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Assets/BITKit/Unity/Scripts/UX/Library/RadialProgress.cs

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+using UnityEngine;
+using UnityEngine.UIElements;
+
+namespace BITKit.UX
+{
+
+    // An element that displays progress inside a partially filled circle
+    public class RadialProgress : VisualElement
+    {
+        public new class UxmlTraits : VisualElement.UxmlTraits
+        {
+            // The progress property is exposed to UXML.
+            private readonly UxmlFloatAttributeDescription m_ProgressAttribute = new UxmlFloatAttributeDescription()
+            {
+                name = "progress"
+            };
+
+            // Use the Init method to assign the value of the progress UXML attribute to the C# progress property.
+            public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
+            {
+                base.Init(ve, bag, cc);
+
+                ((RadialProgress)ve).progress = m_ProgressAttribute.GetValueFromBag(bag, cc);
+            }
+        }
+
+        // Define a factory class to expose this control to UXML.
+        public new class UxmlFactory : UxmlFactory<RadialProgress, UxmlTraits> { }
+
+        // These are USS class names for the control overall and the label.
+        public static readonly string ussClassName = "radial-progress";
+        public static readonly string ussLabelClassName = "radial-progress__label";
+
+        // These objects allow C# code to access custom USS properties.
+        static CustomStyleProperty<Color> s_TrackColor = new CustomStyleProperty<Color>("--track-color");
+        static CustomStyleProperty<Color> s_ProgressColor = new CustomStyleProperty<Color>("--progress-color");
+
+        Color m_TrackColor = Color.gray;
+        Color m_ProgressColor = Color.red;
+
+        // This is the label that displays the percentage.
+        Label m_Label;
+
+        // This is the number that the Label displays as a percentage.
+        float m_Progress;
+
+        // A value between 0 and 100
+        public float progress
+        {
+            // The progress property is exposed in C#.
+            get => m_Progress;
+            set
+            {
+                // Whenever the progress property changes, MarkDirtyRepaint() is named. This causes a call to the
+                // generateVisualContents callback.
+                m_Progress = value;
+                m_Label.text = Mathf.Clamp(Mathf.Round(value), 0, 100) + "%";
+                MarkDirtyRepaint();
+            }
+        }
+
+        // This default constructor is RadialProgress's only constructor.
+        public RadialProgress()
+        {
+            // Create a Label, add a USS class name, and add it to this visual tree.
+            m_Label = new Label();
+            m_Label.AddToClassList(ussLabelClassName);
+            Add(m_Label);
+
+            // Add the USS class name for the overall control.
+            AddToClassList(ussClassName);
+
+            // Register a callback after custom style resolution.
+            RegisterCallback<CustomStyleResolvedEvent>(evt => CustomStylesResolved(evt));
+
+            // Register a callback to generate the visual content of the control.
+            generateVisualContent += GenerateVisualContent;
+
+            progress = 0.0f;
+        }
+
+        static void CustomStylesResolved(CustomStyleResolvedEvent evt)
+        {
+            RadialProgress element = (RadialProgress)evt.currentTarget;
+            element.UpdateCustomStyles();
+        }
+
+        // After the custom colors are resolved, this method uses them to color the meshes and (if necessary) repaint
+        // the control.
+        void UpdateCustomStyles()
+        {
+            bool repaint = false;
+            if (customStyle.TryGetValue(s_ProgressColor, out m_ProgressColor))
+                repaint = true;
+
+            if (customStyle.TryGetValue(s_TrackColor, out m_TrackColor))
+                repaint = true;
+
+            if (repaint)
+                MarkDirtyRepaint();
+        }
+
+        void GenerateVisualContent(MeshGenerationContext context)
+        {
+            float width = contentRect.width;
+            float height = contentRect.height;
+
+            var painter = context.painter2D;
+            painter.lineWidth = 10.0f;
+            painter.lineCap = LineCap.Butt;
+
+            // Draw the track
+            painter.strokeColor = m_TrackColor;
+            painter.BeginPath();
+            painter.Arc(new Vector2(width * 0.5f, height * 0.5f), width * 0.5f, 0.0f, 360.0f);
+            painter.Stroke();
+
+            // Draw the progress
+            painter.strokeColor = m_ProgressColor;
+            painter.BeginPath();
+            painter.Arc(new Vector2(width * 0.5f, height * 0.5f), width * 0.5f, -90.0f, 360.0f * (progress / 100.0f) - 90.0f);
+            painter.Stroke();
+        }
+    }
+}