From c858cd693c8c4d0221c6a303946e7a98ed0a4386 Mon Sep 17 00:00:00 2001
From: Adam Wolf <adam@travefy.com>
Date: Tue, 14 Jan 2025 21:28:36 -0600
Subject: [PATCH] apprt/gtk: add toggle_background_opacity option

---
 include/ghostty.h        |  1 +
 src/Surface.zig          |  6 ++++++
 src/apprt/action.zig     |  4 ++++
 src/apprt/glfw.zig       |  1 +
 src/apprt/gtk/App.zig    | 20 ++++++++++++++++++++
 src/apprt/gtk/Window.zig | 11 +++++++++++
 src/input/Binding.zig    |  4 ++++
 7 files changed, 47 insertions(+)

diff --git a/include/ghostty.h b/include/ghostty.h
index 246fb9ed35..4ce91664a2 100644
--- a/include/ghostty.h
+++ b/include/ghostty.h
@@ -569,6 +569,7 @@ typedef enum {
   GHOSTTY_ACTION_TOGGLE_FULLSCREEN,
   GHOSTTY_ACTION_TOGGLE_TAB_OVERVIEW,
   GHOSTTY_ACTION_TOGGLE_WINDOW_DECORATIONS,
+  GHOSTTY_ACTION_TOGGLE_BACKGROUND_OPACITY,
   GHOSTTY_ACTION_TOGGLE_QUICK_TERMINAL,
   GHOSTTY_ACTION_TOGGLE_VISIBILITY,
   GHOSTTY_ACTION_MOVE_TAB,
diff --git a/src/Surface.zig b/src/Surface.zig
index 5a1d8c01d4..287ea4d360 100644
--- a/src/Surface.zig
+++ b/src/Surface.zig
@@ -4199,6 +4199,12 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             {},
         ),
 
+        .toggle_background_opacity => try self.rt_app.performAction(
+            .{ .surface = self },
+            .toggle_background_opacity,
+            {},
+        ),
+
         .toggle_tab_overview => try self.rt_app.performAction(
             .{ .surface = self },
             .toggle_tab_overview,
diff --git a/src/apprt/action.zig b/src/apprt/action.zig
index fe2039e523..a0a5994fec 100644
--- a/src/apprt/action.zig
+++ b/src/apprt/action.zig
@@ -104,6 +104,9 @@ pub const Action = union(Key) {
     /// Toggle whether window directions are shown.
     toggle_window_decorations,
 
+    /// Toggle the background opacity of the target terminal.
+    toggle_background_opacity,
+
     /// Toggle the quick terminal in or out.
     toggle_quick_terminal,
 
@@ -238,6 +241,7 @@ pub const Action = union(Key) {
         toggle_fullscreen,
         toggle_tab_overview,
         toggle_window_decorations,
+        toggle_background_opacity,
         toggle_quick_terminal,
         toggle_visibility,
         move_tab,
diff --git a/src/apprt/glfw.zig b/src/apprt/glfw.zig
index 686a70ddb6..6473ecd4e1 100644
--- a/src/apprt/glfw.zig
+++ b/src/apprt/glfw.zig
@@ -221,6 +221,7 @@ pub const App = struct {
             .close_tab,
             .toggle_tab_overview,
             .toggle_window_decorations,
+            .toggle_background_opacity,
             .toggle_quick_terminal,
             .toggle_visibility,
             .goto_tab,
diff --git a/src/apprt/gtk/App.zig b/src/apprt/gtk/App.zig
index f49d275de7..3dd59364af 100644
--- a/src/apprt/gtk/App.zig
+++ b/src/apprt/gtk/App.zig
@@ -534,6 +534,7 @@ pub fn performAction(
         .toggle_tab_overview => self.toggleTabOverview(target),
         .toggle_split_zoom => self.toggleSplitZoom(target),
         .toggle_window_decorations => self.toggleWindowDecorations(target),
+        .toggle_background_opacity => self.toggleBackgroundOpacity(target),
         .quit_timer => self.quitTimer(value),
 
         // Unimplemented
@@ -791,6 +792,25 @@ fn toggleWindowDecorations(
     }
 }
 
+fn toggleBackgroundOpacity(
+    _: *App,
+    target: apprt.Target,
+) void {
+    switch (target) {
+        .app => {},
+        .surface => |v| {
+            const window = v.rt_surface.container.window() orelse {
+                log.info(
+                    "toggleBackgroundOpacity invalid for container={s}",
+                    .{@tagName(v.rt_surface.container)},
+                );
+                return;
+            };
+            window.toggleBackgroundOpacity();
+        },
+    }
+}
+
 fn quitTimer(self: *App, mode: apprt.action.QuitTimer) void {
     switch (mode) {
         .start => self.startQuitTimer(),
diff --git a/src/apprt/gtk/Window.zig b/src/apprt/gtk/Window.zig
index 3c8c2c2e7d..121af08c32 100644
--- a/src/apprt/gtk/Window.zig
+++ b/src/apprt/gtk/Window.zig
@@ -559,6 +559,17 @@ pub fn toggleWindowDecorations(self: *Window) void {
     self.headerbar.setVisible(new_decorated);
 }
 
+/// Toggle the background opacity for this window.
+pub fn toggleBackgroundOpacity(self: *Window) void {
+    if (self.app.config.@"background-opacity" >= 1) return;
+
+    if (c.gtk_widget_has_css_class(@ptrCast(self.window), "background") == 1) {
+        c.gtk_widget_remove_css_class(@ptrCast(self.window), "background");
+    } else {
+        c.gtk_widget_add_css_class(@ptrCast(self.window), "background");
+    }
+}
+
 /// Grabs focus on the currently selected tab.
 pub fn focusCurrentTab(self: *Window) void {
     const tab = self.notebook.currentTab() orelse return;
diff --git a/src/input/Binding.zig b/src/input/Binding.zig
index 48725fb13e..8646ac8212 100644
--- a/src/input/Binding.zig
+++ b/src/input/Binding.zig
@@ -400,6 +400,9 @@ pub const Action = union(enum) {
     /// Toggle window decorations on and off. This only works on Linux.
     toggle_window_decorations: void,
 
+    /// Toggle background opacity of window.
+    toggle_background_opacity: void,
+
     /// Toggle secure input mode on or off. This is used to prevent apps
     /// that monitor input from seeing what you type. This is useful for
     /// entering passwords or other sensitive information.
@@ -743,6 +746,7 @@ pub const Action = union(enum) {
             .toggle_maximize,
             .toggle_fullscreen,
             .toggle_window_decorations,
+            .toggle_background_opacity,
             .toggle_secure_input,
             .crash,
             => .surface,