底部弹出PopupWindow并且背景变为半透明效果

来自：http://blog.csdn.net/LANG791534167/article/details/48985101

先来看看运行效果图 

[方式一]实现从底部弹出PopupWindow

原理：定义一个高度为wrap_content的PopupWindow布局文件，根据屏幕底部的位置显示在Bottom

1.首先定义一个高度为wrap_content的PopupWindow布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:padding="8dp"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="vertical"
        android:background="@drawable/shape_info_bg">
        <TextView android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="8dp"
            android:gravity="center"
            android:textColor="@color/theme_blue"
            android:text="拍照"/>
        <View android:layout_width="match_parent" 
            android:layout_height="0.2dp"
            android:background="@color/theme_blue"/>
        <TextView android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="8dp"
            android:gravity="center"
            android:textColor="@color/theme_blue"
            android:text="相冊"/>
    LinearLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:padding="1dp">
        <Button
            android:id="@+id/btn_cancle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:padding="8dp"
            android:textColor="@color/theme_blue"
            android:background="@drawable/shape_info_bg"
            android:text="取消" />
    RelativeLayout>
LinearLayout>

2.在PopupWindow所在的Activity根布局中声明id（在弹出PopupWindow作为位置参考的相对View）

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" 
    android:background="@color/white">

    <Button android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="底部弹出PopupWindow"
        android:onClick="openPop"/>

     <Button android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="半透明底部PopupWindow"
        android:onClick="openPop2"/>
LinearLayout>

3.MainActivity中点击按钮弹出PopupWindow

/** 弹出底部对话框 */
public void openPop(View view) {
    View popView = LayoutInflater.from(mContext).inflate(
            R.layout.pop_bottom, null);
    View rootView = findViewById(R.id.root_main); // 當前頁面的根佈局
    final PopupWindow popupWindow = new PopupWindow(popView,        LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT);

    setBackgroundAlpha(0.5f);//设置屏幕透明度

    popupWindow.setBackgroundDrawable(new BitmapDrawable());
    popupWindow.setFocusable(true);// 点击空白处时，隐藏掉pop窗口
    // 顯示在根佈局的底部
    popupWindow.showAtLocation(rootView, Gravity.BOTTOM | Gravity.LEFT, 0,
            0);

}

4.设置背景变为半透明效果，由于PopupWindow中并未设置背景色，所以弹出时PopupWindow以外的部分显示当前Acitivity的内容，设置背景色原理通过设置当前Activity所在屏幕的透明度来达到背景透明的效果！在退出时popupWindow时，需要恢复屏幕原有透明度

popupWindow.setOnDismissListener(new OnDismissListener() {
            @Override
            public void onDismiss() {
                // popupWindow隐藏时恢复屏幕正常透明度
                setBackgroundAlpha(1.0f);
            }
        });

/**
 * 设置添加屏幕的背景透明度
 * 
 * @param bgAlpha
 *            屏幕透明度0.0-1.0 1表示完全不透明
 */
public void setBackgroundAlpha(float bgAlpha) {
    WindowManager.LayoutParams lp = ((Activity) mContext).getWindow()
            .getAttributes();
    lp.alpha = bgAlpha;
    ((Activity) mContext).getWindow().setAttributes(lp);
}

---

[方式二]全屏PopupWindow实现底部弹出，背景半透明

原理：弹出一个全屏popupWindow，高度为match_parent,将根布局的Gravity属性设置bottom,根布局背景设置为一个半透明的颜色#36000000， 弹出时全屏的popupWindow半透明效果背景覆盖了在Activity之上 给人感觉上是popupWindow弹出后，背景变成半透明

布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="8dp"
    android:orientation="vertical" 
    android:background="#36000000"
    android:gravity="bottom">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="vertical"
        android:background="@drawable/shape_info_bg">
        <TextView android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="8dp"
            android:gravity="center"
            android:textColor="@color/theme_blue"
            android:text="拍照"/>
        <View android:layout_width="match_parent" 
            android:layout_height="0.2dp"
            android:background="@color/theme_blue"/>
        <TextView android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="8dp"
            android:gravity="center"
            android:textColor="@color/theme_blue"
            android:text="相冊"/>
    LinearLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:padding="1dp">
        <Button
            android:id="@+id/btn_cancle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:padding="8dp"
            android:textColor="@color/theme_blue"
            android:background="@drawable/shape_info_bg"
            android:text="取消" />
    RelativeLayout>
LinearLayout>

弹出方法和方式一相似，不过不用再监听popupWindow的退出事件

/**
 * 弹出底部对话框，达到背景背景透明效果
 * 
 * 实现原理：弹出一个全屏popupWindow,将Gravity属性设置bottom,根背景设置为一个半透明的颜色，
 * 弹出时popupWindow的半透明效果背景覆盖了在Activity之上 给人感觉上是popupWindow弹出后，背景变成半透明
 */
public void openPop2(View view) {
    View popView = LayoutInflater.from(mContext).inflate(
            R.layout.pop_bottom_alpha, null);
    View rootView = findViewById(R.id.root_main); // 當前頁面的根佈局
    final PopupWindow popupWindow = new PopupWindow(popView,
            LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

    // 设置弹出动画
    popupWindow.setAnimationStyle(R.style.AnimationFadeBottom);
    popupWindow.setBackgroundDrawable(new BitmapDrawable());
    // 顯示在根佈局的底部
    popupWindow.showAtLocation(rootView, Gravity.BOTTOM | Gravity.LEFT, 0,
            0);
}