Caret positioning for MathEditor

CSharpMath.Apple/Drawing/AppleGraphicsContext.cs

@@ -5,7 +5,7 @@
 using CoreText;
 using CSharpMath.Display.Text;
 using CSharpMath.FrontEnd;
-using CSharpMath.Structures;
+using Color = CSharpMath.Structures.Color;
 using UIKit;
 using TFont = CSharpMath.Apple.AppleMathFont;
 using TGlyph = System.UInt16;

CSharpMath.Editor/Extensions/DisplayEditingExtensions.Fraction.cs

@@ -18,20 +18,24 @@ public static MathListIndex IndexForPoint<TFont, TGlyph>(this FractionDisplay<TF
         //We are after the fraction
         return MathListIndex.Level0Index(self.Range.End);
 
-      //We can be either near the numerator or denominator
-      var numeratorDistance = DistanceFromPointToRect(point, self.Numerator.DisplayBounds);
-      var denominatorDistance = DistanceFromPointToRect(point, self.Denominator.DisplayBounds);
-      if (numeratorDistance < denominatorDistance)
+      if (point.Y > self.LinePosition + PixelDelta)
         return MathListIndex.IndexAtLocation(self.Range.Location, self.Numerator.IndexForPoint(context, point), MathListSubIndexType.Numerator);
-      else
+      else if (point.Y < self.LinePosition - PixelDelta)
         return MathListIndex.IndexAtLocation(self.Range.Location, self.Denominator.IndexForPoint(context, point), MathListSubIndexType.Denominator);
+      if (point.X > self.Position.X + self.Width / 2)
+        return MathListIndex.Level0Index(self.Range.End);
+
+      return MathListIndex.Level0Index(self.Range.Location);
     }
 
     public static PointF? PointForIndex<TFont, TGlyph>(this FractionDisplay<TFont, TGlyph> self, TypesettingContext<TFont, TGlyph> context, MathListIndex index) where TFont : IFont<TGlyph> {
       if (index.SubIndexType != MathListSubIndexType.None)
         throw Arg("The subindex must be none to get the closest point for it.", nameof(index));
-      // draw a caret after the fraction
-      return new PointF(self.DisplayBounds.Right, self.Position.Y);
+      if (index.AtomIndex == self.Range.End)
+        // draw a caret after the fraction
+        return new PointF(self.DisplayBounds.Right, self.Position.Y);
+      // draw a caret before the fraction
+      return new PointF(self.DisplayBounds.Left, self.Position.Y);
     }
 
     public static void HighlightCharacterAt<TFont, TGlyph>(this FractionDisplay<TFont, TGlyph> self, MathListIndex index, Color color) where TFont : IFont<TGlyph> {

CSharpMath.Editor/Extensions/DisplayEditingExtensions.List.cs

@@ -2,7 +2,7 @@ namespace CSharpMath.Editor {
   using System;
   using System.Collections.Generic;
   using System.Drawing;
-
+  using System.Linq;
   using Display;
   using Display.Text;
   using FrontEnd;
@@ -18,10 +18,11 @@ public static MathListIndex IndexForPoint<TFont, TGlyph>(this ListDisplay<TFont,
       float minDistance = float.MaxValue;
       foreach (var display in self.Displays) {
         var bounds = display.DisplayBounds;
-        var maxBoundsX = bounds.Right;
-        if (bounds.X - PixelDelta <= translatedPoint.X && translatedPoint.X <= maxBoundsX + PixelDelta)
+        var rect = new RectangleF(display.Position, bounds.Size);
+        var maxBoundsX = rect.Right;
+        if (rect.X - PixelDelta <= translatedPoint.X && translatedPoint.X <= maxBoundsX + PixelDelta)
           xbounds.Add(display);
-        var distance = DistanceFromPointToRect(translatedPoint, bounds);
+        var distance = DistanceFromPointToRect(translatedPoint, rect);
         if (distance < minDistance) {
           closest = display;
           minDistance = distance;
@@ -33,18 +34,23 @@ public static MathListIndex IndexForPoint<TFont, TGlyph>(this ListDisplay<TFont,
           if (translatedPoint.X <= -PixelDelta)
             // All the way to the left
             return MathListIndex.Level0Index(self.Range.Location);
-          else if (translatedPoint.X >= self.Width + PixelDelta)
+          else if (translatedPoint.X >= self.Width + PixelDelta) {
+            // All the way to the right
+            if (closest != null) {
+              return MathListIndex.Level0Index(closest.Range.End);
+            }
             // All the way to the right
-            return MathListIndex.Level0Index(self.Range.End);
-          else
+            return self.Range.End < 0 ? null : MathListIndex.Level0Index(self.Range.End);
+          } else
             // It is within the ListDisplay but not within the X bounds of any sublist. Use the closest in that case.
             displayWithPoint = closest;
           break;
         case 1:
           displayWithPoint = xbounds[0];
+          var rect = new RectangleF(displayWithPoint.Position, displayWithPoint.DisplayBounds.Size);
           if (translatedPoint.X >= self.Width - PixelDelta)
             //The point is close to the end. Only use the selected X bounds if the Y is within range.
-            if (translatedPoint.Y <= displayWithPoint.DisplayBounds.YMin() - PixelDelta)
+            if (translatedPoint.Y <= rect.YMin() - PixelDelta)
               //The point is less than the Y including the delta. Move the cursor to the end rather than in this atom.
               return MathListIndex.Level0Index(self.Range.End);
           break;
@@ -88,7 +94,19 @@ public static MathListIndex IndexForPoint<TFont, TGlyph>(this ListDisplay<TFont,
             position = display.PointForIndex(context, MathListIndex.Level0Index(nucleusPosition));
             break;
           case MathListSubIndexType.None:
-            position = display.PointForIndex(context, index);
+            if (!display.HasScript) {
+              position = display.PointForIndex(context, index);
+            } else {
+              var mainPosition = display.PointForIndex(context, index);
+              var scripted = self.Displays.SingleOrDefault(d =>
+                d is ListDisplay<TFont, TGlyph> ld &&
+                    ld.IndexInParent == index.AtomIndex - 1
+                  );
+              if (scripted != null && mainPosition != null) {
+                position = new PointF(mainPosition.Value.X + scripted.Width, 0);
+              } else
+                position = mainPosition;
+            }
             break;
           default:
             // Recurse

