macos: transparent titlebar handles transparent background

macos/Ghostty.xcodeproj/project.pbxproj

@@ -12,6 +12,7 @@
 		552964E62B34A9B400030505 /* vim in Resources */ = {isa = PBXBuildFile; fileRef = 552964E52B34A9B400030505 /* vim */; };
 		857F63812A5E64F200CA4815 /* MainMenu.xib in Resources */ = {isa = PBXBuildFile; fileRef = 857F63802A5E64F200CA4815 /* MainMenu.xib */; };
 		9351BE8E3D22937F003B3499 /* nvim in Resources */ = {isa = PBXBuildFile; fileRef = 9351BE8E2D22937F003B3499 /* nvim */; };
+		A50297352DFA0F3400B4E924 /* Double+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = A50297342DFA0F3300B4E924 /* Double+Extension.swift */; };
 		A514C8D62B54A16400493A16 /* Ghostty.Config.swift in Sources */ = {isa = PBXBuildFile; fileRef = A514C8D52B54A16400493A16 /* Ghostty.Config.swift */; };
 		A514C8D72B54A16400493A16 /* Ghostty.Config.swift in Sources */ = {isa = PBXBuildFile; fileRef = A514C8D52B54A16400493A16 /* Ghostty.Config.swift */; };
 		A514C8D82B54DC6800493A16 /* Ghostty.App.swift in Sources */ = {isa = PBXBuildFile; fileRef = A53D0C992B543F3B00305CE6 /* Ghostty.App.swift */; };
@@ -134,6 +135,7 @@
 		552964E52B34A9B400030505 /* vim */ = {isa = PBXFileReference; lastKnownFileType = folder; name = vim; path = "../zig-out/share/vim"; sourceTree = "<group>"; };
 		857F63802A5E64F200CA4815 /* MainMenu.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = MainMenu.xib; sourceTree = "<group>"; };
 		9351BE8E2D22937F003B3499 /* nvim */ = {isa = PBXFileReference; lastKnownFileType = folder; name = nvim; path = "../zig-out/share/nvim"; sourceTree = "<group>"; };
+		A50297342DFA0F3300B4E924 /* Double+Extension.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Double+Extension.swift"; sourceTree = "<group>"; };
 		A514C8D52B54A16400493A16 /* Ghostty.Config.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Ghostty.Config.swift; sourceTree = "<group>"; };
 		A51B78462AF4B58B00F3EDB9 /* LegacyTerminalWindow.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LegacyTerminalWindow.swift; sourceTree = "<group>"; };
 		A51BFC1D2B2FB5CE00E92F16 /* About.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = About.xib; sourceTree = "<group>"; };
@@ -464,6 +466,7 @@
 			isa = PBXGroup;
 			children = (
 				A586366A2DF0A98900E04A10 /* Array+Extension.swift */,
+				A50297342DFA0F3300B4E924 /* Double+Extension.swift */,
 				A586366E2DF25D8300E04A10 /* Duration+Extension.swift */,
 				A53A29802DB44A5E00B6E02C /* KeyboardShortcut+Extension.swift */,
 				A53A297E2DB4480A00B6E02C /* EventModifiers+Extension.swift */,
@@ -737,6 +740,7 @@
 				A51BFC222B2FB6B400E92F16 /* AboutView.swift in Sources */,
 				A5278A9B2AA05B2600CD3039 /* Ghostty.Input.swift in Sources */,
 				A53A29812DB44A6100B6E02C /* KeyboardShortcut+Extension.swift in Sources */,
+				A50297352DFA0F3400B4E924 /* Double+Extension.swift in Sources */,
 				A5CBD0562C9E65B80017A1AE /* DraggableWindowView.swift in Sources */,
 				C1F26EE92B76CBFC00404083 /* VibrantLayer.m in Sources */,
 				A5593FDF2DF8D57C00B47B10 /* TerminalWindow.swift in Sources */,

macos/Sources/Features/Terminal/TerminalController.swift

@@ -449,57 +449,34 @@ class TerminalController: BaseTerminalController {
     }
 
     private func syncAppearance(_ surfaceConfig: Ghostty.SurfaceView.DerivedConfig) {
+        // Let our window handle its own appearance
         if let window = window as? TerminalWindow {
             window.syncAppearance(surfaceConfig)
         }
         
-        guard let window = self.window as? LegacyTerminalWindow else { return }
+        guard let window else { return }
 
-        // Set our explicit appearance if we need to based on the configuration.
+        if let window = window as? LegacyTerminalWindow {
-        window.appearance = surfaceConfig.windowAppearance
+            // Update our window light/darkness based on our updated background color
+            window.isLightTheme = OSColor(surfaceConfig.backgroundColor).isLightColor
 
-        // Update our window light/darkness based on our updated background color
+            // Sync our zoom state for splits
-        window.isLightTheme = OSColor(surfaceConfig.backgroundColor).isLightColor
+            window.surfaceIsZoomed = surfaceTree.zoomed != nil
 
