Hi.
I’m developing a plugin to be loaded by a music software host (VST). There are
some lighter alternatives to provide graphics, network and other kinds of
useful resources but I want to use Qt. I simply Love Qt!
When the plugin is open by the host, it provides a window ref to the plugin. On
Window it is a HWND handle, on Mac it is supposedly a WindowRef.
I have a working prototype for Windows. I don’t think it is all correct but its
working. When the plugin is first started I check for the existence of a
QApplication and start one if not.
Then I create the main controller for my plugin and the QQuickView to draw on
the window. To create the QQuickView i’m first creating a QWindow with the ptr
to HWND handle as parent:
window = QWindow::fromWinId((WId)ptr);
view = new QQuickView(window);
view->setSource(QUrl("qrc:/qml/vstmain.qml"));
view->rootContext()->setContextProperty("controller", _controller);
view->show();
This is actually working quite well on Windows. The same strategy however,
doesn’t work on a Mac. When I try to create a QWindow::fromWinId the result is
a crash with the following stack trace:
2015-09-16 14:26:18.526 Live[91339:1091079] -[NSHIObject
setPostsFrameChangedNotifications:]: unrecognized selector sent to instance
0x19806da0
- The first question is: what is QWindow::fromWinId is expecting to be able to
create a window? An NSView?
- The second question is: the stack trace says that NSHIObject didn’t
recognized the selector setPostsFrameChangedNotifications. What is a
NSHIObject? I can only find references to HIObject from the HIToolbox and that
belongs to the Carbon frame work. So far I haven’t been able to call Carbon
methods inside my Qt environment even referencing -framework Carbon
- Third question: On window I have an issue with the QApplication args and
argv. On debug, there is an ASSERT that says that origArgc is different from
the actual argc/argv. On release mode it crashes. Why does QApplication needs
to receive the exact same arguments as the initial app?
- Fourth question: how should I keep my run loop running without depending on
the host? On Windows I have created a windows thread to call qApp->exec().
Although a warning that exec should be called on main thread it WORKS! How safe
is this? Is there any other recommended option? What about Mac OS X?
I have been google a lot specially about the NSHIObject and I can’t find an
answer, not even a simple lead. The closest I have is vstgui, a GUI framework
for VST plugins that has open source code and support for Carbon and Cocoa
backends but the NSHIObject is intriguing me because I can’t find any explicit
reference on how to deal with it.
Any thoughts would be high appreciated.
Thanks in advance,
With my best regards,
Nuno_______________________________________________
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