Make QGuiApplication::exec() run within NSApplicationMain()

We follow the same pattern as for iOS and Windows ports, making
sure the user's main() runs in a platform friendly environment. In
this particular case, it means calling the user's main() during the
call of NSApplicationMain(), and calling the user's main() function
(renamed to qMain() as in Windows) after receiving
NSApplicationDidFinishLaunchingNotification. In practice, this means
that NSApp is running when qMain() is called, and therefore when
QCoreApplication::exec() is called.

For those command-line utilities running on QGuiApplication, or any
deriving class, and that do not provide a bundle, we override the main
bundle's dictionary and get NSApplicationMain() to run as usual.

Added cocoa/cocoamain "subdir" to build libqtcocoamain.a (together with
cocoa/cocoaplugin -- plugins/platforms/cocoa is made a subdirs project).
This library is linked against all GUI Qt apps and provides the actual
main() function. It also catches the launching NSApplication notifications,
and calls the user's qMain() function. Note that this will happen in the
same cases when the user's application will run with the Cocoa QPA plugin.

Launch related code in QCocoaApplicationDelegate is moved to libqtcocoamain,
QNSApplication is removed (but sendEvent: redirection still there), and
code in QCocoaEventDispatcher dealing with calling [NSApp run] and related
has been removed since it's become unreachable.

ChangeLog: [Qt for Mac] Make QGuiApplication::exec() run within NSApplicationMain()
Change-Id: I790e5138c29aac2e0215a9147d0148fece40ca22
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>

1 files changed, 15 insertions, 31 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoaapplication.mm b/src/plugins/platforms/cocoa/qcocoaapplication.mm
index c293f4cd52..cf9644fe9b 100644
--- a/src/plugins/platforms/cocoa/qcocoaapplication.mm
+++ b/src/plugins/platforms/cocoa/qcocoaapplication.mm
@@ -83,6 +83,8 @@
 
 QT_USE_NAMESPACE
 
+static SEL qt_sendEvent_original_SEL = @selector(qt_sendEvent_original:);
+
 @implementation NSApplication (QT_MANGLE_NAMESPACE(QApplicationIntegration))
 
 - (void)QT_MANGLE_NAMESPACE(qt_setDockMenu):(NSMenu *)newMenu
@@ -153,34 +155,22 @@ static const QByteArray q_macLocalEventType = QByteArrayLiteral("mac_generic_NSE
     return false;
 }
 
-@end
-
-@implementation QNSApplication
-
-- (void)qt_sendEvent_original:(NSEvent *)event
+- (BOOL)qt_filterOrSendEvent:(NSEvent *)event
 {
-    Q_UNUSED(event);
-    // This method will only be used as a signature
-    // template for the method we add into NSApplication
-    // containing the original [NSApplication sendEvent:] implementation
+    if ([self qt_filterEvent:event])
+        return false;
+
+    Q_ASSERT_X([self respondsToSelector:qt_sendEvent_original_SEL], "qt_filterOrSendEvent:",
+            "Running event loop before calling qt_redirectNSApplicationSendEvent()");
+    [self performSelector:qt_sendEvent_original_SEL withObject:event];
+    return true;
 }
 
 - (void)qt_sendEvent_replacement:(NSEvent *)event
 {
     // This method (or its implementation to be precise) will
-    // be called instead of sendEvent if redirection occurs.
-    // 'self' will then be an instance of NSApplication
-    // (and not QNSApplication)
-    if (![NSApp qt_filterEvent:event])
-        [self qt_sendEvent_original:event];
-}
-
-- (void)sendEvent:(NSEvent *)event
-{
-    // This method will be called if
-    // no redirection occurs
-    if (![NSApp qt_filterEvent:event])
-        [super sendEvent:event];
+    // be called instead of sendEvent: after redirection occurs.
+    [self qt_filterOrSendEvent:event];
 }
 
 @end
@@ -189,22 +179,16 @@ QT_BEGIN_NAMESPACE
 
 void qt_redirectNSApplicationSendEvent()
 {
-    if ([NSApp isMemberOfClass:[QNSApplication class]]) {
-        // No need to change implementation since Qt
-        // already controls a subclass of NSApplication
-        return;
-    }
-
     // Change the implementation of [NSApplication sendEvent] to the
-    // implementation of qt_sendEvent_replacement found in QNSApplication.
+    // implementation of qt_sendEvent_replacement.
     // And keep the old implementation that gets overwritten inside a new
     // method 'qt_sendEvent_original' that we add to NSApplication
     qt_cocoa_change_implementation(
             [NSApplication class],
             @selector(sendEvent:),
-            [QNSApplication class],
+            [NSApplication class],
             @selector(qt_sendEvent_replacement:),
-            @selector(qt_sendEvent_original:));
+            qt_sendEvent_original_SEL);
  }
 
 void qt_resetNSApplicationSendEvent()