How to get area of each window?

[VRichardJP]

Hi

I would like to know the position of all egui windows within my application like it is done in memory_ui.

To retrieve the list of window area, memory_ui has access to the areas field in Memory struct which is not public:

egui/egui/src/context.rs

Lines 866 to 888 in 60fd709

	ui.indent("areas", |ui| {
	let layers_ids: Vec<LayerId> = self.memory().areas.order().to_vec();
	for layer_id in layers_ids {
	let area = self.memory().areas.get(layer_id.id).cloned();
	if let Some(area) = area {
	let is_visible = self.memory().areas.is_visible(&layer_id);
	if ui
	.label(format!(
	"{:?} {:?} {}",
	layer_id.order,
	area.rect(),
	if is_visible { "" } else { "(INVISIBLE)" }
	))
	.hovered
	&& is_visible
	{
	ui.ctx()
	.debug_painter()
	.debug_rect(area.rect(), Color32::RED, "");
	}
	}
	}
	});

used_rect() function is public and almost does the job, but it returns the union of all the areas and not a list of areas:

egui/egui/src/context.rs

Lines 644 to 650 in 60fd709

	pub fn used_rect(&self) -> Rect {
	let mut used = self.frame_state().used_by_panels;
	for window in self.memory().areas.visible_windows() {
	used = used.union(window.rect());
	}
	used
	}

Is there any other way to get this information?

[emilk]

Widnwo::show returns where it currently is.

I guess you want an API for getting the position of any Area or Window given its Id.

I think we could add that, e.g. with Memory::get_area_rect() or similar. It is very easy to add if you follow how ctx.memory().areas.get(id) works.

[AadamZ5]

Stumbling across this after finding the warning in the comment of Window::current_pos(...) reads ... If the window is movable it is up to you to keep track of where it moved to!. Additionally, if we use Window::current_pos(...) the response does not include the updated Rect for the in-progress drag. So we can't grab it from the response.

Initial reaction to seeing that was supply current pos, run immediate render/interaction, then update state position with window's new position. It was not straight forward to retrieve this. My first hope was to use the window response InnerResponse.response.drag_delta() but that does not expose window drags, maybe when using current_pos(...).

My goal was to link the window position to another item's position (in my app's "edit mode", I create the window. In "view mode" I use an Area. I want the window to be created where the area was, and vice-versa.)

I arrived at this implementation for now:

let window_response = Window::new("Some window").id(window_id).current_pos(current_window_pos);

let new_window_pos = ctx.memory(|mem| {
    mem.area_rect(window_id)
        .map(|rect| rect.center())
        .unwrap_or(current_window_pos)
});

// Assign new window pos back to your state somehow.