-        // Sync our zoom state for splits
+            // Set the font for the window and tab titles.
-        window.surfaceIsZoomed = surfaceTree.zoomed != nil
+            if let titleFontName = surfaceConfig.windowTitleFontFamily {
+                window.titlebarFont = NSFont(name: titleFontName, size: NSFont.systemFontSize)
+            } else {
+                window.titlebarFont = nil
+            }
+        }
 
         // If our window is not visible, then we do nothing. Some things such as blurring
         // have no effect if the window is not visible. Ultimately, we'll have this called
         // at some point when a surface becomes focused.
         guard window.isVisible else { return }
 
-        // Set the font for the window and tab titles.
+        guard let window = window as? LegacyTerminalWindow, window.hasStyledTabs else { return }
-        if let titleFontName = surfaceConfig.windowTitleFontFamily {
-            window.titlebarFont = NSFont(name: titleFontName, size: NSFont.systemFontSize)
-        } else {
-            window.titlebarFont = nil
-        }
-
-        // If we have window transparency then set it transparent. Otherwise set it opaque.
-
-        // Window transparency only takes effect if our window is not native fullscreen.
-        // In native fullscreen we disable transparency/opacity because the background
-        // becomes gray and widgets show through.
-        if (!window.styleMask.contains(.fullScreen) &&
-            surfaceConfig.backgroundOpacity < 1
-        ) {
-            window.isOpaque = false
-
-            // This is weird, but we don't use ".clear" because this creates a look that
-            // matches Terminal.app much more closer. This lets users transition from
-            // Terminal.app more easily.
-            window.backgroundColor = .white.withAlphaComponent(0.001)
-
-            ghostty_set_window_background_blur(ghostty.app, Unmanaged.passUnretained(window).toOpaque())
-        } else {
-            window.isOpaque = true
-            window.backgroundColor = .windowBackgroundColor
-        }
-
-        window.hasShadow = surfaceConfig.macosWindowShadow
-
-        guard window.hasStyledTabs else { return }
 
         // Our background color depends on if our focused surface borders the top or not.
         // If it does, we match the focused surface. If it doesn't, we use the app

macos/Sources/Features/Terminal/Window Styles/TerminalWindow.swift

@@ -1,4 +1,5 @@
 import AppKit
+import GhosttyKit
 
 /// The base class for all standalone, "normal" terminal windows. This sets the basic
 /// style and configuration of the window based on the app configuration.
@@ -7,6 +8,14 @@ class TerminalWindow: NSWindow {
     /// used by the manual float on top menu item feature.
     static let defaultLevelKey: String = "TerminalDefaultLevel"
 
+    /// The configuration derived from the Ghostty config so we don't need to rely on references.
+    private var derivedConfig: DerivedConfig?
+
+    /// Gets the terminal controller from the window controller.
+    var terminalController: TerminalController? {
+        windowController as? TerminalController
+    }
+
     // MARK: NSWindow Overrides
 
     override func awakeFromNib() {
@@ -15,6 +24,9 @@ class TerminalWindow: NSWindow {
         // All new windows are based on the app config at the time of creation.
         let config = appDelegate.ghostty.config
 
+        // Setup our initial config
+        derivedConfig = .init(config)
+
         // If window decorations are disabled, remove our title
         if (!config.windowDecorations) { styleMask.remove(.titled) }
 
@@ -42,7 +54,71 @@ class TerminalWindow: NSWindow {
     // MARK: Positioning And Styling
 
