Merge pull request #972 from storytold/fix/968-traffic-lights

#968: centre the macOS window buttons on the app bar

Cargo.lock

@@ -4335,6 +4335,7 @@ dependencies = [
  "objc2-core-foundation",
  "objc2-core-text",
  "objc2-foundation 0.3.2",
+ "raw-window-handle",
  "rfd",
  "serde_json",
  "vectorcraft-engine",

apps/vectorcraft/Cargo.toml

@@ -51,10 +51,13 @@ windows = { version = "0.62", features = ["Win32_Graphics_DirectWrite"] }
 # with default features off). Pinned exactly: review the diff before bumping.
 muda = { version = "=0.21.1", default-features = false }
 objc2 = "0.6"
-objc2-app-kit = { version = "0.3", default-features = false, features = ["std", "NSApplication", "NSMenu", "NSEvent", "NSPasteboard", "NSResponder", "NSTextInputContext"] }
+objc2-app-kit = { version = "0.3", default-features = false, features = ["std", "NSApplication", "NSButton", "NSControl", "NSMenu", "NSEvent", "NSPasteboard", "NSResponder", "NSTextInputContext", "NSView", "NSWindow"] }
 # Files opened from Finder and the Dock (src/open_documents.rs) and pasted bitmaps (src/clipboard.rs); both already come with winit, muda and rfd.
-objc2-foundation = { version = "0.3", default-features = false, features = ["std", "block2", "NSArray", "NSData", "NSNotification", "NSOperation", "NSString", "NSURL"] }
+objc2-foundation = { version = "0.3", default-features = false, features = ["std", "block2", "NSArray", "NSData", "NSGeometry", "NSNotification", "NSOperation", "NSString", "NSURL"] }
 block2 = "0.6"
+# The window's AppKit view, to centre its buttons on the app bar (src/mac_window.rs). MIT OR
+# Apache-2.0 OR Zlib, already in the build through eframe and winit.
+raw-window-handle = "0.6"
 # CoreText's font manager (src/mac_fonts.rs): fonts that apps and font managers register from their
 # own folders (#579). Zlib OR Apache-2.0 OR MIT; objc2-core-foundation already comes with
 # objc2-foundation.

apps/vectorcraft/src/mac_window.rs

@@ -0,0 +1,74 @@
+//! macOS: the window buttons (close, minimize, zoom) centred on the app bar (#968).
+//!
+//! AppKit puts the buttons in a standard title bar, shorter than the app bar they sit over, so they
+//! rode high on it. [`center_buttons`] moves them to the middle of the bar, inset from its left as
+//! far as from its top, and makes the title bar as tall as the app bar so they stay clickable.
+//! AppKit lays its title bar out again when the window resizes or leaves full screen, so this runs
+//! every frame and moves the buttons only when they are out of place.
+//!
+//! Reaching the title bar's views from the window's content view has no safe API, hence the scoped
+//! `unsafe_code` allowance.
+#![allow(unsafe_code)]
+
+use objc2::runtime::AnyObject;
+use objc2_app_kit::{NSView, NSWindowButton, NSWindowStyleMask};
+use objc2_foundation::NSPoint;
+use raw_window_handle::{HasWindowHandle, RawWindowHandle};
+
+/// The room the app bar keeps at its left for the buttons in AppKit's own place, before they are
+/// centred (and in full screen, where AppKit shows them elsewhere): their width and a gap.
+pub const DEFAULT_INSET: f32 = 78.0;
+
+/// Differences below this (in points) leave a frame as it is, so a frame in place isn't set again.
+const SLACK: f64 = 0.25;
+
+/// Centre the window's buttons on an app bar `bar` egui points tall, at the window's `zoom` factor
+/// (native points per egui point). Returns the room the app bar keeps clear at its left for them,
+/// in egui points, or `None` when they aren't over the bar (full screen) or can't be found.
+pub fn center_buttons(frame: &eframe::Frame, zoom: f32, bar: f32) -> Option<f32> {
+    let RawWindowHandle::AppKit(handle) = frame.window_handle().ok()?.as_raw() else {
+        return None;
+    };
+    // SAFETY: the handle's view is the window's content view, which AppKit keeps alive while the
+    // window is open, and eframe hands out the handle only while it is.
+    let view = unsafe { handle.ns_view.cast::<NSView>().as_ref() };
+    let window = view.window()?;
+    if window.styleMask().contains(NSWindowStyleMask::FullScreen) {
+        return None;
+    }
+    let close = window.standardWindowButton(NSWindowButton::CloseButton)?;
+    let minimize = window.standardWindowButton(NSWindowButton::MiniaturizeButton)?;
+    let zoom_button = window.standardWindowButton(NSWindowButton::ZoomButton)?;
+    // The buttons sit in the title bar view, inside the title bar container that sets its height.
+    // SAFETY: both views belong to the window, alive while it is; used right away.
+    let container = unsafe { close.superview().and_then(|titlebar| titlebar.superview()) }?;
+    // Another layout (a later macOS) is left as AppKit made it.
+    if AnyObject::class(&container).name() != c"NSTitlebarContainerView" {
+        return None;
+    }
+    let size = close.frame().size;
+    let gap = minimize.frame().origin.x - (close.frame().origin.x + size.width);
+    let height = f64::from(bar * zoom);
+    let margin = (height - size.height) / 2.0;
+    if !(margin.is_finite() && margin > 0.0 && gap.is_finite() && gap >= 0.0 && zoom > 0.0) {
+        return None;
+    }
+    let mut bounds = container.frame();
+    let top = window.frame().size.height - height;
+    if (bounds.size.height - height).abs() > SLACK || (bounds.origin.y - top).abs() > SLACK {
+        bounds.size.height = height;
+        bounds.origin.y = top;
+        container.setFrame(bounds);
+    }
+    let mut x = margin;
+    for button in [close, minimize, zoom_button] {
+        let at = NSPoint::new(x, (height - button.frame().size.height) / 2.0);
+        let now = button.frame().origin;
+        if (now.x - at.x).abs() > SLACK || (now.y - at.y).abs() > SLACK {
+            button.setFrameOrigin(at);
+        }
+        x += size.width + gap;
+    }
+    // The last button's right edge (`x` steps one gap past it) and the margin again after it.
+    Some(((x - gap + margin) / f64::from(zoom)) as f32)
+}

