Refactor macOS cursor code (#2463)

src/platform_impl/macos/appkit/cursor.rs

@@ -0,0 +1,241 @@
+use once_cell::sync::Lazy;
+
+use objc2::foundation::{NSData, NSDictionary, NSNumber, NSObject, NSPoint, NSString};
+use objc2::rc::{DefaultId, Id, Shared};
+use objc2::runtime::Sel;
+use objc2::{extern_class, extern_methods, msg_send_id, ns_string, ClassType};
+
+use super::NSImage;
+use crate::window::CursorIcon;
+
+extern_class!(
+    /// <https://developer.apple.com/documentation/appkit/nscursor?language=objc>
+    #[derive(Debug, PartialEq, Eq, Hash)]
+    pub(crate) struct NSCursor;
+
+    unsafe impl ClassType for NSCursor {
+        type Super = NSObject;
+    }
+);
+
+// SAFETY: NSCursor is immutable, stated here:
+// https://developer.apple.com/documentation/appkit/nscursor/1527062-image?language=objc
+unsafe impl Send for NSCursor {}
+unsafe impl Sync for NSCursor {}
+
+macro_rules! def_cursor {
+    {$(
+        $(#[$($m:meta)*])*
+        pub fn $name:ident();
+    )*} => {$(
+        $(#[$($m)*])*
+        pub fn $name() -> Id<Self, Shared> {
+            unsafe { msg_send_id![Self::class(), $name] }
+        }
+    )*};
+}
+
+macro_rules! def_undocumented_cursor {
+    {$(
+        $(#[$($m:meta)*])*
+        pub fn $name:ident();
+    )*} => {$(
+        $(#[$($m)*])*
+        pub fn $name() -> Id<Self, Shared> {
+            unsafe { Self::from_selector(sel!($name)).unwrap_or_else(|| Default::default()) }
+        }
+    )*};
+}
+
+extern_methods!(
+    /// Documented cursors
+    unsafe impl NSCursor {
+        def_cursor!(
+            pub fn arrowCursor();
+            pub fn pointingHandCursor();
+            pub fn openHandCursor();
+            pub fn closedHandCursor();
+            pub fn IBeamCursor();
+            pub fn IBeamCursorForVerticalLayout();
+            pub fn dragCopyCursor();
+            pub fn dragLinkCursor();
+            pub fn operationNotAllowedCursor();
+            pub fn contextualMenuCursor();
+            pub fn crosshairCursor();
+            pub fn resizeRightCursor();
+            pub fn resizeUpCursor();
+            pub fn resizeLeftCursor();
+            pub fn resizeDownCursor();
+            pub fn resizeLeftRightCursor();
+            pub fn resizeUpDownCursor();
+        );
+
+        // Creating cursors should be thread-safe, though using them for anything probably isn't.
+        pub fn new(image: &NSImage, hotSpot: NSPoint) -> Id<Self, Shared> {
+            let this = unsafe { msg_send_id![Self::class(), alloc] };
+            unsafe { msg_send_id![this, initWithImage: image, hotSpot: hotSpot] }
+        }
+
+        pub fn invisible() -> Id<Self, Shared> {
+            // 16x16 GIF data for invisible cursor
+            // You can reproduce this via ImageMagick.
+            // $ convert -size 16x16 xc:none cursor.gif
+            static CURSOR_BYTES: &[u8] = &[
+                0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x10, 0x00, 0x10, 0x00, 0xF0, 0x00, 0x00, 0x00,
+                0x00, 0x00, 0x00, 0x00, 0x00, 0x21, 0xF9, 0x04, 0x01, 0x00, 0x00, 0x00, 0x00, 0x2C,
+                0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x10, 0x00, 0x00, 0x02, 0x0E, 0x84, 0x8F, 0xA9,
+                0xCB, 0xED, 0x0F, 0xA3, 0x9C, 0xB4, 0xDA, 0x8B, 0xB3, 0x3E, 0x05, 0x00, 0x3B,
+            ];
+
+            static CURSOR: Lazy<Id<NSCursor, Shared>> = Lazy::new(|| {
+                // TODO: Consider using `dataWithBytesNoCopy:`
+                let data = NSData::with_bytes(CURSOR_BYTES);
+                let image = NSImage::new_with_data(&data);
+                NSCursor::new(&image, NSPoint::new(0.0, 0.0))
+            });
+
+            CURSOR.clone()
+        }
+    }
+
+    /// Undocumented cursors
+    unsafe impl NSCursor {
+        #[sel(respondsToSelector:)]
+        fn class_responds_to(sel: Sel) -> bool;
+
+        unsafe fn from_selector_unchecked(sel: Sel) -> Id<Self, Shared> {
+            unsafe { msg_send_id![Self::class(), performSelector: sel] }
+        }
+
+        unsafe fn from_selector(sel: Sel) -> Option<Id<Self, Shared>> {
+            if Self::class_responds_to(sel) {
+                Some(unsafe { Self::from_selector_unchecked(sel) })
+            } else {
+                warn!("Cursor `{:?}` appears to be invalid", sel);
+                None
+            }
+        }
+
+        def_undocumented_cursor!(
+            // Undocumented cursors: https://stackoverflow.com/a/46635398/5435443
+            pub fn _helpCursor();
+            pub fn _zoomInCursor();
+            pub fn _zoomOutCursor();
+            pub fn _windowResizeNorthEastCursor();
+            pub fn _windowResizeNorthWestCursor();
+            pub fn _windowResizeSouthEastCursor();
+            pub fn _windowResizeSouthWestCursor();
+            pub fn _windowResizeNorthEastSouthWestCursor();
+            pub fn _windowResizeNorthWestSouthEastCursor();
+
+            // While these two are available, the former just loads a white arrow,
+            // and the latter loads an ugly deflated beachball!
