Fix the editor's unit minus and warning colour, and tighten the gallery

README.md

@@ -235,6 +235,8 @@ Use `SchemaSerializer` for JSON serialization with `System.Text.Json`. The seria
 The **Schema.Editor** is an ImGui-based desktop application for visually creating and editing `.schema.json` files.
 The [editor gallery](docs/gallery/README.md) shows what it looks like, regenerated from `main` on every build.
 
+[![The member grid with a member's unit, range, default and interpolation open](docs/gallery/member-metadata.png)](docs/gallery/README.md)
+
 ### Running the Editor
 
 ```shell

Schema.Editor/CodeGeneratorPanel.cs

@@ -134,7 +134,7 @@ private void ShowGenerateButton(Schema schema, SchemaCodeGenerator codeGenerator
 	{
 		if (!schema.CanResolvePaths)
 		{
-			using (EditorTheme.Warning())
+			using (EditorTheme.SeverityText(SchemaValidationSeverity.Warning))
 			{
 				ImGui.TextUnformatted("Save the schema before generating: output paths are relative to it.");
 			}

Schema.Editor/MemberSemanticsPanel.cs

@@ -114,13 +114,13 @@ private void ShowUnitField(SchemaMember member)
 	{
 		ShowMetadataLabel("Unit:");
 
-		bool clicked = ImGui.Button(member.Unit is null ? SchemaEditor.NoneOption : member.Unit.ToString(), new Vector2(FieldWidth, 0));
+		bool clicked = ImGui.Button(member.Unit is null ? SchemaEditor.NoneOption : UnitText.ForDisplay(member.Unit), new Vector2(FieldWidth, 0));
 		ImGuiProbes.MarkItem("Unit");
 
 		if (member.Unit is not null && ImGui.IsItemHovered())
 		{
 			ImGui.SetTooltip(UnitRegistry.TryResolve(member.Unit, out IUnit? resolved, out string error)
-				? $"{resolved!.Name} ({resolved.Symbol})"
+				? UnitText.ForDisplay($"{resolved!.Name} ({resolved.Symbol})")
 				: error);
 		}
 

Schema.Editor/Popups.cs

@@ -94,7 +94,7 @@ internal void OpenUnitList(string title, string label, IEnumerable<IUnit> units,
 		{
 			List<IUnit> choices = [.. units];
 			IUnit? selected = UnitRegistry.TryResolve(current, out IUnit? resolved, out _) ? resolved : null;
-			PopupUnitList.Open(title, label, choices, selected, unit => $"{unit.Name} ({unit.Symbol})", onConfirm!);
+			PopupUnitList.Open(title, label, choices, selected, unit => UnitText.ForDisplay($"{unit.Name} ({unit.Symbol})"), onConfirm!);
 		});
 
 	internal void Update()

Schema.Editor/SchemaEditor.Diagnostics.cs

@@ -110,7 +110,7 @@ private void ShowDiagnostic(SchemaValidationIssue issue)
 	{
 		bool isError = issue.Severity == SchemaValidationSeverity.Error;
 
-		using (EditorTheme.Severity(issue.Severity))
+		using (EditorTheme.SeverityText(issue.Severity))
 		{
 			ImGui.TextUnformatted(isError ? "Error" : "Warning");
 		}

Schema.Editor/SchemaEditor.cs

@@ -35,9 +35,9 @@
 	internal static float FieldWidth => ImGui.GetIO().DisplaySize.X * 0.15f;
 	private bool OptionsDirty { get; set; }
 #pragma warning disable IDE0052 // Remove unread private member - reference needed to prevent GC
 	private readonly IntervalAction? autoSaveOptionsAction;
 #pragma warning restore IDE0052
-	private ImGuiWidgets.DividerContainer DividerContainerCols { get; init; }
+	internal ImGuiWidgets.DividerContainer DividerContainerCols { get; init; }
 
 	internal IUndoRedoService UndoRedo { get; }
 
@@ -153,7 +153,7 @@
 		Options.CurrentClassName = CurrentClass?.Name ?? new();
 		Options.DividerStates[DividerContainerCols.Id] = DividerContainerCols.GetSizes();
 		// Note: WindowState property access needs to be updated for the current ImGuiApp version
 		// Options.WindowState = ImGuiApp.WindowState;
 		Options.Popups = Popups;
 		Options.Save();
 	}

Schema.Editor/UnitText.cs

@@ -0,0 +1,49 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.Schema.Editor;
+
+using Hexa.NET.ImGui;
+
+/// <summary>
+/// Spells a unit's text in characters the editor's font can draw.
