1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
// Copyright (C) 2026 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only
use std::cell::RefCell;
use std::ptr::NonNull;
use std::rc::Rc;
use qtbridge_type_lib::{QObject, QVariant};
use crate::qproxies::{QRustProxy, ConstructionMode};
use crate::rustobjectgetter::get_rust_proxy;
use crate::{DispatchMetaCall, QMetaInfo, QmlMethodInvoker};
use std::collections::HashMap;
pub trait QObjectHolder : DispatchMetaCall + QMetaInfo + Default {
/// Alias for the Rust proxy type corresponding to the user-defined type.
/// The Rust proxy is an intermediate layer between the Rust object and the C++ proxy,
/// forwarding calls in both directions and managing borrowing of the Rust object
/// during QAIM calls (and TBD for meta calls as well).
#[doc(hidden)]
type ProxyRust: QRustProxy<ProxyCppType = <Self as QMetaInfo>::CppProxy>;
#[doc(hidden)]
fn try_borrow_mut_proxies_map<F, R>(f: F) -> R
where
F: FnOnce( &mut HashMap<*const u8, *const u8>) -> R
{
thread_local! { static INSTANCES: RefCell<HashMap<*const u8, *const u8>> =
RefCell::new(HashMap::new());
}
INSTANCES.with_borrow_mut(f)
}
/// Return a pointer to the Rust proxy associated with the specified object,
/// or `None` if no proxy is registered.
#[doc(hidden)]
fn try_get_rust_proxy_ptr_from_ptr(rust_obj_ptr: *const Self) -> Option<*mut Self::ProxyRust> {
let proxy_ptr = Self::try_borrow_mut_proxies_map(|map| {
map.get(&rust_obj_ptr.cast::<u8>()).copied().unwrap_or_default()
});
NonNull::new(proxy_ptr as *mut Self::ProxyRust).map(|nn| nn.as_ptr())
}
/// Return a pointer to the Rust proxy associated with the specified object,
/// or `None` if no proxy is registered.
#[doc(hidden)]
fn try_get_rust_proxy_ptr(&self) -> Option<*mut Self::ProxyRust> {
Self::try_get_rust_proxy_ptr_from_ptr(std::ptr::from_ref(self))
}
/// Return `QObject` attached to the specified Rust object.
#[doc(hidden)]
fn get_qobject_ptr(&self) -> *mut QObject {
let Some(proxy_ptr) = Self::try_get_rust_proxy_ptr(self) else {
return std::ptr::null_mut()
};
let rust_proxy = unsafe { &*proxy_ptr };
let cpp_proxy = rust_proxy.get_cpp_proxy();
cpp_proxy as *mut QObject
}
/// Return `QObject` attached to the specified Rust object.
#[doc(hidden)]
fn rc_ref_cell_to_qobject(self_obj: &Rc<RefCell<Self>>) -> *const QObject {
let Some(proxy_ptr) = Self::try_get_rust_proxy_ptr_from_ptr(self_obj.as_ptr()) else {
return std::ptr::null_mut()
};
let rust_proxy = unsafe { &*proxy_ptr };
let cpp_proxy = rust_proxy.get_cpp_proxy();
cpp_proxy as *mut QObject
}
/// Return the Rust object attached to the specified `QObject`.
#[doc(hidden)]
unsafe fn qobject_to_rc_ref_cell(qobj_ptr: *const QObject) -> Rc<RefCell<Self>>
{
let qobj_ref = unsafe { qobj_ptr.as_ref() }
.expect("Input QObject is null");
let proxy_ptr = get_rust_proxy(qobj_ref);
debug_assert!(!proxy_ptr.is_null());
// Verify the QObject really is of type `Self` before reinterpreting
// its proxy/object as `Self`'s - otherwise the casts below are UB.
let qobj_meta_obj = qobj_ref.get_qmeta_object();
let self_meta_obj = <Self as QMetaInfo>::get_shared_dynamic_meta_object_data().get_meta_object();
if qobj_meta_obj != self_meta_obj {
let qobj_name = unsafe { qobj_meta_obj.as_ref() }.map_or("<null>".into(), |m| m.meta_type().name());
let self_name = unsafe { self_meta_obj.as_ref() }.map_or("<null>".into(), |m| m.meta_type().name());
panic!("Value of wrong type is assigned to property: '{qobj_name}' instead of '{self_name}'")
}
let proxy = unsafe { &*(proxy_ptr as *const Self::ProxyRust) };
let rc_adapter = proxy.get_rust_object_rc()
.expect("Rust object associated with given QObject was already dropped");
// SAFETY: the metatype check above proves the `QObject` - and therefore
// the allocation behind `rc_adapter` - was created as `RefCell<Self>`.
