Alternating row contrast (%) setting for the subtitle grid

src/ui/Features/Main/Layout/InitListViewAndEditBox.cs

@@ -175,19 +175,8 @@ internal static Grid MakeLayoutListViewAndEditBox(MainView mainPage, MainViewMod
         if (Se.Settings.Appearance.GridAlternatingRows)
         {
             var isDark = Application.Current?.ActualThemeVariant == ThemeVariant.Dark;
-            var altColorHex = UiTheme.GetGridAlternatingRowColorHex(isDark);
-            try
-            {
-                if (!string.IsNullOrWhiteSpace(altColorHex))
-                {
-                    alternatingRowBrush = new SolidColorBrush(altColorHex.FromHexToColor());
-                    vm.SubtitleGridAlternatingRowBrush = alternatingRowBrush;
-                }
-            }
-            catch
-            {
-                alternatingRowBrush = null;
-            }
+            alternatingRowBrush = new SolidColorBrush(UiTheme.GetGridAlternatingRowColor(isDark));
+            vm.SubtitleGridAlternatingRowBrush = alternatingRowBrush;
         }
 
         // Collapse hidden rows (style bindings evaluate against the row's item).

src/ui/Features/Main/MainViewModel.cs

@@ -15534,15 +15534,7 @@ private void UpdateAlternatingRowBrush()
         // Color notifies every realized row without rebuilding the grid (and losing its state).
         if (SubtitleGridAlternatingRowBrush != null)
         {
-            var colorHex = UiTheme.GetGridAlternatingRowColorHex(Application.Current?.ActualThemeVariant == ThemeVariant.Dark);
-            try
-            {
-                SubtitleGridAlternatingRowBrush.Color = colorHex.FromHexToColor();
-            }
-            catch
-            {
-                // Keep the current brush color when the configured value is invalid.
-            }
+            SubtitleGridAlternatingRowBrush.Color = UiTheme.GetGridAlternatingRowColor(Application.Current?.ActualThemeVariant == ThemeVariant.Dark);
         }
     }
 

src/ui/Features/Options/Settings/SettingsPage.cs

@@ -1144,8 +1144,8 @@ private List<SettingsSection> CreateSections()
             MakeCheckboxSetting(Se.Language.Options.Settings.ShowTimeCodeModeInStatusBar, nameof(_vm.ShowTimeCodeModeInStatusBar)),
             MakeCheckboxSetting(Se.Language.Options.Settings.GridCompactMode, nameof(_vm.GridCompactMode)),
             MakeCheckboxSetting(Se.Language.Options.Settings.GridAlternatingRows, nameof(_vm.GridAlternatingRows)),
-            new SettingsItem(Se.Language.Options.Settings.GridAlternatingRowColor, () => UiUtil.MakeColorPickerButton(_vm, nameof(_vm.GridAlternatingRowColor))),
-            new SettingsItem(Se.Language.Options.Settings.GridAlternatingRowColorDark, () => UiUtil.MakeColorPickerButton(_vm, nameof(_vm.GridAlternatingRowColorDark))),
+            MakeNumericSettingInt(Se.Language.Options.Settings.GridAlternatingRowContrast, nameof(_vm.GridAlternatingRowContrast),
+                UiTheme.MinGridAlternatingRowContrast, UiTheme.MaxGridAlternatingRowContrast),
             new SettingsItem(Se.Language.Options.Settings.ShowGridLines, () => UiUtil.MakeComboBox(_vm.GridLinesVisibilities, _vm, nameof(_vm.SelectedGridLinesVisibility))),
             new SettingsItem(Se.Language.Options.Settings.BookmarkColor, () => UiUtil.MakeColorPickerButton(_vm, nameof(_vm.BookmarkColor))),
             new SettingsItem(Se.Language.Options.Settings.SpellCheckHighlightColor, () => UiUtil.MakeColorPickerButton(_vm, nameof(_vm.SpellCheckHighlightColor))),

src/ui/Features/Options/Settings/SettingsViewModel.cs

@@ -462,8 +462,7 @@ private static int ParseMouseWheelStep(string display)
     [ObservableProperty] private Color _focusedButtonBackgroundColor;
     [ObservableProperty] private Color _bookmarkColor;
     [ObservableProperty] private Color _spellCheckHighlightColor;
-    [ObservableProperty] private Color _gridAlternatingRowColor;
-    [ObservableProperty] private Color _gridAlternatingRowColorDark;
+    [ObservableProperty] private int _gridAlternatingRowContrast;
     [ObservableProperty] private bool _isEditCustomContinuationStyleVisible;
     [ObservableProperty] private bool _isMpvChosen;
 
