Read Krita's .kra~ backup files (#1077)

docs/ENGINES.md

@@ -299,7 +299,9 @@ in it also builds the package (artifact `windows-arm64-package`).
   mask. Grey and RGB pictures go in through PDFsharp as before.
 - **KRA** (Krita's own file, a ZIP of the layers) is read as the merged picture Krita stores at its top for other
   programs (`mergedimage.png`, `Krita.ReadMerged`, at most 256 MB, in memory), so it looks as it does in Krita. A file
-  without one gives a clear error.
+  without one gives a clear error. Krita's backup of the previous save, `name.kra~`, is the same file and is read the
+  same way; its output is named `name.png`. Watch folders skip it (and any name ending in `~`), as it is written next
+  to the drawing on every save.
 - **Live / Motion Photos from a video** (JPG and HEIC targets) are FFmpeg's: the clip and the photo's frame come from
   it, ImageMagick or the HEIC writer only encode that frame (see *Making Live / Motion Photos* there).
 - **Camera RAW** (DNG, CR2, CR3, NEF, ARW, …, and `.raw`) is decoded by LibRaw with the camera's white balance,

src/Filee.App/ViewModels/Pages/ExtensionInput.cs

@@ -18,15 +18,17 @@ public static class ExtensionInput
     /// <remarks>
     /// Two-part extensions are only accepted when Filee knows them (tar.gz, tar.xz ...): files are matched with
     /// <see cref="FormatRegistry.ExtensionOf"/>, which only sees the last part of any other name ("x.foo.bar" → "bar").
+    /// An extension Filee knows is taken as it is, so every suggestion can be added (Krita's backup "kra~").
     /// </remarks>
     public static string? Normalize(string? text)
     {
         var value = (text ?? "").Trim().TrimStart('*', '.').TrimEnd('.').ToLowerInvariant();
         if (value.Length is 0 or > MaxLength || value.Contains("..", StringComparison.Ordinal))
             return null;
-        if (!value.All(c => char.IsLetterOrDigit(c) || c is '-' or '_' or '+' or '.'))
+        var known = FormatRegistry.FindByExtension(value) is not null;
+        if (!known && !value.All(c => char.IsLetterOrDigit(c) || c is '-' or '_' or '+' or '.'))
             return null;
-        if (value.Contains('.') && FormatRegistry.FindByExtension(value) is null)
+        if (value.Contains('.') && !known)
             return null;
         return value;
     }

src/Filee.Core/Formats/FormatRegistry.cs

@@ -54,8 +54,9 @@ public static class FormatRegistry
         // Read on Windows only, with its own codec (HDR screenshots of Windows are JPEG XR).
         new("jxr", "JPEG XR", FormatCategory.Image, ["jxr", "wdp", "hdp"], Writable: false),
         new("xcf", "XCF", FormatCategory.Image, ["xcf"], Writable: false),
-        // Krita's own file (#903): a ZIP whose merged picture (mergedimage.png) is read, as Krita shows it.
-        new("kra", "Krita (KRA)", FormatCategory.Image, ["kra"], Writable: false),
+        // Krita's own file (#903): a ZIP whose merged picture (mergedimage.png) is read, as Krita shows it. ".kra~" is the
+        // backup Krita keeps of the previous save, the same file under another name (#1077).
+        new("kra", "Krita (KRA)", FormatCategory.Image, ["kra", "kra~"], Writable: false),
         // iPhone Live Photo as one ZIP (iCloud downloads): the photo, or its video with FFmpeg.
         new("livp", "Live Photo (LIVP)", FormatCategory.Image, ["livp"], Writable: false),
         new("raw", "RAW", FormatCategory.Image,

src/Filee.Core/Settings/AppSettings.cs

@@ -123,7 +123,7 @@ 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 = 65;
+    public const int CurrentSchemaVersion = 66;
 
     public int SchemaVersion { get; set; } = CurrentSchemaVersion;
 

src/Filee.Core/Settings/UserDataStore.cs

@@ -1012,6 +1012,10 @@ public static bool ApplyToLibrary(int from, List<Preset> presets, List<ToolbarPr
         //      another change takes it first.)
         if (from < 65)
             changed |= LearnExtensions(profiles, out _, ["dbml"]);
+        // v66: Krita's backups (.kra~, #1077) learn the images donut; custom claims stay put. (Schema 66 may be renumbered
+        //      if another change takes it first.)
+        if (from < 66)
+            changed |= LearnExtensions(profiles, out _, ["kra~"]);
         return changed;
     }
 

src/Filee.Core/Watching/FolderWatcher.cs

@@ -224,14 +224,17 @@ public async Task<int> ProcessPendingAsync()
         }
     }
 
