滚动选择器PickerView
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转自
http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2014/1225/2213.html
使用:
1、创建PickerView,复制下面PickerView源码
package com.chen.demo;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 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<String> 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<String> 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); } @Override protected 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<String>(); 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); //TODO// mPaint.setColor(Color.RED); 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); //TODO// mPaint.setColor(Color.BLACK); 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; } @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); }}
2、布局文件:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#000000" > <RelativeLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" android:background="#ffffff" > <com.chen.demo.PickerView android:id="@+id/minute_pv" android:layout_width="80dp" android:layout_height="160dp" /> <TextView android:id="@+id/minute_tv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" android:layout_toRightOf="@id/minute_pv" android:text="分" android:textColor="#ffaa33" android:textSize="26sp" android:textStyle="bold" /> <com.chen.demo.PickerView android:id="@+id/second_pv" android:layout_width="80dp" android:layout_height="160dp" android:layout_toRightOf="@id/minute_tv" /> <TextView android:id="@+id/second_tv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" android:layout_toRightOf="@id/second_pv" android:text="秒" android:textColor="#ffaa33" android:textSize="26sp" android:textStyle="bold" /> </RelativeLayout></RelativeLayout>
3、使用:
package com.chen.demo;import android.app.Activity;import android.os.Bundle;import android.widget.Toast;import java.util.ArrayList;import java.util.List;public class MainActivity extends Activity { PickerView minute_pv; PickerView second_pv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); minute_pv = (PickerView) findViewById(R.id.minute_pv); second_pv = (PickerView) findViewById(R.id.second_pv); List<String> data = new ArrayList<String>(); List<String> seconds = new ArrayList<String>(); for (int i = 0; i < 10; i++) { data.add("0" + i); } for (int i = 0; i < 60; i++) { seconds.add(i < 10 ? "0" + i : "" + i); } minute_pv.setData(data); minute_pv.setOnSelectListener(new PickerView.onSelectListener() { @Override public void onSelect(String text) { Toast.makeText(MainActivity.this, "选择了 " + text + " 分", Toast.LENGTH_SHORT).show(); } }); second_pv.setData(seconds); second_pv.setOnSelectListener(new PickerView.onSelectListener() { @Override public void onSelect(String text) { Toast.makeText(MainActivity.this, "选择了 " + text + " 秒", Toast.LENGTH_SHORT).show(); } }); }}
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