@@ -1057,8 +1056,7 @@ private void LoadSettings()
         FocusedButtonBackgroundColor = appearance.FocusedButtonBackgroundColor.FromHexToColor();
         BookmarkColor = appearance.BookmarkColor.FromHexToColor();
         SpellCheckHighlightColor = appearance.SpellCheckHighlightColor.FromHexToColor();
-        GridAlternatingRowColor = appearance.GridAlternatingRowColor.FromHexToColor();
-        GridAlternatingRowColorDark = appearance.GridAlternatingRowColorDark.FromHexToColor();
+        GridAlternatingRowContrast = UiTheme.ClampGridAlternatingRowContrast(appearance.GridAlternatingRowContrast);
         ShowUpDownStartTime = appearance.ShowUpDownStartTime;
         ShowTimeCodeModeInStatusBar = appearance.ShowTimeCodeModeInStatusBar;
         ShowUpDownEndTime = appearance.ShowUpDownEndTime;
@@ -1972,8 +1970,7 @@ private void SaveSettings()
         appearance.FocusedButtonBackgroundColor = FocusedButtonBackgroundColor.FromColorToHex();
         appearance.BookmarkColor = BookmarkColor.FromColorToHex();
         appearance.SpellCheckHighlightColor = SpellCheckHighlightColor.FromColorToHex();
-        appearance.GridAlternatingRowColor = GridAlternatingRowColor.FromColorToHex();
-        appearance.GridAlternatingRowColorDark = GridAlternatingRowColorDark.FromColorToHex();
+        appearance.GridAlternatingRowContrast = UiTheme.ClampGridAlternatingRowContrast(GridAlternatingRowContrast);
         appearance.ShowUpDownStartTime = ShowUpDownStartTime;
         appearance.ShowTimeCodeModeInStatusBar = ShowTimeCodeModeInStatusBar;
         appearance.ShowUpDownEndTime = ShowUpDownEndTime;

src/ui/Logic/Config/Language/Options/LanguageSettings.cs

@@ -64,8 +64,7 @@ public class LanguageSettings
     public string ShowTimeCodeModeInStatusBar { get; set; }
     public string GridCompactMode { get; set; }
     public string GridAlternatingRows { get; set; }
-    public string GridAlternatingRowColor { get; set; }
-    public string GridAlternatingRowColorDark { get; set; }
+    public string GridAlternatingRowContrast { get; set; }
     public string UiFont { get; set; }
     public string IconTheme { get; set; }
     public string DarkThemeForegroundColor { get; set; }
@@ -462,8 +461,7 @@ public LanguageSettings()
         ShowTimeCodeModeInStatusBar = "Show time code mode in status bar";
         GridCompactMode = "Use compact mode for grids";
         GridAlternatingRows = "Use alternating row colors in grid";
-        GridAlternatingRowColor = "Alternating row color (light theme)";
-        GridAlternatingRowColorDark = "Alternating row color (dark theme)";
+        GridAlternatingRowContrast = "Alternating row contrast (%)";
         UiFont = "UI font";
         IconTheme = "Icon theme";
         DarkThemeForegroundColor = "Dark theme foreground color";

src/ui/Logic/Config/SeAppearance.cs

@@ -63,8 +63,7 @@ public class SeAppearance
     /// </summary>
     public string WindowsRenderingMode { get; set; }
     public bool GridAlternatingRows { get; set; }
-    public string GridAlternatingRowColor { get; set; }
-    public string GridAlternatingRowColorDark { get; set; }
+    public int GridAlternatingRowContrast { get; set; }
     public bool ShowHorizontalLineAboveToolbar { get; set; }
 
