code panics on adding root to treeview about winsafe

[rodrigocfd]

The problem is that you adding a node to the treeview control, but the control doesn't physically exist yet. That is: the treeview object has been created, but the owner window didn't render it yet.

In order to perform this operation, you must do it in the WM_CREATE event (if an ordinary window), or in the WM_INITDIALOG event (if a dialog window).

The example below shows you code, corrected:

#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]

use winsafe::{prelude::*, gui, co, AnyResult, HWND};

#[derive(Clone)]
pub struct MyWindow {
	wnd:       gui::WindowMain,
	tv: gui::TreeView,
}

impl MyWindow {
	pub fn new() -> Self {
		let wnd = gui::WindowMain::new(
			gui::WindowMainOpts {
				title: "My window title".to_owned(),
				size: (300, 150),
				..Default::default()
			},
		);

		let tv = gui::TreeView::new(
			&wnd,
			Default::default(),
		);
		// tv.items().add_root("text", None); THIS LINE GOES TO WM_CREATE

		let new_self = Self { wnd, tv };
		new_self.events(); // add the window event handlers
		new_self
	}

	pub fn run(&self) -> AnyResult<i32> {
		self.wnd.run_main(None)
	}

	fn events(&self) {
		let self2 = self.clone();
		self.wnd.on().wm_create(move |_| { // called right after the window is created
			self2.tv.items().add_root("text", None);
			Ok(0)
		});
	}
}


fn main() {
	if let Err(e) = run_app() {
		HWND::NULL.MessageBox(
			&e.to_string(), "Uncaught error", co::MB::ICONERROR).unwrap();
	}
}

fn run_app() -> AnyResult<i32> {
	MyWindow::new()
		.run()
		.map_err(|err| err.into())
}

The message error doesn't help, though. I'll implement a better error handling for such case.