feat: add Beautify JSON to the text viewer More menu

QuickLook.Plugin/QuickLook.Plugin.TextViewer/JsonBeautifier.cs

@@ -0,0 +1,188 @@
+// Copyright © 2017-2026 QL-Win Contributors
+//
+// This file is part of QuickLook program.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+using System;
+using System.Text;
+
+namespace QuickLook.Plugin.TextViewer;
+
+/// <summary>Validates JSON and inserts indentation without converting any token values.</summary>
+internal sealed class JsonBeautifier
+{
+    private const int MaxDepth = 128;
+    private const int MaxOutputLength = 20 * 1024 * 1024;
+    private readonly string _source;
+    private readonly StringBuilder _output = new();
+    private int _position;
+
+    private JsonBeautifier(string source) => _source = source;
+
+    internal static bool TryFormat(string source, out string formatted)
+    {
+        formatted = null;
+        if (source is null) return false;
+        try
+        {
+            var parser = new JsonBeautifier(source);
+            // EncodingDetector may leave a BOM in the decoded text.
+            if (source.Length > 0 && source[0] == '\uFEFF') parser._position++;
+            parser.Value(0);
+            parser.WhiteSpace();
+            if (parser._position != source.Length) return false;
+            formatted = parser._output.ToString();
+            return true;
+        }
+        catch (FormatException)
+        {
+            return false;
+        }
+    }
+
+    private void WhiteSpace()
+    {
+        while (_position < _source.Length && _source[_position] is ' ' or '\t' or '\r' or '\n')
+            _position++;
+    }
+
+    private char Current => _position < _source.Length ? _source[_position] : '\0';
+
+    private void Append(string value)
+    {
+        if (value.Length > MaxOutputLength - _output.Length) throw new FormatException();
+        _output.Append(value);
+    }
+
+    private void NewLine(int depth)
+    {
+        Append(Environment.NewLine);
+        Append(new string(' ', depth * 2));
+    }
+
+    private void Require(char c)
+    {
+        WhiteSpace();
+        if (Current != c) throw new FormatException();
+        _position++;
+        Append(c.ToString());
+    }
+
+    private void Value(int depth)
+    {
+        WhiteSpace();
+        switch (Current)
+        {
+            case '{': Container(depth, true); break;
+            case '[': Container(depth, false); break;
+            case '"': String(); break;
+            case 't': Literal("true"); break;
+            case 'f': Literal("false"); break;
+            case 'n': Literal("null"); break;
+            default: Number(); break;
+        }
+    }
+
+    private void Container(int depth, bool isObject)
+    {
+        if (depth >= MaxDepth) throw new FormatException();
+        char close = isObject ? '}' : ']';
+        Require(isObject ? '{' : '[');
+        WhiteSpace();
+        if (Current == close) { Require(close); return; }
+        while (true)
+        {
+            NewLine(depth + 1);
+            if (isObject)
+            {
+                WhiteSpace();
+                String();
+                Require(':');
+                Append(" ");
+            }
+            Value(depth + 1);
+            WhiteSpace();
+            if (Current == close) break;
+            Require(',');
+        }
+        NewLine(depth);
+        Require(close);
+    }
+
+    private void String()
+    {
+        if (Current != '"') throw new FormatException();
+        int start = _position++;
+        while (_position < _source.Length)
+        {
+            char c = _source[_position++];
+            if (c == '"')
+            {
+                Append(_source.Substring(start, _position - start));
+                return;
+            }
+            if (c < 0x20) throw new FormatException();
+            if (c != '\\') continue;
+            if (_position >= _source.Length) throw new FormatException();
+            char escape = _source[_position++];
+            if (escape == 'u')
+            {
+                for (int i = 0; i < 4; i++)
+                {
+                    char hex = Current;
+                    if (!(hex is >= '0' and <= '9' or >= 'a' and <= 'f' or >= 'A' and <= 'F'))
+                        throw new FormatException();
+                    _position++;
+                }
+            }
+            else if (!(escape is '"' or '\\' or '/' or 'b' or 'f' or 'n' or 'r' or 't'))
+                throw new FormatException();
+        }
+        throw new FormatException();
+    }
+
+    private void Literal(string literal)
+    {
+        if (_source.Length - _position < literal.Length ||
+            string.CompareOrdinal(_source, _position, literal, 0, literal.Length) != 0)
+            throw new FormatException();
+        _position += literal.Length;
+        Append(literal);
+    }
+
+    private bool IsDigit => Current is >= '0' and <= '9';
+
+    private void Digits()
+    {
+        if (!IsDigit) throw new FormatException();
+        while (IsDigit) _position++;
+    }
+
+    private void Number()
+    {
+        int start = _position;
+        if (Current == '-') _position++;
+        if (Current == '0') _position++;
+        else Digits();
+        if (Current == '.') { _position++; Digits(); }
+        if (Current is 'e' or 'E')
+        {
+            _position++;
+            if (Current is '+' or '-') _position++;
+            Digits();
+        }
+        Append(_source.Substring(start, _position - start));
+    }
+}

