MAUI Blazor Android 输入框软键盘遮挡问题

前言

最近才发现MAUI Blazor Android存在输入框软键盘遮挡这个问题，搜索了一番，原来这是安卓webview一个由来已久的问题，还好有大佬提出了解决方案 AndroidBug5497Workaround，但是这是Java代码，MAUI中需要做一些小的修改，修改一些方法名还有类的明确引用。废话不多说，直接上代码。.

解决方案

第一步

将下面的代码添加到Platforms/Android文件夹中，注意using ，一个也不能少，我最开始就是因为缺少using Rect = Android.Graphics.Rect;没有成功。命名空间也别忘了更改。

using Android.App;
using Android.Widget;
using static Android.Resource;
using Rect = Android.Graphics.Rect;
using View = Android.Views.View;

namespace MauiApp3.Platforms.Android
{
    public class AndroidBug5497Workaround
    {

        // For more information, see https://code.google.com/p/android/issues/detail?id=5497
        // To use this class, simply invoke assistActivity() on an Activity that already has its content view set.

        public static void AssistActivity(Activity activity)
        {
            new AndroidBug5497Workaround(activity);
        }

        private View mChildOfContent;
        private int usableHeightPrevious;
        private FrameLayout.LayoutParams frameLayoutParams;

        private AndroidBug5497Workaround(Activity activity)
        {
            FrameLayout content = (FrameLayout)activity.FindViewById(Id.Content);
            mChildOfContent = content.GetChildAt(0);
            mChildOfContent.ViewTreeObserver.GlobalLayout += (s, o) => PossiblyResizeChildOfContent();
            frameLayoutParams = (FrameLayout.LayoutParams)mChildOfContent.LayoutParameters;
        }

        private void PossiblyResizeChildOfContent()
        {
            int usableHeightNow = ComputeUsableHeight();
            if (usableHeightNow != usableHeightPrevious)
            {
                int usableHeightSansKeyboard = mChildOfContent.RootView.Height;
                int heightDifference = usableHeightSansKeyboard - usableHeightNow;
                if (heightDifference > (usableHeightSansKeyboard / 4))
                {
                    // keyboard probably just became visible
                    frameLayoutParams.Height = usableHeightSansKeyboard - heightDifference;
                }
                else
                {
                    // keyboard probably just became hidden
                    frameLayoutParams.Height = usableHeightSansKeyboard;
                }
                mChildOfContent.RequestLayout();
                usableHeightPrevious = usableHeightNow;
            }
        }

        private int ComputeUsableHeight()
        {
            Rect r = new Rect();
            mChildOfContent.GetWindowVisibleDisplayFrame(r);
            return (int)(r.Bottom - r.Top);// 全屏模式下：return r.bottom
        }

    }
}

第二步

Platforms/Android/MainActivity.cs中添加以下代码

protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        AndroidBug5497Workaround.AssistActivity(this);
    }

后记

网上还有一些其他人针对底部导航栏和华为的修复，貌似加的也不多，参考着改改就能用了