Connected.Components/Components/Overlay/Overlay.razor.cs

using System.Windows.Input;
using Connected.Annotations;
using Connected.Utilities;
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;

namespace Connected.Components;

public partial class Overlay : UIComponent, IDisposable
{
   private bool _visible;

   protected string Classname =>
      new CssBuilder("mud-overlay")
         .AddClass("mud-overlay-absolute", Absolute)
         .AddClass(Class)
         .Build();

   protected string ScrimClassname =>
      new CssBuilder("mud-overlay-scrim")
         .AddClass("mud-overlay-dark", DarkBackground)
         .AddClass("mud-overlay-light", LightBackground)
         .Build();

   protected string Styles =>
      new StyleBuilder()
      .AddStyle("z-index", $"{ZIndex}", ZIndex != 5)
      .AddStyle(Style)
      .Build();

   [Inject] public IScrollManager ScrollManager { get; set; }

   /// <summary>
   /// Child content of the component.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public RenderFragment ChildContent { get; set; }

   /// <summary>
   /// Fires when Visible changes
   /// </summary>
   [Parameter]
   public EventCallback<bool> VisibleChanged { get; set; }

   /// <summary>
   /// If true overlay will be visible. Two-way bindable.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public bool Visible
   {
      get => _visible;
      set
      {
         if (_visible == value)
            return;
         _visible = value;
         VisibleChanged.InvokeAsync(_visible);
      }
   }

   /// <summary>
   /// If true overlay will set Visible false on click.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.ClickAction)]
   public bool AutoClose { get; set; }

   /// <summary>
   /// If true (default), the Document.body element will not be able to scroll
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public bool LockScroll { get; set; } = true;

   /// <summary>
   /// The css class that will be added to body if lockscroll is used.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public string LockScrollClass { get; set; } = "scroll-locked";

   /// <summary>
   /// If true applys the themes dark overlay color.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public bool DarkBackground { get; set; }

   /// <summary>
   /// If true applys the themes light overlay color.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public bool LightBackground { get; set; }

   /// <summary>
   /// Icon class names, separated by space
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public bool Absolute { get; set; }

   /// <summary>
   /// Sets the z-index of the overlay.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.Behavior)]
   public int ZIndex { get; set; } = 5;

   /// <summary>
   /// Command parameter.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.ClickAction)]
   public object CommandParameter { get; set; }

   /// <summary>
   /// Command executed when the user clicks on an element.
   /// </summary>
   [Parameter]
   [Category(CategoryTypes.Overlay.ClickAction)]
   public ICommand Command { get; set; }

   /// <summary>
   /// Fired when the overlay is clicked
   /// </summary>
   [Parameter]
   public EventCallback<MouseEventArgs> OnClick { get; set; }
   protected internal void OnClickHandler(MouseEventArgs ev)
   {
      if (AutoClose)
         Visible = false;
      OnClick.InvokeAsync(ev);
      if (Command?.CanExecute(CommandParameter) ?? false)
      {
         Command.Execute(CommandParameter);
      }
   }

   //if not visible or CSS `position:absolute`, don't lock scroll
   protected override void OnAfterRender(bool firstTime)
   {
      if (!LockScroll || Absolute)
         return;

      if (Visible)
         BlockScroll();
      else
         UnblockScroll();

   }

   //locks the scroll attaching a CSS class to the specified element, in this case the body
   void BlockScroll()
   {
      ScrollManager.LockScrollAsync("body", LockScrollClass);
   }

   //removes the CSS class that prevented scrolling
   void UnblockScroll()
   {
      ScrollManager.UnlockScrollAsync("body", LockScrollClass);
   }

   //When disposing the overlay, remove the class that prevented scrolling
   public void Dispose()
   {
      UnblockScroll();
   }

}