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feat: added SDL_SetWindowHitTest wrapper #268

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Merged
revmischa merged 4 commits into from
Dec 12, 2025
Merged

feat: added SDL_SetWindowHitTest wrapper #268

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9354c8a
feat: added SDL_SetWindowHitTest wrapper
maik205 Dec 10, 2025
760594f
housekeeping: cargo format
maik205 Dec 10, 2025
b90ccb6
fix: added lifetime bound for hit test result and fixed docs
maik205 Dec 11, 2025
96e8623
fix: moved hit_test to Window struct so that it can be freed
maik205 Dec 11, 2025
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83 changes: 83 additions & 0 deletions src/sdl3/video.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -721,6 +721,55 @@ impl FlashOperation {
}
}

// Represents the result of a hit test.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
#[repr(i32)]
pub enum HitTestResult {
Normal = sys::video::SDL_HITTEST_NORMAL.0,
Draggable = sys::video::SDL_HITTEST_DRAGGABLE.0,
ResizeTopLeft = sys::video::SDL_HITTEST_RESIZE_TOPLEFT.0,
ResizeTop = sys::video::SDL_HITTEST_RESIZE_TOP.0,
ResizeTopRight = sys::video::SDL_HITTEST_RESIZE_TOPRIGHT.0,
ResizeRight = sys::video::SDL_HITTEST_RESIZE_RIGHT.0,
ResizeBottomRight = sys::video::SDL_HITTEST_RESIZE_BOTTOMRIGHT.0,
ResizeBottom = sys::video::SDL_HITTEST_RESIZE_BOTTOM.0,
ResizeBottomLeft = sys::video::SDL_HITTEST_RESIZE_BOTTOMLEFT.0,
ResizeLeft = sys::video::SDL_HITTEST_RESIZE_LEFT.0,
}

impl HitTestResult {
pub fn from_ll(result: sys::video::SDL_HitTestResult) -> HitTestResult {
match result {
sys::video::SDL_HITTEST_NORMAL => HitTestResult::Normal,
sys::video::SDL_HITTEST_DRAGGABLE => HitTestResult::Draggable,
sys::video::SDL_HITTEST_RESIZE_TOPLEFT => HitTestResult::ResizeTopLeft,
sys::video::SDL_HITTEST_RESIZE_TOP => HitTestResult::ResizeTop,
sys::video::SDL_HITTEST_RESIZE_TOPRIGHT => HitTestResult::ResizeTopRight,
sys::video::SDL_HITTEST_RESIZE_RIGHT => HitTestResult::ResizeRight,
sys::video::SDL_HITTEST_RESIZE_BOTTOMRIGHT => HitTestResult::ResizeBottomRight,
sys::video::SDL_HITTEST_RESIZE_BOTTOM => HitTestResult::ResizeBottom,
sys::video::SDL_HITTEST_RESIZE_BOTTOMLEFT => HitTestResult::ResizeBottomLeft,
sys::video::SDL_HITTEST_RESIZE_LEFT => HitTestResult::ResizeLeft,
_ => HitTestResult::Normal,
}
}

pub fn to_ll(self) -> sys::video::SDL_HitTestResult {
match self {
HitTestResult::Normal => sys::video::SDL_HITTEST_NORMAL,
HitTestResult::Draggable => sys::video::SDL_HITTEST_DRAGGABLE,
HitTestResult::ResizeTopLeft => sys::video::SDL_HITTEST_RESIZE_TOPLEFT,
HitTestResult::ResizeTop => sys::video::SDL_HITTEST_RESIZE_TOP,
HitTestResult::ResizeTopRight => sys::video::SDL_HITTEST_RESIZE_TOPRIGHT,
HitTestResult::ResizeRight => sys::video::SDL_HITTEST_RESIZE_RIGHT,
HitTestResult::ResizeBottomRight => sys::video::SDL_HITTEST_RESIZE_BOTTOMRIGHT,
HitTestResult::ResizeBottom => sys::video::SDL_HITTEST_RESIZE_BOTTOM,
HitTestResult::ResizeBottomLeft => sys::video::SDL_HITTEST_RESIZE_BOTTOMLEFT,
HitTestResult::ResizeLeft => sys::video::SDL_HITTEST_RESIZE_LEFT,
}
}
}

/// Represents the "shell" of a `Window`.
///
/// You can set get and set many of the `SDL_Window` properties (i.e., border, size, `PixelFormat`, etc)
Expand Down Expand Up @@ -2281,6 +2330,40 @@ impl Window {
Err(get_error())
}
}

/// Sets a hit test function for the window.
#[doc(alias = "SDL_SetWindowHitTest")]
pub fn set_hit_test(
&mut self,
hit_test: impl Fn(crate::rect::Point) -> HitTestResult,
) -> Result<(), Error> {
// Box the closure to extend its lifetime and convert it to a raw pointer.
let boxed: Box<Box<dyn Fn(crate::rect::Point) -> HitTestResult>> =
Box::new(Box::new(hit_test));
Comment on lines +2346 to +2347
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@revmischa revmischa Dec 10, 2025

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why is it in two boxes?

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@maik205 maik205 Dec 11, 2025

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I wrapped the closure twice to relax the trait bounds when dereferencing the callback from c_void pointer, as only Box'ing it once would yield

expected a `Fn(Point)` closure, found `c_void`
the trait `Fn(Point)` is not implemented for `c_void`
required for the cast from `*mut c_void` to `*mut dyn Fn(Point) -> HitTestResult

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@revmischa revmischa Dec 11, 2025

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let callback = &*(data as *const dyn Fn(Point) -> HitTestResult); might work

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@maik205 maik205 Dec 11, 2025

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I tried your solution but it seems the compiler still stops us from casting it into a trait pointer...

expected a `Fn(Point)` closure, found `c_void`
the trait `Fn(Point)` is not implemented for `c_void`
required for the cast from `*mut c_void` to `*const dyn Fn(Point) -> HitTestResult

Casting the void pointer into the trait pointer still requires the void pointer to implement that trait (which c_void doesn't)
I think Box is still needed to relax the trait bounds

let userdata = Box::into_raw(boxed) as *mut c_void;

unsafe extern "C" fn hit_test_sys(
_: *mut sys::video::SDL_Window,
point: *const sys::rect::SDL_Point,
data: *mut c_void,
) -> sys::video::SDL_HitTestResult {
// Reborrow the boxed closure.
let callback = data as *mut Box<dyn Fn(crate::rect::Point) -> HitTestResult>;
let point = crate::rect::Point::from_ll(*point);

(*callback)(point).to_ll()
}

unsafe {
let result =
sys::video::SDL_SetWindowHitTest(self.context.raw, Some(hit_test_sys), userdata);
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@revmischa revmischa Dec 10, 2025

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It seems like the hit_test will never be freed, we could store the userdata pointer on the Window struct and free it on Window drop perhaps.

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@maik205 maik205 Dec 11, 2025 •
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I moved hit_test into the Window struct in 96e8623

if result {
Ok(())
} else {
Err(get_error())
}
}
}
}

#[derive(Copy, Clone)]
Expand Down