Added UI selection parts. Now the text is more useful.

Base/Forms/GraphForm.cs

@@ -238,19 +238,8 @@ public partial class GraphForm : Form
             {
                 if (ables[i].ShouldSelectGraphable(this, graphMousePos, 2.5))
                 {
-                    Float2 selectedPoint = ables[i].GetSelectedPoint(this, graphMousePos);
+                    IEnumerable<IGraphPart> selectionParts = ables[i].GetSelectionItemsToRender(this, graphMousePos);
-                    GraphUiCircle select = new(selectedPoint);
+                    foreach (IGraphPart selPart in selectionParts) selPart.Render(this, g, graphPens[i]);
-
-                    Int2 textPos = GraphSpaceToScreenSpace(select.center);
-                    textPos.y -= (int)(DpiFloat * 32 / 192);
-
-                    string content = $"({selectedPoint.x:0.00}, {selectedPoint.y:0.00})";
-
-                    SizeF textSize = g.MeasureString(content, textFont);
-                    g.FillRectangle(background, new Rectangle(textPos.x, textPos.y,
-                                         (int)textSize.Width, (int)textSize.Height));
-                    g.DrawString(content, textFont, graphPens[i].Brush, new Point(textPos.x, textPos.y));
-                    select.Render(this, g, graphPens[i]);
                 }
             }
         }

Base/Forms/ViewCacheForm.cs

@@ -33,6 +33,7 @@ public partial class ViewCacheForm : Form
         foreach (Graphable able in refForm.Graphables)
         {
             long thisBytes = able.GetCacheBytes();
+            if (thisBytes == 0) continue;
             CachePie.Values.Add((able.Color, thisBytes));
             totalBytes += thisBytes;
 

Base/Graphable.cs

@@ -37,5 +37,5 @@ public abstract class Graphable
     public virtual void Preload(Float2 xRange, Float2 yRange, double step) { }
 
     public virtual bool ShouldSelectGraphable(in GraphForm graph, Float2 graphMousePos, double factor) => false;
-    public virtual Float2 GetSelectedPoint(in GraphForm graph, Float2 graphMousePos) => default;
+    public virtual IEnumerable<IGraphPart> GetSelectionItemsToRender(in GraphForm graph, Float2 graphMousePos) => [];
 }

Base/Graphables/ColumnTable.cs

@@ -2,6 +2,7 @@
 using Graphing.Parts;
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 using System.Linq;
 
 namespace Graphing.Graphables;
@@ -52,6 +53,81 @@ public class ColumnTable : Graphable
         return items;
     }
 
+    public override bool ShouldSelectGraphable(in GraphForm graph, Float2 graphMousePos, double factor)
+    {
+        // Get closest value to mouse pos.
+        double closestDist = double.PositiveInfinity, closestX = 0, closestY = 0;
+        foreach (KeyValuePair<double, double> points in tableXY)
+        {
+            double dist = Math.Abs(points.Key - graphMousePos.x);
+            if (dist < closestDist)
+            {
+                closestDist = dist;
+                closestX = points.Key;
+                closestY = points.Value;
+            }
+        }
+
+        Int2 screenMousePos = graph.GraphSpaceToScreenSpace(graphMousePos);
+        Int2 minBox = graph.GraphSpaceToScreenSpace(new(closestX - width / 2, 0)),
+             maxBox = graph.GraphSpaceToScreenSpace(new(closestX + width / 2, closestY));
+
+        int distX, distY;
+        if (screenMousePos.x < minBox.x) distX = minBox.x - screenMousePos.x; // On left side.
+        else if (screenMousePos.x > maxBox.x) distX = screenMousePos.x - maxBox.x; // On right side.
+        else distX = 0; // Inside.
+
+        if (closestY > 0)
+        {
+            if (screenMousePos.y > minBox.y) distY = screenMousePos.y - minBox.y; // Underneath.
+            else if (screenMousePos.y < maxBox.y) distY = maxBox.y - screenMousePos.y; // Above.
+            else distY = 0; // Inside.
+        }
+        else
+        {
+            if (screenMousePos.y < minBox.y) distY = minBox.y - screenMousePos.y; // Underneath.
+            else if (screenMousePos.y > maxBox.y) distY = screenMousePos.y - maxBox.y; // Above.
+            else distY = 0; // Inside.
+        }
+
+        int totalDist = (int)Math.Sqrt(distX * distX + distY * distY);
+        return totalDist < 50 * factor * graph.DpiFloat / 192;
+    }
+    public override IEnumerable<IGraphPart> GetSelectionItemsToRender(in GraphForm graph, Float2 graphMousePos)
+    {
+        // Get closest value to mouse pos.
+        double closestDist = double.PositiveInfinity, closestX = 0, closestY = 0;
+        foreach (KeyValuePair<double, double> points in tableXY)
+        {
+            double dist = Math.Abs(points.Key - graphMousePos.x);
+            if (dist < closestDist)
+            {
+                closestDist = dist;
+                closestX = points.Key;
+                closestY = points.Value;
+            }
+        }
+
+        Float2 textPoint = new(closestX, closestY);
+        Int2 offset;
+        ContentAlignment alignment;
+        if (textPoint.y >= 0)
+        {
+            offset = new(0, -5);
+            alignment = ContentAlignment.BottomCenter;
+        }
+        else
+        {
+            offset = new(0, 5);
+            alignment = ContentAlignment.TopCenter;
+        }
+
+        return
+        [
+            new GraphUiText($"{closestY:0.00}", textPoint, alignment, offsetPix: offset)
+        ];
+    }
+
     // Nothing to preload, everything is already cached.
     public override void Preload(Float2 xRange, Float2 yRange, double step) { }
 }

