PopupWindow的使用

在Android设计弹出框是一个很常见的交互方式。弹出框的具体实现方式主要有两种一种是Dialog，另一种是PopupWindow。这两者的主要区别是Dialog的显示的位置是固定，而PopupWindow的位置是任意的。关于PopupWindow的官方描述如下:

This class represents a popup window that can be used to display an arbitrary view. The popup window is a floating container that appears on top of the current activity.

文档描述：PopupWindow可以显示任意的View，而且PopupWindow以悬浮在Activity的上部的任意位置。

PopupWindow的使用

PopupWindow的使用比较简单，主要有2步

1. 构建PopupWindow对象并进行必要的初始设置。
2. 调用PopupWindow的显示方法，显示PopupWindow对象。

PopupWindow的构建方法有很多，方法如下

具体使用那个构造方法可以根据具体的场景使用。

PopupWindow的一般的初始化的代码如下：

    View contentView=LayoutInflater.from(context).inflate(R.layout.popup_window_content,null,false);
    PopupWindow popupWindow=new PopupWindow(context);
    popupWindow.setContentView(contentView);
    popupWindow.setHeight(ViewGroup.LayoutParams.WRAP_CONTENT);
    popupWindow.setWidth(ViewGroup.LayoutParams.WRAP_CONTENT);

注意：对于PopupWindow的初始化必须设置3个参数：setContentView，setHeight，setWidth。否则PopupWindow存在无法显示的风险。

PopupWindow的显示主要有4个方法。

PopupWindow的显示代码可以如下代码显示：

    popupWindow.showAsDropDown(anchorView);

一个简单的的PopupWindow显示的通用类

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.PopupWindow;


public class PopupWindowHelper {
    private PopupWindow mPopupWindow;
    private View mContentView;
    private int mWidth;
    private int mHeight;
    private boolean mOutsideTouchable;
    private boolean mFocusable;
    private Context mContext;

    public PopupWindowHelper(Context context) {
        mContext = context;
    }

    private void build() {
        if (mWidth != 0 && mHeight != 0) {
            mPopupWindow = new PopupWindow(mWidth, mHeight);
        } else {
            mPopupWindow = new PopupWindow(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        }
        if (mContentView != null) {
            mPopupWindow.setContentView(mContentView);
        }

        mPopupWindow.setHeight(mHeight);
        mPopupWindow.setWidth(mWidth);
        mPopupWindow.setFocusable(mFocusable);
        mPopupWindow.setTouchable(mOutsideTouchable);
    }

    public void showAsDropDown(View anchor) {
        if (mPopupWindow != null) {
            mPopupWindow.showAsDropDown(anchor);
        }
    }

    public void dismiss(){
        if(mPopupWindow!=null){
            mPopupWindow.dismiss();
        }
    }

    public static class PopupWindowBuilder {
        private PopupWindowHelper popupWindowHelper;
        private Context mContext;

        public PopupWindowBuilder(Context context) {
            mContext = context;
            popupWindowHelper = new PopupWindowHelper(mContext);
        }

        public PopupWindowBuilder setContentView(int resId) {
            popupWindowHelper.mContentView = View.inflate(mContext, resId, null);
            return this;
        }

        public PopupWindowBuilder setContentView(View contentView) {
            popupWindowHelper.mContentView = contentView;
            return this;
        }

        public PopupWindowBuilder setSize(int width, int height) {
            popupWindowHelper.mWidth = width;
            popupWindowHelper.mHeight = height;
            return this;
        }

        public PopupWindowBuilder setOutsideTouchable(boolean touchable) {
            popupWindowHelper.mOutsideTouchable = touchable;
            return this;
        }

        public PopupWindowBuilder setFocusable(boolean focusable) {
            popupWindowHelper.mFocusable = focusable;
            return this;
        }


        public PopupWindowHelper create() {
            popupWindowHelper.build();
            return popupWindowHelper;
        }
    }
}

使用实例

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private PopupWindowHelper mPopupWindowHelper;
    private View contentView;
    private Button btnView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnView = (Button) findViewById(R.id.btn_settopic);
        btnView.setOnClickListener(this);
        contentView = LayoutInflater.from(this).inflate(R.layout.popup_content, null, false);
        contentView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mPopupWindowHelper.dismiss();
            }
        });
        mPopupWindowHelper = new PopupWindowHelper.PopupWindowBuilder(this)
                .setContentView(contentView)
                .setSize(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)
                .setFocusable(true)
                .setOutsideTouchable(true)
                .create();
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.btn_settopic) {
            mPopupWindowHelper.showAsDropDown(btnView);
        }
    }
}