-    /// <summary>True for files a watch folder never converts: temporary, hidden or system files, unknown formats,
-    /// anything inside the output or originals folder, and names the rule's <see cref="WatchRule.Include"/> leaves out.</summary>
+    /// <summary>True for files a watch folder never converts: temporary, hidden or system files, backups of the previous
+    /// save ("sketch.kra~"), unknown formats, anything inside the output or originals folder, and names the rule's
+    /// <see cref="WatchRule.Include"/> leaves out.</summary>
     public static bool ShouldIgnore(string path, WatchRule rule)
     {
         if (Presets.FolderCopy.IsWorkPath(path))
             return true;
         var name = Path.GetFileName(path);
-        if (name.Length == 0 || name.StartsWith("~$", StringComparison.Ordinal) || name.StartsWith('.')
+        // A backup is written next to the file on every save; converting it too would put the previous picture under the
+        // same output name.
+        if (name.Length == 0 || name.StartsWith("~$", StringComparison.Ordinal) || name.StartsWith('.') || name.EndsWith('~')
             || SystemFiles.Contains(name) || TemporaryExtensions.Contains(Path.GetExtension(name)))
             return true;
         // Exclude a dedicated output subtree, but never exclude the entire watch root when output is the same

tests/Filee.App.Tests/ExtensionEditingTests.cs

@@ -29,6 +29,7 @@ public class ExtensionInputTests
     [InlineData("dvr-ms", "dvr-ms")]
     [InlineData("xyz", "xyz")]
     [InlineData("jpg.", "jpg")]
+    [InlineData("*.KRA~", "kra~")] // Krita's backup, a known extension
     public void Normalizes_extensions(string input, string expected) => Assert.Equal(expected, ExtensionInput.Normalize(input));
 
     [Theory]
@@ -39,6 +40,7 @@ public class ExtensionInputTests
     [InlineData("a/b")]
     [InlineData(@"C:\x")]
     [InlineData("a..b")]
+    [InlineData("txt~")] // only known extensions take other characters
     [InlineData("photo.jpg")] // two-part extensions only when Filee knows them
     [InlineData("averyveryverylongextension")]
     public void Rejects_what_cannot_be_an_extension(string input) => Assert.Null(ExtensionInput.Normalize(input));

tests/Filee.Core.Tests/FolderWatcherTests.cs

@@ -206,6 +206,7 @@ public async Task A_file_another_program_holds_open_waits()
     [Theory]
     [InlineData("photo.jpg.crdownload")]
     [InlineData("~$report.docx")]
+    [InlineData("sketch.kra~")] // Krita's backup of the previous save, written next to sketch.kra
     [InlineData(".hidden.jpg")]
     [InlineData("notes.unknownformat")]
     [InlineData("converted/photo.jpg")]

tests/Filee.Core.Tests/ImageExtensionAliasTests.cs

@@ -1,4 +1,5 @@
-// PNG/JPEG download aliases are recognised and learnt by image profiles without taking custom claims.
+// PNG/JPEG download aliases and Krita's backups (.kra~, #1077) are recognised and learnt by image profiles without
+// taking custom claims.
 
 using Filee.Core.Formats;
 using Filee.Core.Presets;
@@ -45,6 +46,41 @@ public void Version_40_libraries_learn_both_aliases_once()
         Assert.False(SettingsMigrations.ApplyToLibrary(40, presets, profiles));
     }
 
+    [Theory]
+    [InlineData("sketch.kra~")]
+    [InlineData("SKETCH.KRA~")]
+    public void A_krita_backup_is_a_kra_named_after_the_drawing(string file)
+    {
+        Assert.Same(FormatRegistry.Get("kra"), FormatRegistry.Detect(file));
+        Assert.Equal("sketch", FormatRegistry.NameWithoutExtension(file).ToLowerInvariant());
+        Assert.Equal("images", ProfileSelector.Select(BuiltInData.CreateProfiles(), [file, "sketch.kra"])?.Id);
+    }
+
+    [Fact]
+    public void A_name_ending_in_a_tilde_is_not_a_kra_by_itself()
+    {
+        Assert.Null(FormatRegistry.Detect("notes.txt~"));
+        Assert.Null(FormatRegistry.Detect("sketch.kr~"));
+    }
+
+    [Fact]
+    public void Version_65_libraries_learn_krita_backups_without_taking_custom_claims()
+    {
+        var presets = BuiltInData.CreatePresets();
+        var profiles = BuiltInData.CreateProfiles();
+        var images = profiles.Single(p => p.Id == "images");
+        images.Extensions.Remove("kra~");
+
+        Assert.True(SettingsMigrations.ApplyToLibrary(65, presets, profiles));
+        Assert.Contains("kra~", images.Extensions);
+        Assert.False(SettingsMigrations.ApplyToLibrary(65, presets, profiles));
+
+        images.Extensions.Remove("kra~");
+        profiles.Insert(0, new ToolbarProfile { Id = "my-krita", Name = "Krita", Extensions = ["kra", "kra~"] });
+        Assert.False(SettingsMigrations.ApplyToLibrary(65, presets, profiles));
+        Assert.DoesNotContain("kra~", images.Extensions); // the user's own donut has it
+    }
+
     [Theory]
     [InlineData("PNG_LARGE", "jpg_large")]
     [InlineData("JPG_LARGE", "png_large")]