QuickLook.Plugin/QuickLook.Plugin.TextViewer/Plugin.MoreMenu.cs

@@ -74,5 +74,13 @@ public IEnumerable<IMenuItem> GetMenuItems()
 
         if (reopen is not null)
             yield return reopen;
+
+        if (extension == ".json" && _beautifyJsonCommand is not null)
+            yield return new MoreMenuItem
+            {
+                Icon = FontSymbols.Code,
+                Header = TranslationHelper.Get("MW_BeautifyJson", translationFile),
+                Command = _beautifyJsonCommand,
+            };
     }
 }

QuickLook.Plugin/QuickLook.Plugin.TextViewer/Plugin.cs

@@ -15,6 +15,7 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+using QuickLook.Common.Commands;
 using QuickLook.Common.Plugin;
 using QuickLook.Common.Plugin.MoreMenu;
 using QuickLook.Plugin.TextViewer.Detectors;
@@ -38,6 +39,7 @@ public partial class Plugin : IViewer, IMoreMenu
 
     private TextViewerPanel _tvp;
     private string _currentPath;
+    private RelayCommand _beautifyJsonCommand;
 
     public int Priority => -5;
 
@@ -92,6 +94,8 @@ public void View(string path, ContextObject context)
         else
         {
             _tvp = new TextViewerPanel();
+            _beautifyJsonCommand = new RelayCommand(_tvp.BeautifyJson, () => _tvp?.CanBeautifyJson == true);
+            _tvp.JsonSourceLoaded += () => _beautifyJsonCommand?.RaiseCanExecuteChanged();
             _tvp.LoadFileAsync(path, context);
             context.ViewerContent = _tvp;
         }
@@ -102,6 +106,7 @@ public void Cleanup()
     {
         _tvp?.Dispose();
         _tvp = null;
+        _beautifyJsonCommand = null;
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]

QuickLook.Plugin/QuickLook.Plugin.TextViewer/TextViewerPanel.cs

@@ -43,6 +43,28 @@ namespace QuickLook.Plugin.TextViewer;
 public partial class TextViewerPanel : TextEditor, IDisposable
 {
     private bool _disposed;
+    private string _jsonSource;
+    internal event Action JsonSourceLoaded;
+    internal bool CanBeautifyJson => !_disposed && _jsonSource is not null;
+
+    internal void BeautifyJson()
+    {
+        if (!CanBeautifyJson) return;
+        if (!JsonBeautifier.TryFormat(_jsonSource, out var formatted) || TruncateLongLinesInText(ref formatted))
+        {
+            string translationFile = Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "Translations.config");
+            MessageBox.Show(Window.GetWindow(this),
+                TranslationHelper.Get("MW_BeautifyJsonInvalid", translationFile),
+                TranslationHelper.Get("MW_BeautifyJson", translationFile),
+                MessageBoxButton.OK, MessageBoxImage.Information);
+            return;
+        }
+
+        // Replace only the read-only preview, never the file on disk. Keep the complete
+        // source: the normal text preview may already have truncated long lines.
+        Document = new TextDocument(formatted);
+        ScrollToHome();
+    }
 
     /// <summary>Maximum number of characters allowed on a single line before it is truncated.</summary>
     private const int MAX_LINE_LENGTH = 10000;
@@ -134,6 +156,8 @@ public TextViewerPanel()
     public void Dispose()
     {
         _disposed = true;
+        _jsonSource = null;
+        JsonSourceLoaded = null;
     }
 
     private void Viewer_ManipulationInertiaStarting(object sender, ManipulationInertiaStartingEventArgs e)
@@ -356,6 +380,7 @@ public void LoadFileAsync(string path, ContextObject context)
 
             var encoding = EncodingDetector.DetectFromBytes(bufferCopy);
             var text = encoding.GetString(bufferCopy);
+            string jsonSource = !fileTooLong && path.EndsWith(".json", StringComparison.OrdinalIgnoreCase) ? text : null;
 
             // Truncate overly long lines to prevent crashes and lag
             bool hasLongLines = TruncateLongLinesInText(ref text);
@@ -368,6 +393,7 @@ public void LoadFileAsync(string path, ContextObject context)
 
             Dispatcher.BeginInvoke(() =>
             {
+                if (_disposed) return;
                 var extension = Path.GetExtension(path);
                 var highlighting = HighlightingThemeManager.GetHighlightingByExtensionOrDetector(path, extension, text);
 
@@ -420,6 +446,8 @@ public void LoadFileAsync(string path, ContextObject context)
                 }
 
                 context.IsBusy = false;
+                _jsonSource = jsonSource;
+                JsonSourceLoaded?.Invoke();
             }, DispatcherPriority.Render);
         });
     }