gtk/
rt.rs

1// Take a look at the license at the top of the repository in the LICENSE file.
2
3use crate::ffi;
4use glib::translate::*;
5use std::cell::Cell;
6use std::sync::atomic::{AtomicBool, Ordering};
7
8#[cfg(target_os = "macos")]
9extern "C" {
10    fn pthread_main_np() -> i32;
11}
12
13thread_local! {
14    static IS_MAIN_THREAD: Cell<bool> = const { Cell::new(false) }
15}
16
17static INITIALIZED: AtomicBool = AtomicBool::new(false);
18
19/// Asserts that this is the main thread and `gtk::init` has been called.
20macro_rules! assert_initialized_main_thread {
21    () => {
22        if !crate::rt::is_initialized_main_thread() {
23            if crate::rt::is_initialized() {
24                panic!("GTK may only be used from the main thread.");
25            } else {
26                panic!("GTK has not been initialized. Call `gtk::init` first.");
27            }
28        }
29    };
30}
31
32/// No-op.
33macro_rules! skip_assert_initialized {
34    () => {};
35}
36
37/// Asserts that `gtk::init` has not been called.
38#[allow(unused_macros)]
39macro_rules! assert_not_initialized {
40    () => {
41        if crate::rt::is_initialized() {
42            panic!("This function has to be called before `gtk::init`.");
43        }
44    };
45}
46
47/// Returns `true` if GTK has been initialized.
48#[inline]
49pub fn is_initialized() -> bool {
50    skip_assert_initialized!();
51    if cfg!(not(feature = "unsafe-assume-initialized")) {
52        INITIALIZED.load(Ordering::Acquire)
53    } else {
54        true
55    }
56}
57
58/// Returns `true` if GTK has been initialized and this is the main thread.
59#[inline]
60pub fn is_initialized_main_thread() -> bool {
61    skip_assert_initialized!();
62    if cfg!(not(feature = "unsafe-assume-initialized")) {
63        IS_MAIN_THREAD.with(|c| c.get())
64    } else {
65        true
66    }
67}
68
69/// Informs this crate that GTK has been initialized and the current thread is the main one.
70///
71/// # Panics
72///
73/// This function will panic if you attempt to initialise GTK from more than
74/// one thread.
75///
76/// # Safety
77///
78/// You must only call this if:
79///
80/// 1. You have initialised the underlying GTK library yourself.
81/// 2. You did 1 on the thread with which you are calling this function
82/// 3. You ensure that this thread is the main thread for the process.
83pub unsafe fn set_initialized() {
84    unsafe {
85        skip_assert_initialized!();
86        if is_initialized_main_thread() {
87            return;
88        } else if is_initialized() {
89            panic!("Attempted to initialize GTK from two different threads.");
90        }
91
92        //  OS X has its own notion of the main thread and init must be called on that thread.
93        #[cfg(target_os = "macos")]
94        {
95            assert_eq!(
96                pthread_main_np(),
97                1,
98                "Attempted to initialize GTK on OSX from non-main thread"
99            );
100        }
101
102        gdk::set_initialized();
103        INITIALIZED.store(true, Ordering::Release);
104        IS_MAIN_THREAD.with(|c| c.set(true));
105    }
106}
107
108/// Tries to initialize GTK+.
109///
110/// Call either this function or [`Application::new`][new] before using any
111/// other GTK+ functions.
112///
113/// [new]: struct.Application.html#method.new
114///
115/// Note that this function calls `gtk_init_check()` rather than `gtk_init()`,
116/// so will not cause the program to terminate if GTK could not be initialized.
117/// Instead, an Ok is returned if the windowing system was successfully
118/// initialized otherwise an Err is returned.
119#[doc(alias = "gtk_init")]
120pub fn init() -> Result<(), glib::BoolError> {
121    skip_assert_initialized!();
122    if is_initialized_main_thread() {
123        return Ok(());
124    } else if is_initialized() {
125        panic!("Attempted to initialize GTK from two different threads.");
126    }
127    unsafe {
128        // We just want to keep the program's name since more arguments could lead to unwanted
129        // behaviors...
130        let argv = ::std::env::args().take(1).collect::<Vec<_>>();
131
132        if from_glib(ffi::gtk_init_check(&mut 1, &mut argv.to_glib_none().0)) {
133            // See https://github.com/gtk-rs/gtk-rs-core/issues/186 for reasoning behind
134            // acquiring and leaking the main context here.
135            let result: bool = from_glib(glib::ffi::g_main_context_acquire(
136                glib::ffi::g_main_context_default(),
137            ));
138            if !result {
139                return Err(glib::bool_error!("Failed to acquire default main context"));
140            }
141            set_initialized();
142            Ok(())
143        } else {
144            Err(glib::bool_error!("Failed to initialize GTK"))
145        }
146    }
147}
148
149#[doc(alias = "gtk_main_quit")]
150pub fn main_quit() {
151    assert_initialized_main_thread!();
152    unsafe {
153        if ffi::gtk_main_level() > 0 {
154            ffi::gtk_main_quit();
155        } else if cfg!(debug_assertions) {
156            panic!("Attempted to quit a GTK main loop when none is running.");
157        }
158    }
159}
160
161#[cfg(test)]
162mod tests {
163    use crate::TEST_THREAD_WORKER;
164
165    #[test]
166    fn init_should_acquire_default_main_context() {
167        TEST_THREAD_WORKER
168            .push(move || {
169                let context = glib::MainContext::ref_thread_default();
170                assert!(context.is_owner());
171            })
172            .expect("Failed to schedule a test call");
173        while TEST_THREAD_WORKER.unprocessed() > 0 {}
174    }
175}
gtk/rt.rs

gtk/
rt.rs
