Cocoa: support modal windows

Qt::WindowModal windows and dialogs are shown using [NSApp
beginSheet:modalForWindow:modalDelegate:didEndSelector:contextInfo:] as
long as they have a valid parent. Otherwise they are behave as
application modal.

Use the existing modal session support in the QCocoaEventDispatcher
(which was inherited from Qt 4) to support Qt::ApplicationModal
windows and dialogs. Some changes to this code are needed to ensure
proper behavior:

1. Window level modification is now done in
QCocoaWindow::recreateWindow() instead of in QCocoaEventDispatcher.
2. Make interrupt() use [NSApp abortModal] to stop a modal session
(previously we were freeing memory from under Cocoa's feet, causing
tools like valgrind and Instruments.app to complain)
3. Do not remove an item from a list and use a const reference to the
removed item immediately after (minor bug fix).

Also make sure that QCocoaEventDispatcher cleans up any modal sessions
and retained user input events on destruction (otherwise we leave
NSApplication in a weird state, which causes some autotest failures).

Change-Id: Iaeefa025400f324b5348b8c81a40384ef026efb4
Reviewed-by: Morten Johan Sørvig <morten.sorvig@nokia.com>

4 files changed, 98 insertions, 32 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h
index c28cfc5e56..4be30c44ed 100644
--- a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h
+++ b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.h
@@ -177,9 +177,10 @@ public:
     void temporarilyStopAllModalSessions();
     void beginModalSession(QWindow *widget);
     void endModalSession(QWindow *widget);
+    void cleanupModalSessions();
+
     void cancelWaitForMoreEvents();
     void maybeCancelWaitForMoreEvents();
-    void cleanupModalSessions();
     void ensureNSAppInitialized();
 
     MacSocketHash macSockets;
diff --git a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
index 7a1e485079..a3bd4a95ca 100644
--- a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
+++ b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
@@ -82,6 +82,7 @@
 #include "qmutex.h"
 #include "qsocketnotifier.h"
 #include <qplatformwindow_qpa.h>
+#include <qplatformnativeinterface_qpa.h>
 #include "private/qthread_p.h"
 #include "private/qguiapplication_p.h"
 #include <qdebug.h>
@@ -781,26 +782,18 @@ NSModalSession QCocoaEventDispatcherPrivate::currentModalSession()
         QCocoaModalSessionInfo &info = cocoaModalSessionStack[i];
         if (!info.window)
             continue;
-//     ### port
-//        if (info.window->testAttribute(Qt::WA_DontShowOnScreen))
-//            continue;
 
         if (!info.session) {
             QCocoaAutoReleasePool pool;
-            NSWindow *window = reinterpret_cast<NSWindow *>(info.window->handle()->winId());
-            if (!window)
+            NSWindow *nswindow = static_cast<NSWindow *>(QGuiApplication::platformNativeInterface()->nativeResourceForWindow("nswindow", info.window));
+            if (!nswindow)
                 continue;
 
             ensureNSAppInitialized();
             QBoolBlocker block1(blockSendPostedEvents, true);
-            info.nswindow = window;
+            info.nswindow = nswindow;
             [(NSWindow*) info.nswindow retain];
-            int levelBeforeEnterModal = [window level];
-            info.session = [NSApp beginModalSessionForWindow:window];
-            // Make sure we don't stack the window lower that it was before
-            // entering modal, in case it e.g. had the stays-on-top flag set:
-            if (levelBeforeEnterModal > [window level])
-                [window setLevel:levelBeforeEnterModal];
+            info.session = [NSApp beginModalSessionForWindow:nswindow];
         }
         currentModalSessionCached = info.session;
         cleanupModalSessionsNeeded = false;
@@ -869,12 +862,14 @@ void QCocoaEventDispatcherPrivate::cleanupModalSessions()
             currentModalSessionCached = info.session;
             break;
         }
-        cocoaModalSessionStack.remove(i);
         currentModalSessionCached = 0;
         if (info.session) {
+            Q_ASSERT(info.nswindow != 0);
             [NSApp endModalSession:info.session];
             [(NSWindow *)info.nswindow release];
         }
+        // remove the info now that we are finished with it
+        cocoaModalSessionStack.remove(i);
     }
 
     updateChildrenWorksWhenModal();
@@ -883,6 +878,14 @@ void QCocoaEventDispatcherPrivate::cleanupModalSessions()
 
 void QCocoaEventDispatcherPrivate::beginModalSession(QWindow *window)
 {
+    // We need to start spinning the modal session. Usually this is done with
+    // QDialog::exec() for QtWidgets based applications, but for others that
+    // just call show(), we need to interrupt(). We call this here, before
+    // setting currentModalSessionCached to zero, so that interrupt() calls
+    // [NSApp abortModal] if another modal session is currently running
+    Q_Q(QCocoaEventDispatcher);
+    q->interrupt();
+
     // Add a new, empty (null), NSModalSession to the stack.
     // It will become active the next time QEventDispatcher::processEvents is called.
     // A QCocoaModalSessionInfo is considered pending to become active if the window pointer
@@ -898,6 +901,8 @@ void QCocoaEventDispatcherPrivate::beginModalSession(QWindow *window)
 
