Fix #388, #368, #369: .lua and .css as text, snap the crop frame to the centre

docs/ARCHITECTURE.md

@@ -133,7 +133,9 @@ multi-frame pictures refused, the EXIF thumbnail dropped), one history entry for
   skipped. Every file starts free and whole, its portrait/landscape choice following the picture.
 - `Controls/CropCanvas` is the stage: the picture inside `ImagePadding`, the part outside the frame frosted (a copy at
   most 40 px across, drawn large) under a veil of the page colour, the frame in the accent colour with round handles,
-  a rule-of-thirds grid while dragging and a size chip that follows the frame. The preview is downscaled once by
+  a rule-of-thirds grid while dragging and a size chip that follows the frame. A frame being moved snaps onto the
+  picture's vertical or horizontal centre line within `CropMath.SnapDistance` (8 px) and shows that line as a dashed
+  guide until the drag ends. The preview is downscaled once by
   `CropService.LoadPreviewAsync`; nothing is decoded again while dragging. Programmatic changes (reset, a ratio, a
   new picture) ease in with tweens read against the clock, so a lost frame never leaves one half done; dragging and
   arrow-key nudges follow at once, and `PlayAnimations` (from `Motion.Enabled`) turns all of it off.

docs/ENGINES.md

@@ -12,7 +12,7 @@ Filee chooses engines automatically. Settings → *Engines* shows their status,
 | PDFsharp | built in (library) | images → PDF, merge, split, page ranges, **compression** (smaller PDFs, see below) |
 | PDFium | built in (library) | PDF → images (multi-page TIFF/GIF supported) |
 | Unhwp | built in (library) | HWP/HWPX → TXT, Markdown, HTML (pictures in a `<name>_files` folder next to the Markdown, embedded in the HTML) |
-| Text & Markdown (Markdig) | built in (library) | **Markdown → HTML, TXT**; **TXT, LOG, PY, PAC, BAT, COMMAND → UTF-8 TXT**, preserving source text without running scripts (and → PDF / DOCX through the HWPX writer, rhwp or LibreOffice) |
+| Text & Markdown (Markdig) | built in (library) | **Markdown → HTML, TXT**; **TXT, LOG, PY, PAC, BAT, COMMAND, LUA, CSS → UTF-8 TXT**, preserving source text without running scripts (and → PDF / DOCX through the HWPX writer, rhwp or LibreOffice) |
 | Spreadsheets (ExcelDataReader for XLS) | built in (library) | **XLSX, XLS, ODS, CSV, TSV → XLSX, ODS, CSV, TSV** (one CSV / TSV per sheet) |
 | Office Open XML | built in | **DOCM / DOTX / DOTM ↔ DOCX, XLSM / XLTX ↔ XLSX, PPTM / POTX / POTM / PPSX ↔ PPTX** (macros removed for macro-free types) |
 | Fonts | built in | **TTF, OTF, WOFF, WOFF2, EOT ↔ each other**; CFF (PostScript) outlines become TrueType for TTF and EOT |

src/Filee.App/Controls/CropCanvas.cs

@@ -103,6 +103,9 @@ public double AspectRatio
     private CropHandle _hoverHandle = CropHandle.None;
     private Point _dragStartPoint;
     private Rect _dragStartCrop;
+
+    // The frame being moved sits on the picture's vertical / horizontal centre line: its guide is drawn.
+    private bool _snappedX, _snappedY;
     private const double MinSizePx = 24.0;
 
     // ───── Motion: tweens evaluated against the clock at each render, so a lost frame never leaves one half done ─────
@@ -409,6 +412,7 @@ public override void Render(DrawingContext context)
             context.DrawImage(SourceImage, source, imgBounds);
 
         DrawGrid(context, crop, _grid.Value(now));
+        DrawCentreGuides(context, imgBounds);
         DrawFrame(context, crop, now);
         DrawSizeChip(context, crop, imgBounds, bounds);
     }
@@ -460,6 +464,20 @@ private static void DrawGrid(DrawingContext context, Rect crop, double opacity)
         }
     }
 
