MVVM Xamarin Forms - 绑定视图模型属性的命令参数

Question

I have the following image with an tap gesture recognizer that calls an command from the View Model:

<Image IsVisible="False" Aspect="Fill" Grid.Column="1" HorizontalOptions="Start" VerticalOptions="Center" Source="po.png" x:Name="img2">
    <Image.GestureRecognizers>
        <TapGestureRecognizer x:Name="gRcgImg2" Command="{Binding FalaCommand}" CommandParameter="po" />
    </Image.GestureRecognizers>
</Image>

I need to change that command parameter when another image is clicked, and I need to do it all by the view model, could you provide me ways to do that?

Answer 1

The best way is bind some value that has this information. For example, you can pass Image.Source and add correct behavior inside your code. For Example:

CommandParameter="{Binding Image.Source RelativeSource={RelativeSource AncestorType=Image}}"

with this you can filter and detect what image is sending the tap command.

[edited] here, how you can change Image.Source from command:

public ICommand MyCommand => new Command((ImageSource) obj) =>
{
    obj = ImageSource.FromFile(filename);
});

Maybe you'll need refresh image, I'm not sure.