     /// <summary>
@@ -150,8 +149,7 @@ public SeAppearance()
         GridLinesAppearance = SeGridLinesVisibility.None.ToString();
         WindowsRenderingMode = nameof(WindowsRenderingModeType.Default);
         GridAlternatingRows = true;
-        GridAlternatingRowColor = new Color(255, 245, 245, 245).FromColorToHex();
-        GridAlternatingRowColorDark = new Color(255, 45, 45, 45).FromColorToHex();
+        GridAlternatingRowContrast = 10;
         DarkModeBackgroundColor = new Color(255, 33, 33, 33).FromColorToHex();
         DarkModeForegroundColor = new Color(255, 220, 220, 220).FromColorToHex();
         UseFocusedButtonBackgroundColor = true;

src/ui/Logic/UiTheme.cs

@@ -1837,39 +1837,53 @@ internal static Color GetLightThemeBackgroundColor(string? themeSetting)
     private static readonly Color PastelBackgroundColor = Color.FromRgb(240, 235, 255);
     internal static readonly Color NordBackgroundColor = Color.FromRgb(0x2E, 0x34, 0x40); // nord0
     internal static readonly Color NordForegroundColor = Color.FromRgb(0xE5, 0xE9, 0xF0); // nord5
-    private static readonly Color NordAlternatingRowColor = Color.FromRgb(0x34, 0x3B, 0x48);
     internal static readonly Color MidnightCinemaBackgroundColor = Color.FromRgb(0x14, 0x12, 0x18);
     internal static readonly Color MidnightCinemaForegroundColor = Color.FromRgb(0xEC, 0xE6, 0xD9);
     internal static readonly Color MidnightCinemaHeaderColor = Color.FromRgb(0x1E, 0x1B, 0x24);
     internal static readonly Color MidnightCinemaAccentColor = Color.FromRgb(0xE8, 0xA3, 0x3D);
-    private static readonly Color MidnightCinemaAlternatingRowColor = Color.FromRgb(0x1A, 0x17, 0x20);
     internal static readonly Color SakuraBackgroundColor = Color.FromRgb(0xFF, 0xF7, 0xF9);
     internal static readonly Color SakuraForegroundColor = Color.FromRgb(0x3A, 0x2A, 0x31);
     internal static readonly Color SakuraAccentColor = Color.FromRgb(0xD9, 0x46, 0x6F);
-    private static readonly Color SakuraAlternatingRowColor = Color.FromRgb(0xFD, 0xEF, 0xF3);
+
+    public const int MinGridAlternatingRowContrast = 4;
+    public const int MaxGridAlternatingRowContrast = 20;
+
+    public static int ClampGridAlternatingRowContrast(int percent) =>
+        Math.Clamp(percent, MinGridAlternatingRowContrast, MaxGridAlternatingRowContrast);
 
     /// <summary>
-    /// The subtitle grid's alternating row color. The fixed-palette themes have their own - the
-    /// gray settings read as stray gray stripes on their tinted rows.
+    /// The subtitle grid's alternating row color: the theme background moved the configured
+    /// percentage toward the theme text color. Following both colors keeps the stripe in the
+    /// theme's own tint (Sakura pink, Nord blue-gray) and makes it darker on light themes and
+    /// lighter on dark ones without a light/dark color pair to keep in step (#16779).
     /// </summary>
-    public static string GetGridAlternatingRowColorHex(bool isDark)
+    public static Color GetGridAlternatingRowColor(bool isDark)
     {
-        var theme = Se.Settings.Appearance.Theme;
-        if (!isDark)
+        Color background;
+        Color foreground;
+        try
         {
-            return theme == ThemeNameSakura
-                ? SakuraAlternatingRowColor.FromColorToHex()
-                : Se.Settings.Appearance.GridAlternatingRowColor;
+            background = isDark ? GetDarkThemeBackgroundColor() : GetLightThemeBackgroundColor(Se.Settings.Appearance.Theme);
+            foreground = isDark ? GetDarkThemeForegroundColor() : GetLightThemeForegroundColor(Se.Settings.Appearance.Theme);
         }
-
-        if (theme == ThemeNameNord)
+        catch
         {
-            return NordAlternatingRowColor.FromColorToHex();
+            // malformed dark-mode colors in the settings file
+            background = isDark ? Color.FromRgb(0x21, 0x21, 0x21) : Colors.White;
+            foreground = isDark ? Color.FromRgb(0xDC, 0xDC, 0xDC) : Colors.Black;
         }
 
