如何在 xamarin 表单（android）上显示共享文件夹中的图像？

Question

我在 xamarin 表单上显示图像时遇到问题。图像存储在我们网络上的共享文件夹中。我正在使用 Sharpcifs。

以下是相关视图模型的代码：

ImageSource ProductImage { get; set; }


    public ProductPositionsViewModel()
    {
        Title = "Produit/Pos";
        Items = new ObservableCollection<ListItem>();

        SharpCifs.Config.SetProperty("jcifs.smb.client.lport", "8080");

        //Get Auth
        var auth = new NtlmPasswordAuthentication("Domain","User","Password");

        //Get target's SmbFile.
        var smb = new SmbFile("smb://file/products/ABY/ABYBAG167.jpg", auth);

        Console.WriteLine($"exists? {smb.Exists()}");
        // It returns true, I can confirm.

        //Get readable stream.
        var readStream = smb.GetInputStream();

        
        

        //Create reading buffer.
        var memStream = new MemoryStream();

        //Get bytes.
        ((Stream)readStream).CopyTo(memStream);

        using (MemoryStream memorystream = memStream)
        {

            ProductImage = ImageSource.FromStream(() => memorystream);
        }

        

        //Dispose readable stream.
        readStream.Dispose();

        LoadItemsCommand = new Command(async () => await ExecuteLoadItemsCommand());
    }

我用泛型替换了域、用户名和密码。我确实使用了正确的域名、用户名和密码。 并在 xaml 中：

<?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:d="http://xamarin.com/schemas/2014/forms/design"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         mc:Ignorable="d"
         x:Class="Picking.Views.ProductPositionsPage"
         Title="{Binding Title}">


<ContentPage.Content>


    <Grid RowSpacing="0">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="70"/>
        </Grid.RowDefinitions>

        <Image Grid.Row="0" Source="{Binding ProductImage}"/>


    </Grid>




</ContentPage.Content>
</ContentPage>

Answer 1

如果你想在运行时设置Image的Source，别忘了在你的ViewModel中实现INotifyPropertyChanged接口

public class ProductPositionsViewModel: INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;


  
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    ImageSource productImage;

    ImageSource ProductImage { 
        
        get
        {
            return productImage;
        }

        set
        {
            if(productImage!=value)
            {
                productImage = value;
                OnPropertyChanged("ProductImage");
            }
        }
    }


    public ProductPositionsViewModel()
    {

        //...
      
        using (MemoryStream memorystream = memStream)
        {

            ProductImage = ImageSource.FromStream(() => {
                
                 //...  // whatever you need to do to create your stream

           });
        }
    }

}