How to use animation in viewModels?

lescper

I created a viewmodel for the xaml page.

there is a stackLayout in the xaml I want to animate it in the viewmodels how to do it?

LeonLu

You can transfer page when bindingContext.

 public partial class HorizontalGridPage : ContentPage
    {
        public HorizontalGridPage()
        {
            InitializeComponent();
            BindingContext = new MonkeysViewModel(this);
        }

Then you can get this ContentPage in the ViewModel's constructor. get the control that you want to add animation

 public MonkeysViewModel(HorizontalGridPage horizontalGridPage)
        {
            this.horizontalGridPage = horizontalGridPage;
        }

AlessandroCaliaro

You can use something like
https://stackoverflow.com/a/59152091

but you should not have "Button" inside your ViewModel... So, your ViewModel could use an Action to execute a method in your xaml.cs that execute the animation.

there is also https://github.com/jsuarezruiz/Xamanimation#progress-animations that can help you

LeonLu

You can transfer page when bindingContext.

 public partial class HorizontalGridPage : ContentPage
    {
        public HorizontalGridPage()
        {
            InitializeComponent();
            BindingContext = new MonkeysViewModel(this);
        }

Then you can get this ContentPage in the ViewModel's constructor. get the control that you want to add animation

 public MonkeysViewModel(HorizontalGridPage horizontalGridPage)
        {
            this.horizontalGridPage = horizontalGridPage;
        }

LeonLu

If I have StackLayout I add Name.

 <StackLayout x:Name="mySl" Margin="20">

Then I can get it like following code.

  public MonkeysViewModel(HorizontalGridPage horizontalGridPage)
        {
            this.horizontalGridPage = horizontalGridPage;

         var sl=   horizontalGridPage.Content.FindByName("mySl");
        }

JohnHardman

@lescper said:
I created a viewmodel for the xaml page.

there is a stackLayout in the xaml I want to animate it in the viewmodels how to do it?

Animation should not be done in View Models. Animation is a purely UI thing, so should be in either the XAML or code behind (remembering too that the user should be able to disable animation from accessibility settings).

If you want animation to start/stop as a result of a state change in the View Model, have the View Model raise an event and then have the View react to that event.

JohnHardman

@LeonLu said:
You can transfer page when bindingContext.

 public partial class HorizontalGridPage : ContentPage
    {
        public HorizontalGridPage()
        {
            InitializeComponent();
            BindingContext = new MonkeysViewModel(this);
        }

Then you can get this ContentPage in the ViewModel's constructor. get the control that you want to add animation

 public MonkeysViewModel(HorizontalGridPage horizontalGridPage)
        {
            this.horizontalGridPage = horizontalGridPage;
        }

@lescper

Doing this breaks MVVM, introduces a circular dependency and increases the likelihood of a memory leak if things are not cleaned up appropriately.

View Models should not contain UI logic.