draft of the "avoid virtual member calls" refactor

Author: Ellpeck

MLEM.Ui/Elements/Button.cs

@@ -81,7 +81,7 @@ public bool TruncateTextIfLong {
         }
         /// <summary>
         /// Whether this button should be able to be selected even if it <see cref="IsDisabled"/>.
-        /// If this is true, <see cref="CanBeSelected"/> will be able to return true even if <see cref="IsDisabled"/> is true.
+        /// If this is true, <see cref="Element.CanBeSelected"/> will be able to return true even if <see cref="IsDisabled"/> is true.
         /// </summary>
         public bool CanSelectDisabled;
         /// <summary>
@@ -90,11 +90,6 @@ public bool TruncateTextIfLong {
         /// </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>
@@ -167,5 +162,15 @@ protected override void InitStyle(UiStyle style) {
             this.DisabledColor = this.DisabledColor.OrStyle(style.ButtonDisabledColor);
         }
 
+        /// <inheritdoc />
+        protected override bool GetCanBeSelected(bool value) {
+            return value && (this.CanSelectDisabled || !this.IsDisabled);
+        }
+
+        /// <inheritdoc />
+        protected override bool GetCanBePressed(bool value) {
+            return value && !this.IsDisabled;
+        }
+
     }
 }

MLEM.Ui/Elements/Checkbox.cs

@@ -90,15 +90,10 @@ public bool Checked {
         public CheckStateChange OnCheckStateChange;
         /// <summary>
         /// Whether this checkbox should be able to be selected even if it <see cref="IsDisabled"/>.
-        /// If this is true, <see cref="CanBeSelected"/> will be able to return true even if <see cref="IsDisabled"/> is true.
+        /// If this is true, <see cref="Element.CanBeSelected"/> will be able to return true even if <see cref="IsDisabled"/> is true.
         /// </summary>
         public bool CanSelectDisabled;
 
-        /// <inheritdoc />
-        public override bool CanBeSelected => base.CanBeSelected && (this.CanSelectDisabled || !this.IsDisabled);
-        /// <inheritdoc />
-        public override bool CanBePressed => base.CanBePressed && !this.IsDisabled;
-
         private bool isChecked;
         private StyleProp<float> textOffsetX;
 
@@ -145,7 +140,7 @@ public override void Draw(GameTime time, SpriteBatch batch, float alpha, SpriteB
             var uncheckedColor = this.UncheckColor.OrDefault(Color.Transparent);
             if (this.Checked)
                 batch.Draw(this.Checkmark, boxDisplayArea, this.CheckColor.OrDefault(Color.White) * alpha);
-            else if(uncheckedColor.A != 0) {
+            else if (uncheckedColor.A != 0) {
                 batch.Draw(this.Checkmark, boxDisplayArea, uncheckedColor * alpha);
             }
             base.Draw(time, batch, alpha, context);
@@ -166,6 +161,16 @@ protected override void InitStyle(UiStyle style) {
             this.TextOffsetX = this.TextOffsetX.OrStyle(style.CheckboxTextOffsetX);
         }
 
+        /// <inheritdoc />
+        protected override bool GetCanBeSelected(bool value) {
+            return value && (this.CanSelectDisabled || !this.IsDisabled);
+        }
+
+        /// <inheritdoc />
+        protected override bool GetCanBePressed(bool value) {
+            return value && !this.IsDisabled;
+        }
+
         /// <summary>
         /// A delegate used for <see cref="Checkbox.OnCheckStateChange"/>
         /// </summary>

