X11 shell cursors (#1755)

CHANGELOG.md

@@ -69,6 +69,7 @@ You can find its changes [documented below](#070---2021-01-01).
 - Fixed layout of scrollbar with very small viewports ([#1715] by [@andrewhickman])
 - Fixed `WindowLevel::Tooltip` on Windows platform ([#1737] by [@djeedai])
 - X11 backend now supports scaling([#1751] by [@Maan2003])
+- X11 backend now supports changing cursors ([#1755] by [@Maan2003])
 
 ### Visual
 
@@ -706,6 +707,7 @@ Last release without a changelog :(
 [#1746]: https://github.com/linebender/druid/pull/1746
 [#1751]: https://github.com/linebender/druid/pull/1751
 [#1754]: https://github.com/linebender/druid/pull/1754
+[#1755]: https://github.com/linebender/druid/pull/1755
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.7.0...master
 [0.7.0]: https://github.com/linebender/druid/compare/v0.6.0...v0.7.0

druid-shell/Cargo.toml

@@ -88,7 +88,7 @@ glib = { version = "0.10.1", optional = true }
 glib-sys = { version = "0.10.0", optional = true }
 gtk-sys = { version = "0.10.0", optional = true }
 nix = { version = "0.18.0", optional = true }
-x11rb = { version = "0.8.0", features = ["allow-unsafe-code", "present", "randr", "xfixes", "resource_manager"], optional = true }
+x11rb = { version = "0.8.0", features = ["allow-unsafe-code", "present", "randr", "xfixes", "resource_manager", "cursor"], optional = true }
 
 [target.'cfg(target_arch="wasm32")'.dependencies]
 wasm-bindgen = "0.2.67"

druid-shell/src/platform/x11/application.rs

@@ -25,7 +25,7 @@ use anyhow::{anyhow, Context, Error};
 use x11rb::connection::Connection;
 use x11rb::protocol::present::ConnectionExt as _;
 use x11rb::protocol::xfixes::ConnectionExt as _;
-use x11rb::protocol::xproto::{ConnectionExt, CreateWindowAux, EventMask, WindowClass};
+use x11rb::protocol::xproto::{self, ConnectionExt, CreateWindowAux, EventMask, WindowClass};
 use x11rb::protocol::Event;
 use x11rb::resource_manager::Database as ResourceDb;
 use x11rb::xcb_ffi::XCBConnection;
@@ -53,6 +53,7 @@ pub(crate) struct Application {
 
     /// The X11 resource database used to query dpi.
     pub(crate) rdb: ResourceDb,
+    pub(crate) cursors: Cursors,
     /// The default screen of the connected display.
     ///
     /// The connected display may also have additional screens.
@@ -92,6 +93,17 @@ struct State {
     windows: HashMap<u32, Rc<Window>>,
 }
 
+#[derive(Clone, Debug)]
+pub(crate) struct Cursors {
+    pub default: Option<xproto::Cursor>,
+    pub text: Option<xproto::Cursor>,
+    pub pointer: Option<xproto::Cursor>,
+    pub crosshair: Option<xproto::Cursor>,
+    pub not_allowed: Option<xproto::Cursor>,
+    pub row_resize: Option<xproto::Cursor>,
+    pub col_resize: Option<xproto::Cursor>,
+}
+
 impl Application {
     pub fn new() -> Result<Application, Error> {
         // If we want to support OpenGL, we will need to open a connection with Xlib support (see
@@ -126,13 +138,32 @@ impl Application {
             }
         };
 
+        let handle = x11rb::cursor::Handle::new(connection.as_ref(), screen_num, &rdb)?.reply()?;
+        let load_cursor = |cursor| {
+            handle
+                .load_cursor(connection.as_ref(), cursor)
+                .map_err(|e| tracing::warn!("Unable to load cursor {}, error: {}", cursor, e))
+                .ok()
+        };
+
+        let cursors = Cursors {
+            default: load_cursor("default"),
+            text: load_cursor("text"),
+            pointer: load_cursor("pointer"),
+            crosshair: load_cursor("crosshair"),
+            not_allowed: load_cursor("not-allowed"),
+            row_resize: load_cursor("row-resize"),
+            col_resize: load_cursor("col-resize"),
+        };
+
         Ok(Application {
             connection,
             rdb,
             screen_num: screen_num as i32,
             window_id,
             state,
             idle_read,
+            cursors,
             idle_write,
             present_opcode,
             marker: std::marker::PhantomData,

druid-shell/src/platform/x11/window.rs

@@ -33,8 +33,8 @@ use x11rb::connection::Connection;
 use x11rb::protocol::present::{CompleteNotifyEvent, ConnectionExt as _, IdleNotifyEvent};
 use x11rb::protocol::xfixes::{ConnectionExt as _, Region as XRegion};
 use x11rb::protocol::xproto::{
-    self, AtomEnum, ConfigureNotifyEvent, ConnectionExt, CreateGCAux, EventMask, Gcontext, Pixmap,
-    PropMode, Rectangle, Visualtype, WindowClass,
+    self, AtomEnum, ChangeWindowAttributesAux, ConfigureNotifyEvent, ConnectionExt, CreateGCAux,
+    EventMask, Gcontext, Pixmap, PropMode, Rectangle, Visualtype, WindowClass,
 };
 use x11rb::wrapper::ConnectionExt as _;
 use x11rb::xcb_ffi::XCBConnection;
@@ -884,6 +884,35 @@ impl Window {
         ));
     }
 
+    fn set_cursor(&self, cursor: &Cursor) {
+        let cursors = &self.app.cursors;
+        #[allow(deprecated)]
+        let cursor = match cursor {
+            Cursor::Arrow => cursors.default,
+            Cursor::IBeam => cursors.text,
+            Cursor::Pointer => cursors.pointer,
+            Cursor::Crosshair => cursors.crosshair,
+            Cursor::OpenHand => {
+                warn!("Cursor::OpenHand not supported for x11 backend. using arrow cursor");
+                None
+            }
+            Cursor::NotAllowed => cursors.not_allowed,
+            Cursor::ResizeLeftRight => cursors.col_resize,
+            Cursor::ResizeUpDown => cursors.row_resize,
+            // TODO: (x11/custom cursor)
+            Cursor::Custom(_) => None,
+        };
+        if cursor.is_none() {
+            warn!("Unable to load cursor {:?}", cursor);
+            return;
+        }
+        let conn = self.app.connection();
+        let changes = ChangeWindowAttributesAux::new().cursor(cursor);
+        if let Err(e) = conn.change_window_attributes(self.id, &changes) {
+            error!("Changing cursor window attribute failed {}", e);
+        };
+    }
+
     fn set_menu(&self, _menu: Menu) {
         // TODO(x11/menus): implement Window::set_menu (currently a no-op)
     }
@@ -1592,8 +1621,10 @@ impl WindowHandle {
         }
     }
 
-    pub fn set_cursor(&mut self, _cursor: &Cursor) {
-        // TODO(x11/cursors): implement WindowHandle::set_cursor
+    pub fn set_cursor(&mut self, cursor: &Cursor) {
+        if let Some(w) = self.window.upgrade() {
+            w.set_cursor(cursor);
+        }
     }
 
     pub fn make_cursor(&self, _cursor_desc: &CursorDesc) -> Option<Cursor> {