+            // pub fn _moveCursor();
+            // pub fn _waitCursor();
+
+            // An even more undocumented cursor...
+            // https://bugs.eclipse.org/bugs/show_bug.cgi?id=522349
+            pub fn busyButClickableCursor();
+        );
+    }
+
+    /// Webkit cursors
+    unsafe impl NSCursor {
+        // Note that loading `busybutclickable` with this code won't animate
+        // the frames; instead you'll just get them all in a column.
+        unsafe fn load_webkit_cursor(name: &NSString) -> Id<Self, Shared> {
+            // Snatch a cursor from WebKit; They fit the style of the native
+            // cursors, and will seem completely standard to macOS users.
+            //
+            // https://stackoverflow.com/a/21786835/5435443
+            let root = ns_string!("/System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/HIServices.framework/Versions/A/Resources/cursors");
+            let cursor_path = root.join_path(name);
+
+            let pdf_path = cursor_path.join_path(ns_string!("cursor.pdf"));
+            let image = NSImage::new_by_referencing_file(&pdf_path);
+
+            // TODO: Handle PLists better
+            let info_path = cursor_path.join_path(ns_string!("info.plist"));
+            let info: Id<NSDictionary<NSObject, NSObject>, Shared> = unsafe {
+                msg_send_id![
+                    <NSDictionary<NSObject, NSObject>>::class(),
+                    dictionaryWithContentsOfFile: &*info_path,
+                ]
+            };
+            let mut x = 0.0;
+            if let Some(n) = info.get(&*ns_string!("hotx")) {
+                if n.is_kind_of::<NSNumber>() {
+                    let ptr: *const NSObject = n;
+                    let ptr: *const NSNumber = ptr.cast();
+                    x = unsafe { &*ptr }.as_cgfloat()
+                }
+            }
+            let mut y = 0.0;
+            if let Some(n) = info.get(&*ns_string!("hotx")) {
+                if n.is_kind_of::<NSNumber>() {
+                    let ptr: *const NSObject = n;
+                    let ptr: *const NSNumber = ptr.cast();
+                    y = unsafe { &*ptr }.as_cgfloat()
+                }
+            }
+
+            let hotspot = NSPoint::new(x, y);
+            Self::new(&image, hotspot)
+        }
+
+        pub fn moveCursor() -> Id<Self, Shared> {
+            unsafe { Self::load_webkit_cursor(ns_string!("move")) }
+        }
+
+        pub fn cellCursor() -> Id<Self, Shared> {
+            unsafe { Self::load_webkit_cursor(ns_string!("cell")) }
+        }
+    }
+);
+
+impl NSCursor {
+    pub fn from_icon(icon: CursorIcon) -> Id<Self, Shared> {
+        match icon {
+            CursorIcon::Default => Default::default(),
+            CursorIcon::Arrow => Self::arrowCursor(),
+            CursorIcon::Hand => Self::pointingHandCursor(),
+            CursorIcon::Grab => Self::openHandCursor(),
+            CursorIcon::Grabbing => Self::closedHandCursor(),
+            CursorIcon::Text => Self::IBeamCursor(),
+            CursorIcon::VerticalText => Self::IBeamCursorForVerticalLayout(),
+            CursorIcon::Copy => Self::dragCopyCursor(),
+            CursorIcon::Alias => Self::dragLinkCursor(),
+            CursorIcon::NotAllowed | CursorIcon::NoDrop => Self::operationNotAllowedCursor(),
+            CursorIcon::ContextMenu => Self::contextualMenuCursor(),
+            CursorIcon::Crosshair => Self::crosshairCursor(),
+            CursorIcon::EResize => Self::resizeRightCursor(),
+            CursorIcon::NResize => Self::resizeUpCursor(),
+            CursorIcon::WResize => Self::resizeLeftCursor(),
+            CursorIcon::SResize => Self::resizeDownCursor(),
+            CursorIcon::EwResize | CursorIcon::ColResize => Self::resizeLeftRightCursor(),
+            CursorIcon::NsResize | CursorIcon::RowResize => Self::resizeUpDownCursor(),
+            CursorIcon::Help => Self::_helpCursor(),
+            CursorIcon::ZoomIn => Self::_zoomInCursor(),
+            CursorIcon::ZoomOut => Self::_zoomOutCursor(),
+            CursorIcon::NeResize => Self::_windowResizeNorthEastCursor(),
+            CursorIcon::NwResize => Self::_windowResizeNorthWestCursor(),
+            CursorIcon::SeResize => Self::_windowResizeSouthEastCursor(),
+            CursorIcon::SwResize => Self::_windowResizeSouthWestCursor(),
+            CursorIcon::NeswResize => Self::_windowResizeNorthEastSouthWestCursor(),
+            CursorIcon::NwseResize => Self::_windowResizeNorthWestSouthEastCursor(),
+            // This is the wrong semantics for `Wait`, but it's the same as
+            // what's used in Safari and Chrome.
+            CursorIcon::Wait | CursorIcon::Progress => Self::busyButClickableCursor(),
+            CursorIcon::Move | CursorIcon::AllScroll => Self::moveCursor(),
+            CursorIcon::Cell => Self::cellCursor(),
+        }
+    }
+}
+
+impl DefaultId for NSCursor {
+    type Ownership = Shared;
+
+    fn default_id() -> Id<Self, Shared> {
+        Self::arrowCursor()
+    }
+}