 void QCocoaEventDispatcherPrivate::endModalSession(QWindow *window)
 {
+    Q_Q(QCocoaEventDispatcher);
+
     // Mark all sessions attached to window as pending to be stopped. We do this
     // by setting the window pointer to zero, but leave the session pointer.
     // We don't tell cocoa to stop any sessions just yet, because cocoa only understands
@@ -909,11 +914,14 @@ void QCocoaEventDispatcherPrivate::endModalSession(QWindow *window)
         if (info.window == window) {
             info.window = 0;
             if (i == stackSize-1) {
-                // The top sessions ended. Interrupt the event dispatcher
-                // to start spinning the correct session immidiatly: 
+                // The top sessions ended. Interrupt the event dispatcher to
+                // start spinning the correct session immediately. Like in
+                // beginModalSession(), we call interrupt() before clearing
+                // currentModalSessionCached to make sure we stop any currently
+                // running modal session with [NSApp abortModal]
+                q->interrupt();
                 currentModalSessionCached = 0;
                 cleanupModalSessionsNeeded = true;
-                QCocoaEventDispatcher::instance()->interrupt();
             }
         }
     }
@@ -1093,16 +1101,23 @@ void QCocoaEventDispatcher::interrupt()
 {
     Q_D(QCocoaEventDispatcher);
     d->interrupt = true;
-    wakeUp();
-
-    // We do nothing more here than setting d->interrupt = true, and
-    // poke the event loop if it is sleeping. Actually stopping
-    // NSApp, or the current modal session, is done inside the send
-    // posted events callback. We do this to ensure that all current pending
-    // cocoa events gets delivered before we stop. Otherwise, if we now stop
-    // the last event loop recursion, cocoa will just drop pending posted
-    // events on the floor before we get a chance to reestablish a new session.
-    d->cancelWaitForMoreEvents();
+    if (d->currentModalSessionCached) {
+        // If a modal session is active, abort it so that we can clean it up
+        // later. We can't use [NSApp stopModal] here, because we do not know
+        // where the interrupt() came from.
+        [NSApp abortModal];
+    } else {
+        wakeUp();
+
+        // We do nothing more here than setting d->interrupt = true, and
+        // poke the event loop if it is sleeping. Actually stopping
+        // NSApp, or the current modal session, is done inside the send
+        // posted events callback. We do this to ensure that all current pending
+        // cocoa events gets delivered before we stop. Otherwise, if we now stop
+        // the last event loop recursion, cocoa will just drop pending posted
+        // events on the floor before we get a chance to reestablish a new session.
+        d->cancelWaitForMoreEvents();
+    }
 }
 
 void QCocoaEventDispatcher::flush()
@@ -1117,6 +1132,21 @@ QCocoaEventDispatcher::~QCocoaEventDispatcher()
     CFRunLoopRemoveSource(mainRunLoop(), d->activateTimersSourceRef, kCFRunLoopCommonModes);
     CFRelease(d->activateTimersSourceRef);
 
+    // end all modal sessions
+    for (int i = 0; i < d->cocoaModalSessionStack.count(); ++i) {
+        QCocoaModalSessionInfo &info = d->cocoaModalSessionStack[i];
+        if (info.session) {
+            [NSApp endModalSession:info.session];
+            [(NSWindow *)info.nswindow release];
+        }
+    }
+
+    // release all queued user input events
+    for (int i = 0; i < d->queuedUserInputEvents.count(); ++i) {
+        NSEvent *nsevent = static_cast<NSEvent *>(d->queuedUserInputEvents.at(i));
+        [nsevent release];
+    }
+
     // Remove CFSockets from the runloop.
     for (MacSocketHash::ConstIterator it = d->macSockets.constBegin(); it != d->macSockets.constEnd(); ++it) {
         MacSocketInfo *socketInfo = (*it);
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.h b/src/plugins/platforms/cocoa/qcocoawindow.h
index b709f384d5..cbcdbcbded 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.h
+++ b/src/plugins/platforms/cocoa/qcocoawindow.h
@@ -144,6 +144,8 @@ public: // for QNSView
 
     bool m_inConstructor;
     QCocoaGLContext *m_glContext;
+
+    bool m_hasModalSession;
 };
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 5c8ea055b5..32c87e752a 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -41,6 +41,7 @@
 #include "qcocoawindow.h"
 #include "qnswindowdelegate.h"
 #include "qcocoaautoreleasepool.h"
+#include "qcocoaeventdispatcher.h"
 #include "qcocoaglcontext.h"
 #include "qcocoahelpers.h"
 #include "qnsview.h"
@@ -98,6 +99,7 @@ QCocoaWindow::QCocoaWindow(QWindow *tlw)
     , m_nsWindow(0)
     , m_inConstructor(true)
     , m_glContext(0)
+    , m_hasModalSession(false)
 {
     QCocoaAutoReleasePool pool;
 
