import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.widget.Scroller;
import java.util.ArrayList;
/**
* 滚轮视图，可设置是否循环模式，实现OnScrollChangedListener接口以监听滚轮变化
* Created by huzn on 2016/10/27.
*/
public class EasyPickerView extends View {
// 文字大小
private int textSize;
// 颜色，默认Color.BLACK
private int textColor;
// 文字之间的间隔，默认10dp
private int textPadding;
// 文字最大放大比例，默认2.0f
private float textMaxScale;
// 文字最小alpha值，范围0.0f~1.0f，默认0.4f
private float textMinAlpha;
// 是否循环模式，默认是
private boolean isRecycleMode;
// 正常状态下最多显示几个文字，默认3（偶数时，边缘的文字会截断）
private int maxShowNum;
private TextPaint textPaint;
private Paint.FontMetrics fm;
private Scroller scroller;
private VelocityTracker velocityTracker;
private int minimumVelocity;
private int maximumVelocity;
private int scaledTouchSlop;
// 数据
private ArrayList<String> dataList = new ArrayList<>();
// 中间x坐标
private int cx;
// 中间y坐标
private int cy;
// 文字最大宽度
private float maxTextWidth;
// 文字高度
private int textHeight;
// 实际内容宽度
private int contentWidth;
// 实际内容高度
private int contentHeight;
// 按下时的y坐标
private float downY;
// 本次滑动的y坐标偏移值
private float offsetY;
// 在fling之前的offsetY
private float oldOffsetY;
// 当前选中项
private int curIndex;
private int offsetIndex;
// 回弹距离
private float bounceDistance;
// 是否正处于滑动状态
private boolean isSliding = false;
public EasyPickerView(Context context) {
this(context, null);
}
public EasyPickerView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public EasyPickerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.EasyPickerView, defStyleAttr, 0);
textSize = a.getDimensionPixelSize(R.styleable.EasyPickerView_epvTextSize, (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));
textColor = a.getColor(R.styleable.EasyPickerView_epvTextColor, Color.BLACK);
textPadding = a.getDimensionPixelSize(R.styleable.EasyPickerView_epvTextPadding, (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_DIP, 20, getResources().getDisplayMetrics()));
textMaxScale = a.getFloat(R.styleable.EasyPickerView_epvTextMaxScale, 2.0f);
textMinAlpha = a.getFloat(R.styleable.EasyPickerView_epvTextMinAlpha, 0.4f);
isRecycleMode = a.getBoolean(R.styleable.EasyPickerView_epvRecycleMode, true);
maxShowNum = a.getInteger(R.styleable.EasyPickerView_epvMaxShowNum, 3);
a.recycle();
textPaint = new TextPaint();
textPaint.setColor(textColor);
textPaint.setTextSize(textSize);
textPaint.setAntiAlias(true);
fm = textPaint.getFontMetrics();
scroller = new Scroller(context);
minimumVelocity = ViewConfiguration.get(getContext()).getScaledMinimumFlingVelocity();
maximumVelocity = ViewConfiguration.get(getContext()).getScaledMaximumFlingVelocity();
scaledTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int mode = MeasureSpec.getMode(widthMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
contentWidth = (int) (maxTextWidth + getPaddingLeft() + getPaddingRight());
if (mode != MeasureSpec.EXACTLY) { // wrap_content
width = contentWidth;
}
mode = MeasureSpec.getMode(heightMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
textHeight = (int) (fm.bottom - fm.top);
contentHeight = textHeight * maxShowNum + textPadding * maxShowNum;
if (mode != MeasureSpec.EXACTLY) { // wrap_content
height = contentHeight + getPaddingTop() + getPaddingBottom();
}
cx = width / 2;
cy = height / 2;
setMeasuredDimension(width, height);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
addVelocityTracker(event);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (!scroller.isFinished()) {
scroller.forceFinished(true);
finishScroll();
}
downY = event.getY();
break;
case MotionEvent.ACTION_MOVE:
offsetY = event.getY() - downY;
if (isSliding || Math.abs(offsetY) > scaledTouchSlop) {
isSliding = true;
reDraw();
}
break;
case MotionEvent.ACTION_UP:
int scrollYVelocity = 2 * getScrollYVelocity() / 3;
if (Math.abs(scrollYVelocity) > minimumVelocity) {
oldOffsetY = offsetY;