// The adapter `Rc` only layers a vtable over that same allocation, so
// its data pointer addresses a real `RefCell<Self>` with matching size
// and alignment; reinterpreting it back is sound. `into_raw` parks the
// `+1` produced by `get_rust_object_rc` and `from_raw` reclaims it, so
// the reference count stays balanced.
let raw_ref_cell = Rc::into_raw(rc_adapter) as *const u8 as *const RefCell<Self>;
unsafe { Rc::from_raw(raw_ref_cell) }
}
/// Returns a [`QmlMethodInvoker`] that can invoke methods on the underlying
/// `QObject` from any thread.
///
/// # Example
///
/// ```
/// # use qtbridge::{qobject, QObjectHolder};
/// # #[qobject]
/// # pub mod example {
/// # #[derive(Default)]
/// # pub struct Backend {}
/// # impl Backend {
/// # #[qsignal]
/// # pub fn data_ready(&mut self);
/// # }
/// # }
/// # use example::Backend;
/// let backend = Backend::default_with_attached_qobject();
/// let invoker = backend.borrow().get_qml_method_invoker();
/// invoker.invoke_method("dataReady");
/// ```
fn get_qml_method_invoker(&self) -> QmlMethodInvoker
{
QmlMethodInvoker::new(self)
}
/// This function has to be implemented on the specific type and
/// provides the conversion from the specific type to the dynamic
/// trait type.
///
/// This function ensures that the type indeed implements the trait
/// specified by the [`QRustProxy`].
#[doc(hidden)]
fn as_adaptor_trait(rust_obj_rc: Rc<RefCell<Self>>) -> Rc<RefCell<<Self::ProxyRust as QRustProxy>::AdapterType>>;
/// Register the given Rust object instance in the multiton.
/// Create Rust and C++ proxies and links them to the Rust object.
/// If `construction` is `AtAddress`, the C++ proxy is created using
/// placement new operator at respective address
#[doc(hidden)]
fn register_instance_in_map(rust_obj_rc: Rc<RefCell<Self>>, construction: ConstructionMode) {
let key = (*rust_obj_rc).as_ptr() as *const u8;
let dyn_rc = Self::as_adaptor_trait(rust_obj_rc);
let dynamic_meta = <Self as QMetaInfo>::get_shared_dynamic_meta_object_data();
let proxy = Self::ProxyRust::new(&dyn_rc, dynamic_meta, construction, Box::new(move || Self::unregister_instance_in_map(key)));
Self::try_borrow_mut_proxies_map(|proxies| {
proxies.insert(key, proxy as *const u8);
})
}
/// Removes the entry associated with the specified Rust object from the multiton map.
#[doc(hidden)]
fn unregister_instance_in_map(rust_obj_ptr: *const u8) {
Self::try_borrow_mut_proxies_map(|proxies| proxies.remove(&rust_obj_ptr))
.expect("Proxy object for rust object is not registered")
.cast_mut();
}
/// Creates a default-initialized instance and attaches the required
/// [`QObject`], enabling its use in QML.
///
/// The returned `Rc<RefCell<Self>>` owns the object. The QML side can access it only through
/// a weak pointer.
///
/// The `drop` implementation of `Self` calls `detach_qobject` and thus destroys the associated
/// `QObject`, which removes it from the QML side as well. If `Self` has a custom [`Drop`]
/// implementation, you need to call [`detach_qobject`] manually.
///
/// The attached `QObject` is bound to this specific allocation, so the object's identity and
/// lifetime must both be preserved.
///
/// **Do not move or replace the `Self` inside the `Rc<RefCell<Self>>`.**
/// Operations such as `Rc::try_unwrap`, `into_inner`, or `get_mut`-then-move will break the
/// connection between `self` and the associated `QObject`. Once the `Self` lives
/// elsewhere, the next call in either direction can no longer reach it.
fn default_with_attached_qobject() -> std::rc::Rc<std::cell::RefCell<Self>> {
let instance = Default::default();
Self::attach_qobject(&instance);
instance
}
/// Attaches a dedicated [`QObject`] to an existing `instance`,
/// enabling its use in QML.
fn attach_qobject(instance: &std::rc::Rc<std::cell::RefCell<Self>>) {
Self::register_instance_in_map(
instance.clone(),
ConstructionMode::Weak
);
}
/// Detaches and removes the dedicated [`QObject`] from this instance.
///
/// Called automatically by the [`Drop`] implementation generated by the
/// `qobject` macro.
fn detach_qobject(&self) {
let qobj_ptr = self.get_qobject_ptr();
if !qobj_ptr.is_null() {
QObject::delete(qobj_ptr);
}
}
/// Returns a [`QVariant`] containing a pointer to this object.
fn as_qvariant(&self) -> QVariant {
let qobj_ptr = self.get_qobject_ptr();
assert!(!qobj_ptr.is_null(), "QObject is not attached");
qobj_ptr.into()
}
}