Cocoa: Fix popup window positioning.

Popup window positions where offset on retina MacBooks
with an connected external monitor.

Fix this by cleaning up the coordinate conversion 
functions:
    
Remove the qt_mac_flipRect overload which tries
to position the window according screen size. This
functionality does not belong inside a coordinate/
type conversion function. Also, it was using the windows's
screen instead of the main screen which is incorrect.

"Y flipping": Use the height of the first screen in
[NSScreen screens], which is documented to always
be the screen that contains the coordinate system
origin. Remove the usages of QApplication::primaryScreen()
("Don't use Qt to implement Qt").

Task-number: QTBUG-36672
Change-Id: I2354d31361f5a4c2c80035cf4c7def939218406f
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>

3 files changed, 41 insertions, 53 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoahelpers.h b/src/plugins/platforms/cocoa/qcocoahelpers.h
index 893aa4408a..3b72184d83 100644
--- a/src/plugins/platforms/cocoa/qcocoahelpers.h
+++ b/src/plugins/platforms/cocoa/qcocoahelpers.h
@@ -103,23 +103,13 @@ CGColorSpaceRef qt_mac_displayColorSpace(const QWidget *widget);
 CGColorSpaceRef qt_mac_colorSpaceForDeviceType(const QPaintDevice *paintDevice);
 QString qt_mac_applicationName();
 
-inline int qt_mac_flipYCoordinate(int y)
-{ return QGuiApplication::primaryScreen()->geometry().height() - y; }
-
-inline qreal qt_mac_flipYCoordinate(qreal y)
-{ return QGuiApplication::primaryScreen()->geometry().height() - y; }
-
-inline QPointF qt_mac_flipPoint(const NSPoint &p)
-{ return QPointF(p.x, qt_mac_flipYCoordinate(p.y)); }
-
-inline NSPoint qt_mac_flipPoint(const QPoint &p)
-{ return NSMakePoint(p.x(), qt_mac_flipYCoordinate(p.y())); }
-
-inline NSPoint qt_mac_flipPoint(const QPointF &p)
-{ return NSMakePoint(p.x(), qt_mac_flipYCoordinate(p.y())); }
+int qt_mac_flipYCoordinate(int y);
+qreal qt_mac_flipYCoordinate(qreal y);
+QPointF qt_mac_flipPoint(const NSPoint &p);
+NSPoint qt_mac_flipPoint(const QPoint &p);
+NSPoint qt_mac_flipPoint(const QPointF &p);
 
 NSRect qt_mac_flipRect(const QRect &rect);
-NSRect qt_mac_flipRect(const QRect &rect, QWindow *window);
 
 Qt::MouseButton cocoaButton2QtButton(NSInteger buttonNum);
 
diff --git a/src/plugins/platforms/cocoa/qcocoahelpers.mm b/src/plugins/platforms/cocoa/qcocoahelpers.mm
index 9b3198224e..8975605e5c 100644
--- a/src/plugins/platforms/cocoa/qcocoahelpers.mm
+++ b/src/plugins/platforms/cocoa/qcocoahelpers.mm
@@ -595,44 +595,42 @@ QString qt_mac_applicationName()
     return appName;
 }
 
-NSRect qt_mac_flipRect(const QRect &rect)
+int qt_mac_mainScreenHeight()
 {
-    int flippedY = qt_mac_flipYCoordinate(rect.y() + rect.height());
-    return NSMakeRect(rect.x(), flippedY, rect.width(), rect.height());
+    // The first screen in the screens array is documented
+    // to have the (0,0) origin.
+    NSRect screenFrame = [[[NSScreen screens] firstObject] frame];
+    return screenFrame.size.height;
 }
 
