Add directional icons to crew monitors (#7404)

Content.Client/UserInterface/Controls/DirectionIcon.cs

@@ -0,0 +1,70 @@
+using Robust.Client.Graphics;
+using Robust.Client.UserInterface.Controls;
+
+namespace Content.Client.UserInterface.Controls;
+
+/// <summary>
+///     Simple control that shows an arrow pointing in some direction.
+/// </summary>
+/// <remarks>
+///     The actual arrow and other icons are defined in the style sheet.
+/// </remarks>
+public sealed class DirectionIcon : TextureRect
+{
+    public static string StyleClassDirectionIconArrow = "direction-icon-arrow"; // south pointing arrow
+    public static string StyleClassDirectionIconHere = "direction-icon-here"; // "you have reached your destination"
+    public static string StyleClassDirectionIconUnknown = "direction-icon-unknown"; // unknown direction / error
+
+    private Angle? _rotation;
+
+    public Angle? Rotation
+    {
+        get => _rotation;
+        set
+        {
+            _rotation = value;
+            SetOnlyStyleClass(value == null ? StyleClassDirectionIconUnknown : StyleClassDirectionIconArrow);
+        }
+    }
+
+    public DirectionIcon()
+    {
+        Stretch = StretchMode.KeepAspectCentered;
+        SetOnlyStyleClass(StyleClassDirectionIconUnknown);
+    }
+
+    public DirectionIcon(Direction direction) : this()
+    {
+        Rotation = direction.ToAngle();
+    }
+
+    /// <summary>
+    ///     Creates an icon with an arrow pointing in some direction.
+    /// </summary>
+    /// <param name="direction">The direction</param>
+    /// <param name="relativeAngle">The relative angle. This may be the players eye rotation, the grid rotation, or
+    /// maybe the world rotation of the entity that owns some BUI</param>
+    /// <param name="snap">If true, will snap the nearest cardinal or diagonal direction</param>
+    /// <param name="minDistance">If the distance is less than this, the arrow icon will be replaced by some other indicator</param>
+    public DirectionIcon(Vector2 direction, Angle relativeAngle, bool snap, float minDistance = 0.1f) : this()
+    {
+        if (direction.EqualsApprox(Vector2.Zero, minDistance))
+        {
+            SetOnlyStyleClass(StyleClassDirectionIconHere);
+            return;
+        }
+
+        var rotation = direction.ToWorldAngle() - relativeAngle;
+        Rotation = snap ? rotation.GetDir().ToAngle()  : rotation; 
+    }
+
+    protected override void Draw(DrawingHandleScreen handle)
+    {
+        if (_rotation != null)
+        {
+            var offset = (-_rotation.Value).RotateVec(Size * UIScale / 2) - Size * UIScale / 2;
+            handle.SetTransform(Matrix3.CreateTransform(GlobalPixelPosition - offset, -_rotation.Value));
+        }
+        base.Draw(handle);
+    }
+}