Change set_cursor_position to return Result<(), String> (#562)

* Change set_cursor_position to return Result<(), String>

This is now consistent with `grab_cursor`, and
enables `window.set_cursor_position(x, y)?` in functions
that return `Result<_, Box<Error>>`.

* Adjust error handling of unimplemented cusor opertions in wayland

* The final nitpick

* Actually one more

CHANGELOG.md

@@ -17,6 +17,7 @@
 - Fixed quirk on macOS where certain keys would generate characters at twice the normal rate when held down.
 - On X11, all event loops now share the same `XConnection`.
 - **Breaking:** `Window::set_cursor_state` and `CursorState` enum removed in favor of the more composable `Window::grab_cursor` and `Window::hide_cursor`. As a result, grabbing the cursor no longer automatically hides it; you must call both methods to retain the old behavior on Windows and macOS. `Cursor::NoneCursor` has been removed, as it's no longer useful.
+- **Breaking:** `Window::set_cursor_position` now returns `Result<(), String>`, thus allowing for `Box<Error>` conversion via `?`.
 
 # Version 0.15.1 (2018-06-13)
 

src/platform/android/mod.rs

@@ -346,9 +346,8 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, _position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, _position: LogicalPosition) -> Result<(), String> {
-        // N/A
+        Err("Setting cursor position is not possible on Android.".to_owned())
-        Ok(())
     }
 
     #[inline]

src/platform/emscripten/mod.rs

@@ -559,8 +559,8 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, _position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, _position: LogicalPosition) -> Result<(), String> {
-        Err(())
+        Err("Setting cursor position is not possible on Emscripten.".to_owned())
     }
 
     #[inline]

src/platform/ios/mod.rs

@@ -408,9 +408,8 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, _position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, _position: LogicalPosition) -> Result<(), String> {
-        // N/A
+        Err("Setting cursor position is not possible on iOS.".to_owned())
-        Ok(())
     }
 
     #[inline]

src/platform/linux/mod.rs

@@ -251,7 +251,7 @@ impl Window {
     pub fn grab_cursor(&self, grab: bool) -> Result<(), String> {
         match self {
             &Window::X(ref window) => window.grab_cursor(grab),
-            &Window::Wayland(ref _window) => Err("Cursor grabbing is not yet possible on Wayland.".to_owned()),
+            &Window::Wayland(ref window) => window.grab_cursor(grab),
         }
     }
 
@@ -259,7 +259,7 @@ impl Window {
     pub fn hide_cursor(&self, hide: bool) {
         match self {
             &Window::X(ref window) => window.hide_cursor(hide),
-            &Window::Wayland(ref _window) => unimplemented!(),
+            &Window::Wayland(ref window) => window.hide_cursor(hide),
         }
     }
 
@@ -272,7 +272,7 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, position: LogicalPosition) -> Result<(), String> {
         match self {
             &Window::X(ref w) => w.set_cursor_position(position),
             &Window::Wayland(ref w) => w.set_cursor_position(position),

src/platform/linux/wayland/window.rs

@@ -235,11 +235,6 @@ impl Window {
         self.frame.lock().unwrap().set_resizable(resizable);
     }
 
-    #[inline]
-    pub fn set_cursor(&self, _cursor: MouseCursor) {
-        // TODO
-    }
-
     #[inline]
     pub fn hidpi_factor(&self) -> i32 {
         self.monitors.lock().unwrap().compute_hidpi_factor()
@@ -273,9 +268,23 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, _pos: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor(&self, _cursor: MouseCursor) {
-        // TODO: not yet possible on wayland
+        // TODO
-        Err(())
+    }
+
+    #[inline]
+    pub fn hide_cursor(&self, _hide: bool) {
+        // TODO: This isn't possible on Wayland yet
+    }
+
+    #[inline]
+    pub fn grab_cursor(&self, _grab: bool) -> Result<(), String> {
+        Err("Cursor grabbing is not yet possible on Wayland.".to_owned())
+    }
+
+    #[inline]
+    pub fn set_cursor_position(&self, _pos: LogicalPosition) -> Result<(), String> {
+        Err("Setting the cursor position is not yet possible on Wayland.".to_owned())
     }
 
     pub fn get_display(&self) -> &Display {

src/platform/linux/x11/window.rs

@@ -1113,7 +1113,7 @@ impl UnownedWindow {
         self.get_current_monitor().hidpi_factor
     }
 