@@ -145,7 +147,10 @@ void QCocoaWindow::setVisible(bool visible)
     qDebug() << "QCocoaWindow::setVisible" << window() << visible;
 #endif
     if (visible) {
+        QCocoaWindow *parentCocoaWindow = 0;
         if (window()->transientParent()) {
+            parentCocoaWindow = static_cast<QCocoaWindow *>(window()->transientParent()->handle());
+
             // The parent window might have moved while this window was hidden,
             // update the window geometry if there is a parent.
             setGeometry(window()->geometry());
@@ -154,8 +159,6 @@ void QCocoaWindow::setVisible(bool visible)
             // close them when needed.
             if (window()->windowType() == Qt::Popup) {
                 // qDebug() << "transientParent and popup" << window()->windowType() << Qt::Popup << (window()->windowType() & Qt::Popup);
-
-                QCocoaWindow *parentCocoaWindow = static_cast<QCocoaWindow *>(window()->transientParent()->handle());
                 parentCocoaWindow->m_activePopupWindow = window();
             }
 
@@ -170,16 +173,40 @@ void QCocoaWindow::setVisible(bool visible)
             syncWindowState(window()->windowState());
 
             if (window()->windowState() != Qt::WindowMinimized) {
-                if ([m_nsWindow canBecomeKeyWindow])
+                if ((window()->windowModality() == Qt::WindowModal
+                     || window()->windowType() == Qt::Sheet)
+                        && parentCocoaWindow) {
+                    // show the window as a sheet
+                    [NSApp beginSheet:m_nsWindow modalForWindow:parentCocoaWindow->m_nsWindow modalDelegate:nil didEndSelector:nil contextInfo:nil];
+                } else if (window()->windowModality() != Qt::NonModal) {
+                    // show the window as application modal
+                    QCocoaEventDispatcher *cocoaEventDispatcher = qobject_cast<QCocoaEventDispatcher *>(QGuiApplication::instance()->eventDispatcher());
+                    Q_ASSERT(cocoaEventDispatcher != 0);
+                    QCocoaEventDispatcherPrivate *cocoaEventDispatcherPrivate = static_cast<QCocoaEventDispatcherPrivate *>(QObjectPrivate::get(cocoaEventDispatcher));
+                    cocoaEventDispatcherPrivate->beginModalSession(window());
+                    m_hasModalSession = true;
+                } else if ([m_nsWindow canBecomeKeyWindow]) {
                     [m_nsWindow makeKeyAndOrderFront:nil];
-                else
+                } else {
                     [m_nsWindow orderFront: nil];
+                }
             }
         }
     } else {
         // qDebug() << "close" << this;
-        if (m_nsWindow)
+        if (m_nsWindow) {
+            if (m_hasModalSession) {
+                QCocoaEventDispatcher *cocoaEventDispatcher = qobject_cast<QCocoaEventDispatcher *>(QGuiApplication::instance()->eventDispatcher());
+                Q_ASSERT(cocoaEventDispatcher != 0);
+                QCocoaEventDispatcherPrivate *cocoaEventDispatcherPrivate = static_cast<QCocoaEventDispatcherPrivate *>(QObjectPrivate::get(cocoaEventDispatcher));
+                cocoaEventDispatcherPrivate->endModalSession(window());
+                m_hasModalSession = false;
+            } else {
+                if ([m_nsWindow isSheet])
+                    [NSApp endSheet:m_nsWindow];
+            }
             [m_nsWindow orderOut:m_nsWindow];
+        }
         if (!QCoreApplication::closingDown())
             QWindowSystemInterface::handleExposeEvent(window(), QRegion());
     }
@@ -363,6 +390,12 @@ void QCocoaWindow::recreateWindow(const QPlatformWindow *parentWindow)
         // Create a new NSWindow if this is a top-level window.
         m_nsWindow = createNSWindow();
         setNSWindow(m_nsWindow);
+
+        if (window()->transientParent()) {
+            // keep this window on the same level as its transient parent (which may be a modal dialog, for example)
+            QCocoaWindow *parentCocoaWindow = static_cast<QCocoaWindow *>(window()->transientParent()->handle());
+            [m_nsWindow setLevel:[parentCocoaWindow->m_nsWindow level]];
+        }
     } else {
         // Child windows have no NSWindow, link the NSViews instead.
         const QCocoaWindow *parentCococaWindow = static_cast<const QCocoaWindow *>(parentWindow);