Change create_custom_cursor() to return Result (#3844)

src/platform_impl/linux/mod.rs

@@ -834,7 +834,10 @@ impl ActiveEventLoop {
         }
     }
 
-    pub fn create_custom_cursor(&self, cursor: CustomCursorSource) -> CustomCursor {
+    pub fn create_custom_cursor(
+        &self,
+        cursor: CustomCursorSource,
+    ) -> Result<CustomCursor, ExternalError> {
         x11_or_wayland!(match self; ActiveEventLoop(evlp) => evlp.create_custom_cursor(cursor))
     }
 

src/platform_impl/linux/wayland/event_loop/mod.rs

@@ -16,7 +16,7 @@ use sctk::reexports::client::{globals, Connection, QueueHandle};
 use crate::application::ApplicationHandler;
 use crate::cursor::OnlyCursorImage;
 use crate::dpi::LogicalSize;
-use crate::error::{EventLoopError, OsError as RootOsError};
+use crate::error::{EventLoopError, ExternalError, OsError as RootOsError};
 use crate::event::{Event, InnerSizeWriter, StartCause, WindowEvent};
 use crate::event_loop::{ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents};
 use crate::platform::pump_events::PumpStatus;
@@ -644,10 +644,13 @@ impl ActiveEventLoop {
     #[inline]
     pub fn listen_device_events(&self, _allowed: DeviceEvents) {}
 
-    pub(crate) fn create_custom_cursor(&self, cursor: CustomCursorSource) -> RootCustomCursor {
-        RootCustomCursor {
+    pub(crate) fn create_custom_cursor(
+        &self,
+        cursor: CustomCursorSource,
+    ) -> Result<RootCustomCursor, ExternalError> {
+        Ok(RootCustomCursor {
             inner: PlatformCustomCursor::Wayland(OnlyCursorImage(Arc::from(cursor.inner.0))),
-        }
+        })
     }
 
     #[cfg(feature = "rwh_06")]

src/platform_impl/linux/x11/mod.rs

@@ -25,7 +25,7 @@ use x11rb::x11_utils::X11Error as LogicalError;
 use x11rb::xcb_ffi::ReplyOrIdError;
 
 use crate::application::ApplicationHandler;
-use crate::error::{EventLoopError, OsError as RootOsError};
+use crate::error::{EventLoopError, ExternalError, OsError as RootOsError};
 use crate::event::{Event, StartCause, WindowEvent};
 use crate::event_loop::{ActiveEventLoop as RootAEL, ControlFlow, DeviceEvents};
 use crate::platform::pump_events::PumpStatus;
@@ -643,8 +643,13 @@ impl ActiveEventLoop {
         self.xconn.primary_monitor().ok()
     }
 
-    pub(crate) fn create_custom_cursor(&self, cursor: CustomCursorSource) -> RootCustomCursor {
-        RootCustomCursor { inner: PlatformCustomCursor::X(CustomCursor::new(self, cursor.inner)) }
+    pub(crate) fn create_custom_cursor(
+        &self,
+        cursor: CustomCursorSource,
+    ) -> Result<RootCustomCursor, ExternalError> {
+        Ok(RootCustomCursor {
+            inner: PlatformCustomCursor::X(CustomCursor::new(self, cursor.inner)?),
+        })
     }
 
     pub fn listen_device_events(&self, allowed: DeviceEvents) {

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

@@ -7,7 +7,8 @@ use x11rb::connection::Connection;
 
 use super::super::ActiveEventLoop;
 use super::*;
-use crate::platform_impl::PlatformCustomCursorSource;
+use crate::error::ExternalError;
+use crate::platform_impl::{OsError, PlatformCustomCursorSource};
 use crate::window::CursorIcon;
 
 impl XConnection {
@@ -123,14 +124,16 @@ impl CustomCursor {
     pub(crate) fn new(
         event_loop: &ActiveEventLoop,
         cursor: PlatformCustomCursorSource,
-    ) -> CustomCursor {
+    ) -> Result<CustomCursor, ExternalError> {
         unsafe {
             let ximage = (event_loop.xconn.xcursor.XcursorImageCreate)(
                 cursor.0.width as i32,
                 cursor.0.height as i32,
             );
             if ximage.is_null() {
-                panic!("failed to allocate cursor image");
+                return Err(ExternalError::Os(os_error!(OsError::Misc(
+                    "`XcursorImageCreate` failed"
+                ))));
             }
             (*ximage).xhot = cursor.0.hotspot_x as u32;
             (*ximage).yhot = cursor.0.hotspot_y as u32;
@@ -147,7 +150,9 @@ impl CustomCursor {
             let cursor =
                 (event_loop.xconn.xcursor.XcursorImageLoadCursor)(event_loop.xconn.display, ximage);
             (event_loop.xconn.xcursor.XcursorImageDestroy)(ximage);
-            Self { inner: Arc::new(CustomCursorInner { xconn: event_loop.xconn.clone(), cursor }) }
+            Ok(Self {
+                inner: Arc::new(CustomCursorInner { xconn: event_loop.xconn.clone(), cursor }),
+            })
         }
     }
 }