MLEM.Ui/Elements/Element.cs

@@ -178,8 +178,8 @@ public RectangleF UnscrolledArea {
         /// 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.
         /// </summary>
-        public virtual bool IsHidden {
-            get => this.isHidden;
+        public bool IsHidden {
+            get => this.GetIsHidden(this.isHidden);
             set {
                 if (this.isHidden == value)
                     return;
@@ -212,8 +212,8 @@ public int Priority {
         /// Set this field to false to disallow the element from being selected.
         /// An unselectable element is skipped by automatic navigation and its <see cref="OnSelected"/> callback will never be called.
         /// </summary>
-        public virtual bool CanBeSelected {
-            get => this.canBeSelected;
+        public bool CanBeSelected {
+            get => this.GetCanBeSelected(this.canBeSelected);
             set {
                 this.canBeSelected = value;
                 if (!this.canBeSelected && this.Root?.SelectedElement == this)
@@ -223,15 +223,18 @@ public virtual bool CanBeSelected {
         /// <summary>
         /// Set this field to false to disallow the element from reacting to being moused over.
         /// </summary>
-        public virtual bool CanBeMoused { get; set; } = true;
+        public bool CanBeMoused { get; set; } = true;
         /// <summary>
         /// Set this field to false to disallow this element's <see cref="OnPressed"/> and <see cref="OnSecondaryPressed"/> events to be called.
         /// </summary>
-        public virtual bool CanBePressed { get; set; } = true;
+        public bool CanBePressed {
+            get => this.GetCanBePressed(this.canBePressed);
+            set => this.canBePressed = value;
+        }
         /// <summary>
         /// Set this field to false to cause auto-anchored siblings to ignore this element as a possible anchor point.
         /// </summary>
-        public virtual bool CanAutoAnchorsAttach {
+        public bool CanAutoAnchorsAttach {
             get => this.canAutoAnchorsAttach;
             set {
                 if (this.canAutoAnchorsAttach != value) {
@@ -244,7 +247,7 @@ public virtual bool CanAutoAnchorsAttach {
         /// Set this field to true to cause this element's width to be automatically calculated based on the area that its <see cref="Children"/> take up.
         /// To use this element's <see cref="Size"/>'s X coordinate as a minimum or maximum width rather than ignoring it, set <see cref="TreatSizeAsMinimum"/> or <see cref="TreatSizeAsMaximum"/> to true.
         /// </summary>
-        public virtual bool SetWidthBasedOnChildren {
+        public bool SetWidthBasedOnChildren {
             get => this.setWidthBasedOnChildren;
             set {
                 if (this.setWidthBasedOnChildren != value) {
@@ -257,7 +260,7 @@ public virtual bool SetWidthBasedOnChildren {
         /// Set this field to true to cause this element's height to be automatically calculated based on the area that its <see cref="Children"/> take up.
         /// To use this element's <see cref="Size"/>'s Y coordinate as a minimum or maximum height rather than ignoring it, set <see cref="TreatSizeAsMinimum"/> or <see cref="TreatSizeAsMaximum"/> to true.
         /// </summary>
-        public virtual bool SetHeightBasedOnChildren {
+        public bool SetHeightBasedOnChildren {
             get => this.setHeightBasedOnChildren;
             set {
                 if (this.setHeightBasedOnChildren != value) {
@@ -271,7 +274,7 @@ public virtual bool SetHeightBasedOnChildren {
         /// For example, if an element's <see cref="Size"/>'s Y coordinate is set to 20, but there is only one child with a height of 10 in it, the element's height would be shrunk to 10 if this value was false, but would remain at 20 if it was true.
         /// Note that this value only has an effect if <see cref="SetWidthBasedOnChildren"/> or <see cref="SetHeightBasedOnChildren"/> are enabled.
         /// </summary>
-        public virtual bool TreatSizeAsMinimum {
+        public bool TreatSizeAsMinimum {
             get => this.treatSizeAsMinimum;
             set {
                 if (this.treatSizeAsMinimum != value) {
@@ -284,7 +287,7 @@ public virtual bool TreatSizeAsMinimum {
         /// If this field is set to true, and <see cref="SetWidthBasedOnChildren"/> or <see cref="SetHeightBasedOnChildren"/>are enabled, the resulting width or height weill always be less than or equal to this element's <see cref="Size"/>.
         /// Note that this value only has an effect if <see cref="SetWidthBasedOnChildren"/> or <see cref="SetHeightBasedOnChildren"/> are enabled.
         /// </summary>
-        public virtual bool TreatSizeAsMaximum {
+        public bool TreatSizeAsMaximum {
             get => this.treatSizeAsMaximum;
             set {
                 if (this.treatSizeAsMaximum != value) {
@@ -298,7 +301,7 @@ public virtual bool TreatSizeAsMaximum {
         /// If the resulting area is too large, the size of this element is shrunk to fit the target area.
         /// This can be useful if an element should fill the remaining area of a parent exactly.
         /// </summary>
-        public virtual bool PreventParentSpill {
+        public bool PreventParentSpill {
             get => this.preventParentSpill;
             set {
                 if (this.preventParentSpill != value) {
@@ -311,7 +314,7 @@ public virtual bool PreventParentSpill {
         /// The transparency (alpha value) that this element is rendered with.
         /// Note that, when <see cref="Draw(Microsoft.Xna.Framework.GameTime,Microsoft.Xna.Framework.Graphics.SpriteBatch,float,MLEM.Graphics.SpriteBatchContext)"/> is called, this alpha value is multiplied with the <see cref="Parent"/>'s alpha value and passed down to this element's <see cref="Children"/>.
         /// </summary>
-        public virtual float DrawAlpha { get; set; } = 1;
+        public float DrawAlpha { get; set; } = 1;
         /// <summary>
         /// Stores whether this element is currently being moused over or touched.
         /// </summary>
@@ -335,7 +338,7 @@ public virtual bool PreventParentSpill {
         /// All elements that share the same auto-nav group will be able to be navigated between, and all other elements will not be reachable from elements of other groups.
         /// Note that, if no element is previously selected and auto-navigation is invoked, this element cannot be chosen as the first element to navigate to if its auto-nav group is non-null.
         /// </summary>
-        public virtual string AutoNavGroup { get; set; }
+        public string AutoNavGroup { get; set; }
 
