Match theme selection color to the theme dark/light mode

CHANGELOG.md

@@ -11,6 +11,7 @@
 ### Improvements
 
 - Display the current editor mode in the document inspector.
+- Use more appropriate system color for the selection background when dark mode or not differs between the editor and theme.
 - Improve VoiceOver support.
 - Deprecate exact recalculation of insertion points when documents are updated by external processes to improve application stability.
 - Improve stability of application launch behavior.

CotEditor/CotEditor.help/Contents/Resources/en.lproj/pgs/releasenotes.html

@@ -37,6 +37,7 @@ <h2>Improvements</h2>
 
 		<ul>
 			<li>Display the current editor mode in the document inspector.</li>
+			<li>Use more appropriate system color for the selection background when dark mode or not differs between the editor and theme.</li>
 			<li>Improve VoiceOver support.</li>
 			<li>Deprecate exact recalculation of insertion points when documents are updated by external processes to improve application stability.</li>
 			<li>Improve stability of application launch behavior.</li>

CotEditor/CotEditor.help/Contents/Resources/ja.lproj/pgs/releasenotes.html

@@ -37,6 +37,7 @@ <h2>改良</h2>
 
 		<ul>
 			<li>書類インスペクタに現在のモードを表示</li>
+			<li>エディタとテーマのダークモードかどうかが異なるときにもより適切なシステムカラーを選択範囲に用いるように改良</li>
 			<li>VoiceOverサポートを強化</li>
 			<li>アプリケーションの安定性向上のために、外部プロセスから書類が更新されたときに新しいカーソル位置を推算する機能おを廃止</li>
 			<li>アプリケーション起動時の安定性を向上</li>

CotEditor/Sources/EditorTextView.swift

@@ -1365,7 +1365,7 @@ class EditorTextView: NSTextView, Themable, CurrentLineHighlighting, MultiCursor
                 indicator.color = self.insertionPointColor
             }
         }
-        self.selectedTextAttributes[.backgroundColor] = theme.effectiveSelectionColor
+        self.selectedTextAttributes[.backgroundColor] = theme.effectiveSelectionColor(for: self.effectiveAppearance)
         (self.layoutManager as? LayoutManager)?.invisiblesColor = theme.invisibles.color
 
         (self.window as? DocumentWindow)?.contentBackgroundColor = theme.background.color

CotEditor/Sources/LayoutManager.swift

@@ -171,12 +171,11 @@ class LayoutManager: NSLayoutManager, InvisibleDrawing, ValidationIgnorable, Lin
         // -> Otherwise, `.unemphasizedSelectedContentBackgroundColor` will be used forcibly and text becomes unreadable
         //    when the window appearance and theme are inconsistent.
         if color == .unemphasizedSelectedContentBackgroundColor,  // check if inactive
-           let textContainer = self.textContainer(forGlyphAt: self.glyphIndexForCharacter(at: charRange.location),
-                                                  effectiveRange: nil, withoutAdditionalLayout: true),
-           let theme = (textContainer.textView as? any Themable)?.theme,
-           let secondarySelectionColor = theme.secondarySelectionColor
+           let textView = self.textContainer(forGlyphAt: self.glyphIndexForCharacter(at: charRange.location),
+                                             effectiveRange: nil, withoutAdditionalLayout: true)?.textView,
+           let theme = (textView as? any Themable)?.theme
         {
-            secondarySelectionColor.setFill()
+            theme.effectiveSecondarySelectionColor(for: textView.effectiveAppearance)?.setFill()
         }
 
         super.fillBackgroundRectArray(rectArray, count: rectCount, forCharacterRange: charRange, color: color)

