Use regular X11 rather than XFIXES to hide cursor

The semantics of the XFIXES cursor hide deal are annoying and make
things harder.

locker/src/monitor.rs

@@ -1,8 +1,8 @@
 use log::{debug, warn};
-use std::{cmp, cell::RefCell};
-use xcb::{x, randr, xfixes, Xid};
+use std::cmp;
+use xcb::{x, randr, Xid};
 
-use bscreensaver_util::{BSCREENSAVER_WM_CLASS, create_atom};
+use bscreensaver_util::{BSCREENSAVER_WM_CLASS, create_atom, destroy_pixmap};
 
 const BACKLIGHT_ATOM_NAME: &[u8] = b"Backlight";
 const BACKLIGHT_FALLBACK_ATOM_NAME: &[u8] = b"BACKLIGHT";
@@ -20,12 +20,11 @@ pub struct Monitor {
     pub output: randr::Output,
     pub blanker_window: x::Window,
     pub unlock_window: x::Window,
+    pub blank_cursor: x::Cursor,
     pub x: i16,
     pub y: i16,
     pub width: u16,
     pub height: u16,
-    // RefCell used here to avoid requiring '&mut self' on blank/unblank
-    cursor_hidden: RefCell<u32>,
     backlight_control: Option<BacklightControl>,
 }
 
@@ -52,6 +51,7 @@ impl Monitor {
                     let reply = conn.wait_for_reply(cookie)?;
 
                     let (blanker_window, unlock_window) = create_windows(conn, &screen, &reply)?;
+                    let blank_cursor = create_blank_cursor(conn, &screen)?;
 
                     let black_gc: x::Gcontext = conn.generate_id();
                     conn.send_and_check_request(&x::CreateGc {
@@ -74,11 +74,11 @@ impl Monitor {
                         output: *output,
                         blanker_window,
                         unlock_window,
+                        blank_cursor,
                         x: reply.x(),
                         y: reply.y(),
                         width: reply.width(),
                         height: reply.height(),
-                        cursor_hidden: RefCell::new(0),
                         backlight_control: backlight_control.ok().flatten(),
                     });
                 }
@@ -196,25 +196,24 @@ impl Monitor {
     }
 
     pub fn show_cursor(&self, conn: &xcb::Connection) {
-        let ok = self.cursor_hidden.try_borrow().map(|ch| *ch > 0).unwrap_or(true);
-        if ok {
-            if let Err(err) = conn.send_and_check_request(&xfixes::ShowCursor {
+        if let Err(err) = conn.send_and_check_request(&x::ChangeWindowAttributes {
             window: self.blanker_window,
+            value_list: &[
+                x::Cw::Cursor(x::CURSOR_NONE),
+            ],
         }) {
             warn!("Failed to show cursor: {}", err);
-            } else {
-                let _ = self.cursor_hidden.try_borrow_mut().map(|mut ch| *ch -= 1);
-            }
         }
     }
 
     pub fn hide_cursor(&self, conn: &xcb::Connection) {
-        if let Err(err) = conn.send_and_check_request(&xfixes::HideCursor {
+        if let Err(err) = conn.send_and_check_request(&x::ChangeWindowAttributes {
             window: self.blanker_window,
+            value_list: &[
+                x::Cw::Cursor(self.blank_cursor),
+            ],
         }) {
             warn!("Failed to hide cursor: {}", err);
-        } else {
-            let _ = self.cursor_hidden.try_borrow_mut().map(|mut ch| *ch += 1);
         }
     }
 
@@ -353,6 +352,37 @@ fn create_windows(conn: &xcb::Connection, screen: &x::Screen, crtc_info: &randr:
     Ok((blanker_window, unlock_window))
 }
 
+fn create_blank_cursor(conn: &xcb::Connection, screen: &x::Screen) -> xcb::Result<x::Cursor> {
+    let blank_cursor: x::Cursor = conn.generate_id();
+    let pixmap: x::Pixmap = conn.generate_id();
+
+    conn.send_and_check_request(&x::CreatePixmap {
+        pid: pixmap,
+        drawable: x::Drawable::Window(screen.root()),
+        depth: 1,
+        width: 1,
+        height: 1,
+    })?;
+
+    conn.send_and_check_request(&x::CreateCursor {
+        cid: blank_cursor,
+        source: pixmap,
+        mask: x::PIXMAP_NONE,
+        fore_red: 0,
+        fore_green: 0,
+        fore_blue: 0,
+        back_red: 0,
+        back_green: 0,
+        back_blue: 0,
+        x: 0,
+        y: 0,
+    })?;
+
+    destroy_pixmap(conn, pixmap)?;
+
+    Ok(blank_cursor)
+}
+
 fn find_backlight_control(conn: &xcb::Connection, output: randr::Output) -> xcb::Result<Option<BacklightControl>> {
     for prop_name in [BACKLIGHT_ATOM_NAME, BACKLIGHT_FALLBACK_ATOM_NAME] {
         let property = create_atom(conn, prop_name)?;

util/src/lib.rs

@@ -32,6 +32,20 @@ pub fn create_atom(conn: &xcb::Connection, name: &[u8]) -> xcb::Result<x::Atom>
     Ok(conn.wait_for_reply(cookie)?.atom())
 }
 
+pub fn destroy_pixmap(conn: &xcb::Connection, pixmap: x::Pixmap) -> xcb::Result<()> {
+    conn.send_and_check_request(&x::FreePixmap {
+        pixmap,
+    })?;
+    Ok(())
+}
+
+pub fn destroy_cursor(conn: &xcb::Connection, cursor: x::Cursor) -> xcb::Result<()> {
+    conn.send_and_check_request(&x::FreeCursor {
+        cursor,
+    })?;
+    Ok(())
+}
+
 pub fn destroy_gc(conn: &xcb::Connection, gc: x::Gcontext) -> xcb::Result<()> {
     conn.send_and_check_request(&x::FreeGc {
         gc,