CSharpMath.Editor/Extensions/DisplayEditingExtensions.TextLine.cs

@@ -10,20 +10,23 @@ namespace CSharpMath.Editor {
 
   public partial class DisplayEditingExtensions {
     public static int? GlyphIndexForXOffset<TFont, TGlyph>(this AttributedGlyphRun<TFont, TGlyph> line, TypesettingContext<TFont, TGlyph> context, float offset) where TFont : IFont<TGlyph> {
-      if (offset < 0) return 0; //Move cursor to index 0
+      if (offset < 0) return 0; // Move cursor to index 0
+      if (line.Placeholder) return 0;
       int i = 0;
       float x = 0;
       var advances = context.GlyphBoundsProvider.GetAdvancesForGlyphs(line.Font, line.Glyphs.AsForEach(), line.Length).Advances;
       foreach (var (advance, kernAfter) in advances.Zip(line.GlyphInfos.Select(g => g.KernAfterGlyph), ValueTuple.Create))
-        if (x <= offset && offset < advance + x)
-          return i;
-        else {
+        if (x <= offset && offset < advance + x) {
+          if (Math.Abs(offset - x) < Math.Abs(advance + x - offset))
+            return i;
+          return i + 1;
+        } else {
           x += advance + kernAfter;
           i++;
-          if (offset < x) //If the point is in the kern after this, then the index is the one after this
+          if (offset < x) // If the point is in the kern after this, then the index is the one after this
             return i;
         }
-      return null;
+      return i;
     }
 
     public static float XOffsetForGlyphIndex<TFont, TGlyph>(this AttributedGlyphRun<TFont, TGlyph> line, TypesettingContext<TFont, TGlyph> context, int index) where TFont : IFont<TGlyph> {
@@ -67,19 +70,16 @@ public static int MathListIndexToStringIndex<TFont, TGlyph>(this TextLineDisplay
     public static MathListIndex IndexForPoint<TFont, TGlyph>(this TextLineDisplay<TFont, TGlyph> self, TypesettingContext<TFont, TGlyph> context, PointF point) where TFont : IFont<TGlyph> {
       // Convert the point to the reference of the CTLine
       var relativePoint = new PointF(point.X - self.Position.X, point.Y - self.Position.Y);
-      var indices = self.Runs.Select(run => run.Run.GlyphIndexForXOffset(context, relativePoint.Plus(run.Position).X)).Where(x => x.HasValue);
-      if (indices.IsEmpty())
+      var indices = self.Runs.Select(run => run.Run.GlyphIndexForXOffset(context, relativePoint.Plus(run.Position).X)).Where(x => x.HasValue).ToArray();
+      if (indices.Length == 0)
         return null;
       var index = indices.Single().GetValueOrDefault();
-      // The index returned is in UTF-16, translate to codepoint index.
-      // NSUInteger codePointIndex = stringIndexToCodePointIndex(self.attributedString.string, index);
-      // Convert the code point index to an index into the mathlist
-      var mlIndex = self.StringIndexToMathListIndex(index);
+
       // index will be between 0 and _range.length inclusive
-      if (mlIndex < 0 || mlIndex > self.Range.Length)
+      if (index < 0 || index > self.Range.Length)
         throw new InvalidCodePathException($"Returned index out of range: {index}, range ({self.Range.Location}, {self.Range.Length})");
       // translate to the current index
-      return MathListIndex.Level0Index(self.Range.Location + mlIndex);
+      return MathListIndex.Level0Index(self.Range.Location + index);
     }
 
     public static (TextRunDisplay<TFont, TGlyph> run, int charIndex) GetRunAndCharIndexFromStringIndex<TFont, TGlyph>(this TextLineDisplay<TFont, TGlyph> self, int lineCharIndex) where TFont : IFont<TGlyph> {

