feat: add set_dock_visibility method

.changes/feat-dock-visibility-on-macos.md

@@ -0,0 +1,5 @@
+---
+'tao': minor
+---
+
+macOS: Add `set_dock_visibility` method to support setting the visibility of the application in the dock.

src/platform/macos.rs

@@ -10,7 +10,7 @@ use crate::{
   dpi::{LogicalSize, Position},
   event_loop::{EventLoop, EventLoopWindowTarget},
   monitor::MonitorHandle,
-  platform_impl::{get_aux_state_mut, set_badge_label, Parent},
+  platform_impl::{get_aux_state_mut, set_badge_label, set_dock_visibility, Parent},
   window::{Window, WindowBuilder},
 };
 
@@ -321,6 +321,13 @@ pub trait EventLoopExtMacOS {
   /// [`EventLoopWindowTargetExtMacOS::set_activation_policy_at_runtime`](crate::platform::macos::EventLoopWindowTargetExtMacOS::set_activation_policy_at_runtime).
   fn set_activation_policy(&mut self, activation_policy: ActivationPolicy);
 
+  /// Sets the visibility of the application in the dock.
+  ///
+  /// This function only takes effect if it's called before calling
+  /// [`run`](crate::event_loop::EventLoop::run) or
+  /// [`run_return`](crate::platform::run_return::EventLoopExtRunReturn::run_return).
+  fn set_dock_visibility(&mut self, visible: bool);
+
   /// Used to prevent the application from automatically activating when launched if
   /// another application is already active
   ///
@@ -340,6 +347,13 @@ impl<T> EventLoopExtMacOS for EventLoop<T> {
     }
   }
 
+  #[inline]
+  fn set_dock_visibility(&mut self, visible: bool) {
+    unsafe {
+      get_aux_state_mut(&**self.event_loop.delegate).dock_visibility = visible;
+    }
+  }
+
   #[inline]
   fn set_activate_ignoring_other_apps(&mut self, ignore: bool) {
     unsafe {
@@ -382,6 +396,12 @@ pub trait EventLoopWindowTargetExtMacOS {
   /// [`EventLoopExtMacOS::set_activation_policy`](crate::platform::macos::EventLoopExtMacOS::set_activation_policy).
   fn set_activation_policy_at_runtime(&self, activation_policy: ActivationPolicy);
 
+  /// Sets the visibility of the application in the dock.
+  ///
+  /// To set the dock visibility before the app starts running, see
+  /// [`EventLoopExtMacOS::set_dock_visibility`](crate::platform::macos::EventLoopExtMacOS::set_dock_visibility).
+  fn set_dock_visibility_at_runtime(&self, visible: bool);
+
   /// Sets the badge label on macos dock
   fn set_badge_label(&self, label: Option<String>);
 }
@@ -420,6 +440,10 @@ impl<T> EventLoopWindowTargetExtMacOS for EventLoopWindowTarget<T> {
     unsafe { msg_send![app, setActivationPolicy: ns_activation_policy] }
   }
 
+  fn set_dock_visibility_at_runtime(&self, visible: bool) {
+    set_dock_visibility(visible);
+  }
+
   fn set_badge_label(&self, label: Option<String>) {
     set_badge_label(label);
   }

src/platform_impl/macos/app_delegate.rs

@@ -28,6 +28,9 @@ pub struct AuxDelegateState {
   /// menubar is initially unresponsive on macOS 10.15 for example.
   pub activation_policy: ActivationPolicy,
 
+  /// Whether the application is visible in the dock.
+  pub dock_visibility: bool,
+
   pub activate_ignoring_other_apps: bool,
 }
 
