Xamarin.forms windows phone - 超出浏览器特定设置不会影响浏览器内应用程序

Question

我有2个xaml页面并尝试在1上选择一个图像，并将其设置在另一个页面上。这一切在Android上工作正常，但在Windows手机上产生错误。 我使用Plugin.media插件来选择图像。（https://github.com/jamesmontemagno/Xamarin.Plugins/tree/master/Media）

我有这个功能来选择图像：

async void OnPictoChoose(object sender, EventArgs args)
    {
        if (!removing) 
        {
            //create the new image and entry and the stacklayout to hold them
            Image chosenImage = (Image)sender;
            Label chosenLabel = new Label ();
            StackLayout currentStack = new StackLayout ();

            //find the stacklayout that holds the chosen image and store in currentStack, we need this to find the correct label/entry
            foreach (StackLayout stack in pictoTheek.Children) 
            {
                foreach (var child in stack.Children.OfType<Image>()) 
                {
                    if (child == chosenImage) 
                    {
                        currentStack = stack;
                    }
                }
            }

            //find the entry that belongs to the image in the currentStack and store it in chosenLabel
            foreach (var child in currentStack.Children.OfType<Label>()) 
            {
                chosenLabel = child;
            }

            //find the root page at the top of the navigationStack
            MyPage stepPage = (MyPage)Navigation.NavigationStack [0];
            //set the image and label with the method on the steppage using the chosenImage and chosenLabel
            stepPage.SetImageAndLabel (chosenImage, chosenLabel);
            //close the pictotheek
            await Navigation.PopAsync ();
        } 

你可以看到我在steppage上调用SetImageAndLabel，如下所示：

public void SetImageAndLabel(Image pictotheekImg, Label pictptheekLabel)
    {
        //create stacklayout as placeholder to find the Label
        StackLayout currentStack = new StackLayout();

        //find the currentstack by looking for the selectedimage in the scrollsteps,
        foreach (StackLayout child in scrollSteps.Children) 
        {
            //set the selected image to the image chosen in the pictotheek
            foreach (Image item in child.Children.OfType<Image>()) 
            {
                if (item == selectedImage) 
                {
                    currentStack = child;
                    item.BackgroundColor = Color.Transparent;
                    item.Source = pictotheekImg.Source; 
                }
            }

            //find the label that belongs to the selectedimage in the currentStack and set the text
            foreach (Label label in currentStack.Children.OfType<Label>()) 
            {
                label.Text = pictptheekLabel.Text;
            }
        }
    }

问题出在行item.Source = pictotheekImg.Source中，它产生：'this.MainWindow'抛出了'System.NotSupportedException'类型的异常。

内部异常sais“”null“，它确实有一条sais消息： “超出浏览器特定设置不会影响浏览器内应用程序”

第1页

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="Lisa.Ruben.MyPage">
    <ContentPage.Content>
			<StackLayout>
	        	<ScrollView Orientation="Horizontal" VerticalOptions="FillAndExpand">
		        	<StackLayout Orientation = "Horizontal" VerticalOptions="FillAndExpand" BackgroundColor="White">
		        		<StackLayout Orientation = "Horizontal" BackgroundColor="Transparent" x:Name="scrollSteps" Padding="31,0,31,0"  VerticalOptions="Center">
	        				<!-- dynamicly added images come here -->
	        			</StackLayout>
		        	</StackLayout>
	        	</ScrollView>
	        	<StackLayout Orientation="Horizontal" BackgroundColor="Silver" HeightRequest="75" >
		        	<Button Text = "Add New Step" HorizontalOptions="End" Clicked="AddNewStep" WidthRequest="200"/>
	        		<Button Text = "Remove Step" Clicked="OnRemoveButtonClick" WidthRequest="200" x:Name="removeButton"/>
	        	</StackLayout>
	   	 	</StackLayout>
	</ContentPage.Content>
</ContentPage>

