Added Element.AutoHideCondition and Button.AutoDisableCondition

CHANGELOG.md

@@ -57,6 +57,7 @@ Additions
 - Added ScrollBar.MouseDragScrolling
 - Added Panel.ScrollToElement
 - Added ElementHelper.MakeGrid
+- Added Element.AutoHideCondition and Button.AutoDisableCondition
 
 Improvements
 - Allow elements to auto-adjust their size even when their children are aligned oddly

MLEM.Ui/Elements/Button.cs

@@ -1,3 +1,4 @@
+using System;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 using MLEM.Graphics;
@@ -51,8 +52,16 @@ namespace MLEM.Ui.Elements {
         /// <summary>
         /// Set this property to true to mark the button as disabled.
         /// A disabled button cannot be moused over, selected or pressed.
+        /// If this value changes often, consider using <see cref="AutoDisableCondition"/> to set it automatically.
         /// </summary>
-        public virtual bool IsDisabled { get; set; }
+        public virtual bool IsDisabled {
+            get {
+                if (this.AutoDisableCondition != null)
+                    this.IsDisabled = this.AutoDisableCondition(this);
+                return this.isDisabled;
+            }
+            set => this.isDisabled = value;
+        }
         /// <summary>
         /// Whether this button's <see cref="Text"/> should be truncated if it exceeds this button's width.
         /// Defaults to false.
@@ -69,12 +78,18 @@ namespace MLEM.Ui.Elements {
         /// If this is true, <see cref="CanBeSelected"/> will be able to return true even if <see cref="IsDisabled"/> is true.
         /// </summary>
         public bool CanSelectDisabled;
+        /// <summary>
+        /// An optional function that can be used to set <see cref="IsDisabled"/> automatically based on a user-defined condition. This removes the need to disable a button based on a condition in <see cref="Element.OnUpdated"/> or manually.
+        /// </summary>
+        public Func<Button, bool> AutoDisableCondition;
 
         /// <inheritdoc />
         public override bool CanBeSelected => base.CanBeSelected && (this.CanSelectDisabled || !this.IsDisabled);
         /// <inheritdoc />
         public override bool CanBePressed => base.CanBePressed && !this.IsDisabled;
 
+        private bool isDisabled;
+
         /// <summary>
         /// Creates a new button with the given settings
         /// </summary>

MLEM.Ui/Elements/Element.cs

@@ -172,9 +172,15 @@ namespace MLEM.Ui.Elements {
         /// <summary>
         /// Set this property to <c>true</c> to cause this element to be hidden.
         /// Hidden elements don't receive input events, aren't rendered and don't factor into auto-anchoring.
+        /// If this value changes often, consider using <see cref="AutoHideCondition"/> to set it automatically.
         /// </summary>
         public virtual bool IsHidden {
-            get => this.isHidden;
+            get {
+                // instead of just returning, we set IsHidden here because we might have to set our area dirty
+                if (this.AutoHideCondition != null)
+                    this.IsHidden = this.AutoHideCondition(this);
+                return this.isHidden;
+            }
             set {
                 if (this.isHidden == value)
                     return;
@@ -430,6 +436,10 @@ namespace MLEM.Ui.Elements {
         /// </summary>
         [Obsolete("OnDisposed will be removed in a future update. To unregister custom event handlers, use OnRemovedFromUi instead.")]
         public GenericCallback OnDisposed;
+        /// <summary>
+        /// An optional function that can be used to set <see cref="IsHidden"/> automatically based on a user-defined condition. This removes the need to hide an element based on a condition in <see cref="Element.OnUpdated"/> or manually.
+        /// </summary>
+        public Func<Element, bool> AutoHideCondition;
 
         /// <summary>
         /// A list of all of this element's direct children.