Add Window::set_content_protected on macOS and Windows (#2525)

* Add `Window::set_content_protect` on macOS and Windows

* Update window.rs

* Add builder variant

* fix import

* fix argument type

* fix import

* fix always visible window on Windows

* update docs

CHANGELOG.md

@@ -8,6 +8,7 @@ And please only add new entries to the top of this list, right below the `# Unre
 
 # Unreleased
 
+- On MacOS and Windows, add `Window::set_content_protected`.
 - On MacOS, add `EventLoopBuilderExtMacOS::with_activate_ignoring_other_apps`.
 - On Windows, fix icons specified on `WindowBuilder` not taking effect for windows created after the first one.
 - On Windows and macOS, add `Window::title` to query the current window title.

src/platform_impl/macos/appkit/mod.rs

@@ -54,7 +54,7 @@ pub(crate) use self::version::NSAppKitVersion;
 pub(crate) use self::view::{NSTrackingRectTag, NSView};
 pub(crate) use self::window::{
     NSBackingStoreType, NSWindow, NSWindowButton, NSWindowLevel, NSWindowOcclusionState,
-    NSWindowStyleMask, NSWindowTitleVisibility,
+    NSWindowSharingType, NSWindowStyleMask, NSWindowTitleVisibility,
 };
 
 #[link(name = "AppKit", kind = "framework")]

src/platform_impl/macos/appkit/window.rs

@@ -84,6 +84,9 @@ extern_methods!(
         #[sel(setMovable:)]
         pub fn setMovable(&self, movable: bool);
 
+        #[sel(setSharingType:)]
+        pub fn setSharingType(&self, sharingType: NSWindowSharingType);
+
         #[sel(setOpaque:)]
         pub fn setOpaque(&self, opaque: bool);
 
@@ -349,3 +352,16 @@ pub enum NSBackingStoreType {
 unsafe impl Encode for NSBackingStoreType {
     const ENCODING: Encoding = NSUInteger::ENCODING;
 }
+
+#[allow(dead_code)]
+#[repr(usize)] // NSUInteger
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum NSWindowSharingType {
+    NSWindowSharingNone = 0,
+    NSWindowSharingReadOnly = 1,
+    NSWindowSharingReadWrite = 2,
+}
+
+unsafe impl Encode for NSWindowSharingType {
+    const ENCODING: Encoding = NSUInteger::ENCODING;
+}

src/platform_impl/macos/window.rs

@@ -45,7 +45,8 @@ use objc2::{declare_class, msg_send, msg_send_id, sel, ClassType};
 use super::appkit::{
     NSApp, NSAppKitVersion, NSAppearance, NSApplicationPresentationOptions, NSBackingStoreType,
     NSColor, NSCursor, NSFilenamesPboardType, NSRequestUserAttentionType, NSResponder, NSScreen,
-    NSWindow, NSWindowButton, NSWindowLevel, NSWindowStyleMask, NSWindowTitleVisibility,
+    NSWindow, NSWindowButton, NSWindowLevel, NSWindowSharingType, NSWindowStyleMask,
+    NSWindowTitleVisibility,
 };
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -305,6 +306,10 @@ impl WinitWindow {
                 this.setTitle(&NSString::from_str(&attrs.title));
                 this.setAcceptsMouseMovedEvents(true);
 
+                if attrs.content_protected {
+                    this.setSharingType(NSWindowSharingType::NSWindowSharingNone);
+                }
+
                 if pl_attrs.titlebar_transparent {
                     this.setTitlebarAppearsTransparent(true);
                 }
@@ -1123,6 +1128,14 @@ impl WinitWindow {
     }
 
     #[inline]
+    pub fn set_content_protected(&self, protected: bool) {
+        self.setSharingType(if protected {
+            NSWindowSharingType::NSWindowSharingNone
+        } else {
+            NSWindowSharingType::NSWindowSharingReadOnly
+        })
+    }
+
     pub fn title(&self) -> String {
         self.title_().to_string()
     }

