iOS: Compute screen available geometry based on safe area insets

In addition to the (deprecated) applicationFrame property, we
base the available geometry on the root view's safe area, which
also takes into account system-reserved areas on iPhone X, and
the screen's bezel in the case of tvOS.

Change-Id: I252d960a0e486dd0c7e30843f88c0bf5684feb24
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

3 files changed, 41 insertions, 5 deletions

diff --git a/src/plugins/platforms/ios/qiosscreen.mm b/src/plugins/platforms/ios/qiosscreen.mm
index 74e81dedf4..1a7004c249 100644
--- a/src/plugins/platforms/ios/qiosscreen.mm
+++ b/src/plugins/platforms/ios/qiosscreen.mm
@@ -175,6 +175,21 @@ static QIOSScreen* qtPlatformScreenFor(UIScreen *uiScreen)
 
 @end
 
+@interface UIScreen (Compatibility)
+@property (nonatomic, readonly) CGRect qt_applicationFrame;
+@end
+
+@implementation UIScreen (Compatibility)
+- (CGRect)qt_applicationFrame
+{
+#ifdef Q_OS_IOS
+    return self.applicationFrame;
+#else
+    return self.bounds;
+#endif
+}
+@end
+
 // -------------------------------------------------------------------------
 
 QT_BEGIN_NAMESPACE
@@ -271,11 +286,15 @@ void QIOSScreen::updateProperties()
     QRect previousAvailableGeometry = m_availableGeometry;
 
     m_geometry = QRectF::fromCGRect(m_uiScreen.bounds).toRect();
-#ifdef Q_OS_TVOS
-    m_availableGeometry = m_geometry;
-#else
-    m_availableGeometry = QRectF::fromCGRect(m_uiScreen.applicationFrame).toRect();
-#endif
+
+    // The application frame doesn't take safe area insets into account, and
+    // the safe area insets are not available before the UIWindow is shown,
+    // and do not take split-view constraints into account, so we have to
+    // combine the two to get the correct available geometry.
+    QRect applicationFrame = QRectF::fromCGRect(m_uiScreen.qt_applicationFrame).toRect();
+    UIEdgeInsets safeAreaInsets = m_uiWindow.qt_safeAreaInsets;
+    m_availableGeometry = m_geometry.adjusted(safeAreaInsets.left, safeAreaInsets.top,
+        -safeAreaInsets.right, -safeAreaInsets.bottom).intersected(applicationFrame);
 
 #ifndef Q_OS_TVOS
     if (m_uiScreen == [UIScreen mainScreen]) {
diff --git a/src/plugins/platforms/ios/quiview.h b/src/plugins/platforms/ios/quiview.h
index 1500f0b41c..1ce9007a35 100644
--- a/src/plugins/platforms/ios/quiview.h
+++ b/src/plugins/platforms/ios/quiview.h
@@ -77,5 +77,6 @@ QT_END_NAMESPACE
 - (QWindow *)qwindow;
 - (UIViewController *)viewController;
 - (QIOSViewController*)qtViewController;
+@property (nonatomic, readonly) UIEdgeInsets qt_safeAreaInsets;
 @end
 
diff --git a/src/plugins/platforms/ios/quiview.mm b/src/plugins/platforms/ios/quiview.mm
index a405fecee2..79f9d6871a 100644
--- a/src/plugins/platforms/ios/quiview.mm
+++ b/src/plugins/platforms/ios/quiview.mm
@@ -545,6 +545,22 @@
     return nil;
 }
 
+- (UIEdgeInsets)qt_safeAreaInsets
+{
+#if QT_DARWIN_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_NA, 110000, 110000, __WATCHOS_NA)
+    if (__builtin_available(iOS 11, tvOS 11, *))
+        return self.safeAreaInsets;
+#endif
+
+    // Fallback for iOS < 11
+    UIEdgeInsets safeAreaInsets = UIEdgeInsetsZero;
+    CGPoint topInset = [self convertPoint:CGPointMake(0, self.viewController.topLayoutGuide.length) fromView:nil];
+    CGPoint bottomInset = [self convertPoint:CGPointMake(0, self.viewController.bottomLayoutGuide.length) fromView:nil];
+    safeAreaInsets.top = topInset.y;
+    safeAreaInsets.bottom = bottomInset.y;
+    return safeAreaInsets;
+}
+
 @end
 
 #ifndef QT_NO_ACCESSIBILITY