apps/vectorcraft/src/main.rs

@@ -31,6 +31,8 @@ mod mac_fonts;
 #[cfg(target_os = "macos")]
 mod mac_menu;
 #[cfg(target_os = "macos")]
+mod mac_window;
+#[cfg(target_os = "macos")]
 mod open_documents;
 mod prefs_dir;
 mod printing;
@@ -69,7 +71,14 @@ impl eframe::App for App {
         }
         file_access::unconfined(|| self.app.raw_input_hook(raw));
     }
-    fn ui(&mut self, ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
+    #[cfg_attr(not(target_os = "macos"), allow(unused_variables))]
+    fn ui(&mut self, ui: &mut egui::Ui, frame: &mut eframe::Frame) {
+        #[cfg(target_os = "macos")]
+        {
+            let bar = vectorcraft_ui_egui::chrome::APP_BAR_HEIGHT;
+            let inset = mac_window::center_buttons(frame, ui.ctx().zoom_factor(), bar);
+            self.app.titlebar_inset = inset.unwrap_or(mac_window::DEFAULT_INSET);
+        }
         file_access::unconfined(|| self.app.ui(ui));
         #[cfg(target_os = "macos")]
         if self.app.take_ime_discard() {
@@ -566,7 +575,6 @@ fn main() -> std::process::ExitCode {
                 {
                     app.graphics_adapter = Some("OpenGL (Windows 7 compatibility)".into());
                 }
-                app.integrated_titlebar = cfg!(target_os = "macos");
                 app.custom_titlebar = CUSTOM_TITLEBAR;
                 if let Some(port) = control_port {
                     let rx = control_server::start(port, cc.egui_ctx.clone());

crates/ui-egui/src/chrome.rs

@@ -12,15 +12,18 @@ use crate::theme::{self, Tokens};
 use crate::widgets;
 use crate::{VectorcraftApp, icons, menus, titlebar};
 
+/// The application bar's height, in points.
+pub const APP_BAR_HEIGHT: f32 = 44.0;
+
 /// The application bar: brand mark, Home, menus, then Discord, search and the workspace switcher
 /// at the right. With [`VectorcraftApp::custom_titlebar`] it is also the window's title bar
 /// ([`titlebar`]): the caption buttons take the right end and the rest of the bar drags the window.
 pub fn app_bar(app: &mut VectorcraftApp, ui: &mut Ui) {
     let t = Tokens::get(ui.ctx());
     let custom = app.custom_titlebar;
-    let left = if app.integrated_titlebar { 78 } else { 8 };
+    let left = app.titlebar_inset.clamp(8.0, f32::from(i8::MAX)) as i8;
     let frame = egui::Frame::NONE.fill(t.app_bar).inner_margin(egui::Margin { left, right: if custom { 0 } else { 14 }, top: 0, bottom: 0 });
-    let bar = egui::Panel::top("app_bar").exact_size(44.0).frame(frame.stroke(Stroke::new(1.0, t.border))).show(ui, |ui| {
+    let bar = egui::Panel::top("app_bar").exact_size(APP_BAR_HEIGHT).frame(frame.stroke(Stroke::new(1.0, t.border))).show(ui, |ui| {
         if custom {
             titlebar::drag_area(ui, ui.max_rect());
         }

crates/ui-egui/src/lib.rs

@@ -314,8 +314,9 @@ pub struct VectorcraftApp {
     pub services: Services,
     pub canvas: CanvasCache,
     pub perf: Perf,
-    /// macOS: draw our own title strip under the traffic lights.
-    pub integrated_titlebar: bool,
+    /// macOS: the room the app bar keeps at its left for the window buttons over it, in points
+    /// (0 where the OS draws no buttons over the app bar).
+    pub titlebar_inset: f32,
     /// Last applied effect (Effect → Apply Last Effect).
     pub last_effect: Option<(String, serde_json::Value)>,
     /// Commands run through [`Self::run`] so far: the native menu bar reads its rows again when it
@@ -440,7 +441,7 @@ impl VectorcraftApp {
                 cursors: Default::default(),
             },
             perf: Perf::default(),
-            integrated_titlebar: false,
+            titlebar_inset: 0.0,
             last_effect: None,
             run_count: 0,
             clipboard_out: None,