tests/Filee.Core.Tests/OutputPathResolverTests.cs

@@ -20,6 +20,17 @@ public void Default_pattern_keeps_the_source_name()
         Assert.Equal(Path.Combine(dir.Path, "photo.png"), path);
     }
 
+    [Fact]
+    public void A_krita_backup_is_named_after_the_drawing()
+    {
+        using var dir = new TempDir();
+        var source = dir.File("sketch.kra~");
+
+        var path = OutputPathResolver.Resolve(new OutputRule(), Tokens(source), "png", File.Exists);
+
+        Assert.Equal(Path.Combine(dir.Path, "sketch.png"), path);
+    }
+
     [Fact]
     public void Two_part_extensions_are_one_extension()
     {

tests/Filee.Core.Tests/SmallParsersTests.cs

@@ -35,6 +35,7 @@ public class FormatRegistryTests
     [InlineData("archive.7z.001", "split")]
     [InlineData("archive.zip.001", "split")]
     [InlineData("archive.tar.001", "split")]
+    [InlineData("sketch.kra~", "kra")] // Krita's backup of the previous save
     public void Detects_formats(string path, string id) => Assert.Equal(id, FormatRegistry.Detect(path)?.Id);
 
     [Fact]

tests/Filee.Engines.Tests/KritaTests.cs

@@ -1,4 +1,5 @@
-// Krita's .kra (issue #903): read as the merged picture it keeps at its top, built here as Krita lays the file out.
+// Krita's .kra (issue #903) and its .kra~ backup (#1077): read as the merged picture it keeps at its top, built here as
+// Krita lays the file out.
 
 using System.IO.Compression;
 using Filee.Core.Conversion;
@@ -14,9 +15,9 @@ public class KritaTests(EngineFixture fx) : IClassFixture<EngineFixture>
     /// A .kra as Krita writes it: the mimetype first, the document, a layer and its small preview, and the merged picture
     /// (left red, right transparent). <paramref name="merged"/> false leaves the merged picture out.
     /// </summary>
-    private string Kra(bool merged = true)
+    private string Kra(bool merged = true, string name = "sketch.kra")
     {
-        var path = Path.Combine(fx.NewFolder(), "sketch.kra");
+        var path = Path.Combine(fx.NewFolder(), name);
         using var zip = ZipFile.Open(path, ZipArchiveMode.Create);
         Add(zip, "mimetype", "application/x-krita"u8.ToArray());
         Add(zip, "maindoc.xml", "<DOC><IMAGE width=\"64\" height=\"32\"/></DOC>"u8.ToArray());
@@ -69,6 +70,21 @@ public async Task A_kra_reaches_the_targets_the_issue_asked_for(string target)
         Assert.EndsWith("." + target, Assert.Single(job.Outputs));
     }
 
+    [Fact]
+    public async Task A_krita_backup_converts_like_the_kra_and_is_named_after_the_drawing()
+    {
+        // Krita keeps the previous save as "sketch.kra~" (#1077): the same file under another name.
+        var backup = Kra(name: "sketch.kra~");
+        Assert.Equal("kra", FormatRegistry.Detect(backup)!.Id);
+
+        var job = await fx.ConvertAsync([backup], new Preset { TargetFormat = "png" });
+        Assert.True(job.State == JobState.Completed, string.Join("; ", job.Files.Select(f => $"{f.ErrorKey}: {f.ErrorDetail}")));
+        var output = Assert.Single(job.Outputs);
+        Assert.Equal("sketch.png", Path.GetFileName(output));
+        using var png = new MagickImage(output);
+        Assert.Equal((64u, 32u), (png.Width, png.Height));
+    }
+
     [Fact]
     public async Task A_kra_without_its_merged_picture_says_so()
     {