Make special blending mode class more generic

This allows us to specify what kind of context we'd like our vibrant
layer to exist in (light or dark).

macos/Ghostty.xcodeproj/project.pbxproj

@@ -70,7 +70,7 @@
 		C159E81D2B66A06B00FDFE9C /* OSColor+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = C159E81C2B66A06B00FDFE9C /* OSColor+Extension.swift */; };
 		C159E89D2B69A2EF00FDFE9C /* OSColor+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = C159E81C2B66A06B00FDFE9C /* OSColor+Extension.swift */; };
 		C1F26EA72B738B9900404083 /* NSView+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = C1F26EA62B738B9900404083 /* NSView+Extension.swift */; };
-		C1F26EE92B76CBFC00404083 /* TerminalWindowButtonsBackdropOverlayLayer.m in Sources */ = {isa = PBXBuildFile; fileRef = C1F26EE82B76CBFC00404083 /* TerminalWindowButtonsBackdropOverlayLayer.m */; };
+		C1F26EE92B76CBFC00404083 /* VibrantLayer.m in Sources */ = {isa = PBXBuildFile; fileRef = C1F26EE82B76CBFC00404083 /* VibrantLayer.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -133,8 +133,8 @@
 		AEF9CE232B6AD07A0017E195 /* TerminalToolbar.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TerminalToolbar.swift; sourceTree = "<group>"; };
 		C159E81C2B66A06B00FDFE9C /* OSColor+Extension.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "OSColor+Extension.swift"; sourceTree = "<group>"; };
 		C1F26EA62B738B9900404083 /* NSView+Extension.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "NSView+Extension.swift"; sourceTree = "<group>"; };
-		C1F26EE72B76CBFC00404083 /* TerminalWindowButtonsBackdropOverlayLayer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TerminalWindowButtonsBackdropOverlayLayer.h; sourceTree = "<group>"; };
+		C1F26EE72B76CBFC00404083 /* VibrantLayer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = VibrantLayer.h; sourceTree = "<group>"; };
-		C1F26EE82B76CBFC00404083 /* TerminalWindowButtonsBackdropOverlayLayer.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = TerminalWindowButtonsBackdropOverlayLayer.m; sourceTree = "<group>"; };
+		C1F26EE82B76CBFC00404083 /* VibrantLayer.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = VibrantLayer.m; sourceTree = "<group>"; };
 		C1F26EEA2B76CC2400404083 /* ghostty-bridging-header.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ghostty-bridging-header.h"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -202,6 +202,8 @@
 				A59FB5D02AE0DEA7009128F3 /* MetalView.swift */,
 				C159E81C2B66A06B00FDFE9C /* OSColor+Extension.swift */,
 				C1F26EA62B738B9900404083 /* NSView+Extension.swift */,
+				C1F26EE72B76CBFC00404083 /* VibrantLayer.h */,
+				C1F26EE82B76CBFC00404083 /* VibrantLayer.m */,
 				A5CEAFDA29B8005900646FDA /* SplitView */,
 			);
 			path = Helpers;
@@ -293,8 +295,6 @@
 				A5D0AF3A2B36A1DE00D21823 /* TerminalRestorable.swift */,
 				A596309D2AEE1D6C00D64628 /* TerminalView.swift */,
 				A51B78462AF4B58B00F3EDB9 /* TerminalWindow.swift */,
-				C1F26EE72B76CBFC00404083 /* TerminalWindowButtonsBackdropOverlayLayer.h */,
-				C1F26EE82B76CBFC00404083 /* TerminalWindowButtonsBackdropOverlayLayer.m */,
 				AEF9CE232B6AD07A0017E195 /* TerminalToolbar.swift */,
 				A535B9D9299C569B0017E2E4 /* ErrorView.swift */,
 			);
@@ -488,7 +488,7 @@
 				A56D58892ACDE6CA00508D2C /* ServiceProvider.swift in Sources */,
 				A51BFC222B2FB6B400E92F16 /* AboutView.swift in Sources */,
 				A5278A9B2AA05B2600CD3039 /* Ghostty.Input.swift in Sources */,
-				C1F26EE92B76CBFC00404083 /* TerminalWindowButtonsBackdropOverlayLayer.m in Sources */,
+				C1F26EE92B76CBFC00404083 /* VibrantLayer.m in Sources */,
 				A59630972AEE163600D64628 /* HostingWindow.swift in Sources */,
 				A59630A02AEF6AEB00D64628 /* TerminalManager.swift in Sources */,
 				A51BFC2B2B30F6BE00E92F16 /* UpdateDelegate.swift in Sources */,

macos/Sources/App/macOS/ghostty-bridging-header.h

@@ -1,3 +1,3 @@
 // C imports here are exposed to Swift.
 
-#import "TerminalWindowButtonsBackdropOverlayLayer.h"
+#import "VibrantLayer.h"

macos/Sources/Features/Terminal/TerminalWindow.swift

@@ -350,7 +350,7 @@ fileprivate class WindowDragView: NSView {
 
 // A view that matches the color of selected and unselected tabs in the adjacent tab bar.
 fileprivate class WindowButtonsBackdropView: NSView {
-    private let overlayLayer = TerminalWindowButtonsBackdropOverlayLayer()
+    private let overlayLayer = VibrantLayer()
     private let isLightTheme: Bool
 
     var isHighlighted: Bool = true {

macos/Sources/Features/Terminal/TerminalWindowButtonsBackdropOverlayLayer.h

@@ -1,4 +0,0 @@
-#import <QuartzCore/QuartzCore.h>
-
-@interface TerminalWindowButtonsBackdropOverlayLayer: CALayer
-@end

macos/Sources/Features/Terminal/TerminalWindowButtonsBackdropOverlayLayer.m

@@ -1,9 +0,0 @@
-#import "TerminalWindowButtonsBackdropOverlayLayer.h"
-
-@implementation TerminalWindowButtonsBackdropOverlayLayer
-
-// A private compositing filter ("plus darker") that is used in titlebar
-// tab bars to create the effect of recessed, unselected tabs.
-- (id)compositingFilter { return @"plusD"; }
-
-@end

macos/Sources/Helpers/VibrantLayer.h

@@ -0,0 +1,16 @@
+#import <QuartzCore/QuartzCore.h>
+
+typedef NS_ENUM(NSUInteger, VibrantLayerType) {
+    VibrantLayerTypeLight,
+    VibrantLayerTypeDark
+};
+
+// This layer can be used to recreate the "vibrant" appearance you see of
+// views placed inside `NSVisualEffectView`s. When a light NSAppearance is
+// active, we will use the private "plus darker" blend mode. For dark
+// appearances we use "plus lighter".
+@interface VibrantLayer : CALayer
+
+- (id)initForAppearance:(VibrantLayerType)type;
+
+@end

macos/Sources/Helpers/VibrantLayer.m

@@ -0,0 +1,27 @@
+#import "VibrantLayer.h"
+
+@interface VibrantLayer()
+
+@property (nonatomic) VibrantLayerType type;
+
+@end
+
+@implementation VibrantLayer
+
+- (id)initForAppearance:(VibrantLayerType)type {
+    self = [super init];
+    if (self) {
+        _type = type;
+    }
+    return self;
+}
+
+- (id)compositingFilter {
+    if (self.type == VibrantLayerTypeLight) {
+        return @"plusD";
+    } else {
+        return @"plusL";
+    }
+}
+
+@end