安卓中滑动选择控件WheelView

安卓中的滑动选择控件WheelView，可以用它来实现各种各样的滑动选择控件，例如日期选择、城市选择等等。

YSoup

3086人浏览 · 2022-07-17 16:16:48

YSoup · 2022-07-17 16:16:48 发布

前言

其实github上有很多开源的滑动选择控件，不过很多都是耦合十分严重的，不是那种复制过来改改就能用的。今天分享一个github上复制过来改改就能用的滑动选择控件，这是原项目的github地址。下图是我修改后的样子：
在这里插入图片描述

代码

代码其实很少，我在原来的基础上加了一些设置字体大小、颜色等方法。如果您需要修改，直接复制WheelView这个类到您的项目里面就可以了，没有额外的依赖，适合熟练掌握cv大法的人士。

WheelView.java

package com.example.wheelviewdemo;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.ScrollView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class WheelView extends ScrollView {
    private String selectedTextColor="#333333";//被选中的文字的颜色
    private String unSelectedTextColor="#999999";//未被选中的文字的颜色
    private String dividerColor="#eeeeee";//分割线的颜色
    private int itemPadding=10;//item上下的padding，单位dp
    private int itemTextSize=16;//item的字体大小，单位sp
    public static final String TAG = WheelView.class.getSimpleName();

    public interface OnWheelViewListener {
        void onSelected(int selectedIndex, String item);
    }

    private Context context;

    private LinearLayout views;

    public WheelView(Context context) {
        super(context);
        init(context);
    }

    public WheelView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public WheelView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    List<String> items;

    private List<String> getItems() {
        return items;
    }

    public void setItems(List<String> list) {
        if (null == items) {
            items = new ArrayList<String>();
        }
        items.clear();
        items.addAll(list);

        // 前面和后面补全
        for (int i = 0; i < offset; i++) {
            items.add(0, "");
            items.add("");
        }

        initData();

    }


    public static final int OFF_SET_DEFAULT = 1;
    int offset = OFF_SET_DEFAULT; // 偏移量（需要在最前面和最后面补全）

    public int getOffset() {
        return offset;
    }

    public void setOffset(int offset) {
        this.offset = offset;
    }

    int displayItemCount; // 每页显示的数量

    int selectedIndex = 1;


    private void init(Context context) {
        this.context = context;
        Log.d(TAG, "parent: " + this.getParent());
        this.setVerticalScrollBarEnabled(false);

        views = new LinearLayout(context);
        views.setOrientation(LinearLayout.VERTICAL);
        this.addView(views);

        scrollerTask = new Runnable() {

            public void run() {

                int newY = getScrollY();
                if (initialY - newY == 0) { // stopped
                    final int remainder = initialY % itemHeight;
                    final int divided = initialY / itemHeight;
                    if (remainder == 0) {
                        selectedIndex = divided + offset;

                        onSeletedCallBack();
                    } else {
                        if (remainder > itemHeight / 2) {
                            WheelView.this.post(new Runnable() {
                                @Override
                                public void run() {
                                    WheelView.this.smoothScrollTo(0, initialY - remainder + itemHeight);
                                    selectedIndex = divided + offset + 1;
                                    onSeletedCallBack();
                                }
                            });
                        } else {
                            WheelView.this.post(new Runnable() {
                                @Override
                                public void run() {
                                    WheelView.this.smoothScrollTo(0, initialY - remainder);
                                    selectedIndex = divided + offset;
                                    onSeletedCallBack();
                                }
                            });
                        }


                    }


                } else {
                    initialY = getScrollY();
                    WheelView.this.postDelayed(scrollerTask, newCheck);
                }
            }
        };


    }

    int initialY;

    Runnable scrollerTask;
    int newCheck = 50;

    public void startScrollerTask() {

        initialY = getScrollY();
        this.postDelayed(scrollerTask, newCheck);
    }

    private void initData() {
        displayItemCount = offset * 2 + 1;

        for (String item : items) {
            views.addView(createView(item));
        }

        refreshItemView(0);
    }

    int itemHeight = 0;

    private TextView createView(String item) {
        TextView tv = new TextView(context);
        tv.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
        tv.setSingleLine(true);
        tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, itemTextSize);
        tv.setText(item);
        tv.setGravity(Gravity.CENTER);
        int padding = dip2px(itemPadding);
        tv.setPadding(padding, padding, padding, padding);
        if (0 == itemHeight) {
            itemHeight = getViewMeasuredHeight(tv);
            Log.d(TAG, "itemHeight: " + itemHeight);
            views.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, itemHeight * displayItemCount));
            LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) this.getLayoutParams();
            this.setLayoutParams(new LinearLayout.LayoutParams(lp.width, itemHeight * displayItemCount));
        }
        return tv;
    }


    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        refreshItemView(t);
        if (t > oldt) {//向下滚动
            scrollDirection = SCROLL_DIRECTION_DOWN;
        } else {//向上滚动
            scrollDirection = SCROLL_DIRECTION_UP;

        }


    }

    private void refreshItemView(int y) {
        int position = y / itemHeight + offset;
        int remainder = y % itemHeight;
        int divided = y / itemHeight;

        if (remainder == 0) {
            position = divided + offset;
        } else {
            if (remainder > itemHeight / 2) {
                position = divided + offset + 1;
            }
        }

        int childSize = views.getChildCount();
        for (int i = 0; i < childSize; i++) {
            TextView itemView = (TextView) views.getChildAt(i);
            if (null == itemView) {
                return;
            }
            if (position == i) {
                itemView.setTextColor(Color.parseColor(selectedTextColor));//设置被选中的item的字体颜色
            } else {
                itemView.setTextColor(Color.parseColor(unSelectedTextColor));
            }
        }
    }