+/// </summary>
+/// <remarks>
+/// <para>
+/// Unit symbols come from ktsu.Semantics.Quantities and write a negative exponent with the
+/// superscript minus, U+207B: <c>s⁻¹</c>, <c>m·s⁻²</c>. The font ImGuiApp ships, JetBrains Mono
+/// Nerd Font, has every superscript digit and the superscript plus but not that one character, so
+/// it drew as the fallback glyph and a frequency read <c>s?¹</c>. Widening the glyph ranges cannot
+/// help, because the glyph is missing from the font rather than from the ranges.
+/// </para>
+/// <para>
+/// Where the font has no glyph for it, the minus is drawn as a macron, U+00AF, which sits at the
+/// height of the superscript digits beside it and is the usual stand-in for a raised minus. This is
+/// display only: what is written to the schema file is untouched, and as soon as the font gains the
+/// real glyph it is drawn instead.
+/// </para>
+/// </remarks>
+internal static class UnitText
+{
+	/// <summary>The superscript minus unit symbols use for negative exponents.</summary>
+	internal const char SuperscriptMinus = '⁻';
+
+	/// <summary>The raised bar drawn in its place when the font has no superscript minus.</summary>
+	internal const char RaisedBar = '¯';
+
+	/// <summary>
+	/// Returns <paramref name="text"/> as it should be drawn in the current font.
+	/// </summary>
+	/// <remarks>Call during a frame: whether the font has the glyph is asked of the font in use.</remarks>
+	/// <param name="text">A unit's symbol, or text containing one.</param>
+	/// <returns>The text, with the superscript minus replaced when the font cannot draw it.</returns>
+	internal static string ForDisplay(string text) =>
+		text.Contains(SuperscriptMinus) && !FontHasSuperscriptMinus()
+			? text.Replace(SuperscriptMinus, RaisedBar)
+			: text;
+
+	private static bool FontHasSuperscriptMinus()
+	{
+		ImFontPtr font = ImGui.GetFont();
+		return !font.IsNull && font.IsGlyphInFont(SuperscriptMinus);
+	}
+}

tests/Schema.Editor.UITests/Gallery/EditorGallery.cs

@@ -31,8 +31,18 @@ public sealed class EditorGallery
 	/// <summary>The environment variable naming the directory the gallery is written to.</summary>
 	internal const string OutputVariable = "SCHEMA_GALLERY_OUT";
 
-	/// <summary>The display the gallery is drawn at: larger than a test's, so the panels have room.</summary>
-	internal static readonly HarnessOptions Display = new() { Width = 1440, Height = 900 };
+	/// <summary>
+	/// The display the gallery is drawn at: larger than a test's, so the panels have room, and no
+	/// taller than the sample schema's tree, so a picture is of the editor rather than of the empty
+	/// space under it.
+	/// </summary>
+	internal static readonly HarnessOptions Display = new() { Width = 1480, Height = 620 };
+
+	/// <summary>
+	/// The share of the window the schema tree is given in the gallery: enough that the tree's
+	/// tab labels, Code Generators included, are drawn whole rather than elided.
