Added the ScissorGroup element

CHANGELOG.md

@@ -27,8 +27,10 @@ Improvements
 Additions
 - Added the ability to set the anchor that should be used when a tooltip attaches to an element or the mouse
 - Added the ability to display tooltips using the auto-nav style even when using the mouse
+- Added the ScissorGroup element, which applies a scissor rectangle when drawing its content
 
 Improvements
+- **Include the SpriteBatchContext in OnDrawn, OnElementDrawn and OnSelectedElementDrawn**
 - Allow scrolling panels to set height based on children by setting TreatSizeAsMaximum
 
 Fixes

MLEM.Ui/Elements/Element.cs

@@ -1148,9 +1148,9 @@ namespace MLEM.Ui.Elements {
         /// <param name="alpha">The alpha to draw this element and its children with</param>
         /// <param name="context">The sprite batch context to use for drawing</param>
         public virtual void Draw(GameTime time, SpriteBatch batch, float alpha, SpriteBatchContext context) {
-            this.System.InvokeOnElementDrawn(this, time, batch, alpha);
+            this.System.InvokeOnElementDrawn(this, time, batch, alpha, context);
             if (this.IsSelected)
-                this.System.InvokeOnSelectedElementDrawn(this, time, batch, alpha);
+                this.System.InvokeOnSelectedElementDrawn(this, time, batch, alpha, context);
 
             foreach (var child in this.GetRelevantChildren()) {
                 if (!child.IsHidden) {
@@ -1387,7 +1387,8 @@ namespace MLEM.Ui.Elements {
         /// <param name="time">The game's time</param>
         /// <param name="batch">The sprite batch used for drawing</param>
         /// <param name="alpha">The alpha this element is drawn with</param>
-        public delegate void DrawCallback(Element element, GameTime time, SpriteBatch batch, float alpha);
+        /// <param name="context">The sprite batch context to use for drawing</param>
+        public delegate void DrawCallback(Element element, GameTime time, SpriteBatch batch, float alpha, SpriteBatchContext context);
 
         /// <summary>
         /// A generic delegate used inside of <see cref="Element.Update"/>

MLEM.Ui/Elements/ScissorGroup.cs

@@ -0,0 +1,61 @@
+using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework.Graphics;
+using MLEM.Extensions;
+using MLEM.Graphics;
+
+namespace MLEM.Ui.Elements {
+    /// <summary>
+    /// A scissor group is a <see cref="Group"/> that sets the <see cref="GraphicsDevice.ScissorRectangle"/> before drawing its content (and thus, its <see cref="Element.Children"/>), preventing them from being drawn outside of this group's <see cref="Element.DisplayArea"/>'s bounds.
+    /// </summary>
+    public class ScissorGroup : Group {
+
+        /// <summary>
+        /// The rasterizer state that this scissor group should use when drawing.
+        /// By default, <see cref="CullMode"/> is set to <see cref="CullMode.CullCounterClockwiseFace"/> in accordance with <see cref="SpriteBatch"/>'s default behavior, and <see cref="RasterizerState.ScissorTestEnable"/> is set to <see langword="true"/>.
+        /// </summary>
+        public readonly RasterizerState Rasterizer = new RasterizerState {
+            // use the default cull mode from SpriteBatch, but with scissor test enabled
+            CullMode = CullMode.CullCounterClockwiseFace,
+            ScissorTestEnable = true
+        };
+
+        /// <summary>
+        /// Creates a new scissor group with the given settings
+        /// </summary>
+        /// <param name="anchor">The group's anchor</param>
+        /// <param name="size">The group's size</param>
+        /// <param name="setHeightBasedOnChildren">Whether the group's height should be based on its children's height, see <see cref="Element.SetHeightBasedOnChildren"/>.</param>
+        public ScissorGroup(Anchor anchor, Vector2 size, bool setHeightBasedOnChildren = true) : base(anchor, size, setHeightBasedOnChildren) {}
+
+        /// <summary>
+        /// Creates a new scissor group with the given settings
+        /// </summary>
+        /// <param name="anchor">The group's anchor</param>
+        /// <param name="size">The group's size</param>
+        /// <param name="setWidthBasedOnChildren">Whether the group's width should be based on its children's width, see <see cref="Element.SetWidthBasedOnChildren"/>.</param>
+        /// <param name="setHeightBasedOnChildren">Whether the group's height should be based on its children's height, see <see cref="Element.SetHeightBasedOnChildren"/>.</param>
+        public ScissorGroup(Anchor anchor, Vector2 size, bool setWidthBasedOnChildren, bool setHeightBasedOnChildren) : base(anchor, size, setWidthBasedOnChildren, setHeightBasedOnChildren) {}
+
+        /// <inheritdoc />
+        public override void Draw(GameTime time, SpriteBatch batch, float alpha, SpriteBatchContext context) {
+            batch.End();
+
+            // apply our scissor rectangle
+            var lastScissor = batch.GraphicsDevice.ScissorRectangle;
+            batch.GraphicsDevice.ScissorRectangle = (Rectangle) this.DisplayArea.OffsetCopy(context.TransformMatrix.Translation.ToVector2());
+
+            // enable scissor test
+            var localContext = context;
+            localContext.RasterizerState = this.Rasterizer;
+            batch.Begin(localContext);
+
+            base.Draw(time, batch, alpha, localContext);
+
+            // revert back to previous behavior
+            batch.End();
+            batch.GraphicsDevice.ScissorRectangle = lastScissor;
+            batch.Begin(context);
+        }
+
+    }
+}

