feat: cursor, linux, Xwayland (#12859)

Signed-off-by: fufesou <linlong1266@gmail.com>

src/server/connection.rs

@@ -3709,13 +3709,13 @@ impl Connection {
                 #[cfg(not(target_os = "windows"))]
                 let is_lower_win10 = false;
                 #[cfg(target_os = "linux")]
-                let is_wayland = !crate::platform::linux::is_x11();
+                let is_linux_supported = crate::whiteboard::is_supported();
                 #[cfg(not(target_os = "linux"))]
-                let is_wayland = false;
+                let is_linux_supported = false;
                 let not_support_msg = if is_lower_win10 {
                     "Windows 10 or greater is required."
-                } else if is_wayland {
-                    "This feature is not supported on Wayland, please switch to X11."
+                } else if cfg!(target_os = "linux") && !is_linux_supported {
+                    "This feature is not supported on native Wayland, please install XWayland or switch to X11."
                 } else {
                     ""
                 };

src/whiteboard/linux.rs

@@ -61,7 +61,44 @@ extern "C" {
 
 const SHAPE_INPUT: std::ffi::c_int = 2;
 
+fn get_display_from_xwayland() -> Option<String> {
+    if let Ok(output) = crate::platform::run_cmds("pgrep -a Xwayland") {
+        // 1410 /usr/bin/Xwayland :1 -auth /run/user/1000/xauth_RoDZey -listenfd 8 -listenfd 9 -displayfd 76 -wm 78 -rootless -enable-ei-portal
+        if output.contains("Xwayland") {
+            if let Some(display) = output.split_whitespace().nth(2) {
+                if display.starts_with(':') {
+                    return Some(display.to_string());
+                }
+            }
+        }
+    }
+    None
+}
+
+fn preset_env() -> bool {
+    if crate::platform::is_x11() {
+        return true;
+    }
+    if let Some(display) = get_display_from_xwayland() {
+        // https://github.com/rust-windowing/winit/blob/f6893a4390dfe6118ce4b33458d458fd3efd3025/src/event_loop.rs#L99
+        // It is acceptable to modify global environment variables here because this process is an isolated,
+        // dedicated "whiteboard" process.
+        std::env::set_var("DISPLAY", display);
+        std::env::remove_var("WAYLAND_DISPLAY");
+        return true;
+    }
+    false
+}
+
+pub fn is_supported() -> bool {
+    crate::platform::is_x11() || get_display_from_xwayland().is_some()
+}
+
 pub fn run() {
+    if !preset_env() {
+        return;
+    }
+
     let event_loop = match EventLoop::<(String, CustomEvent)>::with_user_event().build() {
         Ok(el) => el,
         Err(e) => {

src/whiteboard/mod.rs

@@ -16,6 +16,8 @@ mod win_linux;
 use windows::create_event_loop;
 #[cfg(target_os = "macos")]
 use macos::create_event_loop;
+#[cfg(target_os = "linux")]
+pub use linux::is_supported;
 
 pub use client::*;
 pub use server::*;

src/whiteboard/win_linux.rs

@@ -158,11 +158,11 @@ pub(super) fn create_font_face() -> ResultType<Face<'static>> {
     let mut font_db = fontdb::Database::new();
     font_db.load_system_fonts();
     let query = fontdb::Query {
-        families: &[fontdb::Family::Monospace],
+        families: &[fontdb::Family::Monospace, fontdb::Family::SansSerif],
         ..fontdb::Query::default()
     };
     let Some(font_id) = font_db.query(&query) else {
-        bail!("No monospace font found!");
+        bail!("No monospace or sans-serif font found!");
     };
     let Some((font_source, face_index)) = font_db.face_source(font_id) else {
         bail!("No face found for font!");