cxx-qt-lib: Add two more QtLogging functions

This adds two new global functions available in <QtLogging>:
qFormatLogMessage and qSetMessagePattern.

qFormatLogMessage is similar to qt_message_output, but actually
documented. Instead of going to the default message handler though, it
outputs to a QString. This is probably not useful without message
handler support, but it's easy to expose.

qSetMessagePattern is very useful, as it allows CXX-Qt applications to
set custom Qt message patterns for logging.

Author: redstrate

CHANGELOG.md

@@ -32,6 +32,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `#[base = T]` is now suported in `extern "C++Qt"` blocks
 - Casting is automatically implmented for qobjects or types which have `#[base = T]` in `"RustQt"` or `"C++Qt"` blocks
 - Support for `QMessageLogContext` and sending log messages to the Qt message handler.
+- Support for setting Qt log message patterns with `set_message_pattern`.
 
 ### Removed
 

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

@@ -110,7 +110,9 @@ mod qvector;
 pub use qvector::{QVector, QVectorElement};
 
 mod qtlogging;
-pub use qtlogging::{qt_message_output, QMessageLogContext, QtMsgType};
+pub use qtlogging::{
+    format_log_message, qt_message_output, set_message_pattern, QMessageLogContext, QtMsgType,
+};
 
 #[cxx::bridge]
 mod ffi {

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

@@ -36,6 +36,18 @@ mod ffi {
         /// Outputs a message in the Qt message handler.
         fn qt_message_output(msgType: QtMsgType, context: &QMessageLogContext, string: &QString);
 
+        /// Generates a formatted string out of the type, context, str arguments.
+        #[cxx_name = "qFormatLogMessage"]
+        fn format_log_message(
+            msgType: QtMsgType,
+            context: &QMessageLogContext,
+            string: &QString,
+        ) -> QString;
+
+        /// Generates a formatted string out of the type, context, str arguments.
+        #[cxx_name = "qSetMessagePattern"]
+        fn set_message_pattern(pattern: &QString);
+
         #[cxx_name = "qmessagelogcontext_line"]
         #[doc(hidden)]
         fn line(context: &QMessageLogContext) -> i32;
@@ -131,4 +143,4 @@ unsafe impl ExternType for QMessageLogContext<'_> {
 }
 
 use crate::const_assert;
-pub use ffi::{qt_message_output, QtMsgType};
+pub use ffi::{format_log_message, qt_message_output, set_message_pattern, QtMsgType};