scroller.fling(0, 0, 0, scrollYVelocity, 0, 0, -Integer.MAX_VALUE, Integer.MAX_VALUE);
invalidate();
} else {
finishScroll();
}
// 没有滑动，则判断点击事件
if (!isSliding) {
if (downY < contentHeight / 3)
moveBy(-1);
else if (downY > 2 * contentHeight / 3)
moveBy(1);
}
isSliding = false;
recycleVelocityTracker();
break;
}
return true;
}
@Override
protected void onDraw(Canvas canvas) {
if (null != dataList && dataList.size() > 0) {
canvas.clipRect(
cx - contentWidth / 2,
cy - contentHeight / 2,
cx + contentWidth / 2,
cy + contentHeight / 2
);
// 绘制文字，从当前中间项往前2个开始，往后一共绘制5个字
int size = dataList.size();
int centerPadding = textHeight + textPadding;
int half = maxShowNum / 2 + 1;
for (int i = -half; i <= half; i++) {
int index = curIndex - offsetIndex + i;
if (isRecycleMode) {
if (index < 0)
index = (index + 1) % dataList.size() + dataList.size() - 1;
else if (index > dataList.size() - 1)
index = index % dataList.size();
}
if (index >= 0 && index < size) {
// 计算每个字的中间y坐标
int tempY = cy + i * centerPadding;
tempY += offsetY % centerPadding;
// 根据每个字中间y坐标到cy的距离，计算出scale值
float scale = 1.0f - (1.0f * Math.abs(tempY - cy) / centerPadding);
// 根据textMaxScale，计算出tempScale值，即实际text应该放大的倍数，范围 1~textMaxScale
float tempScale = scale * (textMaxScale - 1.0f) + 1.0f;
tempScale = tempScale < 1.0f ? 1.0f : tempScale;
textPaint.setTextSize(textSize * tempScale);
textPaint.setAlpha((int) (255 * textMinAlpha * tempScale));
// 绘制
Paint.FontMetrics tempFm = textPaint.getFontMetrics();
String text = dataList.get(index);
float textWidth = textPaint.measureText(text);
canvas.drawText(text, cx - textWidth / 2, tempY - (tempFm.ascent + tempFm.descent) / 2, textPaint);
}
}
}
}
@Override
public void computeScroll() {
if (scroller.computeScrollOffset()) {
offsetY = oldOffsetY + scroller.getCurrY();
if (!scroller.isFinished())
reDraw();
else
finishScroll();
}
}
private void addVelocityTracker(MotionEvent event) {
if (velocityTracker == null)
velocityTracker = VelocityTracker.obtain();
velocityTracker.addMovement(event);
}
private void recycleVelocityTracker() {
if (velocityTracker != null) {
velocityTracker.recycle();
velocityTracker = null;
}
}
private int getScrollYVelocity() {
velocityTracker.computeCurrentVelocity(1000, maximumVelocity);
int velocity = (int) velocityTracker.getYVelocity();
return velocity;
}
private void reDraw() {
// curIndex需要偏移的量
int i = (int) (offsetY / (textHeight + textPadding));
if (isRecycleMode || (curIndex - i >= 0 && curIndex - i < dataList.size())) {
if (offsetIndex != i) {
offsetIndex = i;
if (null != onScrollChangedListener)
onScrollChangedListener.onScrollChanged(getNowIndex(-offsetIndex));
}
postInvalidate();
} else {
finishScroll();
}
}
private void finishScroll() {
// 判断结束滑动后应该停留在哪个位置
int centerPadding = textHeight + textPadding;
float v = offsetY % centerPadding;
if (v > 0.5f * centerPadding)
++offsetIndex;
else if (v < -0.5f * centerPadding)
--offsetIndex;
// 重置curIndex
curIndex = getNowIndex(-offsetIndex);
// 计算回弹的距离
bounceDistance = offsetIndex * centerPadding - offsetY;
offsetY += bounceDistance;
// 更新
if (null != onScrollChangedListener)
onScrollChangedListener.onScrollFinished(curIndex);
// 重绘
reset();
postInvalidate();
}
private int getNowIndex(int offsetIndex) {
int index = curIndex + offsetIndex;
if (isRecycleMode) {
if (index < 0)
index = (index + 1) % dataList.size() + dataList.size() - 1;
else if (index > dataList.size() - 1)
index = index % dataList.size();
} else {
if (index < 0)
index = 0;
else if (index > dataList.size() - 1)
index = dataList.size() - 1;
}
return index;
}
private void reset() {
offsetY = 0;
oldOffsetY = 0;
offsetIndex = 0;
bounceDistance = 0;
}
/**
* 设置要显示的数据
*
* @param dataList 要显示的数据
*/
public void setDataList(ArrayList<String> dataList) {
this.dataList.clear();
this.dataList.addAll(dataList);
// 更新maxTextWidth
if (null != dataList && dataList.size() > 0) {