Base/Graphables/Equation.cs

@@ -3,6 +3,7 @@ using Graphing.Forms;
 using Graphing.Parts;
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 
 namespace Graphing.Graphables;
 
@@ -148,8 +149,15 @@ public class Equation : Graphable, IIntegrable, IDerivable, ITranslatableXY, ICo
         double totalDist = Math.Sqrt(dist.x * dist.x + dist.y * dist.y);
         return totalDist <= allowedDist;
     }
-    public override Float2 GetSelectedPoint(in GraphForm graph, Float2 graphMousePos) =>
+    public override IEnumerable<IGraphPart> GetSelectionItemsToRender(in GraphForm graph, Float2 graphMousePos)
-        new(graphMousePos.x, GetFromCache(graphMousePos.x, 1e-3));
+    {
+        Float2 point = new(graphMousePos.x, GetFromCache(graphMousePos.x, 1e-3));
+        return
+        [
+            new GraphUiText($"({point.x:0.00}, {point.y:0.00})", point, ContentAlignment.BottomLeft),
+            new GraphUiCircle(point),
+        ];
+    }
 
     public override void Preload(Float2 xRange, Float2 yRange, double step)
     {

Base/Graphables/EquationDifference.cs

@@ -1,7 +1,9 @@
 using Graphing.Abstract;
 using Graphing.Forms;
 using Graphing.Parts;
+using System;
 using System.Collections.Generic;
+using System.Drawing;
 
 namespace Graphing.Graphables;
 
@@ -42,16 +44,50 @@ public class EquationDifference : Graphable, ITranslatableX, IConvertEquation
     public override IEnumerable<IGraphPart> GetItemsToRender(in GraphForm graph)
     {
         Float2 pA = new(Position, points.x),
-               pB = new(Position, points.y),
+               pB = new(Position, points.y);
-               pC = new(Position, (points.x + points.y) / 2);
+        return
-        return [new GraphUiText($"{points.x - points.y:0.00}", pC),
+        [
-                new GraphUiCircle(pA), new GraphUiCircle(pB), new GraphLine(pA, pB)];
+            new GraphUiCircle(pA),
+            new GraphUiCircle(pB),
+            new GraphLine(pA, pB)
+        ];
     }
 
     public double DistanceAtPoint(double x) => equA.GetValueAt(x) - equB.GetValueAt(x);
 
     public override Graphable ShallowCopy() => new EquationDifference(Position, equA, equB);
 
