Fixed some inconsistencies with element transformations and mouse interaction

CHANGELOG.md

@@ -40,6 +40,7 @@ Fixes
 - Fixed VerticalSpace height parameter being an integer
 - Fixed text not being pasted into a text field at all if it contains characters that don't match the input rule
 - Fixed panels that don't auto-hide their scroll bars ignoring their width for child padding
+- Fixed some inconsistencies with element transformations and mouse interaction
 
 Removals
 - *Removed ScrollBar ScrollerOffset*

MLEM.Ui/Elements/Element.cs

@@ -956,8 +956,7 @@ 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));
+            position = this.TransformInverse(position);
             var relevant = this.GetRelevantChildren();
             for (var i = relevant.Count - 1; i >= 0; i--) {
                 var element = relevant[i].GetElementUnderPos(position);
@@ -1019,6 +1018,28 @@ namespace MLEM.Ui.Elements {
             this.SecondActionSound.SetFromStyle(style.ActionSound);
         }
 
+        /// <summary>
+        /// Transforms the given <paramref name="position"/> by the inverse of this element's <see cref="Transform"/> matrix.
+        /// </summary>
+        /// <param name="position">The position to transform</param>
+        /// <returns>The transformed position</returns>
+        protected Vector2 TransformInverse(Vector2 position) {
+            return this.Transform != Matrix.Identity ? Vector2.Transform(position, Matrix.Invert(this.Transform)) : position;
+        }
+
+        /// <summary>
+        /// Transforms the given <paramref name="position"/> by this element's <see cref="Root"/>'s <see cref="RootElement.InvTransform"/>, the inverses of all of the <see cref="Transform"/> matrices of this element's parent tree (<see cref="GetParentTree"/>), and the inverse of this element's <see cref="Transform"/> matrix.
+        /// Note that, when using <see cref="UiControls.GetElementUnderPos"/>, this operation is done recursively, which is more efficient.
+        /// </summary>
+        /// <param name="position">The position to transform</param>
+        /// <returns>The transformed position</returns>
+        protected Vector2 TransformInverseAll(Vector2 position) {
+            position = Vector2.Transform(position, this.Root.InvTransform);
+            foreach (var parent in this.GetParentTree().Reverse())
+                position = parent.TransformInverse(position);
+            return this.TransformInverse(position);
+        }
+
         /// <summary>
         /// A delegate used for the <see cref="Element.OnTextInput"/> event.
         /// </summary>

MLEM.Ui/Elements/Panel.cs

@@ -189,8 +189,9 @@ namespace MLEM.Ui.Elements {
         /// <inheritdoc />
         public override Element GetElementUnderPos(Vector2 position) {
             // if overflow is handled, don't propagate mouse checks to hidden children
-            if (this.scrollOverflow && !this.GetRenderTargetArea().Contains(position))
-                return !this.IsHidden && this.CanBeMoused && this.DisplayArea.Contains(position) ? this : null;
+            var transformed = this.TransformInverse(position);
+            if (this.scrollOverflow && !this.GetRenderTargetArea().Contains(transformed))
+                return !this.IsHidden && this.CanBeMoused && this.DisplayArea.Contains(transformed) ? this : null;
             return base.GetElementUnderPos(position);
         }
 

MLEM.Ui/Elements/Paragraph.cs

@@ -251,7 +251,7 @@ namespace MLEM.Ui.Elements {
                     return ret;
                 // check if any of our token's parts are hovered
                 foreach (var rect in this.Token.GetArea(this.Parent.DisplayArea.Location, this.Scale * this.textScale)) {
-                    if (rect.Contains(position))
+                    if (rect.Contains(this.TransformInverse(position)))
                         return this;
                 }
                 return null;

MLEM.Ui/Elements/ScrollBar.cs

@@ -137,15 +137,14 @@ namespace MLEM.Ui.Elements {
 
             // MOUSE INPUT
             var moused = this.Controls.MousedElement;
-            var mousedPos = Vector2.Transform(this.Input.MousePosition.ToVector2(), this.Root.InvTransform);
             if (moused == this && this.Controls.Input.IsMouseButtonPressed(MouseButton.Left)) {
                 this.isMouseHeld = true;
-                this.scrollStartOffset = mousedPos - this.ScrollerPosition;
+                this.scrollStartOffset = this.TransformInverseAll(this.Input.MousePosition.ToVector2()) - this.ScrollerPosition;
             } else if (this.isMouseHeld && !this.Controls.Input.IsMouseButtonDown(MouseButton.Left)) {
                 this.isMouseHeld = false;
             }
             if (this.isMouseHeld)
-                this.ScrollToPos(mousedPos);
+                this.ScrollToPos(this.TransformInverseAll(this.Input.MousePosition.ToVector2()));
             if (!this.Horizontal && moused != null && (moused == this.Parent || moused.GetParentTree().Contains(this.Parent))) {
                 var scroll = this.Input.LastScrollWheel - this.Input.ScrollWheel;
                 if (scroll != 0)
@@ -157,7 +156,7 @@ namespace MLEM.Ui.Elements {
                 // are we dragging on top of the panel?
                 if (this.Input.GetGesture(GestureType.VerticalDrag, out var drag)) {
                     // if the element under the drag's start position is on top of the panel, start dragging
-                    var touched = this.Parent.GetElementUnderPos(Vector2.Transform(drag.Position, this.Root.InvTransform));
+                    var touched = this.Parent.GetElementUnderPos(this.TransformInverseAll(drag.Position));
                     if (touched != null && touched != this)
                         this.isDragging = true;
 
@@ -173,7 +172,7 @@ namespace MLEM.Ui.Elements {
                 this.isTouchHeld = false;
             } else {
                 foreach (var loc in this.Input.TouchState) {
-                    var pos = Vector2.Transform(loc.Position, this.Root.InvTransform);
+                    var pos = this.TransformInverseAll(loc.Position);
                     // if we just started touching and are on top of the scroller, then we should start scrolling
                     if (this.DisplayArea.Contains(pos) && !loc.TryGetPreviousLocation(out _)) {
                         this.isTouchHeld = true;

MLEM.Ui/UiControls.cs

@@ -237,11 +237,10 @@ namespace MLEM.Ui {
         /// Throughout the ui system, this is used for mouse input querying.
         /// </summary>
         /// <param name="position">The position to query</param>
-        /// <param name="transform">If this value is true, the <see cref="RootElement.Transform"/> will be applied.</param>
         /// <returns>The element under the position, or null if there isn't one</returns>
-        public virtual Element GetElementUnderPos(Vector2 position, bool transform = true) {
+        public virtual Element GetElementUnderPos(Vector2 position) {
             foreach (var root in this.System.GetRootElements()) {
-                var pos = transform ? Vector2.Transform(position, root.InvTransform) : position;
+                var pos = Vector2.Transform(position, root.InvTransform);
                 var moused = root.Element.GetElementUnderPos(pos);
                 if (moused != null)
                     return moused;