int size = dataList.size();
for (int i = 0; i < size; i++) {
float tempWidth = textPaint.measureText(dataList.get(i));
if (tempWidth > maxTextWidth)
maxTextWidth = tempWidth;
}
curIndex = 0;
}
requestLayout();
}
/**
* 获取当前状态下，选中的下标
*
* @return 选中的下标
*/
public int getCurIndex() {
return curIndex - offsetIndex;
}
/**
* 滚动到指定位置
*
* @param index 需要滚动到的指定位置
*/
public void moveTo(int index) {
if (index < 0 || index >= dataList.size() || curIndex == index)
return;
if (!scroller.isFinished())
scroller.forceFinished(true);
finishScroll();
int dy = 0;
int centerPadding = textHeight + textPadding;
if (!isRecycleMode) {
dy = (curIndex - index) * centerPadding;
} else {
int offsetIndex = curIndex - index;
int d1 = Math.abs(offsetIndex) * centerPadding;
int d2 = (dataList.size() - Math.abs(offsetIndex)) * centerPadding;
if (offsetIndex > 0) {
if (d1 < d2)
dy = d1; // ascent
else
dy = -d2; // descent
} else {
if (d1 < d2)
dy = -d1; // descent
else
dy = d2; // ascent
}
}
scroller.startScroll(0, 0, 0, dy, 500);
invalidate();
}
/**
* 滚动指定的偏移量
*
* @param offsetIndex 指定的偏移量
*/
public void moveBy(int offsetIndex) {
moveTo(getNowIndex(offsetIndex));
}
/**
* 滚动发生变化时的回调接口
*/
public interface OnScrollChangedListener {
public void onScrollChanged(int curIndex);
public void onScrollFinished(int curIndex);
}
private OnScrollChangedListener onScrollChangedListener;
public void setOnScrollChangedListener(OnScrollChangedListener onScrollChangedListener) {
this.onScrollChangedListener = onScrollChangedListener;
}
}
MainActivity.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private int hour;
private int minute;
private TextView tv;
private EasyPickerView epvH;
private EasyPickerView epvM;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.tv);
// hours
initHours();
// minutes
initMinutes();
// btns
initBtns();
}
private void initHours() {
epvH = (EasyPickerView) findViewById(R.id.epv_h);
final ArrayList<String> hDataList = new ArrayList<>();
for (int i = 0; i < 24; i++)
hDataList.add("" + i);
epvH.setDataList(hDataList);
epvH.setOnScrollChangedListener(new EasyPickerView.OnScrollChangedListener() {
@Override
public void onScrollChanged(int curIndex) {
hour = Integer.parseInt(hDataList.get(curIndex));
tv.setText(hour + "h" + minute + "m");
}
@Override
public void onScrollFinished(int curIndex) {
hour = Integer.parseInt(hDataList.get(curIndex));
tv.setText(hour + "h" + minute + "m");
}
});
}
private void initMinutes() {
epvM = (EasyPickerView) findViewById(R.id.epv_m);
final ArrayList<String> dataList2 = new ArrayList<>();
for (int i = 0; i < 60; i++)
dataList2.add("" + i);
epvM.setDataList(dataList2);
epvM.setOnScrollChangedListener(new EasyPickerView.OnScrollChangedListener() {
@Override
public void onScrollChanged(int curIndex) {
minute = Integer.parseInt(dataList2.get(curIndex));
tv.setText(hour + "h" + minute + "m");
}
@Override
public void onScrollFinished(int curIndex) {
minute = Integer.parseInt(dataList2.get(curIndex));
tv.setText(hour + "h" + minute + "m");
}
});
}
private void initBtns() {
// hours
final EditText et_h = (EditText) findViewById(R.id.et_h);
Button btnTo = (Button) findViewById(R.id.btn_to_h);
btnTo.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!TextUtils.isEmpty(et_h.getText())) {
int index = Integer.parseInt(et_h.getText().toString());
epvH.moveTo(index);
}
}
});
Button btnBy = (Button) findViewById(R.id.btn_by_h);
btnBy.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!TextUtils.isEmpty(et_h.getText())) {
int index = Integer.parseInt(et_h.getText().toString());
epvH.moveBy(index);
}
}
});
// minutes
final EditText et_m = (EditText) findViewById(R.id.et_m);
Button btnTo_m = (Button) findViewById(R.id.btn_to_m);
btnTo_m.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!TextUtils.isEmpty(et_m.getText())) {
int index = Integer.parseInt(et_m.getText().toString());
