Xamarin Forms content page make background color transparent

问题

I have a requirement where in I need to display a list in a modal popup page.I am able to display a list but I cant make the background color transparent or semi transparent so that the page under it is partially visible.

I am pushing the page from my View Model using the folowing:

NavigationParameters oNavParams = new NavigationParameters();
oNavParams.Add("Mode", "FeedBack");
oNavParams.Add("selectedItem", txtFeedback);
_navigationService.NavigateAsync("PopupBox", oNavParams);

Here is my xaml code:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
             xmlns:local="clr-namespace:MyApp"
             prism:ViewModelLocator.AutowireViewModel="True"
             x:Class="MyApp.Views.PopupBox">
    <ContentPage.Content>
        <AbsoluteLayout Padding="0" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
            <ContentView x:Name="popupListView" BackgroundColor="Transparent" Padding="10, 0" IsVisible="false" AbsoluteLayout.LayoutBounds="0, 0, 1, 1" AbsoluteLayout.LayoutFlags="All">
                <StackLayout VerticalOptions="Center" HorizontalOptions="Center">
                    <StackLayout Orientation="Vertical" HeightRequest="200" WidthRequest="300" BackgroundColor="White">
                        <ListView x:Name="sampleList">
                        </ListView>
                    </StackLayout>
                </StackLayout>
            </ContentView>
        </AbsoluteLayout>
    </ContentPage.Content>
</ContentPage>

Here is my code behind:

  public PopupBox()
        {
            try
            {
                InitializeComponent();
                NavigationPage.SetHasNavigationBar(this, false);
                sampleList.ItemsSource = new List<string>
            {
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView",
                "Test ListView"
            };

                 popupListView.IsVisible = true;


            }
            catch (Exception ex)
            {

            }
            }

Here is the output:

I have also tried setting the following:

  this.BackgroundColor= new Color(0, 0, 0, 0.4);

But it does not work.Is there any way I can achieve this?Using custom renderers or any other workaround to display a modal. I don't wan't to use the Rg.Plugins.Popup as I had issues with it.So I was looking for an alternative.Please help.

回答1:

This will not work without custom renderers. A common way of obtaining the desired today is simply using Popup Page Plugin for Xamarin Forms (https://github.com/rotorgames/Rg.Plugins.Popup) nuget Rg.Plugins.Popup available.

回答2:

As per @nicks comment please make changes into your code I will add few sample line of code that may help you.Rg.Plugins.Popup use this plugin and remove ContentPage add this one.

<?xml version="1.0" encoding="utf-8" ?>
<pages:PopupPage 
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:pages="clr-namespace:Rg.Plugins.Popup.Pages;assembly=Rg.Plugins.Popup"
    xmlns:animations="clr-namespace:Rg.Plugins.Popup.Animations;assembly=Rg.Plugins.Popup">

           <ListView x:Name="lst" BackgroundColor="Gray"  HasUnevenRows="True" >
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <ViewCell>
                            <Grid HorizontalOptions="FillAndExpand" Padding="10" BackgroundColor="White">
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                </Grid.RowDefinitions>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="Auto"/>
                                    <ColumnDefinition Width="Auto"/>
                                </Grid.ColumnDefinitions>
                                <Label Text="{Binding DisplayName}" HorizontalOptions="StartAndExpand" Grid.Row="0"  Grid.Column="0" FontAttributes="Bold"/>
                                <Label Text="{Binding DisplayContact}" HorizontalOptions="EndAndExpand" Grid.Row="0" Grid.Column="1" FontSize="11"/>
                                <Label Text="{Binding DisplayAddress}" VerticalOptions="StartAndExpand" Grid.Row="1" Grid.Column="0" FontSize="11"/>
                            </Grid>
                        </ViewCell>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>
</pages:PopupPage>

.cs file

using Rg.Plugins.Popup.Extensions;
using Rg.Plugins.Popup.Pages;

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class className : PopupPage
{

}

So after last invoking above class as a popup from a button click etc. so below is code

using Rg.Plugins.Popup.Extensions;
{
ClassName _className = new ClassName();
void Button1Click(object sender, System.EventArgs e)
  {
    Navigation.PushPopupAsync(_className);
   }
}

Hope this will help you!!!!

回答3:

As previously mentioned, you can use Rg.Plugins.Popup, and then just set the background as transparent as in the image (so that it is not just opaque).

Example of my popup page:

And on click:

Device.BeginInvokeOnMainThread(async () =>
        {
          Task<yourPopUpPage> task = Task.Run(() =>
          {
            return new yourPopUpPage();
          });

          task.Wait();

          if (task.Status == TaskStatus.RanToCompletion)
          {
            Device.BeginInvokeOnMainThread(async () =>
            {
              await App.GetCurrentPage().Navigation.PushPopupAsync(task.Result);
            });
          };
        });

回答4:

If you update to Xamarin Forms 4.6 you can set:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage
...
BackgroundColor="Transparent"
xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
ios:Page.ModalPresentationStyle="OverFullScreen">

<StackLayout HorizontalOptions="FillAndExpand"

</StackLayout>

</ContentPage>

and it works. Pull Request: https://github.com/xamarin/Xamarin.Forms/pull/8551

来源：https://stackoverflow.com/questions/52159573/xamarin-forms-content-page-make-background-color-transparent