I am having some trouble binding in Image to my viewmodel. I finally got rid of the XamlParseException, but the image does not come up. I even hard coded the image in the ViewModel. Can someone see what I am doing wrong?
View:
<Image HorizontalAlignment="Left" Margin="0,0,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Bottom" Grid.Row="8" Width="200" Grid.ColumnSpan="2" > <Image.Source> <BitmapImage DecodePixelWidth="200" UriSource="{Binding Path=DisplayedImage, Mode=TwoWay}" /> </Image.Source>
ViewModel:
string _DisplayedImagePath = @"C:\Users\Public\Pictures\Sample Pictures\Chrysanthemum.jpg";//string.Empty; int _DisplayedImageIndex; BitmapImage _DisplayedImage = null; public BitmapImage DisplayedImage { get { _DisplayedImage = new BitmapImage(); if (!string.IsNullOrEmpty(_DisplayedImagePath)) { _Rail1DisplayedImage.BeginInit(); _Rail1DisplayedImage.CacheOption = BitmapCacheOption.OnLoad; _Rail1DisplayedImage.CreateOptions = BitmapCreateOptions.IgnoreImageCache; _Rail1DisplayedImage.UriSource = new Uri(_DisplayedImagePath); _Rail1DisplayedImage.DecodePixelWidth = 200; _Rail1DisplayedImage.EndInit(); } return _Rail1DisplayedImage; } set { _Rail1DisplayedImage = value; OnPropertyChanged("DisplayedImage"); } }
MVVM – WPF Data Bindings For data binding you need to have a view or set of UI elements constructed, and then you need some other object that the bindings are going to point to. The UI elements in a view are bound to the properties which are exposed by the ViewModel.
Data binding is a mechanism in WPF applications that provides a simple and easy way for Windows Runtime apps to display and interact with data. In this mechanism, the management of data is entirely separated from the way data. Data binding allows the flow of data between UI elements and data object on user interface.
In One Way binding, source control updates the target control, which means if you change the value of the source control, it will update the value of the target control. So, in our example, if we change the value of the slider control, it will update the textbox value, as shown below.
Displaying an Image
in WPF is much easier than that. Try this:
<Image Source="{Binding DisplayedImagePath}" HorizontalAlignment="Left" Margin="0,0,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Bottom" Grid.Row="8" Width="200" Grid.ColumnSpan="2" />
And the property can just be a string
:
public string DisplayedImage { get { return @"C:\Users\Public\Pictures\Sample Pictures\Chrysanthemum.jpg"; } }
Although you really should add your images to a folder named Images
in the root of your project and set their Build Action to Resource in the Properties Window in Visual Studio... you could then access them using this format:
public string DisplayedImage { get { return "/AssemblyName;component/Images/ImageName.jpg"; } }
UPDATE >>>
As a final tip... if you ever have a problem with a control not working as expected, simply type 'WPF', the name of that control and then the word 'class' into a search engine. In this case, you would have typed 'WPF Image Class'. The top result will always be MSDN and if you click on the link, you'll find out all about that control and most pages have code examples as well.
UPDATE 2 >>>
If you followed the examples from the link to MSDN and it's not working, then your problem is not the Image
control. Using the string
property that I suggested, try this:
<StackPanel> <Image Source="{Binding DisplayedImagePath}" /> <TextBlock Text="{Binding DisplayedImagePath}" /> </StackPanel>
If you can't see the file path in the TextBlock
, then you probably haven't set your DataContext
to the instance of your view model. If you can see the text, then the problem is with your file path.
UPDATE 3 >>>
In .NET 4, the above Image.Source
values would work. However, Microsoft made some horrible changes in .NET 4.5 that broke many different things and so in .NET 4.5, you'd need to use the full pack
path like this:
<Image Source="pack://application:,,,/AssemblyName;component/Images/image_to_use.png">
For further information on pack URIs, please see the Pack URIs in WPF page on Microsoft Docs.
@Sheridan thx.. if I try your example with "DisplayedImagePath" on both sides, it works with absolute path as you show.
As for the relative paths, this is how I always connect relative paths, I first include the subdirectory (!) and the image file in my project.. then I use ~ character to denote the bin-path..
public string DisplayedImagePath { get { return @"~\..\images\osc.png"; } }
This was tested, see below my Solution Explorer in VS2015..
)
Note: if you want a Click event, use the Button tag around the image,
<Button Click="image_Click" Width="128" Height="128" Grid.Row="2" VerticalAlignment="Top" HorizontalAlignment="Left"> <Image x:Name="image" Source="{Binding DisplayedImagePath}" Margin="0,0,0,0" /> </Button>
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