw view according index        if (isInit)            drawData(canvas);    }    private void drawData(Canvas canvas) {        // First draw the selected text and then draw up the rest of the text        float scale = parabola(mViewHeight / 4.0f, mMoveLen);        float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;        mPaint.setTextSize(textSizeUp);        mPaint.setColor(0xffea9566);        mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));        // Text center draw, pay attention to the calculation of baseline to achieve the center, y value is text center coordinates        float x = (float) (mViewWidth / 2.0);        float y = (float) (mViewHeight / 2.0 + mMoveLen);        Paint.FontMetricsInt fmi = mPaint.getFontMetricsInt();        float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));        canvas.drawText(mDataList.get(mCurrentSelected), x, baseline, mPaint);        // Draw top data        for (int i = 1; (mCurrentSelected - i) >= 0; i++) {            drawOtherText(canvas, i, -1);        }        // Draw below data        for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++) {            drawOtherText(canvas, i, 1);        }    }    /**     * @param canvas     * @param position     *            Distance mCurrentSelected difference     * @param type     *            1 represents down drawing, -1 means up drawing     */    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(textSizeDown);        mPaint.setColor(0x333333);        mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));        float y = (float) (mViewHeight / 2.0 + type * d);        Paint.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);    }    /**     * parabola     *     * @param zero     *            Zero coordinates     * @param x     *            Offset     * @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) {            // Slide down            moveTailToHead();            mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;        } else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2) {            // Slide up            moveHeadToTail();            mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;        }        mLastDownY = event.getY();        invalidate();    }    private void doUp(MotionEvent event) {        // Raise the position after mCurrentSelected from the current position to the middle of the selected position        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);    }}

2：应用

package com.arch.datetimepicker;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import com.arch.datetimepicker.PickerView.onSelectListener;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity {    private PickerView mHourPicker;    private PickerView mMinutePicker;    List hour = new ArrayList<>();    List minute = new ArrayList<>();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mHourPicker = (PickerView) findViewById(R.id.choose_hour);        mMinutePicker = (PickerView) findViewById(R.id.choose_minute);        mHourPicker.setPaintTextSizeDivide(140,140,2.8f);        mMinutePicker.setPaintTextSizeDivide(140,140,2.8f);        mHourPicker.setOnSelectListener(new onSelectListener() {            @Override            public void onSelect(String hour) {                android.util.Log.i("PickerView","hour "+hour);            }        });        mMinutePicker.setOnSelectListener(new onSelectListener() {            @Override            public void onSelect(String minute) {                android.util.Log.i("PickerView","minute "+minute);            }        });        for (int i = 0; i < 24; i++) {            hour.add(i < 10 ? "0" + i : "" + i);        }        mHourPicker.setData(hour);        for (int i = 0; i < 60; i++) {            minute.add(i < 10 ? "0" + i : "" + i);        }        mMinutePicker.setData(minute);        mHourPicker.setSelected(0);        mMinutePicker.setSelected(0);    }}

3：布局

<?xml version="1.0" encoding="utf-8"?>

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