src/platform_impl/macos/appkit/image.rs

@@ -0,0 +1,37 @@
+use objc2::foundation::{NSData, NSObject, NSString};
+use objc2::rc::{Id, Shared};
+use objc2::{extern_class, extern_methods, msg_send_id, ClassType};
+
+extern_class!(
+    // TODO: Can this be mutable?
+    #[derive(Debug, PartialEq, Eq, Hash)]
+    pub(crate) struct NSImage;
+
+    unsafe impl ClassType for NSImage {
+        type Super = NSObject;
+    }
+);
+
+// Documented Thread-Unsafe, but:
+// > One thread can create an NSImage object, draw to the image buffer,
+// > and pass it off to the main thread for drawing. The underlying image
+// > cache is shared among all threads.
+// <https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Multithreading/ThreadSafetySummary/ThreadSafetySummary.html#//apple_ref/doc/uid/10000057i-CH12-126728>
+//
+// So really only unsafe to mutate on several threads.
+unsafe impl Send for NSImage {}
+unsafe impl Sync for NSImage {}
+
+extern_methods!(
+    unsafe impl NSImage {
+        pub fn new_by_referencing_file(path: &NSString) -> Id<Self, Shared> {
+            let this = unsafe { msg_send_id![Self::class(), alloc] };
+            unsafe { msg_send_id![this, initByReferencingFile: path] }
+        }
+
+        pub fn new_with_data(data: &NSData) -> Id<Self, Shared> {
+            let this = unsafe { msg_send_id![Self::class(), alloc] };
+            unsafe { msg_send_id![this, initWithData: data] }
+        }
+    }
+);

src/platform_impl/macos/appkit/mod.rs

@@ -1,11 +1,18 @@
 #![deny(unsafe_op_in_unsafe_fn)]
+// Objective-C methods have different conventions, and it's much easier to
+// understand if we just use the same names
+#![allow(non_snake_case)]
 
 mod application;
+mod cursor;
+mod image;
 mod responder;
 mod view;
 mod window;
 
 pub(crate) use self::application::NSApplication;
+pub(crate) use self::cursor::NSCursor;
+pub(crate) use self::image::NSImage;
 pub(crate) use self::responder::NSResponder;
 pub(crate) use self::view::NSView;
 pub(crate) use self::window::NSWindow;

src/platform_impl/macos/appkit/view.rs

@@ -1,7 +1,7 @@
-use objc2::foundation::NSObject;
-use objc2::{extern_class, ClassType};
+use objc2::foundation::{NSObject, NSRect};
+use objc2::{extern_class, extern_methods, ClassType};
 
-use super::NSResponder;
+use super::{NSCursor, NSResponder};
 
 extern_class!(
     #[derive(Debug, PartialEq, Eq, Hash)]
@@ -12,3 +12,17 @@ extern_class!(
         type Super = NSResponder;
     }
 );
+
+extern_methods!(
+    /// Getter methods
+    unsafe impl NSView {
+        #[sel(bounds)]
+        pub fn bounds(&self) -> NSRect;
+    }
+
+    unsafe impl NSView {
+        #[sel(addCursorRect:cursor:)]
+        // NSCursor safe to take by shared reference since it is already immutable
+        pub fn addCursorRect(&self, rect: NSRect, cursor: &NSCursor);
+    }
+);