     /// This is called by the controller when there is a need to reset the window apperance.
-    func syncAppearance(_ surfaceConfig: Ghostty.SurfaceView.DerivedConfig) {}
+    func syncAppearance(_ surfaceConfig: Ghostty.SurfaceView.DerivedConfig) {
+        // If our window is not visible, then we do nothing. Some things such as blurring
+        // have no effect if the window is not visible. Ultimately, we'll have this called
+        // at some point when a surface becomes focused.
+        guard isVisible else { return }
+
+        // Basic properties
+        appearance = surfaceConfig.windowAppearance
+        hasShadow = surfaceConfig.macosWindowShadow
+
+        // Window transparency only takes effect if our window is not native fullscreen.
+        // In native fullscreen we disable transparency/opacity because the background
+        // becomes gray and widgets show through.
+        if !styleMask.contains(.fullScreen) &&
+            surfaceConfig.backgroundOpacity < 1
+        {
+            isOpaque = false
+
+            // This is weird, but we don't use ".clear" because this creates a look that
+            // matches Terminal.app much more closer. This lets users transition from
+            // Terminal.app more easily.
+            backgroundColor = .white.withAlphaComponent(0.001)
+
+            if let appDelegate = NSApp.delegate as? AppDelegate {
+                ghostty_set_window_background_blur(
+                    appDelegate.ghostty.app,
+                    Unmanaged.passUnretained(self).toOpaque())
+            }
+        } else {
+            isOpaque = true
+
+            let backgroundColor = preferredBackgroundColor ?? NSColor(surfaceConfig.backgroundColor)
+            self.backgroundColor = backgroundColor.withAlphaComponent(1)
+        }
+    }
+
+    /// The preferred window background color. The current window background color may not be set
+    /// to this, since this is dynamic based on the state of the surface tree.
+    ///
+    /// This background color will include alpha transparency if set. If the caller doesn't want that,
+    /// change the alpha channel again manually.
+    var preferredBackgroundColor: NSColor? {
+        if let terminalController, !terminalController.surfaceTree.isEmpty {
+            // If our focused surface borders the top then we prefer its background color
+            if let focusedSurface = terminalController.focusedSurface,
+               let treeRoot = terminalController.surfaceTree.root,
+               let focusedNode = treeRoot.node(view: focusedSurface),
+               treeRoot.spatial().doesBorder(side: .up, from: focusedNode),
+               let backgroundcolor = focusedSurface.backgroundColor {
+                let alpha = focusedSurface.derivedConfig.backgroundOpacity.clamped(to: 0.001...1)
+                return NSColor(backgroundcolor).withAlphaComponent(alpha)
+            }
+
+            // Doesn't border the top or we don't have a focused surface, so
+            // we try to match the top-left surface.
+            let topLeftSurface = terminalController.surfaceTree.root?.leftmostLeaf()
+            if let topLeftBgColor = topLeftSurface?.backgroundColor {
+                let alpha = topLeftSurface?.derivedConfig.backgroundOpacity.clamped(to: 0.001...1) ?? 1
+                return NSColor(topLeftBgColor).withAlphaComponent(alpha)
+            }
+        }
+
+        let alpha = derivedConfig?.backgroundOpacity.clamped(to: 0.001...1) ?? 1
+        return derivedConfig?.backgroundColor.withAlphaComponent(alpha)
+    }
 
     private func setInitialWindowPosition(x: Int16?, y: Int16?, windowDecorations: Bool) {
         // If we don't have an X/Y then we try to use the previously saved window pos.
@@ -72,4 +148,21 @@ class TerminalWindow: NSWindow {
         standardWindowButton(.miniaturizeButton)?.isHidden = true
         standardWindowButton(.zoomButton)?.isHidden = true
     }
+
+    // MARK: Config
+
+    struct DerivedConfig {
+        let backgroundColor: NSColor
+        let backgroundOpacity: Double
+
+        init() {
+            self.backgroundColor = NSColor.windowBackgroundColor
+            self.backgroundOpacity = 1
+        }
+
+        init(_ config: Ghostty.Config) {
+            self.backgroundColor = NSColor(config.backgroundColor)
+            self.backgroundOpacity = config.backgroundOpacity
+        }
+    }
 }

macos/Sources/Features/Terminal/Window Styles/TransparentTitlebarTerminalWindow.swift

@@ -33,6 +33,8 @@ class TransparentTitlebarTerminalWindow: TerminalWindow {
     // MARK: Appearance
 
     override func syncAppearance(_ surfaceConfig: Ghostty.SurfaceView.DerivedConfig) {
+        super.syncAppearance(surfaceConfig)
+        
         lastSurfaceConfig = surfaceConfig
         if #available(macOS 26.0, *) {
             syncAppearanceTahoe(surfaceConfig)
@@ -43,9 +45,23 @@ class TransparentTitlebarTerminalWindow: TerminalWindow {
 
     @available(macOS 26.0, *)
     private func syncAppearanceTahoe(_ surfaceConfig: Ghostty.SurfaceView.DerivedConfig) {
-        guard let titlebarBackgroundView else { return }
+        // When we have transparency, we need to set the titlebar background to match the
-        titlebarBackgroundView.isHidden = true
+        // window background but with opacity. The window background is set using the
-        backgroundColor = NSColor(surfaceConfig.backgroundColor)
+        // "preferred background color" property.
+        //
+        // As an inverse, if we don't have transparency, we don't bother with this because
+        // the window background will be set to the correct color so we can just hide the
+        // titlebar completely and we're good to go.
+        if !isOpaque {
+            if let titlebarView = titlebarContainer?.firstDescendant(withClassName: "NSTitlebarView") {
+                titlebarView.wantsLayer = true
+                titlebarView.layer?.backgroundColor = preferredBackgroundColor?.cgColor
+            }
+        }
+
+        // In all cases, we have to hide the background view since this has multiple subviews
+        // that force a background color.
+        titlebarBackgroundView?.isHidden = true
     }
 
     @available(macOS 13.0, *)

macos/Sources/Helpers/Extensions/Double+Extension.swift

@@ -0,0 +1,5 @@
+extension Double {
+    func clamped(to range: ClosedRange<Double>) -> Double {
+        return Swift.min(Swift.max(self, range.lowerBound), range.upperBound)
+    }
+}