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Android PopupWindow用法 Android PopupWindow用法解析

圣骑士wind 人气:0
想了解Android PopupWindow用法解析的相关内容吗,圣骑士wind在本文为您仔细讲解Android PopupWindow用法的相关知识和一些Code实例,欢迎阅读和指正,我们先划重点:Android,PopupWindow,下面大家一起来学习吧。

PopupWindow使用

PopupWindow这个类用来实现一个弹出框,可以使用任意布局的View作为其内容,这个弹出框是悬浮在当前activity之上的。

PopupWindow使用Demo

这个类的使用,不再过多解释,直接上代码吧。
比如弹出框的布局: 

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

 <TextView
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:padding="10dp"
  android:text="Hello My Window"
  android:textSize="20sp" />

 <Button
  android:id="@+id/button1"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:padding="10dp"
  android:text="Button"
  android:textSize="20sp" />

</LinearLayout>

Activity的布局中只有一个按钮,按下后会弹出框,Activity代码如下: 

package com.example.hellopopupwindow;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.PopupWindow;
import android.widget.Toast;

public class MainActivity extends Activity {

 private Context mContext = null;

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

  mContext = this;

  Button button = (Button) findViewById(R.id.button);
  button.setOnClickListener(new View.OnClickListener() {

   @Override
   public void onClick(View view) {

    showPopupWindow(view);
   }
  });
 }

 private void showPopupWindow(View view) {

  // 一个自定义的布局,作为显示的内容
  View contentView = LayoutInflater.from(mContext).inflate(
    R.layout.pop_window, null);
  // 设置按钮的点击事件
  Button button = (Button) contentView.findViewById(R.id.button1);
  button.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View v) {
    Toast.makeText(mContext, "button is pressed",
      Toast.LENGTH_SHORT).show();
   }
  });

  final PopupWindow popupWindow = new PopupWindow(contentView,
    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, true);

  popupWindow.setTouchable(true);

  popupWindow.setTouchInterceptor(new OnTouchListener() {

   @Override
   public boolean onTouch(View v, MotionEvent event) {

    Log.i("mengdd", "onTouch : ");

    return false;
    // 这里如果返回true的话,touch事件将被拦截
    // 拦截后 PopupWindow的onTouchEvent不被调用,这样点击外部区域无法dismiss
   }
  });

  // 如果不设置PopupWindow的背景,无论是点击外部区域还是Back键都无法dismiss弹框
  // 我觉得这里是API的一个bug
  popupWindow.setBackgroundDrawable(getResources().getDrawable(
    R.drawable.selectmenu_bg_downward));

  // 设置好参数之后再show
  popupWindow.showAsDropDown(view);

 }

}

弹出框的布局中有一个TextView和一个Button,Button点击后显示Toast,如图: 

第一次实现的时候遇到了问题,就是弹出框不会在按下Back键的时候消失,点击弹框外区域也没有正常消失,搜索了一下,都说只要设置背景就好了。
然后我就找了个图片,果然弹框能正常dismiss了(见注释)。

PopupWindow源码分析

为了解答一下上面的问题,看看源码(最新API Level 19,Android 4.4.2)。

1.显示方法

显示提供了两种形式:

showAtLocation()显示在指定位置,有两个方法重载:

public void showAtLocation(View parent, int gravity, int x, int y)
public void showAtLocation(IBinder token, int gravity, int x, int y) 

showAsDropDown()显示在一个参照物View的周围,有三个方法重载:

public void showAsDropDown(View anchor)
public void showAsDropDown(View anchor, int xoff, int yoff)
public void showAsDropDown(View anchor, int xoff, int yoff, int gravity) 

最后一种带Gravity参数的方法是API 19新引入的。
弹出的方法中首先需要preparePopup() ,最后再invokePopup()
prepare的方法中可以看到有无背景的分别: 

 /**
  * <p>Prepare the popup by embedding in into a new ViewGroup if the
  * background drawable is not null. If embedding is required, the layout
  * parameters' height is mnodified to take into account the background's
  * padding.</p>
  *
  * @param p the layout parameters of the popup's content view
  */
 private void preparePopup(WindowManager.LayoutParams p) {
  if (mContentView == null || mContext == null || mWindowManager == null) {
   throw new IllegalStateException("You must specify a valid content view by "
     + "calling setContentView() before attempting to show the popup.");
  }

  if (mBackground != null) {
   final ViewGroup.LayoutParams layoutParams = mContentView.getLayoutParams();
   int height = ViewGroup.LayoutParams.MATCH_PARENT;
   if (layoutParams != null &&
     layoutParams.height == ViewGroup.LayoutParams.WRAP_CONTENT) {
    height = ViewGroup.LayoutParams.WRAP_CONTENT;
   }

