Replace VisualElement for IInteractable

Visual elements will be obsolete, insteadd they are replaced by the Visual class, both classes implement IInteractable as a temporal solution for the migration to the new way of buiilding custom visuuals in the library.

src/LiveChartsCore/Chart.cs

@@ -352,9 +352,9 @@ protected internal virtual void InvokePointerDown(LvcPoint point, bool isSeconda
 
             // fire the visual elements event.
             var hitElements =
-                _everMeasuredElements.OfType<CoreVisualElement>()
-                    .Cast<CoreVisualElement>()
-                    .SelectMany(x => x.IsHitBy(this, point));
+                _everMeasuredElements
+                    .OfType<IInternalInteractable>()
+                    .Where(x => x.GetHitBox().Contains(point));
 
             foreach (var ve in hitElements)
                 ve.InvokePointerDown(new VisualElementEventArgs(this, ve, point));

src/LiveChartsCore/Drawing/LvcRectangle.cs

@@ -20,6 +20,8 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+using System.Drawing;
+
 namespace LiveChartsCore.Drawing;
 
 /// <summary>
@@ -59,12 +61,12 @@ private LvcRectangle(bool empty)
     /// <summary>
     /// Gets the X location coordinate.
     /// </summary>
-    public float X => Location.X;
+    public readonly float X => Location.X;
 
     /// <summary>
     /// Gets the Y location coordinate.
     /// </summary>
-    public float Y => Location.Y;
+    public readonly float Y => Location.Y;
 
     /// <summary>
     /// Gets or sets the size.
@@ -74,18 +76,30 @@ private LvcRectangle(bool empty)
     /// <summary>
     /// Gets the width.
     /// </summary>
-    public float Width => Size.Width;
+    public readonly float Width => Size.Width;
 
     /// <summary>
     /// Gets the height.
     /// </summary>
-    public float Height => Size.Height;
+    public readonly float Height => Size.Height;
 
     /// <summary>
     /// Gets or sets whether the instance is empty.
     /// </summary>
     private bool IsEmpty { get; set; }
 
+    /// <summary>
+    /// Determines whether the given point is contained in the rectangle.
+    /// </summary>
+    /// <param name="point">The point.</param>
+    /// <returns>True if contained, otherwise false.</returns>
+    public readonly bool Contains(LvcPoint point)
+    {
+        return
+            point.X >= Location.X && point.X <= Location.X + Size.Width &&
+            point.Y >= Location.Y && point.Y <= Location.Y + Size.Height;
+    }
+
     /// <summary>
     /// Determines whether the instance is equals to the given instance.
     /// </summary>

src/LiveChartsCore/Kernel/Events/VisualElementEventArgs.cs

@@ -21,7 +21,6 @@
 // SOFTWARE.
 
 using LiveChartsCore.Drawing;
-using LiveChartsCore.Kernel.Sketches;
 using LiveChartsCore.VisualElements;
 
 namespace LiveChartsCore.Kernel.Events;
@@ -37,10 +36,9 @@ namespace LiveChartsCore.Kernel.Events;
 /// <param name="visualElement">The visual element.</param>
 public class VisualElementEventArgs(
     Chart chart,
-    CoreVisualElement visualElement,
+    IInteractable visualElement,
     LvcPoint pointerLocation)
 {
-
     /// <summary>
     /// Gets the chart.
     /// </summary>
@@ -54,5 +52,5 @@ public class VisualElementEventArgs(
     /// <summary>
     /// Gets the visual elements found.
     /// </summary>
-    public CoreVisualElement VisualElement { get; } = visualElement;
+    public IInteractable VisualElement { get; } = visualElement;
 }

src/LiveChartsCore/Kernel/Events/VisualElementHandler.cs

@@ -30,4 +30,4 @@ namespace LiveChartsCore.Kernel.Events;
 /// <param name="visual">The sender visual.</param>
 /// <param name="visualElementsArgs">The visual elements arguments.</param>
 public delegate void VisualElementHandler(
-    CoreVisualElement visual, VisualElementEventArgs visualElementsArgs);
+    IInteractable visual, VisualElementEventArgs visualElementsArgs);

src/LiveChartsCore/Kernel/Events/VisualElementsEventArgs.cs

@@ -24,7 +24,6 @@
 using System.Collections.Generic;
 using System.Linq;
 using LiveChartsCore.Drawing;
-using LiveChartsCore.Kernel.Sketches;
 using LiveChartsCore.VisualElements;
 
 namespace LiveChartsCore.Kernel.Events;
@@ -40,10 +39,10 @@ namespace LiveChartsCore.Kernel.Events;
 /// <param name="visualElements">The visual elements.</param>
 public class VisualElementsEventArgs(
     Chart chart,
-    IEnumerable<CoreVisualElement> visualElements,
+    IEnumerable<IInteractable> visualElements,
     LvcPoint pointerLocation)
 {
-    private CoreVisualElement? _closer;
+    private IInteractable? _closer;
 
     /// <summary>
     /// Gets the chart.
@@ -58,24 +57,24 @@ public class VisualElementsEventArgs(
     /// <summary>
     /// Gets the closest visual element to the pointer position.
     /// </summary>
-    public CoreVisualElement? ClosestToPointerVisualElement => _closer ??= FindClosest();
+    public IInteractable? ClosestToPointerVisualElement => _closer ??= FindClosest();
 
     /// <summary>
     /// Gets all the visual elements that were found.
     /// </summary>
-    public IEnumerable<CoreVisualElement> VisualElements { get; } = visualElements;
+    public IEnumerable<IInteractable> VisualElements { get; } = visualElements;
 
