Windows: cache custom cursors (#3293)

src/platform_impl/windows/icon.rs

@@ -17,9 +17,12 @@ use windows_sys::{
 };
 
 use crate::icon::*;
-use crate::{cursor::CursorImage, dpi::PhysicalSize};
+use crate::{
+    cursor::{CursorImage, OnlyCursorImageBuilder},
+    dpi::PhysicalSize,
+};
 
-use super::util;
+use super::{util, EventLoopWindowTarget};
 
 impl Pixel {
     fn convert_to_bgra(&mut self) {
@@ -169,7 +172,7 @@ pub fn unset_for_window(hwnd: HWND, icon_type: IconType) {
 #[derive(Debug, Clone)]
 pub enum SelectedCursor {
     Named(CursorIcon),
-    Custom(WinCursor),
+    Custom(Arc<RaiiCursor>),
 }
 
 impl Default for SelectedCursor {
@@ -178,23 +181,14 @@ impl Default for SelectedCursor {
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct WinCursor {
-    inner: Arc<RaiiCursor>,
+#[derive(Clone, Debug, Hash, Eq, PartialEq)]
+pub enum WinCursor {
+    Cursor(Arc<RaiiCursor>),
+    Failed,
 }
 
 impl WinCursor {
-    pub fn as_raw_handle(&self) -> HICON {
-        self.inner.handle
-    }
-
-    fn from_handle(handle: HCURSOR) -> Self {
-        Self {
-            inner: Arc::new(RaiiCursor { handle }),
-        }
-    }
-
-    pub(crate) fn new(image: &CursorImage) -> Result<Self, io::Error> {
+    fn new(image: &CursorImage) -> Result<Self, io::Error> {
         let mut bgra = image.rgba.clone();
         bgra.chunks_exact_mut(4).for_each(|chunk| chunk.swap(0, 2));
 
@@ -239,13 +233,23 @@ impl WinCursor {
                 return Err(io::Error::last_os_error());
             }
 
-            Ok(Self::from_handle(handle))
+            Ok(Self::Cursor(Arc::new(RaiiCursor { handle })))
+        }
+    }
+
+    pub(crate) fn build<T>(cursor: OnlyCursorImageBuilder, _: &EventLoopWindowTarget<T>) -> Self {
+        match Self::new(&cursor.0) {
+            Ok(cursor) => cursor,
+            Err(err) => {
+                log::warn!("Failed to create custom cursor: {err}");
+                Self::Failed
+            }
         }
     }
 }
 
-#[derive(Debug)]
-struct RaiiCursor {
+#[derive(Debug, Hash, Eq, PartialEq)]
+pub struct RaiiCursor {
     handle: HCURSOR,
 }
 
@@ -254,3 +258,9 @@ impl Drop for RaiiCursor {
         unsafe { DestroyCursor(self.handle) };
     }
 }
+
+impl RaiiCursor {
+    pub fn as_raw_handle(&self) -> HICON {
+        self.handle
+    }
+}

src/platform_impl/windows/mod.rs

@@ -16,8 +16,8 @@ pub(crate) use self::{
     window::Window,
 };
 
+pub(crate) use self::icon::WinCursor as PlatformCustomCursor;
 pub use self::icon::WinIcon as PlatformIcon;
-pub(crate) use crate::cursor::OnlyCursorImage as PlatformCustomCursor;
 pub(crate) use crate::cursor::OnlyCursorImageBuilder as PlatformCustomCursorBuilder;
 use crate::platform_impl::Fullscreen;
 

src/platform_impl/windows/window.rs

@@ -407,10 +407,10 @@ impl Window {
                 });
             }
             Cursor::Custom(cursor) => {
-                let new_cursor = match WinCursor::new(&cursor.inner.0) {
-                    Ok(cursor) => cursor,
-                    Err(err) => {
-                        warn!("Failed to create custom cursor: {err}");
+                let new_cursor = match cursor.inner {
+                    WinCursor::Cursor(cursor) => cursor,
+                    WinCursor::Failed => {
+                        warn!("Requested to apply failed cursor");
                         return;
                     }
                 };