enhance: avoid that diff view refresh more than one times

Signed-off-by: leo <longshuang@msn.cn>

src/Commands/Diff.cs

@@ -8,6 +8,10 @@ namespace SourceGit.Commands
     {
         [GeneratedRegex(@"^@@ \-(\d+),?\d* \+(\d+),?\d* @@")]
         private static partial Regex REG_INDICATOR();
+
+        [GeneratedRegex(@"^index\s([0-9a-f]{6,40})\.\.([0-9a-f]{6,40})(\s[1-9]{6})?")]
+        private static partial Regex REG_HASH_CHANGE();
+
         private const string PREFIX_LFS_NEW = "+version https://git-lfs.github.com/spec/";
         private const string PREFIX_LFS_DEL = "-version https://git-lfs.github.com/spec/";
         private const string PREFIX_LFS_MODIFY = " version https://git-lfs.github.com/spec/";
@@ -100,19 +104,33 @@ namespace SourceGit.Commands
             }
 
             if (_result.TextDiff.Lines.Count == 0)
-            {
-                var match = REG_INDICATOR().Match(line);
-                if (!match.Success)
             {
                 if (line.StartsWith("Binary", StringComparison.Ordinal))
+                {
                     _result.IsBinary = true;
                     return;
                 }
 
+                if (string.IsNullOrEmpty(_result.OldHash))
+                {
+                    var match = REG_HASH_CHANGE().Match(line);
+                    if (!match.Success)
+                        return;
+
+                    _result.OldHash = match.Groups[1].Value;
+                    _result.NewHash = match.Groups[2].Value;
+                }
+                else
+                {
+                    var match = REG_INDICATOR().Match(line);
+                    if (!match.Success)
+                        return;
+
                     _oldLine = int.Parse(match.Groups[1].Value);
                     _newLine = int.Parse(match.Groups[2].Value);
                     _result.TextDiff.Lines.Add(new Models.TextDiffLine(Models.TextDiffLineType.Indicator, line, 0, 0));
                 }                
+            }
             else
             {
                 if (line.Length == 0)

src/Models/DiffResult.cs

@@ -674,6 +674,8 @@ namespace SourceGit.Models
     {
         public bool IsBinary { get; set; } = false;
         public bool IsLFS { get; set; } = false;
+        public string OldHash { get; set; } = string.Empty;
+        public string NewHash { get; set; } = string.Empty;
         public string OldMode { get; set; } = string.Empty;
         public string NewMode { get; set; } = string.Empty;
         public TextDiff TextDiff { get; set; } = null;

src/ViewModels/DiffContext.cs

@@ -33,12 +33,6 @@ namespace SourceGit.ViewModels
             private set => SetProperty(ref _fileModeChange, value);
         }
 
-        public bool IsLoading
-        {
-            get => _isLoading;
-            private set => SetProperty(ref _isLoading, value);
-        }
-
         public bool IsTextDiff
         {
             get => _isTextDiff;
@@ -68,6 +62,7 @@ namespace SourceGit.ViewModels
                 _content = previous._content;
                 _unifiedLines = previous._unifiedLines;
                 _ignoreWhitespace = previous._ignoreWhitespace;
+                _info = previous._info;
             }
 
             if (string.IsNullOrEmpty(_option.OrgPath) || _option.OrgPath == "/dev/null")
@@ -109,7 +104,6 @@ namespace SourceGit.ViewModels
             {
                 Content = null;
                 IsTextDiff = false;
-                IsLoading = false;
                 return;
             }
 
@@ -119,10 +113,14 @@ namespace SourceGit.ViewModels
                 // There is no way to tell a git-diff to use "ALL lines of context",
                 // so instead we set a very high number for the "lines of context" parameter.
                 var numLines = Preference.Instance.UseFullTextDiff ? 999999999 : _unifiedLines;
-
                 var latest = new Commands.Diff(_repo, _option, numLines, _ignoreWhitespace).Result();
-                var rs = null as object;
+                var info = new Info(_option, numLines, _ignoreWhitespace, latest);
+                if (_info != null && info.IsSame(_info))
+                    return;
 
+                _info = info;
+
+                var rs = null as object;
                 if (latest.TextDiff != null)
                 {
                     var count = latest.TextDiff.Lines.Count;
@@ -219,7 +217,6 @@ namespace SourceGit.ViewModels
                     FileModeChange = latest.FileModeChange;
                     Content = rs;
                     IsTextDiff = rs is Models.TextDiff;
-                    IsLoading = false;
                 });
             });
         }
@@ -252,14 +249,41 @@ namespace SourceGit.ViewModels
             ".ico", ".bmp", ".jpg", ".png", ".jpeg", ".webp"
         };
 
+        private class Info
+        {
+            public string Argument { get; set; }
+            public int UnifiedLines { get; set; }
+            public bool IgnoreWhitespace { get; set; }
+            public string OldHash { get; set; }
+            public string NewHash { get; set; }
+
+            public Info(Models.DiffOption option, int unifiedLines, bool ignoreWhitespace, Models.DiffResult result)
+            {
+                Argument = option.ToString();
+                UnifiedLines = unifiedLines;
+                IgnoreWhitespace = ignoreWhitespace;
+                OldHash = result.OldHash;
+                NewHash = result.NewHash;
+            }
+
+            public bool IsSame(Info other)
+            {
+                return Argument.Equals(other.Argument, StringComparison.Ordinal) &&
+                    UnifiedLines == other.UnifiedLines &&
+                    IgnoreWhitespace == other.IgnoreWhitespace &&
+                    OldHash.Equals(other.OldHash, StringComparison.Ordinal) &&
+                    NewHash.Equals(other.NewHash, StringComparison.Ordinal);
+            }
+        }
+
         private readonly string _repo;
         private readonly Models.DiffOption _option = null;
         private string _title;
         private string _fileModeChange = string.Empty;
         private int _unifiedLines = 4;
-        private bool _isLoading = true;
         private bool _isTextDiff = false;
         private bool _ignoreWhitespace = false;
         private object _content = null;
+        private Info _info = null;
     }
 }