How to set image source via trigger from code behind in wpf

Question

I've something like this in the xaml.

 <Image.Style>
            <Style TargetType="Image">
                <Setter Property="Source" Value="../Images/FolderImage.png" />
                <Style.Triggers>
                    <DataTrigger Binding="{Binding ElementName=img, Path=IsEnabled}" 
                                                                           value="False">
                        <Setter Property="Source" Value="../Images/FolderImage_Disabled.png" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </Image.Style>

and I want to implement the same thing in code behind. I've done the following:

 Style imgStyle = new Style();

        imgStyle.TargetType = typeof(Image);

        Setter imgSetter = new Setter();
        imgSetter.Property = Image.SourceProperty;
        imgSetter.Value = bmpImg;
        imgStyle.Setters.Add(imgSetter);

        disabledImage = new BitmapImage();
        disabledImage.BeginInit();
        disabledImage.UriSource = new Uri("pack://application:,,,/../Images/FolderImage_Disabled.png");
        disabledImage.EndInit();

        DataTrigger trg = new DataTrigger();
        Binding trgBinding = new Binding();
        trgBinding.ElementName = "img";
        trgBinding.Path = new PropertyPath("IsEnabled");
        trg.Value = false;
        trg.Binding = trgBinding;
        imgStyle.Triggers.Add(trg);

        imgSetter = new Setter();
        imgSetter.Property = Image.SourceProperty;
        imgSetter.Value = disabledImage;
        trg.Setters.Add(imgSetter);
        menuIcon.SetValue(Image.StyleProperty, imgStyle);

I get the following error in the VS output

"System.Windows.Data Error: 4 : Cannot find source for binding with 
    reference 'ElementName=img'. BindingExpression:Path=IsEnabled; DataItem=null;
    target element is 'Image' (Name='img'); target property is 'NoTarget' (type 'Object')"

Any help here will be appreciated!

mdm20 · Accepted Answer · 2012-09-27 14:28:26Z

2

I'm not sure why you'd want to do it like that.. but, try setting the binding source.

tryBinding.Source = this;

Here is another way you might want to consider.

create a boolean property in the code behind
bind that property to the IsEnabled property of the img - twoway mode
in the setter of the property, change the source of the image depending on the value.

answered Sep 27, 2012 at 14:28

mdm20

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1 Comment

Alerter Over a year ago

I had to move the xaml part to code behind to reduce the load time. And you are right...due to lack of time, I was blindly following the xaml. Thanks for showing the right way :) Appreciate it :)

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