问题描述

当PopupWindow的高度设置为MATCH_PARENT时，showAsDropDown的位置会失效

解决方法

发现问题之后，上网搜了很多解决方案，发现都不能完美解决问题，如以下代码：
方法1.

if (Build.VERSION.SDK_INT >= 24) {
     int[] location = new int[2];
     anchor.getLocationOnScreen(location);
     // 7.1 版本处理
     if (Build.VERSION.SDK_INT == 25) {
         WindowManager windowManager = (WindowManager) pw.getContentView().getContext().getSystemService(Context.WINDOW_SERVICE);
         if (windowManager != null) {
             int screenHeight = windowManager.getDefaultDisplay().getHeight();
             // PopupWindow height for match_parent, will occupy the entire screen, it needs to do special treatment in Android 7.1
             pw.setHeight(screenHeight - location[1] - anchor.getHeight() - yoff);
         }
     }
     pw.showAtLocation(anchor, Gravity.NO_GRAVITY, xoff, location[1] + anchor.getHeight() + yoff);

 } else {
     pw.showAsDropDown(anchor, xoff, yoff);
 }

方法2.

public static void showAsDropDown(final PopupWindow pw, final View anchor, final int xoff, final int yoff) {
    if (Build.VERSION.SDK_INT >= 24) {
        Rect visibleFrame = new Rect();
        anchor.getGlobalVisibleRect(visibleFrame);
        int height = anchor.getResources().getDisplayMetrics().heightPixels - visibleFrame.bottom;
        pw.setHeight(height);
        pw.showAsDropDown(anchor, xoff, yoff);
    } else {
        pw.showAsDropDown(anchor, xoff, yoff);
    }
}

这两种代码如果在含有虚拟按键或者全面屏手机下会存在兼容问题，显示的位置还是错误的

于是就产生了下面的方法

在你的PopupWindow的布局文件底部加一个LinearLayout占位 ,然后高度设置多一点，我这里设置了1000dp

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:id="@+id/ll_root"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:background="#50000000"
              android:orientation="vertical">


    <ListView
        android:id="@+id/lv_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:divider="@null"
        android:background="@color/white"
        android:listSelector="@color/transparent"
        android:scrollbars="none"
        />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="1000dp"
        android:background="#50000000"/>


</LinearLayout>

然后将PopupWindow的高度设置为WRAP_CONTENT, 部分代码如下

	setWidth(LayoutParams.MATCH_PARENT);
	setHeight(LayoutParams.WRAP_CONTENT);
	setContentView(contentView);
	setFocusable(true);
	setOutsideTouchable(true);
	setBackgroundDrawable(new BitmapDrawable());

然后正常调用即可 showAsDropDown(view, 0, 0);

效果图：