epvM.moveTo(index);
}
}
});
Button btnBy_m = (Button) findViewById(R.id.btn_by_m);
btnBy_m.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!TextUtils.isEmpty(et_m.getText())) {
int index = Integer.parseInt(et_m.getText().toString());
epvM.moveBy(index);
}
}
});
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:custom="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.hzn.easypickerview.MainActivity"
>
<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="30dp"
android:textColor="#8f8f8f"
android:textSize="20sp"
/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<com.hzn.easypickerview.EasyPickerView
android:id="@+id/epv_h"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="15dp"
android:paddingRight="15dp"
custom:epvMaxShowNum="3"
custom:epvRecycleMode="true"
custom:epvTextColor="#4aa4a4"
custom:epvTextMaxScale="2.0"
custom:epvTextMinAlpha="0.35"
custom:epvTextPadding="10dp"
custom:epvTextSize="30sp"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_marginTop="70dp"
android:text="h"
android:textColor="#4aa4a4"
android:textSize="20sp"
/>
<com.hzn.easypickerview.EasyPickerView
android:id="@+id/epv_m"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:paddingLeft="15dp"
android:paddingRight="15dp"
custom:epvMaxShowNum="3"
custom:epvRecycleMode="false"
custom:epvTextColor="#e98d3c"
custom:epvTextMaxScale="2.0"
custom:epvTextMinAlpha="0.35"
custom:epvTextPadding="10dp"
custom:epvTextSize="30sp"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_marginTop="70dp"
android:text="m"
android:textColor="#e98d3c"
android:textSize="20sp"
/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="40dp"
android:gravity="center"
android:orientation="horizontal"
>
<EditText
android:id="@+id/et_h"
android:layout_width="60dp"
android:layout_height="40dp"
android:hint="h"
android:inputType="numberSigned"
android:textColor="#4aa4a4"
android:textColorHint="#dedede"
/>
<Button
android:id="@+id/btn_to_h"
android:layout_width="wrap_content"
android:layout_height="30dp"
android:layout_marginLeft="10dp"
android:background="#4aa4a4"
android:text="move to"
android:textColor="#ffffff"
/>
<Button
android:id="@+id/btn_by_h"
android:layout_width="wrap_content"
android:layout_height="30dp"
android:layout_marginLeft="10dp"
android:background="#4aa4a4"
android:minHeight="0dp"
android:text="move by"
android:textColor="#ffffff"
/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:gravity="center"
android:orientation="horizontal"
>
<EditText
android:id="@+id/et_m"
android:layout_width="60dp"
android:layout_height="40dp"
android:hint="m"
android:inputType="numberSigned"
android:textColor="#4aa4a4"
android:textColorHint="#dedede"
/>
<Button
android:id="@+id/btn_to_m"
android:layout_width="wrap_content"
android:layout_height="30dp"
android:layout_marginLeft="10dp"
android:background="#e98d3c"
android:text="move to"
android:textColor="#ffffff"
/>
<Button
android:id="@+id/btn_by_m"
android:layout_width="wrap_content"
android:layout_height="30dp"
android:layout_marginLeft="10dp"
android:background="#e98d3c"
android:text="move by"
android:textColor="#ffffff"
/>
</LinearLayout>
</LinearLayout>
rec.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle"
>
<corners android:radius="8dp"/>
<solid android:color="#f1f1f1"/>
<stroke
android:width="1dp"
android:color="#af1e7f"
/>
</shape>
atts.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="EasyPickerView">
<attr name="epvTextSize" format="dimension"/>
<attr name="epvTextColor" format="color"/>
<attr name="epvTextPadding" format="dimension"/>
<attr name="epvTextMaxScale" format="float"/>
<attr name="epvTextMinAlpha" format="float"/>
<attr name="epvRecycleMode" format="boolean"/>
<attr name="epvMaxShowNum" format="integer"/>
</declare-styleable>
</resources>
效果图：
学习来源：http://blog.csdn.net/u012199331/article/details/72778973