allow for the transformation matrix to modify mouse positions

MLEM.Ui/Elements/CustomDrawGroup.cs

@@ -11,12 +11,14 @@ namespace MLEM.Ui.Elements {
     [Obsolete("CustomDrawGroup mechanics have been moved down to Element, which means custom draw groups are no longer necessary.")]
     public class CustomDrawGroup : Group {
         
+        public readonly TransformCallback TransformGetter;
+
         /// <summary>
         /// Creates a new custom draw group with the given settings
         /// </summary>
         /// <param name="anchor">The group's anchor</param>
         /// <param name="size">The group's size</param>
-        /// <param name="transformGetter">The group's <see cref="Element.TransformGetter"/></param>
+        /// <param name="transformGetter">The group's <see cref="TransformGetter"/></param>
         /// <param name="beginImpl">The group's <see cref="Element.BeginImpl"/></param>
         /// <param name="setHeightBasedOnChildren">Whether this group should automatically calculate its height based on its children</param>
         public CustomDrawGroup(Anchor anchor, Vector2 size, TransformCallback transformGetter = null, BeginDelegate beginImpl = null, bool setHeightBasedOnChildren = true) :
@@ -31,5 +33,20 @@ namespace MLEM.Ui.Elements {
             this.ScaleTransform(scale, origin);
         }
 
+        /// <inheritdoc />
+        public override void Draw(GameTime time, SpriteBatch batch, float alpha, BlendState blendState, SamplerState samplerState, Matrix matrix) {
+            if (this.Transform == Matrix.Identity)
+                this.Transform = this.TransformGetter(this, time, matrix);
+            base.Draw(time, batch, alpha, blendState, samplerState, matrix);
+        }
+
+        /// <summary>
+        /// A delegate method used for <see cref="CustomDrawGroup.TransformGetter"/>
+        /// </summary>
+        /// <param name="element">The element whose transform to get</param>
+        /// <param name="time">The game's time</param>
+        /// <param name="matrix">The regular transform matrix</param>
+        public delegate Matrix TransformCallback(Element element, GameTime time, Matrix matrix);
+
     }
 }

MLEM.Ui/Elements/Element.cs

@@ -230,11 +230,7 @@ namespace MLEM.Ui.Elements {
         /// Can easily be scaled using <see cref="ScaleTransform"/>.
         /// Note that, when this is non-null, a new <see cref="SpriteBatch.Begin"/> call is used for this element.
         /// </summary>
-        public Matrix? Transform;
+        public Matrix Transform = Matrix.Identity;
-        /// <summary>
-        /// A callback for retrieving this element's <see cref="Transform"/> automatically.
-        /// </summary>
-        public TransformCallback TransformGetter = (e, time, m) => Matrix.Identity;
         /// <summary>
         /// The call that this element should make to <see cref="SpriteBatch"/> to begin drawing.
         /// Note that, when this is non-null, a new <see cref="SpriteBatch.Begin"/> call is used for this element.
@@ -832,9 +828,8 @@ namespace MLEM.Ui.Elements {
         /// <param name="samplerState">The sampler state that is used for drawing</param>
         /// <param name="matrix">The transformation matrix that is used for drawing</param>
         public void DrawTransformed(GameTime time, SpriteBatch batch, float alpha, BlendState blendState, SamplerState samplerState, Matrix matrix) {
-            var transform = this.Transform ?? this.TransformGetter(this, time, matrix);
+            var customDraw = this.BeginImpl != null || this.Transform != Matrix.Identity;
-            var customDraw = this.BeginImpl != null || transform != Matrix.Identity;
+            var mat = this.Transform * matrix;
-            var mat = transform * matrix;
             if (customDraw) {
                 // end the usual draw so that we can begin our own
                 batch.End();
@@ -902,6 +897,8 @@ namespace MLEM.Ui.Elements {
         public virtual Element GetElementUnderPos(Vector2 position) {
             if (this.IsHidden)
                 return null;
+            if (this.Transform != Matrix.Identity)
+                position = Vector2.Transform(position, Matrix.Invert(this.Transform));
             var children = this.GetRelevantChildren();
             for (var i = children.Count - 1; i >= 0; i--) {
                 var element = children[i].GetElementUnderPos(position);
@@ -1020,13 +1017,5 @@ namespace MLEM.Ui.Elements {
         /// <param name="matrix">The transform matrix used for drawing</param>
         public delegate void BeginDelegate(Element element, GameTime time, SpriteBatch batch, float alpha, BlendState blendState, SamplerState samplerState, Matrix matrix);
 
-        /// <summary>
-        /// A delegate method used for <see cref="TransformGetter"/>
-        /// </summary>
-        /// <param name="element">The element whose transform to get</param>
-        /// <param name="time">The game's time</param>
-        /// <param name="matrix">The regular transform matrix</param>
-        public delegate Matrix TransformCallback(Element element, GameTime time, Matrix matrix);
-
     }
 }