MLEM.Ui/UiSystem.cs

@@ -215,7 +215,7 @@ namespace MLEM.Ui {
             this.Controls = new UiControls(this, inputHandler);
             this.style = style;
 
-            this.OnElementDrawn += (e, time, batch, alpha) => e.OnDrawn?.Invoke(e, time, batch, alpha);
+            this.OnElementDrawn += (e, time, batch, alpha, context) => e.OnDrawn?.Invoke(e, time, batch, alpha, context);
             this.OnElementUpdated += (e, time) => e.OnUpdated?.Invoke(e, time);
             this.OnElementPressed += e => e.OnPressed?.Invoke(e);
             this.OnElementSecondaryPressed += e => e.OnSecondaryPressed?.Invoke(e);
@@ -230,7 +230,7 @@ namespace MLEM.Ui {
             this.OnMousedElementChanged += e => this.ApplyToAll(t => t.OnMousedElementChanged?.Invoke(t, e));
             this.OnTouchedElementChanged += e => this.ApplyToAll(t => t.OnTouchedElementChanged?.Invoke(t, e));
             this.OnSelectedElementChanged += e => this.ApplyToAll(t => t.OnSelectedElementChanged?.Invoke(t, e));
-            this.OnSelectedElementDrawn += (element, time, batch, alpha) => {
+            this.OnSelectedElementDrawn += (element, time, batch, alpha, context) => {
                 if (this.Controls.IsAutoNavMode && element.SelectionIndicator.HasValue())
                     batch.Draw(element.SelectionIndicator, element.DisplayArea, Color.White * alpha, element.Scale / 2);
             };
@@ -427,12 +427,12 @@ namespace MLEM.Ui {
             }
         }
 
-        internal void InvokeOnElementDrawn(Element element, GameTime time, SpriteBatch batch, float alpha) {
+        internal void InvokeOnElementDrawn(Element element, GameTime time, SpriteBatch batch, float alpha, SpriteBatchContext context) {
-            this.OnElementDrawn?.Invoke(element, time, batch, alpha);
+            this.OnElementDrawn?.Invoke(element, time, batch, alpha, context);
         }
 
-        internal void InvokeOnSelectedElementDrawn(Element element, GameTime time, SpriteBatch batch, float alpha) {
+        internal void InvokeOnSelectedElementDrawn(Element element, GameTime time, SpriteBatch batch, float alpha, SpriteBatchContext context) {
-            this.OnSelectedElementDrawn?.Invoke(element, time, batch, alpha);
+            this.OnSelectedElementDrawn?.Invoke(element, time, batch, alpha, context);
         }
 
         internal void InvokeOnElementUpdated(Element element, GameTime time) {