Loxodonframework quick start

One 、 brief introduction

LoxodonFramework What is it? , What is it for . I won't introduce it here , Direct up link ：vovgou/loxodon-framework: An MVVM & Databinding framework that can use C# and Lua to develop games (github.com)

There is a full introduction and tutorial in the link , This article mainly records the experience of learning and understanding the framework .

Two 、 Quick start

I have used it before WPF Of MVVM frame –Prism, So in unity Also want to find a similar framework , that LoxodonFramework Can it also be like Prism So easy to use ？ Now we can simply try .

3、 ... and 、 Example

We have created the above project , Want to do such a thing ： After entering a value in the input box, the slider will slide to the corresponding value , When the slider slides, the input box will display the corresponding value .

Just imagine , If not applicable MVVM Thought , We can mount a script , These two controls are found in the script properties , Then assign values to each other during operation , This should be a very simple job . But use MVVM How should I do it ？

3.1Model

Because the data model of the example is very simple , Basic data types can be used , So this layer is omitted .

3.2ViewModel

This layer is our interaction logic . Data update and event response logic code are here .

3.3View

Here is UI layer , Only controls are involved , It does not involve data business . Let's talk about the train of thought , Usually in UI Control to mount a script , This script is what we need View layer , Of course, it will inherit UIView class , Then bind in the script . Binding is mainly to UI The properties or events of the control are bound to ViewModel Properties or methods in . therefore ViewModel It's not a script , There is no need to mount on the control .

Then take a look at the specific implementation of the code ：

public class SampleViewModel : ViewModelBase
{
    
    private float sliderValue;
    public float SliderValue
    {
    
        get {
     return sliderValue; }
        set {
     Set<float>(ref sliderValue, value, "SliderValue"); }
    }

    public void OnSliderValueChanged(float newValue)
    {
    
        if (newValue != sliderValue)
        {
    
            this.SliderValue = newValue;
            Debug.Log($"NewValue:{
      newValue}");
        }
    }

    public void OnInputFieldChanged(string str)
    {
    
        this.SliderValue = int.Parse(str);

    }
}

public class SampleView : UIView
{
    
    public InputField input;
    public Slider slider;

    protected override void Awake()
    {
    
        // Get the application context 
        ApplicationContext context = Context.GetApplicationContext();
        // Start the data binding service 
        BindingServiceBundle bindingService = new BindingServiceBundle(context.GetContainer());
        bindingService.Start();
    }

    protected override void Start()
    {
    
        // Get the data binding context 
        IBindingContext bindingContext = this.BindingContext();
        bindingContext.DataContext = new SampleViewModel {
     SliderValue = 98 };

        // binding UI Control to view model 
        BindingSet<SampleView, SampleViewModel> bindingSet;
        bindingSet = this.CreateBindingSet<SampleView, SampleViewModel>();

        // take VM The value in is bound to UI Controls , Note that here is one-way binding vm=>v
        bindingSet.Bind(this.input).For(v => v.text).To(vm => vm.SliderValue).OneWay();
        bindingSet.Bind(this.slider).For(v => v.value).To(vm => vm.SliderValue).OneWay();
        
        // Then bind the event of the control to vm The methods of , Be careful To To use generics , The parameters of the method are consistent with those of the event method .
        // Of course, it can also be bound to commands （ Later we will introduce ）
        bindingSet.Bind(this.slider).For(v => v.onValueChanged).To<float>(vm => vm.OnSliderValueChanged);
        bindingSet.Bind(this.input).For(v => v.onEndEdit).To<string>(vm=>vm.OnInputFieldChanged);

        // This sentence should not be forgotten 
        bindingSet.Build();
    }
}

The idea of binding is similar .

Four 、 About binding

There is such a piece of code in the above example ：

        // Get the data binding context 
        IBindingContext bindingContext = this.BindingContext();
        bindingContext.DataContext = new SampleViewModel {
     SliderValue = 98 };

The above code can also be modified as follows ：

this.SetDataContext(new SampleViewModel {
     SliderValue = 98 });

Behaviour Class extends SetDataContext Method , Its internal implementation also uses IBindingContext Interface .
Yes WPF Bound students must be familiar , you 're right , There's also DataContext The concept of . About DataContext, The author of the framework has such a description in the document :

Generally speaking, data binding is initialized in the view creation function , adopt BindingSet To configure the binding relationship between the view control and the view model , When calling BindingSet Of Build Function time ,
Binder Will create BindingSet All binding pairs in , The created binding pair will be saved in the current view BindingContext in .BindingContext Automatically create on the first call , Same as
Automatically generates a BindingContextLifecycle Script , Hang on the current view object , It controls BindingContext Life cycle of , When the view is destroyed ,BindingContext Meeting
And then destroy it , Store in BindingContext The binding relationship pairs in will also be destroyed .

therefore , about View Layer of DataContext, We can set it externally , Or later changes , It is not necessarily the same as the example in build Set it up .