Add custom cursor icon support on Linux

src/platform_impl/linux/x11/util/cursor.rs

@@ -1,4 +1,6 @@
-use crate::window::CursorIcon;
+use std::slice;
+
+use crate::window::{CursorIcon, CursorRgba};
 
 use super::*;
 
@@ -13,6 +15,44 @@ impl XConnection {
         self.update_cursor(window, cursor);
     }
 
+    pub fn set_cursor_rgba(&self, window: ffi::Window, cursor: CursorRgba) {
+        // Create new cursor
+        let new_cursor = unsafe {
+            let image = (self.xcursor.XcursorImageCreate)(
+                cursor.width.into(),
+                cursor.height.into());
+            if image == ptr::null_mut() {
+                panic!("failed to allocate image for cursor");
+            }
+
+            (*image).xhot = cursor.xhot.into();
+            (*image).yhot = cursor.yhot.into();
+            (*image).delay = 0;
+
+            let dst = slice::from_raw_parts_mut(
+                (*image).pixels,
+                (cursor.width * cursor.height).into());
+
+            dst.copy_from_slice(cursor.data.as_slice());
+
+            let cursor = (self.xcursor.XcursorImageLoadCursor)(self.display, image);
+            (self.xcursor.XcursorImageDestroy)(image);
+
+            cursor
+        };
+
+        // Drop old cursor if required, and store the new one
+        let mut cursor_rgba = self.cursor_rgba.lock();
+        if let Some(old_cursor) = cursor_rgba.take() {
+            unsafe { (self.xlib.XFreeCursor)(self.display, old_cursor); }
+        }
+
+        *cursor_rgba = Some(new_cursor);
+
+        // Display
+        self.update_cursor(window, new_cursor);
+    }
+
     fn create_empty_cursor(&self) -> ffi::Cursor {
         let data = 0;
         let pixmap = unsafe {

src/platform_impl/linux/x11/window.rs

@@ -1240,7 +1240,11 @@ impl UnownedWindow {
     }
 
     #[inline]
-    pub fn set_cursor_rgba(&self, _cursor: CursorRgba) {}
+    pub fn set_cursor_rgba(&self, cursor: CursorRgba) {
+        if *self.cursor_visible.lock() {
+            self.xconn.set_cursor_rgba(self.xwindow, cursor);
+        }
+    }
 
     #[inline]
     pub fn set_cursor_grab(&self, grab: bool) -> Result<(), ExternalError> {

src/platform_impl/linux/x11/xdisplay.rs

@@ -22,6 +22,7 @@ pub struct XConnection {
     pub x11_fd: c_int,
     pub latest_error: Mutex<Option<XError>>,
     pub cursor_cache: Mutex<HashMap<Option<CursorIcon>, ffi::Cursor>>,
+    pub cursor_rgba: Mutex<Option<ffi::Cursor>>,
 }
 
 unsafe impl Send for XConnection {}
@@ -68,6 +69,7 @@ impl XConnection {
             x11_fd: fd,
             latest_error: Mutex::new(None),
             cursor_cache: Default::default(),
+            cursor_rgba: Mutex::new(None),
         })
     }
 
@@ -98,6 +100,10 @@ impl fmt::Debug for XConnection {
 impl Drop for XConnection {
     #[inline]
     fn drop(&mut self) {
+        if let Some(cursor_rgba) = self.cursor_rgba.lock().take() {
+            unsafe { (self.xlib.XFreeCursor)(self.display, cursor_rgba); }
+        }
+
         unsafe { (self.xlib.XCloseDisplay)(self.display) };
     }
 }