Cursor icon support through Game trait

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   interface.
 - `Mesh::new_with_tolerance`, which allows to control the tolerance of line
   segment approximations. [#100]
+- `Game::cursor_icon`, which allows customization of the mouse cursor icon.
 
 ### Changed
 - `Mesh::stroke` now takes an `f32` as `line_width` instead of a `u16`.

src/game.rs

@@ -2,7 +2,7 @@ mod r#loop;
 
 pub(crate) use r#loop::Loop;
 
-use crate::graphics::{Frame, Window, WindowSettings};
+use crate::graphics::{CursorIcon, Frame, Window, WindowSettings};
 use crate::input::{keyboard, Input};
 use crate::load::{LoadingScreen, Task};
 use crate::{Debug, Result, Timer};
@@ -124,6 +124,13 @@ pub trait Game {
     /// [`Window`]: graphics/struct.Window.html
     fn update(&mut self, _window: &Window) {}
 
+    /// Defines the cursor icon of the window.
+    ///
+    /// By default, it returns platform-dependent default cursor.
+    fn cursor_icon(&self) -> CursorIcon {
+        CursorIcon::Default
+    }
+
     /// Displays debug information.
     ///
     /// This method is called after [`draw`] once per frame when debug has been

src/game/loop.rs

@@ -4,6 +4,7 @@ use crate::graphics::{Window, WindowSettings};
 use crate::input::{self, gamepad, keyboard, mouse, window, Input};
 use crate::load::{Join, LoadingScreen, Task};
 use crate::{Result, Timer};
+use std::convert::TryInto;
 
 pub trait Loop<Game: super::Game> {
     type Attributes;
@@ -226,10 +227,11 @@ where
 
     fn after_draw(
         &mut self,
-        _game: &mut Game,
+        game: &mut Game,
         _input: &mut Game::Input,
-        _window: &mut Window,
+        window: &mut Window,
         _debug: &mut Debug,
     ) {
+        window.update_cursor(game.cursor_icon().try_into().ok());
     }
 }

src/graphics.rs

@@ -141,4 +141,4 @@ pub use text::{HorizontalAlignment, Text, VerticalAlignment};
 pub use texture_array::TextureArray;
 pub use transformation::Transformation;
 pub use vector::Vector;
-pub use window::{Frame, Settings as WindowSettings, Window};
+pub use window::{CursorIcon, Frame, Settings as WindowSettings, Window};

src/graphics/window.rs

@@ -1,8 +1,10 @@
+mod cursor_icon;
 mod frame;
 mod settings;
 
 pub(crate) use winit;
 
+pub use cursor_icon::CursorIcon;
 pub use frame::Frame;
 pub use settings::Settings;
 
@@ -20,6 +22,7 @@ pub struct Window {
     width: f32,
     height: f32,
     is_fullscreen: bool,
+    cursor_icon: Option<winit::window::CursorIcon>,
 }
 
 impl Window {
@@ -60,6 +63,7 @@ impl Window {
             surface,
             width,
             height,
+            cursor_icon: Some(winit::window::CursorIcon::Default),
         })
     }
 
@@ -131,9 +135,17 @@ impl Window {
 
     pub(crate) fn update_cursor(
         &mut self,
-        new_cursor: winit::window::CursorIcon,
+        new_cursor: Option<winit::window::CursorIcon>,
     ) {
-        self.surface.window().set_cursor_icon(new_cursor);
+        if self.cursor_icon != new_cursor {
+            if let Some(cursor_icon) = new_cursor {
+                self.surface.window().set_cursor_icon(cursor_icon);
+            }
+            self.surface
+                .window()
+                .set_cursor_visible(new_cursor.is_some());
+            self.cursor_icon = new_cursor;
+        }
     }
 }
 

src/graphics/window/cursor_icon.rs

@@ -0,0 +1,39 @@
+use crate::graphics::window::winit;
+use std::convert::TryFrom;
+
+/// Describes the appearance of the mouse cursor.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum CursorIcon {
+    /// The platform-dependent default cursor.
+    Default,
+    /// A simple crosshair.
+    Crosshair,
+    /// A hand (often used to indicate links in web browsers).
+    Hand,
+    /// Hides the cursor.
+    Hidden,
+    /// Indicates something is to be moved.
+    Move,
+}
+
+impl Default for CursorIcon {
+    fn default() -> Self {
+        Self::Default
+    }
+}
+
+impl TryFrom<CursorIcon> for winit::window::CursorIcon {
+    type Error = ();
+
+    fn try_from(
+        cursor_icon: CursorIcon,
+    ) -> Result<winit::window::CursorIcon, ()> {
+        match cursor_icon {
+            CursorIcon::Default => Ok(winit::window::CursorIcon::Default),
+            CursorIcon::Crosshair => Ok(winit::window::CursorIcon::Crosshair),
+            CursorIcon::Hand => Ok(winit::window::CursorIcon::Hand),
+            CursorIcon::Hidden => Err(()),
+            CursorIcon::Move => Ok(winit::window::CursorIcon::Move),
+        }
+    }
+}

src/ui.rs

@@ -179,6 +179,7 @@ use crate::input::{self, mouse, Input as _};
 use crate::load::Task;
 use crate::ui::core::{Event, Interface, MouseCursor, Renderer as _};
 use crate::{Debug, Game, Result};
+use std::convert::TryInto;
 
 /// The user interface of your game.
 ///
@@ -353,9 +354,15 @@ impl<UI: UserInterface> game::Loop<UI> for Loop<UI> {
                 input.update(input::Event::Mouse(mouse::Event::CursorTaken));
             }
 
-            window.update_cursor(new_cursor.into());
             self.mouse_cursor = new_cursor;
         }
+        // Use the game cursor if cursor is not on a UI element, use the mouse cursor otherwise
+        if self.mouse_cursor == MouseCursor::OutOfBounds {
+            let game_cursor = ui.cursor_icon();
+            window.update_cursor(game_cursor.try_into().ok());
+        } else {
+            window.update_cursor(Some(self.mouse_cursor.into()));
+        }
 
         for message in messages.drain(..) {
             ui.react(message, window);