         /// <summary>
         /// This Element's current <see cref="UiStyle"/>.
@@ -551,6 +554,7 @@ protected IList<Element> SortedChildren {
         private bool treatSizeAsMaximum;
         private bool preventParentSpill;
         private int layoutRecursion;
+        private bool canBePressed = true;
 
         /// <summary>
         /// Creates a new element with the given anchor and size and sets up some default event reactions.
@@ -1073,6 +1077,33 @@ public Vector2 TransformInverseAll(Vector2 position) {
             return this.TransformInverse(position);
         }
 
+        /// <summary>
+        /// A method that allows derived classes to modify the return value of the <see cref="IsHidden"/> property.
+        /// </summary>
+        /// <param name="value">The <see cref="IsHidden"/> property's actual current value.</param>
+        /// <returns>The value that <see cref="IsHidden"/> should return.</returns>
+        protected virtual bool GetIsHidden(bool value) {
+            return value;
+        }
+
+        /// <summary>
+        /// A method that allows derived classes to modify the return value of the <see cref="CanBeSelected"/> property.
+        /// </summary>
+        /// <param name="value">The <see cref="CanBeSelected"/> property's actual current value.</param>
+        /// <returns>The value that <see cref="CanBeSelected"/> should return.</returns>
+        protected virtual bool GetCanBeSelected(bool value) {
+            return value;
+        }
+
+        /// <summary>
+        /// A method that allows derived classes to modify the return value of the <see cref="CanBePressed"/> property.
+        /// </summary>
+        /// <param name="value">The <see cref="CanBePressed"/> property's actual current value.</param>
+        /// <returns>The value that <see cref="CanBePressed"/> should return.</returns>
+        protected virtual bool GetCanBePressed(bool value) {
+            return value;
+        }
+
         /// <summary>
         /// Called when this element is added to a <see cref="UiSystem"/> and, optionally, a given <see cref="RootElement"/>.
         /// This method is called in <see cref="AddChild{T}"/> for a parent whose <see cref="System"/> is set, as well as <see cref="UiSystem.Add"/>.

MLEM.Ui/Elements/Image.cs

@@ -103,9 +103,6 @@ public bool SetHeightBasedOnAspect {
         /// </summary>
         public SamplerState SamplerState;
 
-        /// <inheritdoc />
-        public override bool IsHidden => base.IsHidden || this.Texture == null;
-
         private bool scaleToImage;
         private bool setWidthBasedOnAspect;
         private bool setHeightBasedOnAspect;
@@ -198,6 +195,11 @@ public override void Draw(GameTime time, SpriteBatch batch, float alpha, SpriteB
             base.Draw(time, batch, alpha, context);
         }
 
+        /// <inheritdoc />
+        protected override bool GetIsHidden(bool value) {
+            return value || this.Texture == null;
+        }
+
         private void CheckTextureChange() {
             var newTexture = this.GetTextureCallback?.Invoke(this) ?? this.explicitlySetTexture;
             if (this.displayedTexture == newTexture)

MLEM.Ui/Elements/Paragraph.cs

@@ -161,9 +161,6 @@ public StyleProp<TextAlignment> Alignment {
         /// </summary>
         public int? DrawEndIndex;
 
-        /// <inheritdoc />
-        public override bool IsHidden => base.IsHidden || string.IsNullOrWhiteSpace(this.Text);
-
         private string displayedText;
         private string explicitlySetText;
         private StyleProp<TextAlignment> alignment;
@@ -278,6 +275,11 @@ protected override void InitStyle(UiStyle style) {
             this.LinkColor = this.LinkColor.OrStyle(style.LinkColor);
         }
 
+        /// <inheritdoc />
+        protected override bool GetIsHidden(bool value) {
+            return value || string.IsNullOrWhiteSpace(this.Text);
+        }
+
         private void SetTextDirty() {
             this.tokenizedText = null;
             // only set our area dirty if our size changed as a result of this action

MLEM.Ui/Elements/Tooltip.cs

@@ -106,9 +106,6 @@ public StyleProp<float> ParagraphWidth {
         /// </summary>
         public virtual Rectangle? Viewport { get; set; }
 
-        /// <inheritdoc />
-        public override bool IsHidden => this.autoHidden || base.IsHidden;
-
         private TimeSpan delayCountdown;
         private bool autoHidden;
         private Element autoNavSnapElement;
@@ -315,6 +312,11 @@ public void AddToElement(Element elementToHover) {
             };
         }
 
+        /// <inheritdoc />
+        protected override bool GetIsHidden(bool value) {
+            return value || this.autoHidden;
+        }
+
         private void Init(Element elementToHover) {
             this.SetWidthBasedOnChildren = true;
             this.SetHeightBasedOnChildren = true;