PopupWindow自定義對話框的使用技巧

PopupWindow的構造函數爲

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

contentView爲要顯示的view，width和height爲寬和高，值爲像素值，也可以是MATCHT_PARENT和WRAP_CONTENT。

focusable爲是否可以獲得焦點，這是一個很重要的參數，也可以通過

public void setFocusable(boolean focusable)

來設置，如果focusable爲false，在一個Activity彈出一個PopupWindow，按返回鍵，由於PopupWindow沒有焦點，會直接退出Activity。如果focusable爲true，PopupWindow彈出後，所有的觸屏和物理按鍵都有PopupWindows處理。

如果PopupWindow中有Editor的話，focusable要爲true。

下面實現一個簡單的PopupWindow

<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爲：

<?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的代碼爲：

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);
            }
        });
    }
}

這三行代碼

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

的作用是點擊空白處的時候PopupWindow會消失

mPopupWindow.showAsDropDown(v);

這一行代碼將PopupWindow以一種向下彈出的動畫的形式顯示出來

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

這個函數的第一個參數爲一個View，我們這裏是一個Button，那麼PopupWindow會在這個Button下面顯示，xoff，yoff爲顯示位置的偏移。

點擊按鈕，就會顯示出PopupWindow
很多時候我們把PopupWindow用作自定義的菜單，需要一個從底部向上彈出的效果，這就需要爲PopupWindow添加動畫。

在工程res下新建anim文件夾，在anim文件夾先新建兩個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添加一個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修改爲

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);
    }
}

這樣點擊菜單鍵會彈出自定義的PopupWindow，點擊空白處或者返回鍵、菜單鍵，PopupWindow會消失。