第2页：

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="Lisa.Ruben.PictotheekPage">
	<ContentPage.Content>
		<StackLayout>
			<ScrollView Orientation="Horizontal" VerticalOptions="CenterAndExpand" x:Name="pictoScroll">
     			<StackLayout Orientation = "Horizontal" BackgroundColor="White" VerticalOptions="CenterAndExpand" Padding="15,15,0,20"  x:Name="pictoTheek">
	    			<StackLayout>
				       	<Image Source="alien.jpg" WidthRequest="260" HeightRequest="226"  VerticalOptions="Center">
		       				<Image.GestureRecognizers>
		       					<TapGestureRecognizer NumberOfTapsRequired="1" Tapped="OnPictoChoose"/>
		       				</Image.GestureRecognizers>
		       			</Image>
	    				<Label Text="alien" BackgroundColor="Black" TextColor="White" VerticalOptions="Center" HorizontalTextAlignment="Center" />    			
	        		</StackLayout>
	        		<StackLayout>	
	        			<Image Source="levelup.jpg" WidthRequest="260" HeightRequest="226" VerticalOptions="Center" >
	        				<Image.GestureRecognizers>
	        					<TapGestureRecognizer NumberOfTapsRequired="1" Tapped="OnPictoChoose"/>
	        				</Image.GestureRecognizers>
	        			</Image>
	        			<Label Text="level up" BackgroundColor="Black" TextColor="White" VerticalOptions="Center" HorizontalTextAlignment="Center"/>
	        		</StackLayout>
	        		<StackLayout>
	        			<Image Source="bloem.jpg" WidthRequest="260" HeightRequest="226" VerticalOptions="Center" >
	        				<Image.GestureRecognizers>
	        					<TapGestureRecognizer NumberOfTapsRequired="1" Tapped="OnPictoChoose"/>
	        				</Image.GestureRecognizers>
	        			</Image>
	        			<Label Text="bloem" BackgroundColor="Black" TextColor="White" VerticalOptions="Center" HorizontalTextAlignment="Center"/>
	        		</StackLayout>
	        		<StackLayout>
	        			<Image Source="mario.jpg" WidthRequest="260" HeightRequest="226" VerticalOptions="Center">
	        				<Image.GestureRecognizers>
	        					<TapGestureRecognizer NumberOfTapsRequired="1" Tapped="OnPictoChoose"/>
	        				</Image.GestureRecognizers>
	        			</Image>
	        			<Label Text="mario" BackgroundColor="Black" TextColor="White" VerticalOptions="Center" HorizontalTextAlignment="Center"/>
	        		</StackLayout>
	        		<StackLayout>
	        			<Image Source="chrome.jpg" WidthRequest="260" HeightRequest="226" VerticalOptions="Center">
	        				<Image.GestureRecognizers>
	        					<TapGestureRecognizer NumberOfTapsRequired="1" Tapped="OnPictoChoose"/>
	        				</Image.GestureRecognizers>
	        			</Image>
	        			<Label Text="chrome" BackgroundColor="Black" TextColor="White" VerticalOptions="Center" HorizontalTextAlignment="Center" />
	        		</StackLayout>
	        		<StackLayout>
	        			<Image Source="circle.jpg" WidthRequest="260" HeightRequest="226" VerticalOptions="Center">
	        				<Image.GestureRecognizers>
	        					<TapGestureRecognizer NumberOfTapsRequired="1" Tapped="OnPictoChoose"/>
	        				</Image.GestureRecognizers>
	        			</Image>
        			<Label Text="circle" BackgroundColor="Black" TextColor="White" VerticalOptions="Center" HorizontalTextAlignment="Center"/>
        			</StackLayout>
        		</StackLayout>
    		</ScrollView>
        	<StackLayout Orientation="Horizontal" BackgroundColor="Silver" HeightRequest="75" x:Name="buttonBar">
				<Button Text = "Add New Picto" Clicked="AddNewPicto" WidthRequest="150" VerticalOptions="Center"/>
				<Button Text = "Create New Picto" Clicked="CreateNewPicto" WidthRequest="150" VerticalOptions="Center"/>
				<Button Text = "Remove Picto" Clicked="OnRemovePictoClick" WidthRequest="150" VerticalOptions="Center" x:Name="removePictoButton"/>
	        </StackLayout>
	   	</StackLayout>
	</ContentPage.Content>
</ContentPage>