+    /// <summary>The picture's centre line the moved frame snapped to, across the whole picture.</summary>
+    private void DrawCentreGuides(DrawingContext context, Rect picture)
+    {
+        if (_activeHandle != CropHandle.Body || !(_snappedX || _snappedY))
+            return;
+        var pen = new Pen(AccentBrush ?? Brushes.MediumPurple, 1, DashStyle.Dash);
+        var x = Math.Round(picture.Center.X) + 0.5;
+        var y = Math.Round(picture.Center.Y) + 0.5;
+        if (_snappedX)
+            context.DrawLine(pen, new Point(x, picture.Top), new Point(x, picture.Bottom));
+        if (_snappedY)
+            context.DrawLine(pen, new Point(picture.Left, y), new Point(picture.Right, y));
+    }
+
     private void DrawFrame(DrawingContext context, Rect crop, long now)
     {
         var accent = AccentBrush ?? Brushes.MediumPurple;
@@ -738,6 +756,8 @@ protected override void OnPointerMoved(PointerEventArgs e)
 
             var newX = SafeClamp(_dragStartCrop.X + deltaX, imgBounds.Left, Math.Max(imgBounds.Left, imgBounds.Right - _dragStartCrop.Width));
             var newY = SafeClamp(_dragStartCrop.Y + deltaY, imgBounds.Top, Math.Max(imgBounds.Top, imgBounds.Bottom - _dragStartCrop.Height));
+            (newX, _snappedX) = CropMath.SnapToCentre(newX, _dragStartCrop.Width, imgBounds.Left, imgBounds.Right);
+            (newY, _snappedY) = CropMath.SnapToCentre(newY, _dragStartCrop.Height, imgBounds.Top, imgBounds.Bottom);
 
             SetCropFromScreen(new Rect(newX, newY, _dragStartCrop.Width, _dragStartCrop.Height), imgBounds);
             return;
@@ -897,6 +917,7 @@ protected override void OnPointerPressed(PointerPressedEventArgs e)
         {
             _dragStartPoint = pt;
             _dragStartCrop = crop;
+            _snappedX = _snappedY = false;
             e.Pointer.Capture(this);
             e.Handled = true;
             PopHandle(_activeHandle);

src/Filee.App/Controls/CropMath.cs

@@ -60,6 +60,22 @@ public static Rect Nudge(Rect normalized, int dx, int dy, int width, int height)
         return new Rect((double)x / width, (double)y / height, normalized.Width, normalized.Height);
     }
 
+    /// <summary>How close (screen pixels) the frame's centre has to come to the picture's centre line to snap to it.</summary>
+    public const double SnapDistance = 8;
+
+    /// <summary>
+    /// One side of a frame being dragged (issue #369): its start moved so its centre sits on the centre of
+    /// <paramref name="min"/>…<paramref name="max"/> when it comes within <see cref="SnapDistance"/> of it. A frame as
+    /// wide as the picture has nowhere to go and never counts as snapped.
+    /// </summary>
+    public static (double Start, bool Snapped) SnapToCentre(double start, double length, double min, double max)
+    {
+        var centre = (min + max) / 2;
+        if (length >= max - min - 0.5 || Math.Abs(start + length / 2 - centre) > SnapDistance)
+            return (start, false);
+        return (centre - length / 2, true);
+    }
+
     /// <summary>Space between the frame and the size chip.</summary>
     public const double ChipGap = 10;
 

src/Filee.Core/Formats/FormatRegistry.cs

@@ -134,8 +134,9 @@ public static class FormatRegistry
         new("sda", "SDA", FormatCategory.Presentation, ["sda", "sdd"], Writable: false),
 