CotEditor/Sources/NSAppearance.swift

@@ -8,7 +8,7 @@
 //
 //  ---------------------------------------------------------------------------
 //
-//  © 2018-2023 1024jp
+//  © 2018-2024 1024jp
 //
 //  Licensed under the Apache License, Version 2.0 (the "License");
 //  you may not use this file except in compliance with the License.
@@ -45,4 +45,73 @@ extension NSAppearance {
                 false
         }
     }
+
+
+    /// THe corresponding appearance for the light/dark mode.
+    ///
+    /// - Parameter isDark: Whether the return value to be for dark mode or not.
+    /// - Returns: A new appearance, or `self` if no change required.
+    final func appearance(for isDark: Bool) -> Self {
+
+        if isDark == self.isDark {
+            self
+        } else {
+            Self(named: self.name.name(for: isDark)) ?? self
+        }
+    }
+}
+
+
+extension NSColor {
+
+    /// Forcibly creates the appropriate color for the given appearance.
+    ///
+    /// - Parameter appearance: The appearance to match.
+    /// - Returns: A new color.
+    func solve(for appearance: NSAppearance?) -> NSColor {
+
+        guard self.type != .componentBased else { return self }
+
+        var color = self
+        appearance?.performAsCurrentDrawingAppearance {
+            color = NSColor(cgColor: color.cgColor) ?? color
+        }
+        return color
+    }
+
+
+    /// Forcibly creates the appropriate color for the light/dark mode.
+    ///
+    /// - Parameter isDark: Whether the return value to be for dark mode or not.
+    /// - Returns: A new color.
+    func forDarkMode(_ isDark: Bool) -> NSColor {
+
+        guard self.type != .componentBased else { return self }
+
+        return self.solve(for: NSAppearance(named: isDark ? .darkAqua : .aqua)!)
+    }
+}
+
+
+private extension NSAppearance.Name {
+
+    /// The corresponding appearance name for the light/dark mode.
+    ///
+    /// - Parameter isDark: Whether the return value to be for dark mode or not.
+    /// - Returns: An appearance name.
+    func name(for isDark: Bool) -> Self {
+
+        switch self {
+            case .aqua, .darkAqua:
+                isDark ? .darkAqua : .aqua
+            case .vibrantLight, .vibrantDark:
+                isDark ? .vibrantDark : .vibrantLight
+            case .accessibilityHighContrastAqua, .accessibilityHighContrastDarkAqua:
+                isDark ? .accessibilityHighContrastDarkAqua : .accessibilityHighContrastAqua
+            case .accessibilityHighContrastVibrantLight, .accessibilityHighContrastVibrantDark:
+                isDark ? .accessibilityHighContrastVibrantDark : .accessibilityHighContrastVibrantLight
+            default:
+                self
+        }
+    }
 }

CotEditor/Sources/Theme.swift

@@ -145,18 +145,6 @@ struct Theme: Equatable {
     }
 
 
-    /// Selection color for inactive text view.
-    var secondarySelectionColor: NSColor? {
-
-        guard
-            !self.selection.usesSystemSetting,
-            let color = self.selection.color.usingColorSpace(.genericRGB)
-        else { return nil }
-
-        return NSColor(calibratedWhite: color.lightnessComponent, alpha: 1.0)
-    }
-
-
     /// Insertion point color to use.
     var effectiveInsertionPointColor: NSColor {
 
@@ -168,10 +156,41 @@ struct Theme: Equatable {
     }
 
 
-    /// Selected text background color to use.
-    var effectiveSelectionColor: NSColor {
-
-        self.selection.usesSystemSetting ? .selectedTextBackgroundColor : self.selection.color
+    /// Returns the selection color to use with the given appearance.
+    ///
+    /// - Parameter appearance: The current appearance of the text view to draw.
+    /// - Returns: A color.
+    func effectiveSelectionColor(for appearance: NSAppearance) -> NSColor {
+
+        if self.selection.usesSystemSetting {
+            if self.isDarkTheme == appearance.isDark {
+                .selectedTextBackgroundColor
+            } else {
+                .selectedTextBackgroundColor.solve(for: appearance.appearance(for: self.isDarkTheme))
+            }
+        } else {
+            self.selection.color
+        }
+    }
+
+
+    /// Returns the selection color to use for inactive views.
+    ///
+    /// - Parameter appearance: The current appearance of the text view to draw.
+    /// - Returns: A color.
+    func effectiveSecondarySelectionColor(for appearance: NSAppearance) -> NSColor? {
+
+        if self.selection.usesSystemSetting {
+            return if self.isDarkTheme == appearance.isDark {
+                .unemphasizedSelectedTextBackgroundColor
+            } else {
+                .unemphasizedSelectedTextBackgroundColor.solve(for: appearance.appearance(for: self.isDarkTheme))
+            }
+        } else {
+            guard let color = self.selection.color.usingColorSpace(.genericRGB) else { return nil }
+
+            return NSColor(calibratedWhite: color.lightnessComponent, alpha: 1.0)
+        }
     }
 
 

CotEditor/Sources/ThemeEditorView.swift

@@ -64,7 +64,7 @@ struct ThemeEditorView: View {
                                 selection: $theme.lineHighlight.binding, supportsOpacity: false)
                     SystemColorPicker(String(localized: "Selection:", table: "ThemeEditor"),
                                       selection: $theme.selection,
-                                      systemColor: Color(nsColor: .selectedTextBackgroundColor),
+                                      systemColor: Color(nsColor: .selectedTextBackgroundColor.forDarkMode(self.theme.isDarkTheme)),
                                       supportsOpacity: false)
                 }.accessibilityElement(children: .contain)
             }.accessibilityElement(children: .contain)