From a436301b3960aa750ec97c78e969b7f5e7161d2a Mon Sep 17 00:00:00 2001
From: Joshua Goins <joshua.goins@kdab.com>
Date: Fri, 14 Mar 2025 08:58:56 -0400
Subject: [PATCH] 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.
---
 CHANGELOG.md                            |  1 +
 crates/cxx-qt-lib/src/core/mod.rs       |  4 +++-
 crates/cxx-qt-lib/src/core/qtlogging.rs | 17 ++++++++++++++++-
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2fbe8d465..bea91689c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Support for `QMessageLogContext` and sending log messages to the Qt message handler.
 - Serde support for further types: `QByteArray`, `QSet`, `QStringList`, `QVector`, `QUrl`
 - Added `QEventLoop` to cxx-qt-lib-extras.
+- Support for setting Qt log message patterns with `q_set_message_pattern` and formatting log messages ith `q_format_log_message`.
 
 ### Removed
 
diff --git a/crates/cxx-qt-lib/src/core/mod.rs b/crates/cxx-qt-lib/src/core/mod.rs
index 51e9acb5d..e3a725ee2 100644
--- a/crates/cxx-qt-lib/src/core/mod.rs
+++ b/crates/cxx-qt-lib/src/core/mod.rs
@@ -113,7 +113,9 @@ mod qvector;
 pub use qvector::{QVector, QVectorElement};
 
 mod qtlogging;
-pub use qtlogging::{qt_message_output, QMessageLogContext, QtMsgType};
+pub use qtlogging::{
+    q_format_log_message, q_set_message_pattern, qt_message_output, QMessageLogContext, QtMsgType,
+};
 
 #[cxx::bridge]
 mod ffi {
diff --git a/crates/cxx-qt-lib/src/core/qtlogging.rs b/crates/cxx-qt-lib/src/core/qtlogging.rs
index f24c5501f..0ca320e19 100644
--- a/crates/cxx-qt-lib/src/core/qtlogging.rs
+++ b/crates/cxx-qt-lib/src/core/qtlogging.rs
@@ -36,6 +36,21 @@ 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 q_format_log_message(
+            msgType: QtMsgType,
+            context: &QMessageLogContext,
+            string: &QString,
+        ) -> QString;
+
+        /// Changes the output of the default message handler.
+        ///
+        /// # Safety
+        /// This function is marked as unsafe because it is not guaranteed to be thread-safe.
+        #[cxx_name = "qSetMessagePattern"]
+        unsafe fn q_set_message_pattern(pattern: &QString);
+
         #[cxx_name = "qmessagelogcontext_line"]
         #[doc(hidden)]
         fn line(context: &QMessageLogContext) -> i32;
@@ -131,4 +146,4 @@ unsafe impl ExternType for QMessageLogContext<'_> {
 }
 
 use crate::const_assert;
-pub use ffi::{qt_message_output, QtMsgType};
+pub use ffi::{q_format_log_message, q_set_message_pattern, qt_message_output, QtMsgType};