如何解决我从全屏webview视频页面回来的问题

Question

我有一个页面，显示一个ListView的视频，从网址获得像这样的WebView细胞：

            <ListView HasUnevenRows="True">
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <ViewCell>
                            <StackLayout BackgroundColor="Transparent" Margin="15,0,15,15">
                                <controls:FullScreenEnabledWebView VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" Source="{Binding viewSource}"/>
                            </StackLayout>
                        </ViewCell>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>

其中controls:FullScreenEnabledWebView是这样的自定义渲染：

   public class FullScreenEnabledWebView : WebView
        {
            public event Action action = delegate { };
            public static readonly BindableProperty EnterFullScreenCommandProperty =
                BindableProperty.Create(
                    nameof(EnterFullScreenCommand),
                    typeof(ICommand),
                    typeof(FullScreenEnabledWebView));

            public static readonly BindableProperty ExitFullScreenCommandProperty =
                BindableProperty.Create(
                    nameof(ExitFullScreenCommand),
                    typeof(ICommand),
                    typeof(FullScreenEnabledWebView));

            public ICommand EnterFullScreenCommand
            {
                get => (ICommand)GetValue(EnterFullScreenCommandProperty); 
                set => SetValue(EnterFullScreenCommandProperty, value); 
            }


            public ICommand ExitFullScreenCommand
            {
                get => (ICommand)GetValue(ExitFullScreenCommandProperty);
                set => SetValue(ExitFullScreenCommandProperty, value);
            }

            public FullScreenEnabledWebView()
            {
                this.EnterFullScreenCommand = new Command<View>(DefaultEnterAsync);
                this.ExitFullScreenCommand = new Command(DefaultExitAsync);
            }


            private async void DefaultEnterAsync(View view)
            {
                var page = new FullScreenVideoPage()
                {

                    Content = view,
                };
                page.BackButtonPressed += () => { action.Invoke(); };
                await Application.Current.MainPage.Navigation.PushModalAsync(page);
            }

            private async void DefaultExitAsync()
            {
                await Application.Current.MainPage.Navigation.PopModalAsync();
            }
  }

和我的android代码：

[assembly: ExportRenderer(typeof(HBRS.Controls.FullScreenEnabledWebView),typeof(FullScreenEnabledWebViewRenderer))]
namespace HBRS.Droid.Renderers.Controls
{
    public class FullScreenEnabledWebViewRenderer : WebViewRenderer
    {
        private FullScreenEnabledWebView _webView;
        FullScreenEnabledWebChromeClient client;
        public FullScreenEnabledWebViewRenderer(Context context) : base(context)
        {
        }

        /// <inheritdoc/>
        protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
        {
            base.OnElementChanged(e);
            _webView = (FullScreenEnabledWebView)e.NewElement;
            _webView.action += client.OnHideCustomView;
        }
        protected override FormsWebChromeClient GetFormsWebChromeClient()
        {
            client = new FullScreenEnabledWebChromeClient();
            client.EnterFullscreenRequested += OnEnterFullscreenRequested;
            client.ExitFullscreenRequested += OnExitFullscreenRequested;
            return client;
        }
        private void OnEnterFullscreenRequested(
            object sender,
            EnterFullScreenRequestedEventArgs eventArgs)
        {
            if (_webView.EnterFullScreenCommand != null && _webView.EnterFullScreenCommand.CanExecute(null))
            {
                _webView.EnterFullScreenCommand.Execute(eventArgs.View.ToView());
            }
        }
        private void OnExitFullscreenRequested(object sender, EventArgs eventArgs)
        {
            if (_webView.ExitFullScreenCommand != null && _webView.ExitFullScreenCommand.CanExecute(null))
            {
                _webView.ExitFullScreenCommand.Execute(null);
            }
        }
    }
}

其中FullScreenEnabledWebChromeClient是：

public class FullScreenEnabledWebChromeClient : FormsWebChromeClient
    {
        public event EventHandler<EnterFullScreenRequestedEventArgs> EnterFullscreenRequested;
        public event EventHandler ExitFullscreenRequested;
        public override void OnHideCustomView()
        {
            base.OnHideCustomView();
            ExitFullscreenRequested?.Invoke(this, EventArgs.Empty);
        }
        public override void OnShowCustomView(View view, ICustomViewCallback callback)
        {
            base.OnShowCustomView(view,callback);
            EnterFullscreenRequested?.Invoke(this, new EnterFullScreenRequestedEventArgs(view));
        }
        public override bool OnCreateWindow(WebView view, bool isDialog, bool isUserGesture, Message resultMsg)
        {
            return base.OnCreateWindow(view, isDialog, isUserGesture, resultMsg);
        }
    }

除了下面的场景外，整个过程都很好：1。列表视图显示视频。 2.打开一些视频全屏。 3.通过使用Android设备返回按钮，而不更改它打开全屏之前的视频状态。 4.WebView将是黑色的黑屏，我不知道为什么!!!

但是当使用webview按钮关闭全屏时它工作正常，当我改变视频状态（暂停播放或反之亦然）时，至少一次然后通过使用Android设备返回按钮返回它也很好用！。有一些帮助吗？

Answer 1

问题应该是当你点击后退按钮时，webview视频也是全屏状态。所以你需要在点击后退按钮时退出全屏。 Android Back按钮可以覆盖如下：

public override void OnBackPressed()
{
    if (Fullscreen)
    {
        exitFullscreen();
        //if is fullscreen ,need to exit 
    }else
    {
        if (mWebView != null)
        {
            mWebView.onPause();
            backToFrontPage();
            //if a small screen, best pause webview first,then back to frontpage       
        }
    }

    base.OnBackPressed();
}

Answer 2

它只需要关注内容。

在FullScreenEnabledWebview类中有以下乐趣：

private async void DefaultEnterAsync(View view)
{
    var page = new FullScreenVideoPage()
    {
        Content = view,
    };
    page.BackButtonPressed += () => { action.Invoke(); };
    await Application.Current.MainPage.Navigation.PushModalAsync(page);
}

只需将其修改为：

private async void DefaultEnterAsync(View view)
{
    var page = new FullScreenVideoPage()
    {
        Content = view,
    };
    page.BackButtonPressed += () => { action.Invoke(); };
    await Application.Current.MainPage.Navigation.PushModalAsync(page);
    page.Content.Focus();
}

有关更多信息，请参阅https://github.com/mhaggag/XFAndroidFullScreenWebView，并查看问题（它与相同的存储库相关）：https://github.com/mhaggag/XFAndroidFullScreenWebView/issues/3