feat: add function to set window cursor position callback

1 files changed, 46 insertions, 1 deletions

diff --git a/glfw/src/window.rs b/glfw/src/window.rs
index a9512d6..0fb5978 100644
--- a/glfw/src/window.rs
+++ b/glfw/src/window.rs
@@ -1,5 +1,5 @@
 use std::cell::RefCell;
-use std::ffi::{c_int, CString};
+use std::ffi::{c_double, c_int, CString};
 use std::hint::unreachable_unchecked;
 use std::io::{stdout, Write};
 use std::panic::catch_unwind;
@@ -149,6 +149,23 @@ impl Window
         }
     }
 
+    /// Sets the cursor position callback.
+    ///
+    /// The callback is provided with the position, in screen coordinates, relative to the
+    /// upper-left corner of the content area of the window.
+    pub fn set_cursor_pos_callback(&self, callback: impl Fn(CursorPosition) + 'static)
+    {
+        CURSOR_POS_CALLBACK.with_borrow_mut(|cursor_pos_callback| {
+            *cursor_pos_callback = Some(Box::new(callback));
+        });
+
+        // SAFETY: The initialize function (called when the window is created) makes sure
+        // the current thread is the main thread
+        unsafe {
+            crate::ffi::glfwSetCursorPosCallback(self.handle, Some(cursor_pos_callback));
+        }
+    }
+
     /// Returns the last reported state of a keyboard key.
     ///
     /// # Errors
@@ -633,10 +650,12 @@ pub struct CursorPosition
 
 type FramebufferSizeCb = Box<dyn Fn(Size)>;
 type KeyCallback = Box<dyn Fn(Key, i32, KeyState, KeyModifiers)>;
+type CursorPositionCallback = Box<dyn Fn(CursorPosition)>;
 
 thread_local! {
 static FRAMEBUFFER_SIZE_CB: RefCell<Option<FramebufferSizeCb>> = RefCell::new(None);
 static KEY_CALLBACK: RefCell<Option<KeyCallback>> = RefCell::new(None);
+static CURSOR_POS_CALLBACK: RefCell<Option<CursorPositionCallback>> = RefCell::new(None);
 }
 
 extern "C" fn framebuffer_size_callback(
@@ -708,3 +727,29 @@ extern "C" fn key_callback(
         write!(stdout(), "ERROR: Panic in key callback").ok();
     }
 }
+
+extern "C" fn cursor_pos_callback(
+    _window: *mut crate::ffi::GLFWwindow,
+    x_pos: c_double,
+    y_pos: c_double,
+)
+{
+    // Unwinds are catched because unwinding from Rust code into foreign code is UB.
+    let res = catch_unwind(|| {
+        CURSOR_POS_CALLBACK
+            .try_with(|cursor_pos_callback| {
+                if let Some(cb) = cursor_pos_callback.borrow().as_deref() {
+                    cb(CursorPosition { x: x_pos, y: y_pos });
+                }
+            })
+            .ok();
+    });
+
+    if res.is_err() {
+        write!(
+            stdout(),
+            "ERROR: Cursor position callback panicked: {res:?}"
+        )
+        .ok();
+    }
+}