+	/// </summary>
+	private const float LeftPaneShare = 0.27f;
 
 	private static readonly Lazy<string> TemporaryOutput = new(() =>
 		Path.Join(Path.GetTempPath(), $"schema-gallery-{Guid.NewGuid():N}"));
@@ -66,10 +76,11 @@ public void Photograph(string name)
 		GalleryEntry entry = GalleryCatalog.Entries.Single(candidate => candidate.Name == name);
 
 		EditField.Reset();
-		using EditorHarness harness = EditorHarness.Start(Display);
+		using EditorHarness harness = EditorHarness.Start(entry.Display ?? Display);
 		try
 		{
 			Assert.IsTrue(GalleryFonts.Load(), "ImGuiApp's own font could not be found, so the pictures would not look like the editor.");
+			harness.Editor.DividerContainerCols.SetSizesFromList([LeftPaneShare, 1f - LeftPaneShare]);
 			harness.App.Mouse.MoveTo(-100f, -100f);
 			harness.App.Step(2);
 

tests/Schema.Editor.UITests/Gallery/GalleryCatalog.cs

@@ -28,11 +28,14 @@ internal static class GalleryCatalog
 			"The editor opens on whatever was open last, or on nothing. The File menu creates, opens and saves `.schema.json` files and keeps the recent ones to hand.",
 			harness =>
 			{
+				// Open Recent is disabled until something has been opened, so the picture starts
+				// from an editor that has been used rather than one just installed.
+				harness.Editor.Options.RecordRecentFile(GallerySchema.Path);
 				harness.OpenMenu("File");
 				Park(harness);
 			})
 		{
-			Crop = _ => new Rectangle(0, 0, 720, 450),
+			Crop = _ => new Rectangle(0, 0, 560, 200),
 		},
 		new(
 			"Editing a class",
@@ -126,7 +129,11 @@ internal static class GalleryCatalog
 				harness.StepUntil(() => harness.IsOnScreen("theme-card/Dracula"), "the theme browser opening");
 				harness.App.Step(3);
 				Park(harness);
-			}),
+			})
+		{
+			// The browser is a fixed size, taller than the editor's own pictures.
+			Display = new() { Width = 1480, Height = 800 },
+		},
 	];
 
 	/// <summary>Opens the sample schema with its main class selected, as a user would find it.</summary>

tests/Schema.Editor.UITests/Gallery/GalleryEntry.cs

@@ -24,6 +24,11 @@ internal sealed record GalleryEntry(string Name, string Description, Action<Edit
 	/// </summary>
 	public Func<EditorHarness, Rectangle?>? Crop { get; init; }
 
+	/// <summary>
+	/// Gets the display this picture is drawn at, or null for <see cref="EditorGallery.Display"/>.
+	/// </summary>
+	public HarnessOptions? Display { get; init; }
+
 	/// <summary>Gets the file name the picture is written under, without its extension.</summary>
 	public string Slug => MakeSlug(Name);
 

tests/Schema.Editor.UITests/UnitTextTests.cs

@@ -0,0 +1,51 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.Schema.Editor.UITests;
+
+using Hexa.NET.ImGui;
+
+/// <summary>
+/// A unit's negative exponent is drawn in a glyph the editor's font has.
+/// </summary>
+/// <remarks>
+/// The bundled font has every superscript digit but not the superscript minus, so a frequency used
+/// to draw as <c>s?¹</c>. These ask the font in a real frame, because that is what the editor asks.
+/// </remarks>
+[TestClass]
+public sealed class UnitTextTests
+{
+	private WidgetHarness harness = null!;
+
+	[TestInitialize]
+	public void StartHarness() => harness = WidgetHarness.Start();
+
+	[TestCleanup]
+	public void StopHarness() => harness.Dispose();
+
+	[TestMethod]
+	public void ANegativeExponentIsDrawnInAGlyphTheFontHas()
+	{
+		string? drawn = null;
+		bool fontHasDrawnMinus = false;
+		harness.Draw = () =>
+		{
+			drawn = UnitText.ForDisplay("s⁻¹");
+			char minus = drawn[1];
+			fontHasDrawnMinus = ImGui.GetFont().IsGlyphInFont(minus);
+		};
+		harness.App.Step(2);
+
+		Assert.IsNotNull(drawn);
+		Assert.IsTrue(fontHasDrawnMinus, $"'{drawn}' is drawn with a minus the font has no glyph for.");
+	}
+
+	[TestMethod]
+	public void TextWithoutASuperscriptMinusIsUnchanged()
+	{
+		string? drawn = null;
+		harness.Draw = () => drawn = UnitText.ForDisplay("m/s");
+		harness.App.Step(2);
+
+		Assert.AreEqual("m/s", drawn);
+	}
+}