    /**
     * 获取选中区域的边界
     */
    int[] selectedAreaBorder;

    private int[] obtainSelectedAreaBorder() {
        if (null == selectedAreaBorder) {
            selectedAreaBorder = new int[2];
            selectedAreaBorder[0] = itemHeight * offset;
            selectedAreaBorder[1] = itemHeight * (offset + 1);
        }
        return selectedAreaBorder;
    }


    private int scrollDirection = -1;
    private static final int SCROLL_DIRECTION_UP = 0;
    private static final int SCROLL_DIRECTION_DOWN = 1;

    Paint paint;
    int viewWidth;

    @Override
    public void setBackgroundDrawable(Drawable background) {

        if (viewWidth == 0) {
            viewWidth = ((Activity) context).getWindowManager().getDefaultDisplay().getWidth();
            Log.d(TAG, "viewWidth: " + viewWidth);
        }

        if (null == paint) {
            paint = new Paint();
            paint.setColor(Color.parseColor(dividerColor));
            paint.setStrokeWidth(dip2px(1f));
        }

        background = new Drawable() {
            @Override
            public void draw(Canvas canvas) {
                canvas.drawLine(viewWidth * 1 / 6, obtainSelectedAreaBorder()[0], viewWidth * 5 / 6, obtainSelectedAreaBorder()[0], paint);
                canvas.drawLine(viewWidth * 1 / 6, obtainSelectedAreaBorder()[1], viewWidth * 5 / 6, obtainSelectedAreaBorder()[1], paint);
            }

            @Override
            public void setAlpha(int alpha) {

            }

            @Override
            public void setColorFilter(ColorFilter cf) {

            }

            @Override
            public int getOpacity() {
                return PixelFormat.TRANSLUCENT;
            }
        };


        super.setBackgroundDrawable(background);

    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        Log.d(TAG, "w: " + w + ", h: " + h + ", oldw: " + oldw + ", oldh: " + oldh);
        viewWidth = w;
        setBackgroundDrawable(null);
    }

    /**
     * 选中回调
     */
    private void onSeletedCallBack() {
        if (null != onWheelViewListener) {
            try {
                onWheelViewListener.onSelected(selectedIndex, items.get(selectedIndex));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

    public void setSeletion(int position) {
        final int p = position;
        selectedIndex = p + offset;
        this.post(new Runnable() {
            @Override
            public void run() {
                WheelView.this.smoothScrollTo(0, p * itemHeight);
            }
        });

    }

    public String getSeletedItem() {
        return items.get(selectedIndex);
    }

    public int getSeletedIndex() {
        return selectedIndex - offset;
    }


    @Override
    public void fling(int velocityY) {
        super.fling(velocityY / 3);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if (ev.getAction() == MotionEvent.ACTION_UP) {

            startScrollerTask();
        }
        return super.onTouchEvent(ev);
    }

    private OnWheelViewListener onWheelViewListener;

    public OnWheelViewListener getOnWheelViewListener() {
        return onWheelViewListener;
    }

    public void setOnWheelViewListener(OnWheelViewListener onWheelViewListener) {
        this.onWheelViewListener = onWheelViewListener;
    }

    private int dip2px(float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }

    private int getViewMeasuredHeight(View view) {
        int width = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST);
        view.measure(width, expandSpec);
        return view.getMeasuredHeight();
    }

    public String getSelectedTextColor() {
        return selectedTextColor;
    }

    public void setSelectedTextColor(String selectedTextColor) {
        this.selectedTextColor = selectedTextColor;
    }

    public String getUnSelectedTextColor() {
        return unSelectedTextColor;
    }

    public void setUnSelectedTextColor(String unSelectedTextColor) {
        this.unSelectedTextColor = unSelectedTextColor;
    }

    public String getDividerColor() {
        return dividerColor;
    }

    public void setDividerColor(String dividerColor) {
        this.dividerColor = dividerColor;
    }

    public int getItemPadding() {
        return itemPadding;
    }

    public void setItemPadding(int itemPadding) {
        this.itemPadding = itemPadding;
    }

    public int getItemTextSize() {
        return itemTextSize;
    }

    public void setItemTextSize(int itemTextSize) {
        this.itemTextSize = itemTextSize;
    }
}

用法示例MainActivity.java

package com.example.wheelviewdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.TextView;

import java.util.Arrays;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private WheelView wv;
    private TextView tv;
    private final List<String> list= Arrays.asList("鲁班","后羿","猴子","猪八戒","妲己","安琪拉","孙尚香");

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        wv=findViewById(R.id.wv);
        tv=findViewById(R.id.tv);
        wv.setItems(list);
        wv.setSeletion(2);
        wv.setOnWheelViewListener(new WheelView.OnWheelViewListener() {
            @Override
            public void onSelected(int selectedIndex, String item) {
                tv.setText("您选择的英雄是："+selectedIndex+"-"+item);
            }
        });
    }
}

MainActivity的布局activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <com.example.wheelviewdemo.WheelView
        android:id="@+id/wv"
        android:overScrollMode="never"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <TextView
        android:id="@+id/tv"
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        tools:text="选中的是第几项"
        android:gravity="center"/>
</LinearLayout>

源码

代码我放在码云上了，点我跳到码云。

结语

这么一看WheelView好像并没用什么实际用处，其实，这里的WheelView只是起到了一个基石的作用。在真正的项目中，我们一般是在一个弹框里去滑动选择，上面我给的图，它并没有弹框。要把WheelView放到弹框里，其实很简单，这里就不另外贴代码了，相信你会自定义弹框。有了这个WheelView，您还可以实现日期滑动选择控件，不过可能有点废功夫。对于一般的滑动选择控件，直接复制WheelView改改就好了。