CSharpMath.Editor/Extensions/DisplayEditingExtensions.cs

@@ -67,7 +67,8 @@ public static float DistanceFromPointToRect(PointF point, RectangleF rect) {
         distance += point.Y - rect.YMax();
       return distance;
     }
-
+    public static float DistanceBetweenY(PointF p1, PointF p2) => (p1.Y - p2.Y) * (p1.Y - p2.Y);
+
     /// <summary>
     /// Finds the index in the mathlist before which a new character should be inserted.Returns null if it cannot find the index.
     /// </summary>

CSharpMath.Forms.Example/CSharpMath.Forms.Example/EditorPage.xaml

@@ -3,11 +3,4 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              x:Class="CSharpMath.Forms.Example.EditorPage"
              Title="Editor">
-    <ContentPage.Content>
-        <StackLayout>
-            <Label Text="Welcome to Xamarin.Forms!"
-                VerticalOptions="CenterAndExpand" 
-                HorizontalOptions="CenterAndExpand" />
-        </StackLayout>
-    </ContentPage.Content>
 </ContentPage>

CSharpMath.Forms.Example/CSharpMath.Forms.Example/EditorPage.xaml.cs

@@ -3,24 +3,43 @@
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
-
+using CSharpMath.Editor;
+using SkiaSharp.Views.Forms;
 using Xamarin.Forms;
 using Xamarin.Forms.Xaml;
 
 namespace CSharpMath.Forms.Example {
   [XamlCompilation(XamlCompilationOptions.Compile)]
   public partial class EditorPage : ContentPage {
+
     public EditorPage() {
       InitializeComponent();
-      var view = new global::SkiaSharp.Views.Forms.SKCanvasView { WidthRequest = 320, HeightRequest = 225 };
+      this.Content = new EditorView();
+    }
+
+  }
+
+  public class EditorView : ContentView {
+    private MathKeyboard keyboard;
+
+    public EditorView() {
+      keyboard = new MathKeyboard();
+
+      var view = new SKCanvasView { WidthRequest = 320, HeightRequest = 225, EnableTouchEvents = true };
+      view.Touch +=
+        (sender, e) => {
+          if (e.ActionType == SKTouchAction.Pressed) {
+            keyboard.Tap(new System.Drawing.PointF(e.Location.X, e.Location.Y));
+          }
+        };
+
       var painter = new SkiaSharp.MathPainter { TextColor = global::SkiaSharp.SKColors.Black };
-      var keyboard = new MathKeyboard();
       keyboard.RedrawRequested += (_, __) => view.InvalidateSurface();
       view.PaintSurface +=
         (sender, e) => {
           e.Surface.Canvas.Clear();
           SkiaSharp.MathPainter.DrawDisplay(painter, keyboard.Display, e.Surface.Canvas);
-          keyboard.DrawCaret(e.Surface.Canvas, Rendering.CaretShape.UpArrow);
+          keyboard.DrawCaret(e.Surface.Canvas, Rendering.CaretShape.IBeam);
         };
       Content = new StackLayout { Children = { view, keyboard } };
     }

CSharpMath.Forms/MathKeyboard.xaml.cs

@@ -8,13 +8,17 @@
 using Xamarin.Forms.Xaml;
 
 namespace CSharpMath.Forms {
+  using CSharpMath.Editor;
   using Rendering;
   [XamlCompilation(XamlCompilationOptions.Compile)]
   public partial class MathKeyboard : ContentView {
     public MathKeyboard() {
       InitializeComponent();
     }
 
+
+    public void Tap(System.Drawing.PointF point) => Keyboard.Tap(point);
+
     public void DrawCaret(global::SkiaSharp.SKCanvas canvas, CaretShape shape = CaretShape.UpArrow) =>
       Keyboard.DrawCaret(new SkiaSharp.SkiaCanvas(canvas, global::SkiaSharp.SKStrokeCap.Butt, false), shape);
     public event EventHandler RedrawRequested {
@@ -30,7 +34,7 @@ public event EventHandler DismissPressed {
       remove => Keyboard.DismissPressed -= value;
     }
 
-    public IDisplay<Rendering.Fonts, Rendering.Glyph> Display => Keyboard.Display;
+    public IDisplay<Fonts, Glyph> Display => Keyboard.Display;
 
     private void SwitchTab(Grid tab) {
       tab.IsVisible = true;

CSharpMath/CSharpMath.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard1.1</TargetFramework>
     <LangVersion>latest</LangVersion>
@@ -38,7 +38,7 @@
   <ItemGroup>
     <PackageReference Include="System.Buffers" Version="4.5.0" />
     <PackageReference Include="System.Memory" Version="4.5.1" />
-    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.5.2" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.5.1" />
   </ItemGroup>
   <Import Project="..\packages\NuGet.Build.Packaging.0.2.2\build\NuGet.Build.Packaging.targets" Condition="Exists('..\packages\NuGet.Build.Packaging.0.2.2\build\NuGet.Build.Packaging.targets') And '$(Configuration)' == 'Release-iOS'" />
 </Project>