-    pub(crate) fn set_cursor_position_physical(&self, x: i32, y: i32) -> Result<(), ()> {
+    pub fn set_cursor_position_physical(&self, x: i32, y: i32) -> Result<(), String> {
         unsafe {
             (self.xconn.xlib.XWarpPointer)(
                 self.xconn.display,
@@ -1126,12 +1126,12 @@ impl UnownedWindow {
                 x,
                 y,
             );
-            self.xconn.flush_requests().map_err(|_| ())
+            self.xconn.flush_requests().map_err(|e| format!("`XWarpPointer` failed: {:?}", e))
         }
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, logical_position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, logical_position: LogicalPosition) -> Result<(), String> {
         let (x, y) = logical_position.to_physical(self.get_hidpi_factor()).into();
         self.set_cursor_position_physical(x, y)
     }

src/platform/macos/window.rs

@@ -1025,17 +1025,18 @@ impl Window2 {
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, cursor_position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, cursor_position: LogicalPosition) -> Result<(), String> {
         let window_position = self.get_inner_position()
-            .expect("`get_inner_position` failed");
+            .ok_or("`get_inner_position` failed".to_owned())?;
         let point = appkit::CGPoint {
             x: (cursor_position.x + window_position.x) as CGFloat,
             y: (cursor_position.y + window_position.y) as CGFloat,
         };
         CGDisplay::warp_mouse_cursor_position(point)
-            .expect("`CGWarpMouseCursorPosition` failed");
+            .map_err(|e| format!("`CGWarpMouseCursorPosition` failed: {:?}", e))?;
         CGDisplay::associate_mouse_and_mouse_cursor_position(true)
-            .expect("`CGAssociateMouseAndMouseCursorPosition` failed");
+            .map_err(|e| format!("`CGAssociateMouseAndMouseCursorPosition` failed: {:?}", e))?;
+
         Ok(())
     }
 

src/platform/windows/window.rs

@@ -438,21 +438,21 @@ impl Window {
         get_window_scale_factor(self.window.0, self.window.1)
     }
 
-    fn set_cursor_position_physical(&self, x: i32, y: i32) -> Result<(), ()> {
+    fn set_cursor_position_physical(&self, x: i32, y: i32) -> Result<(), String> {
         let mut point = POINT { x, y };
         unsafe {
             if winuser::ClientToScreen(self.window.0, &mut point) == 0 {
-                return Err(());
+                return Err("`ClientToScreen` failed".to_owned());
             }
             if winuser::SetCursorPos(point.x, point.y) == 0 {
-                return Err(());
+                return Err("`SetCursorPos` failed".to_owned());
             }
         }
         Ok(())
     }
 
     #[inline]
-    pub fn set_cursor_position(&self, logical_position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, logical_position: LogicalPosition) -> Result<(), String> {
         let dpi_factor = self.get_hidpi_factor();
         let (x, y) = logical_position.to_physical(dpi_factor).into();
         self.set_cursor_position_physical(x, y)

src/window.rs

@@ -322,7 +322,7 @@ impl Window {
 
     /// Changes the position of the cursor in window coordinates.
     #[inline]
-    pub fn set_cursor_position(&self, position: LogicalPosition) -> Result<(), ()> {
+    pub fn set_cursor_position(&self, position: LogicalPosition) -> Result<(), String> {
         self.window.set_cursor_position(position)
     }