+    public override bool ShouldSelectGraphable(in GraphForm graph, Float2 graphMousePos, double factor)
+    {
+        Float2 nearestPoint = new(Position, graphMousePos.y);
+        double upper = double.Max(points.x, points.y),
+               lower = double.Min(points.x, points.y);
+        if (nearestPoint.y > upper) nearestPoint.y = upper;
+        else if (nearestPoint.y < lower) nearestPoint.y = lower;
+
+        Int2 nearestPixelPoint = graph.GraphSpaceToScreenSpace(nearestPoint);
+        Int2 screenMousePos = graph.GraphSpaceToScreenSpace(graphMousePos);
+
+        Int2 diff = new(screenMousePos.x - nearestPixelPoint.x,
+                        screenMousePos.y - nearestPixelPoint.y);
+        int dist = (int)Math.Sqrt(diff.x * diff.x + diff.y * diff.y);
+        return dist < 50 * factor * graph.DpiFloat / 192;
+    }
+    public override IEnumerable<IGraphPart> GetSelectionItemsToRender(in GraphForm graph, Float2 graphMousePos)
+    {
+        Float2 nearestPoint = new(Position, graphMousePos.y);
+        double upper = double.Max(points.x, points.y),
+               lower = double.Min(points.x, points.y);
+        if (nearestPoint.y > upper) nearestPoint.y = upper;
+        else if (nearestPoint.y < lower) nearestPoint.y = lower;
+
+        return
+        [
+            new GraphUiText($"Δ = {points.x - points.y:0.000}", nearestPoint, ContentAlignment.MiddleLeft, offsetPix: new Int2(15, 0)),
+            new GraphUiCircle(nearestPoint)
+        ];
+    }
+
     public Equation ToEquation() => new(DistanceAtPoint)
     {
         Color = Color,

Base/Graphables/IntegralEquation.cs

@@ -234,6 +234,6 @@ public class IntegralEquation : Graphable, IIntegrable, IDerivable
         double totalDist = Math.Sqrt(dist.x * dist.x + dist.y * dist.y);
         return totalDist <= allowedDist;
     }
-    public override Float2 GetSelectedPoint(in GraphForm graph, Float2 graphMousePos) =>
+    public override IEnumerable<IGraphPart> GetSelectionItemsToRender(in GraphForm graph, Float2 graphMousePos) =>
-        new(graphMousePos.x, IntegralAtPoint(graphMousePos.x));
+        [new GraphUiCircle(new(graphMousePos.x, IntegralAtPoint(graphMousePos.x)))];
 }

Base/Graphables/SlopeField.cs

@@ -2,6 +2,7 @@
 using Graphing.Parts;
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 
 namespace Graphing.Graphables;
 
@@ -101,7 +102,7 @@ public class SlopeField : Graphable
         double totalDist = Math.Sqrt(dist.x * dist.x + dist.y * dist.y);
         return totalDist <= allowedDist;
     }
-    public override Float2 GetSelectedPoint(in GraphForm graph, Float2 graphMousePos)
+    public override IEnumerable<IGraphPart> GetSelectionItemsToRender(in GraphForm graph, Float2 graphMousePos)
     {
         Float2 nearestPos = new(Math.Round(graphMousePos.x * detail) / detail,
                                 Math.Round(graphMousePos.y * detail) / detail);
@@ -114,7 +115,11 @@ public class SlopeField : Graphable
                lineY = slope * (lineX - nearestPos.x) + nearestPos.y;
         Float2 point = new(lineX, lineY);
 
-        return point;
+        return
+        [
+            new GraphUiText($"M = {slope:0.000}", point, ContentAlignment.BottomLeft),
+            new GraphUiCircle(point)
+        ];
     }
 
     public override void Preload(Float2 xRange, Float2 yRange, double step)

Base/Graphables/TangentLine.cs

@@ -3,6 +3,7 @@ using Graphing.Forms;
 using Graphing.Parts;
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 
 namespace Graphing.Graphables;
 
@@ -58,7 +59,11 @@ public class TangentLine : Graphable, IConvertEquation, ITranslatableX
     public override IEnumerable<IGraphPart> GetItemsToRender(in GraphForm graph)
     {
         Float2 point = new(Position, currentSlope.y);
-        return [MakeSlopeLine(), new GraphUiCircle(point)];
+        return
+        [
+            MakeSlopeLine(),
+            new GraphUiCircle(point)
+        ];
     }
     protected GraphLine MakeSlopeLine()
     {
@@ -107,7 +112,7 @@ public class TangentLine : Graphable, IConvertEquation, ITranslatableX
         double totalDist = Math.Sqrt(dist.x * dist.x + dist.y * dist.y);
         return totalDist <= allowedDist;
     }
-    public override Float2 GetSelectedPoint(in GraphForm graph, Float2 graphMousePos)
+    public override IEnumerable<IGraphPart> GetSelectionItemsToRender(in GraphForm graph, Float2 graphMousePos)
     {
         GraphLine line = MakeSlopeLine();
 
@@ -115,7 +120,15 @@ public class TangentLine : Graphable, IConvertEquation, ITranslatableX
                                   Math.Min(line.a.x, line.b.x),
                                   Math.Max(line.a.x, line.b.x)),
                lineY = currentSlope.x * (lineX - Position) + currentSlope.y;
-        return new Float2(lineX, lineY);
+
+        double slope = currentSlope.x;
+        Float2 point = new(lineX, lineY);
+
+        return
+        [
+            new GraphUiText($"M = {slope:0.000}", point, ContentAlignment.BottomLeft),
+            new GraphUiCircle(new(lineX, lineY))
+        ];
     }
 
     public override void Preload(Float2 xRange, Float2 yRange, double step)

