Android PopupWindow的使用技巧

2014-01-24 16:28

PopupWindow是Android上自定义弹出窗口,使用起来很方便。

PopupWindow的构造函数为

public PopupWindow(View contentView, int width, int height, boolean focusable)

contentView为要显示的view,width和height为宽和高,值为像素值,也可以是MATCHT_PARENT和WRAP_CONTENT。

focusable为是否可以获得焦点,这是一个很重要的参数,也可以通过

public void setFocusable(boolean focusable)

来设置,如果focusable为false,在一个Activity弹出一个PopupWindow,按返回键,由于PopupWindow没有焦点,会直接退出Activity。如果focusable为true,PopupWindow弹出后,所有的触屏和物理按键都有PopupWindows处理。

如果PopupWindow中有Editor的话,focusable要为true。

下面实现一个简单的PopupWindow

主界面的layout为:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/layout_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    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=".MainActivity" >

    <Button
        android:id="@+id/btn_test_popupwindow"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="@string/app_name" />

</RelativeLayout>

PopupWindow的layout为:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="#000000" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="80dp"
        android:text="@string/app_name" 
        android:textColor="#ffffffff"
        android:layout_centerInParent="true"
        android:gravity="center"/>

</RelativeLayout>

Activity的代码为:

public class MainActivity extends Activity {

    private Button mButton;
    private PopupWindow mPopupWindow;

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

        View popupView = getLayoutInflater().inflate(R.layout.layout_popupwindow, null);

        mPopupWindow = new PopupWindow(popupView, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT, true);
        mPopupWindow.setTouchable(true);
        mPopupWindow.setOutsideTouchable(true);
        mPopupWindow.setBackgroundDrawable(new BitmapDrawable(getResources(), (Bitmap) null));

        mButton = (Button) findViewById(R.id.btn_test_popupwindow);
        mButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                mPopupWindow.showAsDropDown(v);
            }
        });
    }
}

这三行代码

mPopupWindow.setTouchable(true);
mPopupWindow.setOutsideTouchable(true);
mPopupWindow.setBackgroundDrawable(new BitmapDrawable(getResources(), (Bitmap) null));

的作用是点击空白处的时候PopupWindow会消失

mPopupWindow.showAsDropDown(v);

这一行代码将PopupWindow以一种向下弹出的动画的形式显示出来

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

这个函数的第一个参数为一个View,我们这里是一个Button,那么PopupWindow会在这个Button下面显示,xoff,yoff为显示位置的偏移。

点击按钮,就会显示出PopupWindow

很多时候我们把PopupWindow用作自定义的菜单,需要一个从底部向上弹出的效果,这就需要为PopupWindow添加动画。

在工程res下新建anim文件夹,在anim文件夹先新建两个xml文件

menu_bottombar_in.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >

    <translate
        android:duration="250"
        android:fromYDelta="100.0%"
        android:toYDelta="0.0" />

</set>

menu_bottombar_out.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >

    <translate
        android:duration="250"
        android:fromYDelta="0.0"
        android:toYDelta="100%" />

</set>

在res/value/styles.xml添加一个sytle

    <style name="anim_menu_bottombar">
        <item name="android:windowEnterAnimation">@anim/menu_bottombar_in</item>
        <item name="android:windowExitAnimation">@anim/menu_bottombar_out</item>
    </style>

Acivity修改为

public class MainActivity extends Activity {

    private PopupWindow mPopupWindow;

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

        View popupView = getLayoutInflater().inflate(R.layout.layout_popupwindow, null);

        mPopupWindow = new PopupWindow(popupView, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT, true);
        mPopupWindow.setTouchable(true);
        mPopupWindow.setOutsideTouchable(true);
        mPopupWindow.setBackgroundDrawable(new BitmapDrawable(getResources(), (Bitmap) null));

        mPopupWindow.getContentView().setFocusableInTouchMode(true);
        mPopupWindow.getContentView().setFocusable(true);
        mPopupWindow.getContentView().setOnKeyListener(new OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_MENU && event.getRepeatCount() == 0
                        && event.getAction() == KeyEvent.ACTION_DOWN) {
                    if (mPopupWindow != null && mPopupWindow.isShowing()) {
                        mPopupWindow.dismiss();
                    }
                    return true;
                }
                return false;
            }
        });
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_MENU && event.getRepeatCount() == 0) {
            if (mPopupWindow != null && !mPopupWindow.isShowing()) {
                mPopupWindow.showAtLocation(findViewById(R.id.layout_main), Gravity.BOTTOM, 0, 0);
            }
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
}

这样点击菜单键会弹出自定义的PopupWindow,点击空白处或者返回键、菜单键,PopupWindow会消失。