         // Plain text / markup
-        // Text logs and source/proxy scripts are read as plain text, never executed (issues #273, #284, #254).
-        new("txt", "TXT", FormatCategory.Text, ["txt", "log", "py", "pac", "bat", "command"]),
+        // Text logs, source/proxy scripts and style sheets are read as plain text, never executed (issues #273, #284, #254,
+        // #388, #368).
+        new("txt", "TXT", FormatCategory.Text, ["txt", "log", "py", "pac", "bat", "command", "lua", "css"]),
         new("md", "Markdown", FormatCategory.Text, ["md", "markdown"]),
         new("html", "HTML", FormatCategory.Text, ["html", "htm", "xhtml"]),
         // A web page saved with its pictures in one MIME file (Chrome, Edge, Word); read as the page it holds.

src/Filee.Core/Settings/AppSettings.cs

@@ -112,7 +112,7 @@ public static bool IsFlipKeyAllowed(string key, IEnumerable<TriggerGesture> gest
 public sealed class AppSettings
 {
     /// <summary>Current schema version. Increase when the format changes and add a migration.</summary>
-    public const int CurrentSchemaVersion = 32;
+    public const int CurrentSchemaVersion = 33;
 
     public int SchemaVersion { get; set; } = CurrentSchemaVersion;
 

src/Filee.Core/Settings/UserDataStore.cs

@@ -750,6 +750,9 @@ public static bool ApplyToLibrary(int from, List<Preset> presets, List<ToolbarPr
         // v32: logs and script source, Video CD DAT and Workbench archives learn their donuts; custom claims stay put.
         if (from < 32)
             changed |= LearnExtensions(profiles, out _, ["log", "py", "pac", "bat", "command", "dat", "wbpz"]);
+        // v33: Lua scripts and CSS style sheets learn the text donut; custom claims stay put.
+        if (from < 33)
+            changed |= LearnExtensions(profiles, out _, ["lua", "css"]);
         return changed;
     }
 

tests/Filee.App.Tests/CropMathTests.cs

@@ -1,5 +1,5 @@
-// The crop overlay's arithmetic: ratios and their portrait forms, keyboard nudges, the frame in pixels and where the
-// size chip goes.
+// The crop overlay's arithmetic: ratios and their portrait forms, keyboard nudges, snapping to the centre, the frame
+// in pixels and where the size chip goes.
 
 using Avalonia;
 using Filee.App.Controls;
@@ -22,6 +22,24 @@ public void Ratios_and_their_portrait_forms(string mode, bool portrait, double e
         Assert.Equal(expected, CropMath.Ratio(mode, portrait, 1600, 1000), 6);
     }
 
+    [Theory]
+    // A 100 px wide frame over a 0…1000 px picture: centred at 500 when its start is 450.
+    [InlineData(450, 450, true)]   // already centred
+    [InlineData(443, 450, true)]   // 7 px off: pulled in
+    [InlineData(458, 450, true)]   // 8 px off: still pulled in
+    [InlineData(459, 459, false)]  // 9 px off: left alone
+    [InlineData(100, 100, false)]  // far away
+    public void A_moved_frame_snaps_to_the_centre_line(double start, double expected, bool snapped)
+    {
+        Assert.Equal((expected, snapped), CropMath.SnapToCentre(start, 100, 0, 1000));
+    }
+
+    [Fact]
+    public void A_frame_as_wide_as_the_picture_never_counts_as_snapped()
+    {
+        Assert.Equal((0.0, false), CropMath.SnapToCentre(0, 1000, 0, 1000));
+    }
+
     [Fact]
     public void Only_fixed_ratios_that_arent_square_swap()
     {

tests/Filee.App.Tests/CropOverlayTests.cs

@@ -111,6 +111,32 @@ public void Dragging_shows_the_grid_and_the_size_chip_follows_the_frame()
         });
     }
 
