Cannot implicitly convert type 'string' to 'Windows.UI.Xaml.Media.Imaging.BitmapImage

问题

I am trying to show an image stored in local directory inside XAML design.

I have the path to local image.

ImagePage.xaml

<ScrollViewer>
    <ListView x:Name="ViewImage" SelectionMode="None" IsActiveView="True">
        <ListView.ItemsPanel>
             <ItemsPanelTemplate>
                 <WrapGrid Orientation="Horizontal" MaximumRowsOrColumns="1" />
             </ItemsPanelTemplate>
        </ListView.ItemsPanel>
        <ListView.ItemTemplate>
             <DataTemplate>
                 <Grid x:Name="imgGrid">
                      <Grid.RowDefinitions>
                          <RowDefinition Height="Auto" />
                          <RowDefinition Height="Auto" />
                      </Grid.RowDefinitions>
                      <StackPanel>
                          <Grid Height="50" Width="50">
                              <Grid Margin="2" Background="red">
                                  <Image Source="{Binding imgArt}" Stretch="UniformToFill"
                                         Height="40" Width="40"/>
                              </Grid>
                          </Grid>
                      </StackPanel>
                 </Grid>
             </DataTemplate>
         </ListView.ItemTemplate>
     </ListView>
</ScrollViewer>

ImagePage.xaml.cs

string strImgPath = "ms-appx:///Images/Music/localImg.png";
public string imgPath
{
     get { return strImgPath; }
}
imageClaz obj = new imageClaz();
obj.imgArt = imgPath;

imageClaz()

public class imageClaz
{
     public string imgArt { get; set; }
}

回答1:

You should use Windows.UI.Xaml.Media.Imaging.BitmapImage if you are targeting WinRT app.

Just change the imgArt froms string to BitmapImage

public class imageClaz
{
     public BitmapImage imgArt { get; set; }
}

and set the Image like this,

    string strImgPath = "ms-appx:///Images/Music/localImg.png";
    imageClaz obj = new imageClaz();
    obj.imgArt = new BitmapImage(new Uri(strImgPath, UriKind.Absolute));

回答2:

Both answers about BitmapImage are only partially right. In fact XAML has a build in converter and you can surely pass there a string unless you provide a converter. There may be several problems in your code:

you are not notifying UI about the change of the property - lack of INotifyPropertyChanged:

Example :

public sealed partial class MainPage : Page, INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string name)
    {
        if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(name));
    }
}

private string imgArt;

public string ImgArt
{
    get { return imgArt; }
    set { imgArt = value; OnPropertyChanged("ImgArt"); }
}

the second thing - I'm not sure if you had set the DataContext of image or its parents:
```
public MainPage()
{
    this.InitializeComponent();
    DataContext = this;
} 
```

A sample you can download from GitHub.

回答3:

Source is of type ImageSource, not string. You can set the view model with something like this:

public class ImageClaz
{
    public ImageClaz(Uri uri)
    {
        this.ImgArt = new BitmapImage(uri);
    }

    public ImageSource ImgArt { get; set; }
}

Where you use the path to create the Uri:

var imgeClass = new ImageClaz(new Uri("ms-appx:///Images/Music/localImg.png"));

来源：https://stackoverflow.com/questions/27163604/cannot-implicitly-convert-type-string-to-windows-ui-xaml-media-imaging-bitmap

标签

xaml

windows-phone-8

windows-phone-8.1