feat(glfw): add function to set framebuffer size callback

1 files changed, 51 insertions, 1 deletions

diff --git a/glfw/src/window.rs b/glfw/src/window.rs
index e3e6383..a080161 100644
--- a/glfw/src/window.rs
+++ b/glfw/src/window.rs
@@ -1,4 +1,6 @@
-use std::ffi::{CStr, CString};
+use std::cell::RefCell;
+use std::ffi::{c_int, CStr, CString};
+use std::panic::catch_unwind;
 use std::ptr::null_mut;
 
 use crate::init::{initialize, Glfw};
@@ -140,6 +142,22 @@ impl Window
             height: height as u32,
         })
     }
+
+    pub fn set_framebuffer_size_callback(&self, callback: impl Fn(Size) + 'static)
+    {
+        FRAMEBUFFER_SIZE_CB.with_borrow_mut(|framebuffer_size_cb| {
+            *framebuffer_size_cb = 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::glfwSetFramebufferSizeCallback(
+                self.handle,
+                Some(framebuffer_size_callback),
+            );
+        }
+    }
 }
 
 /// Window size.
@@ -148,3 +166,35 @@ pub struct Size
     pub width: u32,
     pub height: u32,
 }
+
+type FramebufferSizeCb = Box<dyn Fn(Size)>;
+
+thread_local! {
+static FRAMEBUFFER_SIZE_CB: RefCell<Option<FramebufferSizeCb>> = RefCell::new(None);
+}
+
+extern "C" fn framebuffer_size_callback(
+    _window: *mut crate::ffi::GLFWwindow,
+    c_width: c_int,
+    c_height: c_int,
+)
+{
+    // Width and height can't possibly have their sign bit set
+    let width = u32::from_le_bytes(c_width.to_le_bytes());
+    let height = u32::from_le_bytes(c_height.to_le_bytes());
+
+    // Unwinds are catched because unwinding from Rust code into foreign code is UB.
+    let res = catch_unwind(|| {
+        FRAMEBUFFER_SIZE_CB
+            .try_with(|framebuffer_size_cb| {
+                if let Some(cb) = framebuffer_size_cb.borrow().as_deref() {
+                    cb(Size { width, height });
+                }
+            })
+            .ok();
+    });
+
+    if res.is_err() {
+        println!("ERROR: Panic in framebuffer size callback");
+    }
+}