+    [AvaloniaFact]
+    public void A_frame_moved_near_the_middle_snaps_to_the_centre_lines()
+    {
+        WithOverlay("en", false, ["harbour.jpg"], (window, vm, _suffix) =>
+        {
+            var canvas = window.CropCanvas;
+            canvas.NormalizedCropRect = new Rect(0.1, 0.1, 0.5, 0.5); // centre at 35 %, 35 %
+            Settle(window);
+            var image = canvas.CalculateImageBounds();
+            var origin = canvas.TranslatePoint(default, window)!.Value;
+            var start = canvas.GetScreenCropRect(image).Center + (Vector)origin;
+            // To 3 screen pixels short of the picture's centre on both axes: inside the snap distance.
+            var target = image.Center + (Vector)origin - new Vector(3, 3);
+            window.MouseDown(start, MouseButton.Left);
+            window.MouseMove(start + (target - start) / 2);
+            window.MouseMove(target);
+            Pump();
+            Save(window, "crop-snap-en.png");
+            window.MouseUp(target, MouseButton.Left);
+
+            var frame = canvas.NormalizedCropRect;
+            Assert.Equal(0.5, frame.X + frame.Width / 2, 3);
+            Assert.Equal(0.5, frame.Y + frame.Height / 2, 3);
+        });
+    }
+
     [AvaloniaFact]
     public void Keys_nudge_the_frame_open_the_dial_reset_and_close()
     {

tests/Filee.Core.Tests/ScriptTextTests.cs

@@ -0,0 +1,33 @@
+// Lua scripts and CSS style sheets are plain text (issues #388, #368): recognised, and learnt by existing text donuts.
+
+using Filee.Core.Formats;
+using Filee.Core.Presets;
+using Filee.Core.Profiles;
+using Filee.Core.Settings;
+
+namespace Filee.Core.Tests;
+
+public class ScriptTextTests
+{
+    [Theory]
+    [InlineData("init.lua")]
+    [InlineData("site.css")]
+    public void Scripts_and_style_sheets_are_text(string name) => Assert.Equal("txt", FormatRegistry.Detect(name)?.Id);
+
+    [Fact]
+    public void Version_32_text_donuts_learn_them_without_taking_custom_claims()
+    {
+        var presets = BuiltInData.CreatePresets();
+        var profiles = BuiltInData.CreateProfiles();
+        foreach (var profile in profiles)
+            profile.Extensions.RemoveAll(e => e is "lua" or "css");
+        profiles.Insert(0, new ToolbarProfile { Id = "my-web", Name = "Web", Extensions = ["css"] });
+
+        Assert.True(SettingsMigrations.ApplyToLibrary(32, presets, profiles));
+
+        var text = profiles.Single(p => p.Id == "text").Extensions;
+        Assert.Contains("lua", text);
+        Assert.DoesNotContain("css", text); // the user's own donut has it
+        Assert.False(SettingsMigrations.ApplyToLibrary(32, presets, profiles));
+    }
+}

tests/Filee.Engines.Tests/ScriptTextTests.cs

@@ -0,0 +1,27 @@
+// Lua scripts and CSS style sheets (issues #388, #368) become a PDF of their text, never run.
+
+using Filee.Core.Conversion;
+using Filee.Core.Presets;
+using Filee.Engines.Pdf;
+
+namespace Filee.Engines.Tests;
+
+public class ScriptTextTests(EngineFixture fx) : IClassFixture<EngineFixture>
+{
+    [Theory]
+    [InlineData("site.css", "body { color: #1d9e75; }")]
+    [InlineData("init.lua", "local greeting = \"hello\" print(greeting)")]
+    public async Task The_code_becomes_a_pdf_of_its_text(string name, string code)
+    {
+        var available = fx.Converters.Where(c => fx.Catalog.StatusOf(c).IsAvailable).Select(c => c.Id).ToHashSet();
+        Assert.SkipUnless(available.Contains("rhwp") || available.Contains("libreoffice"), "neither rhwp nor LibreOffice is available");
+        var path = Path.Combine(fx.NewFolder(), name);
+        await File.WriteAllTextAsync(path, code, TestContext.Current.CancellationToken);
+
+        var job = await fx.ConvertAsync([path], new Preset { TargetFormat = "pdf" });
+
+        Assert.True(job.State == JobState.Completed, string.Join("; ", job.Files.Select(f => $"{f.ErrorKey} {f.ErrorDetail}")));
+        var text = PdfDocumentReader.PlainText(PdfDocumentReader.ReadText(Assert.Single(job.Outputs)));
+        Assert.Contains(code.Split(' ')[1], text);
+    }
+}