   // when a background is available, we embed the content view
   // within another view that owns the background drawable
   PopupViewContainer popupViewContainer = new PopupViewContainer(mContext);
   PopupViewContainer.LayoutParams listParams = new PopupViewContainer.LayoutParams(
     ViewGroup.LayoutParams.MATCH_PARENT, height
   );
   popupViewContainer.setBackgroundDrawable(mBackground);
   popupViewContainer.addView(mContentView, listParams);

   mPopupView = popupViewContainer;
  } else {
   mPopupView = mContentView;
  }
  mPopupViewInitialLayoutDirectionInherited =
    (mPopupView.getRawLayoutDirection() == View.LAYOUT_DIRECTION_INHERIT);
  mPopupWidth = p.width;
  mPopupHeight = p.height;
 }

2.背景是否为空对Touch事件的影响
如果有背景,则会在contentView外面包一层PopupViewContainer之后作为mPopupView,如果没有背景,则直接用contentView作为mPopupView。
而这个PopupViewContainer是一个内部私有类,它继承了FrameLayout,在其中重写了Key和Touch事件的分发处理: 

 @Override
  public boolean dispatchKeyEvent(KeyEvent event) {
   if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
    if (getKeyDispatcherState() == null) {
     return super.dispatchKeyEvent(event);
    }

    if (event.getAction() == KeyEvent.ACTION_DOWN
      && event.getRepeatCount() == 0) {
     KeyEvent.DispatcherState state = getKeyDispatcherState();
     if (state != null) {
      state.startTracking(event, this);
     }
     return true;
    } else if (event.getAction() == KeyEvent.ACTION_UP) {
     KeyEvent.DispatcherState state = getKeyDispatcherState();
     if (state != null && state.isTracking(event) && !event.isCanceled()) {
      dismiss();
      return true;
     }
    }
    return super.dispatchKeyEvent(event);
   } else {
    return super.dispatchKeyEvent(event);
   }
  }

  @Override
  public boolean dispatchTouchEvent(MotionEvent ev) {
   if (mTouchInterceptor != null && mTouchInterceptor.onTouch(this, ev)) {
    return true;
   }
   return super.dispatchTouchEvent(ev);
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
   final int x = (int) event.getX();
   final int y = (int) event.getY();
   
   if ((event.getAction() == MotionEvent.ACTION_DOWN)
     && ((x < 0) || (x >= getWidth()) || (y < 0) || (y >= getHeight()))) {
    dismiss();
    return true;
   } else if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {
    dismiss();
    return true;
   } else {
    return super.onTouchEvent(event);
   }
  }

由于PopupView本身并没有重写Key和Touch事件的处理,所以如果没有包这个外层容器类,点击Back键或者外部区域是不会导致弹框消失的。

补充Case: 弹窗不消失,但是事件向下传递
如上所述:
设置了PopupWindow的background,点击Back键或者点击弹窗的外部区域,弹窗就会dismiss.
相反,如果不设置PopupWindow的background,那么点击back键和点击弹窗的外部区域,弹窗是不会消失的.
那么,如果我想要一个效果,点击外部区域,弹窗不消失,但是点击事件会向下面的activity传递,比如下面是一个WebView,我想点击里面的链接等.

研究了半天,说是要给Window设置一个Flag,WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
看了源码,这个Flag的设置与否是由一个叫mNotTouchModal的字段控制,但是设置该字段的set方法被标记为@hide。
所以要通过反射的方法调用: 

   /**
  * Set whether this window is touch modal or if outside touches will be sent
  * to
  * other windows behind it.
  *
  */
 public static void setPopupWindowTouchModal(PopupWindow popupWindow,
   boolean touchModal) {
  if (null == popupWindow) {
   return;
  }
  Method method;
  try {

   method = PopupWindow.class.getDeclaredMethod("setTouchModal",
     boolean.class);
   method.setAccessible(true);
   method.invoke(popupWindow, touchModal);

  }
  catch (Exception e) {
   e.printStackTrace();
  }

 }

然后在程序中:
UIUtils.setPopupWindowTouchModal(popupWindow, false);

该popupWindow外部的事件就可以传递给下面的Activity了。

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