From 4a7c9cea9bb384492b518eb0bff1487627174514 Mon Sep 17 00:00:00 2001 From: mappu Date: Sat, 11 Jan 2025 16:12:47 +1300 Subject: [PATCH] doc/README: add notes on unsafePointer() widget comparisons --- README.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/README.md b/README.md index 38f63e42..b5a489d1 100644 --- a/README.md +++ b/README.md @@ -96,6 +96,8 @@ Qt class inherited types are projected as a Go embedded struct. For example, to - When a Qt subclass adds a method overload (e.g. `QMenu::addAction(QString)` vs `QWidget::addAction(QAction*)`), the base class version is shadowed and can only be called via `myQMenu.QWidget.AddAction(QAction*)`. +- A MIQT pointer points to a Go struct, not to the raw C++ Qt widget class. Therefore `QTabWidget.CurrentWidget() == MyTab` will never compare equal because `CurrentWidget()` created a new Go struct wrapping the same C++ pointer. You can compare `QTabWidget.CurrentIndex()`, or, you can use: `QTabWidget.CurrentWidget().UnsafePointer() == MyTab.UnsafePointer()`. + The Go runtime migrates goroutines between OS threads, but Qt expects fixed OS threads to be used for each QObject. When you first call `qt.NewQApplication` in MIQT, that will be considered the [Qt main thread](https://doc.qt.io/qt-6/thread-basics.html#gui-thread-and-worker-thread) and will automatically signal the Go runtime to bind to a fixed OS thread using `runtime.LockOSThread()`. - When accessing Qt objects from inside another goroutine, it's safest to use `(qt6/mainthread).Wait()` to access the Qt objects from Qt's main thread.