Base/Parts/GraphRectangle.cs

@@ -45,7 +45,9 @@ public record struct GraphRectangle : IGraphPart
                         start.y - end.y);
 
         if (size.x == 0 || size.y == 0) return;
+        Color initialColor = pen.Color;
         pen.Color = Color.FromArgb((int)(opacity * 255), pen.Color);
         g.FillRectangle(pen.Brush, new Rectangle(start.x, end.y, size.x, size.y));
+        pen.Color = initialColor;
     }
 }

Base/Parts/GraphUiText.cs

@@ -9,16 +9,22 @@ public record struct GraphUiText : IGraphPart
     public Float2 position;
     public bool background;
 
+    public ContentAlignment alignment;
+    public Int2 offsetPix;
+
     private readonly Font font;
     private readonly Brush? backgroundBrush;
 
-    public GraphUiText(string text, Float2 position, bool background = true)
+    public GraphUiText(string text, Float2 position, ContentAlignment alignment,
+                       bool background = true, Int2? offsetPix = null)
     {
         font = new Font("Segoe UI", 8, FontStyle.Bold);
 
         this.text = text;
         this.position = position;
         this.background = background;
+        this.alignment = alignment;
+        this.offsetPix = offsetPix ?? new();
 
         if (background) backgroundBrush = new SolidBrush(GraphForm.BackgroundColor);
     }
@@ -26,10 +32,53 @@ public record struct GraphUiText : IGraphPart
     public readonly void Render(in GraphForm form, in Graphics g, in Pen p)
     {
         Int2 posScreen = form.GraphSpaceToScreenSpace(position);
-        posScreen.y -= (int)(form.DpiFloat * font.Size * 2 / 192);
+        SizeF size = g.MeasureString(text, font);
+
+        // Adjust X position based on alignment.
+        switch (alignment)
+        {
+            case ContentAlignment.TopLeft or
+                 ContentAlignment.MiddleLeft or
+                 ContentAlignment.BottomLeft: break; // Nothing to offset.
+
+            case ContentAlignment.TopCenter or
+                 ContentAlignment.MiddleCenter or
+                 ContentAlignment.BottomCenter:
+                posScreen.x -= (int)(size.Width / 2);
+                break;
+
+            case ContentAlignment.TopRight or
+                 ContentAlignment.MiddleRight or
+                 ContentAlignment.BottomRight:
+                posScreen.x -= (int)size.Width;
+                break;
+        }
+
+        // Adjust Y position based on alignment.
+        switch (alignment)
+        {
+            case ContentAlignment.TopLeft or
+                 ContentAlignment.TopCenter or
+                 ContentAlignment.TopRight: break; // Nothing to offset.
+
+            case ContentAlignment.MiddleLeft or
+                 ContentAlignment.MiddleCenter or
+                 ContentAlignment.MiddleRight:
+                posScreen.y -= (int)(size.Height / 2);
+                break;
+
+            case ContentAlignment.BottomLeft or
+                 ContentAlignment.BottomCenter or
+                 ContentAlignment.BottomRight:
+                posScreen.y -= (int)size.Height; 
+                break;
+        }
+
+        posScreen.x += (int)(offsetPix.x * form.DpiFloat / 192);
+        posScreen.y += (int)(offsetPix.y * form.DpiFloat / 192);
+
         if (background)
         {
-            SizeF size = g.MeasureString(text, font);
             g.FillRectangle(backgroundBrush!, new Rectangle(posScreen.x, posScreen.y,
                                                             (int)size.Width, (int)size.Height));
         }

Testing/Program.cs

@@ -20,7 +20,8 @@ internal static class Program
                  equB = new(Math.Cos);
         EquationDifference diff = new(2, equA, equB);
         ParametricEquation equC = new(0, 20, t => 0.0375 * t * Math.Cos(t), t => 0.0625 * t * Math.Sin(t) + 3);
-        graph.Graph(equA, equB, diff, equC, equA.ToColumnTable(-1, 1, 2));
+        TangentLine tanA = new(2, 2, equA);
+        graph.Graph(equA, equB, diff, equC, equB.ToColumnTable(-3, 3, 2), tanA);
 
         Application.Run(graph);
     }