-    private CoreVisualElement? FindClosest()
+    private IInteractable? FindClosest()
     {
         return VisualElements.Select(visual =>
         {
-            var size = visual.Measure(Chart);
+            var hitbox = visual.GetHitBox();
 
             return new
             {
                 distance = Math.Sqrt(
-                    Math.Pow(PointerLocation.X - (visual.X + size.Width * 0.5), 2) +
-                    Math.Pow(PointerLocation.Y - (visual.Y + size.Height * 0.5), 2)),
+                    Math.Pow(PointerLocation.X - (hitbox.X + hitbox.Width * 0.5), 2) +
+                    Math.Pow(PointerLocation.Y - (hitbox.Y + hitbox.Height * 0.5), 2)),
                 visual
             };
         })

src/LiveChartsCore/Kernel/Sketches/IChartView.cs

@@ -275,5 +275,5 @@ public interface IChartView
     /// </summary>
     /// <param name="visualElements">The visual elements.</param>
     /// <param name="pointer">The pointer location.</param>
-    void OnVisualElementPointerDown(IEnumerable<CoreVisualElement> visualElements, LvcPoint pointer);
+    void OnVisualElementPointerDown(IEnumerable<IInteractable> visualElements, LvcPoint pointer);
 }

src/LiveChartsCore/VisualElements/CoreVisualElement.cs

@@ -34,7 +34,7 @@ namespace LiveChartsCore.VisualElements;
 /// <summary>
 /// Defines the base visual element class, inheriting from this class makes it easy to implement a visual element.
 /// </summary>
-public abstract class CoreVisualElement : ChartElement, INotifyPropertyChanged
+public abstract class CoreVisualElement : ChartElement, INotifyPropertyChanged, IInternalInteractable
 {
     internal double _x;
     internal double _y;
@@ -44,6 +44,7 @@ public abstract class CoreVisualElement : ChartElement, INotifyPropertyChanged
     private int _scalesYAt;
     private MeasureUnit _locationUnit = MeasureUnit.Pixels;
     private ClipMode _clippingMode = ClipMode.XY;
+    private Chart? _chart;
 
     /// <summary>
     /// Gets the primary scaler.
@@ -104,14 +105,14 @@ public abstract class CoreVisualElement : ChartElement, INotifyPropertyChanged
     /// </summary>
     public ClipMode ClippingMode { get => _clippingMode; set => SetProperty(ref _clippingMode, value); }
 
-    /// <summary>
-    /// Called when the pointer goes down on the visual.
-    /// </summary>
+    /// <inheritdoc cref="IInteractable.PointerDown"/>
     public event VisualElementHandler? PointerDown;
 
     /// <inheritdoc cref="ChartElement.Invalidate(Chart)"/>
     public override void Invalidate(Chart chart)
     {
+        _chart = chart;
+
         if (chart is CartesianChartEngine cc)
         {
             var primaryAxis = cc.YAxes[ScalesYAt];
@@ -207,12 +208,17 @@ protected internal virtual IEnumerable<CoreVisualElement> IsHitBy(Chart chart, L
         }
     }
 
-    /// <summary>
-    /// Called when the pointer goes down on the visual.
-    /// </summary>
-    /// <param name="args">The event arguments.</param>
-    protected internal void InvokePointerDown(VisualElementEventArgs args) =>
-        PointerDown?.Invoke(this, args);
+    /// <inheritdoc cref="IInteractable.GetHitBox"/>
+    public LvcRectangle GetHitBox()
+    {
+        if (_chart is null) return new();
+
+        var location = GetActualCoordinate();
+        var translatedLocation = new LvcPoint(location.X + _translate.X, location.Y + Translate.Y);
+        var size = Measure(_chart);
+
+        return new(translatedLocation, size);
+    }
 
     /// <summary>
     /// Gets the geometries to draw.
@@ -236,8 +242,18 @@ protected virtual void ApplyTheme<T>()
         _isInternalSet = false;
     }
 
+    /// <inheritdoc cref="ChartElement.RemoveFromUI(Chart)"/>
+    public override void RemoveFromUI(Chart chart)
+    {
+        base.RemoveFromUI(chart);
+        _chart = null;
+    }
+
     internal virtual void AlignToTopLeftCorner()
     {
         // just a workaround to align labels as the rest of the geometries.
     }
+
+    void IInternalInteractable.InvokePointerDown(VisualElementEventArgs args) =>
+        PointerDown?.Invoke(this, args);
 }

src/LiveChartsCore/VisualElements/IInteractable.cs

@@ -0,0 +1,43 @@
+// The MIT License(MIT)
+//
+// Copyright(c) 2021 Alberto Rodriguez Orozco & LiveCharts Contributors
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+using LiveChartsCore.Drawing;
+using LiveChartsCore.Kernel.Events;
+
+namespace LiveChartsCore.VisualElements;
+
+/// <summary>
+/// Defines an object that the user can interact with.
+/// </summary>
+public interface IInteractable
+{
+    /// <summary>
+    /// Called when the pointer goes down on the visual.
+    /// </summary>
+    event VisualElementHandler? PointerDown;
+
+    /// <summary>
+    /// Gets the hit box, an area where the user can interact with the object.
+    /// </summary>
+    /// <returns>The hitbox rectangle.</returns>
+    LvcRectangle GetHitBox();
+}

src/LiveChartsCore/VisualElements/IInternalInteractable.cs

@@ -0,0 +1,30 @@
+// The MIT License(MIT)
+//
+// Copyright(c) 2021 Alberto Rodriguez Orozco & LiveCharts Contributors
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+using LiveChartsCore.Kernel.Events;
+
+namespace LiveChartsCore.VisualElements;
+
+internal interface IInternalInteractable : IInteractable
+{
+    void InvokePointerDown(VisualElementEventArgs args);
+}