QMacNativeWidget Class

Detailed Description

The QMacNativeWidget class provides a widget for macOS that provides a way to put Qt widgets into Cocoa hierarchies.

On macOS, there is a difference between a window and view; normally expressed as widgets in Qt. Qt makes assumptions about its parent-child hierarchy that make it complex to put an arbitrary Qt widget into a hierarchy of "normal" views from Apple frameworks. QMacNativeWidget bridges the gap between views and windows and makes it possible to put a hierarchy of Qt widgets into a non-Qt window or view.

QMacNativeWidget pretends it is a window (i.e. isWindow() will return true), but it cannot be shown on its own. It needs to be put into a window when it is created or later through a native call.

Here is an example showing how to put a QPushButton into a NSWindow:

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSWindow *window = [[NSWindow alloc] initWithContentRect:NSMakeRect(200, app.desktop()->height() - 200, 239, 200)
                        styleMask:NSTitledWindowMask | NSClosableWindowMask
                                  | NSMiniaturizableWindowMask | NSResizableWindowMask
                        backing:NSBackingStoreBuffered defer:NO];

    QMacNativeWidget *nativeWidget = new QMacNativeWidget();
    nativeWidget->move(0, 0);
    nativeWidget->setPalette(QPalette(Qt::red));
    nativeWidget->setAutoFillBackground(true);
    QVBoxLayout *layout = new QVBoxLayout();
    QPushButton *pushButton = new QPushButton("An Embedded Qt Button!", nativeWidget);
    pushButton->setAttribute(Qt::WA_LayoutUsesWidgetRect); // Don't use the layout rect calculated from QMacStyle.
    layout->addWidget(pushButton);
    nativeWidget->setLayout(layout);

    // Adjust Cocoa layouts
    NSView *nativeWidgetView = reinterpret_cast<NSView *>(nativeWidget->winId());
    NSView *contentView = [window contentView];
    [contentView setAutoresizesSubviews:YES];
    [nativeWidgetView setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
    [nativeWidgetView setAutoresizesSubviews:YES];
    NSView *pushButtonView = reinterpret_cast<NSView *>(pushButton->winId());
    [pushButtonView setAutoresizingMask:NSViewWidthSizable];

    // Add the nativeWidget to the window.
    [contentView addSubview:nativeWidgetView positioned:NSWindowAbove relativeTo:nil];
    nativeWidget->show();
    pushButton->show();

    // Show the window.
    [window makeKeyAndOrderFront:window];
    [pool release];

Note that QMacNativeWidget requires knowledge of Cocoa. All it does is get the Qt hierarchy into a window not owned by Qt. It is then up to the programmer to ensure it is placed correctly in the window and responds correctly to events.