-/*
-    Mac window coordinates are in the first quadrant: 0, 0 is at the lower-left
-    corner of the primary screen. This function converts the given rect to an
-    NSRect for the window geometry, flipping from 4th quadrant to 1st quadrant
-    and simultaneously ensuring that as much of the window as possible will be
-    onscreen. If the rect is too tall for the screen, the OS will reduce the
-    window's height anyway; but by moving the window upwards we can have more
-    of it onscreen.  But the application can still control the y coordinate
-    in case it really wants the window to be positioned partially offscreen.
-*/
-NSRect qt_mac_flipRect(const QRect &rect, QWindow *window)
-{
-    QPlatformScreen *onScreen = QPlatformScreen::platformScreenForWindow(window);
-    int flippedY = onScreen->geometry().height() - (rect.y() + rect.height());
-    QList<QScreen *> screens = QGuiApplication::screens();
-    if (screens.size() > 1) {
-        int height = 0;
-        foreach (QScreen *scr, screens)
-            height = qMax(height, scr->size().height());
-        int difference = height - onScreen->geometry().height();
-        if (difference > 0)
-            flippedY += difference;
-        else
-            flippedY -= difference;
-    }
-    // In case of automatic positioning, try to put as much of the window onscreen as possible.
-    if (window->isTopLevel() && qt_window_private(const_cast<QWindow*>(window))->positionAutomatic && flippedY < 0)
-        flippedY = onScreen->geometry().height() - onScreen->availableGeometry().height() - onScreen->availableGeometry().y();
-#ifdef QT_COCOA_ENABLE_WINDOW_DEBUG
-    qDebug() << Q_FUNC_INFO << rect << "flippedY" << flippedY <<
-                "screen" << onScreen->geometry() << "available" << onScreen->availableGeometry();
-#endif
+int qt_mac_flipYCoordinate(int y)
+{
+    return qt_mac_mainScreenHeight() - y;
+}
+
+qreal qt_mac_flipYCoordinate(qreal y)
+{
+    return qt_mac_mainScreenHeight() - y;
+}
+
+QPointF qt_mac_flipPoint(const NSPoint &p)
+{
+    return QPointF(p.x, qt_mac_flipYCoordinate(p.y));
+}
+
+NSPoint qt_mac_flipPoint(const QPoint &p)
+{
+    return NSMakePoint(p.x(), qt_mac_flipYCoordinate(p.y()));
+}
+
+NSPoint qt_mac_flipPoint(const QPointF &p)
+{
+    return NSMakePoint(p.x(), qt_mac_flipYCoordinate(p.y()));
+}
+
+NSRect qt_mac_flipRect(const QRect &rect)
+{
+    int flippedY = qt_mac_flipYCoordinate(rect.y() + rect.height());
     return NSMakeRect(rect.x(), flippedY, rect.width(), rect.height());
 }
 
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 9321c1a48b..bf41270d12 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -392,7 +392,7 @@ void QCocoaWindow::setCocoaGeometry(const QRect &rect)
         QWindowSystemInterface::handleGeometryChange(window(), rect);
         QWindowSystemInterface::handleExposeEvent(window(), rect);
     } else if (m_nsWindow) {
-        NSRect bounds = qt_mac_flipRect(rect, window());
+        NSRect bounds = qt_mac_flipRect(rect);
         [m_nsWindow setFrame:[m_nsWindow frameRectForContentRect:bounds] display:YES animate:NO];
     } else {
         [m_contentView setFrame : NSMakeRect(rect.x(), rect.y(), rect.width(), rect.height())];
@@ -418,7 +418,7 @@ void QCocoaWindow::clipWindow(const NSRect &clipRect)
 
     NSRect clippedWindowRect = NSZeroRect;
     if (!NSIsEmptyRect(clipRect)) {
-        NSRect windowFrame = qt_mac_flipRect(QRect(window()->mapToGlobal(QPoint(0, 0)), geometry().size()), window());
+        NSRect windowFrame = qt_mac_flipRect(QRect(window()->mapToGlobal(QPoint(0, 0)), geometry().size()));
         clippedWindowRect = NSIntersectionRect(windowFrame, clipRect);
         // Clipping top/left offsets the content. Move it back.
         NSPoint contentViewOffset = NSMakePoint(qMax(CGFloat(0), NSMinX(clippedWindowRect) - NSMinX(windowFrame)),
@@ -1208,7 +1208,7 @@ NSWindow * QCocoaWindow::createNSWindow()
     QCocoaAutoReleasePool pool;
 
     QRect rect = initialGeometry(window(), window()->geometry(), defaultWindowWidth, defaultWindowHeight);
-    NSRect frame = qt_mac_flipRect(rect, window());
+    NSRect frame = qt_mac_flipRect(rect);
 
     Qt::WindowType type = window()->type();
     Qt::WindowFlags flags = window()->flags();