-        return theme == ThemeNameMidnightCinema
-            ? MidnightCinemaAlternatingRowColor.FromColorToHex()
-            : Se.Settings.Appearance.GridAlternatingRowColorDark;
+        return BlendGridAlternatingRowColor(background, foreground, Se.Settings.Appearance.GridAlternatingRowContrast);
+    }
+
+    internal static Color BlendGridAlternatingRowColor(Color background, Color foreground, int percent)
+    {
+        var amount = ClampGridAlternatingRowContrast(percent) / 100.0;
+        static byte Mix(byte from, byte to, double t) => (byte)Math.Round(from + (to - from) * t);
+        return Color.FromRgb(
+            Mix(background.R, foreground.R, amount),
+            Mix(background.G, foreground.G, amount),
+            Mix(background.B, foreground.B, amount));
     }
 
     private static readonly WaveformColors MidnightCinemaWaveformColors = new(
@@ -1996,9 +2010,12 @@ public static Color GetThemeForegroundColor()
             return GetDarkThemeForegroundColor();
         }
 
-        return ThemeName == ThemeNameSakura ? SakuraForegroundColor : Colors.Black;
+        return GetLightThemeForegroundColor(ThemeName);
     }
 
+    internal static Color GetLightThemeForegroundColor(string? themeSetting) =>
+        themeSetting == ThemeNameSakura ? SakuraForegroundColor : Colors.Black;
+
     public static Color GetDarkThemeForegroundColor()
     {
         var theme = Se.Settings.Appearance.Theme;

tests/UI/Logic/GridAlternatingRowContrastTests.cs

@@ -0,0 +1,53 @@
+using Avalonia.Media;
+using Nikse.SubtitleEdit.Logic;
+using Nikse.SubtitleEdit.Logic.Config;
+
+namespace UITests.Logic;
+
+/// <summary>
+/// The grid's alternating row tint is the theme background moved a percentage (4-20%) toward
+/// the theme text color, so it is visible on every theme without hand-picked colors (#16779).
+/// </summary>
+public class GridAlternatingRowContrastTests
+{
+    [Fact]
+    public void Light_Theme_Darkens_White_By_The_Percentage()
+    {
+        var color = UiTheme.BlendGridAlternatingRowColor(Colors.White, Colors.Black, 10);
+
+        Assert.Equal(Color.FromRgb(230, 230, 230), color);
+    }
+
+    [Fact]
+    public void Dark_Theme_Lightens_Toward_Foreground()
+    {
+        var background = Color.FromRgb(33, 33, 33);
+        var foreground = Color.FromRgb(220, 220, 220);
+
+        var color = UiTheme.BlendGridAlternatingRowColor(background, foreground, 20);
+
+        Assert.True(color.R > background.R);
+        Assert.Equal(Color.FromRgb(70, 70, 70), color);
+    }
+
+    [Theory]
+    [InlineData(0, 4)]
+    [InlineData(4, 4)]
+    [InlineData(12, 12)]
+    [InlineData(20, 20)]
+    [InlineData(99, 20)]
+    public void Percentage_Is_Clamped(int value, int expected)
+    {
+        Assert.Equal(expected, UiTheme.ClampGridAlternatingRowContrast(value));
+    }
+
+    [Fact]
+    public void Default_Is_Visible_On_Light_Theme()
+    {
+        Assert.Equal(10, new SeAppearance().GridAlternatingRowContrast);
+        var color = UiTheme.BlendGridAlternatingRowColor(Colors.White, Colors.Black, 10);
+
+        // The old default was #F5F5F5, too faint to notice on many screens.
+        Assert.Equal(Color.FromRgb(230, 230, 230), color);
+    }
+}