@@ -85,6 +88,7 @@ extern "C" fn new(class: &Class, _: Sel) -> id {
       Box::into_raw(Box::new(RefCell::new(AuxDelegateState {
         activation_policy: ActivationPolicy::Regular,
         activate_ignoring_other_apps: true,
+        dock_visibility: true,
       }))) as *mut c_void,
     );
     this

src/platform_impl/macos/dock.rs

@@ -0,0 +1,87 @@
+#![allow(non_snake_case, non_upper_case_globals)]
+
+use std::{
+  sync::Mutex,
+  time::{Duration, Instant},
+};
+
+use cocoa::base::{id, NO};
+
+#[link(name = "ApplicationServices", kind = "framework")]
+extern "C" {
+  fn TransformProcessType(psn: *const ProcessSerialNumber, transformState: i32) -> i32;
+}
+
+#[repr(C)]
+struct ProcessSerialNumber {
+  highLongOfPSN: u32,
+  lowLongOfPSN: u32,
+}
+
+/// https://developer.apple.com/documentation/applicationservices/1501096-anonymous/kcurrentprocess?language=objc
+pub const kCurrentProcess: u32 = 2;
+/// https://developer.apple.com/documentation/applicationservices/1501117-anonymous/kprocesstransformtouielementapplication?language=objc
+pub const kProcessTransformToUIElementApplication: i32 = 4;
+/// https://developer.apple.com/documentation/applicationservices/1501117-anonymous/kprocesstransformtoforegroundapplication?language=objc
+pub const kProcessTransformToForegroundApplication: i32 = 1;
+
+lazy_static! {
+  static ref LAST_DOCK_SHOW: Mutex<Option<Instant>> = Mutex::new(None);
+}
+
+pub fn set_dock_visibility(visible: bool) {
+  if visible {
+    set_dock_show();
+  } else {
+    set_dock_hide();
+  }
+}
+
+fn set_dock_hide() {
+  // Transforming application state from UIElement to Foreground is an
+  // asynchronous operation, and unfortunately there is currently no way to know
+  // when it is finished.
+  // So if we call DockHide => DockShow => DockHide => DockShow in a very short
+  // time, we would trigger a bug of macOS that, there would be multiple dock
+  // icons of the app left in system.
+  // To work around this, we make sure DockHide does nothing if it is called
+  // immediately after DockShow. After some experiments, 1 second seems to be
+  // a proper interval.
+  let now = Instant::now();
+  let last_dock_show = LAST_DOCK_SHOW.lock().unwrap();
+  if let Some(last_dock_show_time) = *last_dock_show {
+    if now.duration_since(last_dock_show_time) < Duration::new(1, 0) {
+      return;
+    }
+  }
+
+  unsafe {
+    let app: id = msg_send![class!(NSApplication), sharedApplication];
+    let windows: id = msg_send![app, windows];
+
+    // Assuming windows is an NSArray, and calling setCanHide on each window
+    let selector = sel!(setCanHide:);
+    let _: () = msg_send![windows, makeObjectsPerformSelector:selector withObject:NO];
+
+    let psn = ProcessSerialNumber {
+      highLongOfPSN: 0,
+      lowLongOfPSN: kCurrentProcess,
+    };
+    TransformProcessType(&psn, kProcessTransformToUIElementApplication);
+  }
+}
+
+fn set_dock_show() {
+  let now = Instant::now();
+  let mut last_dock_show = LAST_DOCK_SHOW.lock().unwrap();
+  *last_dock_show = Some(now);
+
+  unsafe {
+    let psn = ProcessSerialNumber {
+      highLongOfPSN: 0,
+      lowLongOfPSN: kCurrentProcess,
+    };
+
+    TransformProcessType(&psn, kProcessTransformToForegroundApplication);
+  }
+}

src/platform_impl/macos/mod.rs

@@ -8,6 +8,7 @@ mod app;
 mod app_delegate;
 mod app_state;
 mod badge;
+mod dock;
 mod event;
 mod event_loop;
 mod ffi;
@@ -37,7 +38,7 @@ use crate::{
   error::OsError as RootOsError, event::DeviceId as RootDeviceId, window::WindowAttributes,
 };
 pub(crate) use badge::set_badge_label;
-
+pub(crate) use dock::set_dock_visibility;
 pub(crate) use icon::PlatformIcon;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]