Add qobject extension trait

- cxx-qt-lib trait for additional qobject wrappers
- adds first signal blockSignals

Author: BenFordTytherington

crates/cxx-qt-lib/build.rs

@@ -151,6 +151,7 @@ fn main() {
         "core/qmarginsf",
         "core/qmodelindex",
         "core/qpersistentmodelindex",
+        "core/qobject",
         "core/qpoint",
         "core/qpointf",
         "core/qrect",

crates/cxx-qt-lib/src/core/mod.rs

@@ -4,6 +4,7 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
 mod qbytearray;
+
 pub use qbytearray::QByteArray;
 
 mod qcoreapplication;
@@ -109,7 +110,11 @@ pub use qvariant::{QVariant, QVariantValue};
 mod qvector;
 pub use qvector::{QVector, QVectorElement};
 
+mod qobject;
 mod qtlogging;
+
+pub use qobject::QObjectExt;
+
 pub use qtlogging::{qt_message_output, QMessageLogContext, QtMsgType};
 
 #[cxx::bridge]

crates/cxx-qt-lib/src/core/qobject.rs

@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: 2025 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+// SPDX-FileContributor: Ben Ford <ben.ford@kdab.com>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+use cxx_qt::QObject;
+use std::pin::Pin;
+
+#[cxx_qt::bridge]
+mod ffi {
+    unsafe extern "C++" {
+        #[rust_name = "QObjectExternal"]
+        type QObject;
+
+        #[cxx_name = "blockSignals"]
+        pub fn blockSignalsQObject(self: Pin<&mut QObjectExternal>, block: bool) -> bool;
+    }
+}
+
+use ffi::QObjectExternal;
+
+pub trait QObjectExt {
+    fn block_signals(self: Pin<&mut Self>, block: bool) -> bool;
+}
+
+fn cast(obj: Pin<&mut QObject>) -> Pin<&mut QObjectExternal> {
+    unsafe {
+        let mut_ptr = obj.get_unchecked_mut() as *mut QObject as *mut QObjectExternal;
+        Pin::new_unchecked(&mut *mut_ptr)
+    }
+}
+
+impl QObjectExt for QObject {
+    fn block_signals(self: Pin<&mut Self>, block: bool) -> bool {
+        cast(self).blockSignalsQObject(block)
+    }
+}