src/platform_impl/windows/window.rs

@@ -42,11 +42,12 @@ use windows_sys::Win32::{
             CreateWindowExW, FlashWindowEx, GetClientRect, GetCursorPos, GetForegroundWindow,
             GetSystemMetrics, GetWindowPlacement, GetWindowTextLengthW, GetWindowTextW,
             IsWindowVisible, LoadCursorW, PeekMessageW, PostMessageW, RegisterClassExW, SetCursor,
-            SetCursorPos, SetForegroundWindow, SetWindowPlacement, SetWindowPos, SetWindowTextW,
+            SetCursorPos, SetForegroundWindow, SetWindowDisplayAffinity, SetWindowPlacement,
-            CS_HREDRAW, CS_VREDRAW, CW_USEDEFAULT, FLASHWINFO, FLASHW_ALL, FLASHW_STOP,
+            SetWindowPos, SetWindowTextW, CS_HREDRAW, CS_VREDRAW, CW_USEDEFAULT, FLASHWINFO,
-            FLASHW_TIMERNOFG, FLASHW_TRAY, GWLP_HINSTANCE, HTCAPTION, MAPVK_VK_TO_VSC, NID_READY,
+            FLASHW_ALL, FLASHW_STOP, FLASHW_TIMERNOFG, FLASHW_TRAY, GWLP_HINSTANCE, HTCAPTION,
-            PM_NOREMOVE, SM_DIGITIZER, SWP_ASYNCWINDOWPOS, SWP_NOACTIVATE, SWP_NOSIZE,
+            MAPVK_VK_TO_VSC, NID_READY, PM_NOREMOVE, SM_DIGITIZER, SWP_ASYNCWINDOWPOS,
-            SWP_NOZORDER, WM_NCLBUTTONDOWN, WNDCLASSEXW,
+            SWP_NOACTIVATE, SWP_NOSIZE, SWP_NOZORDER, WDA_EXCLUDEFROMCAPTURE, WDA_NONE,
+            WM_NCLBUTTONDOWN, WNDCLASSEXW,
         },
     },
 };
@@ -738,6 +739,20 @@ impl Window {
             unsafe { force_window_active(window.0) };
         }
     }
+
+    #[inline]
+    pub fn set_content_protected(&self, protected: bool) {
+        unsafe {
+            SetWindowDisplayAffinity(
+                self.hwnd(),
+                if protected {
+                    WDA_EXCLUDEFROMCAPTURE
+                } else {
+                    WDA_NONE
+                },
+            )
+        };
+    }
 }
 
 impl Drop for Window {
@@ -908,6 +923,10 @@ impl<'a, T: 'static> InitData<'a, T> {
 
         let attributes = self.attributes.clone();
 
+        if attributes.content_protected {
+            win.set_content_protected(true);
+        }
+
         // Set visible before setting the size to ensure the
         // attribute is correctly applied.
         win.set_visible(attributes.visible);

src/window.rs

@@ -136,6 +136,7 @@ pub(crate) struct WindowAttributes {
     pub window_icon: Option<Icon>,
     pub preferred_theme: Option<Theme>,
     pub resize_increments: Option<Size>,
+    pub content_protected: bool,
 }
 
 impl Default for WindowAttributes {
@@ -157,6 +158,7 @@ impl Default for WindowAttributes {
             window_icon: None,
             preferred_theme: None,
             resize_increments: None,
+            content_protected: false,
         }
     }
 }
@@ -365,6 +367,23 @@ impl WindowBuilder {
         self
     }
 
+    /// Prevents the window contents from being captured by other apps.
+    ///
+    /// The default is `false`.
+    ///
+    /// ## Platform-specific
+    ///
+    /// - **macOS**: if `false`, [`NSWindowSharingNone`] is used but doesn't completely
+    /// prevent all apps from reading the window content, for instance, QuickTime.
+    /// - **iOS / Android / Web / x11:** Ignored.
+    ///
+    /// [`NSWindowSharingNone`]: https://developer.apple.com/documentation/appkit/nswindowsharingtype/nswindowsharingnone
+    #[inline]
+    pub fn with_content_protected(mut self, protected: bool) -> Self {
+        self.window.content_protected = protected;
+        self
+    }
+
     /// Builds the window.
     ///
     /// Possible causes of error include denied permission, incompatible system, and lack of memory.
@@ -953,6 +972,20 @@ impl Window {
         self.window.theme()
     }
 
+    /// Prevents the window contents from being captured by other apps.
+    ///
+    /// ## Platform-specific
+    ///
+    /// - **macOS**: if `false`, [`NSWindowSharingNone`] is used but doesn't completely
+    /// prevent all apps from reading the window content, for instance, QuickTime.
+    /// - **iOS / Android / x11 / Wayland / Web:** Unsupported.
+    ///
+    /// [`NSWindowSharingNone`]: https://developer.apple.com/documentation/appkit/nswindowsharingtype/nswindowsharingnone
+    pub fn set_content_protected(&self, _protected: bool) {
+        #[cfg(any(target_os = "macos", target_os = "windows"))]
+        self.window.set_content_protected(_protected);
+    }
+
     /// Gets the current title of the window.
     ///
     /// ## Platform-specific