iOS: Detect external screen connections and expose as additional QScreen

The additional QScreen can not be used for anything yet, since we don't
set up a window and root view controller for it.

Change-Id: I335b796bdd89fc58a27ec4e20c5ed355be0cab66
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

src/plugins/platforms/ios/qiosintegration.h

@@ -84,13 +84,14 @@ public:
     QTouchDevice *touchDevice();
     QPlatformAccessibility *accessibility() const Q_DECL_OVERRIDE;
 
+    void addScreen(QPlatformScreen *screen) { screenAdded(screen); }
+
     static QIOSIntegration *instance();
 
 private:
     QPlatformFontDatabase *m_fontDatabase;
     QPlatformClipboard *m_clipboard;
     QPlatformInputContext *m_inputContext;
-    QPlatformScreen *m_screen;
     QTouchDevice *m_touchDevice;
     QIOSApplicationState m_applicationState;
     QIOSServices *m_platformServices;

src/plugins/platforms/ios/qiosintegration.mm

@@ -73,7 +73,6 @@ QIOSIntegration::QIOSIntegration()
     : m_fontDatabase(new QCoreTextFontDatabase)
     , m_clipboard(new QIOSClipboard)
     , m_inputContext(new QIOSInputContext)
-    , m_screen(new QIOSScreen(QIOSScreen::MainScreen))
     , m_platformServices(new QIOSServices)
     , m_accessibility(0)
 {
@@ -89,7 +88,8 @@ QIOSIntegration::QIOSIntegration()
     // Set current directory to app bundle folder
     QDir::setCurrent(QString::fromUtf8([[[NSBundle mainBundle] bundlePath] UTF8String]));
 
-    screenAdded(m_screen);
+    for (UIScreen *screen in [UIScreen screens])
+        addScreen(new QIOSScreen(screen));
 
     m_touchDevice = new QTouchDevice;
     m_touchDevice->setType(QTouchDevice::TouchScreen);
@@ -110,8 +110,8 @@ QIOSIntegration::~QIOSIntegration()
     delete m_inputContext;
     m_inputContext = 0;
 
-    delete m_screen;
-    m_screen = 0;
+    foreach (QScreen *screen, QGuiApplication::screens())
+        delete screen->handle();
 
     delete m_platformServices;
     m_platformServices = 0;

src/plugins/platforms/ios/qiosscreen.h

@@ -55,11 +55,9 @@ class QIOSScreen : public QObject, public QPlatformScreen
     Q_OBJECT
 
 public:
-    QIOSScreen(unsigned int screenIndex);
+    QIOSScreen(UIScreen *screen);
     ~QIOSScreen();
 
-    enum ScreenIndex { MainScreen = 0 };
-
     QRect geometry() const;
     QRect availableGeometry() const;
     int depth() const;

src/plugins/platforms/ios/qiosscreen.mm

@@ -40,6 +40,7 @@
 ****************************************************************************/
 
 #include "qiosglobal.h"
+#include "qiosintegration.h"
 #include "qiosscreen.h"
 #include "qioswindow.h"
 #include <qpa/qwindowsysteminterface.h>
@@ -48,6 +49,63 @@
 
 #include <sys/sysctl.h>
 
+// -------------------------------------------------------------------------
+
+static QIOSScreen* qtPlatformScreenFor(UIScreen *uiScreen)
+{
+    foreach (QScreen *screen, QGuiApplication::screens()) {
+        QIOSScreen *platformScreen = static_cast<QIOSScreen *>(screen->handle());
+        if (platformScreen->uiScreen() == uiScreen)
+            return platformScreen;
+    }
+
+    return 0;
+}
+
+@interface QIOSScreenTracker : NSObject
+@end
+
+@implementation QIOSScreenTracker
+
++ (void)load
+{
+    NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
+    [center addObserver:self selector:@selector(screenConnected:)
+            name:UIScreenDidConnectNotification object:nil];
+    [center addObserver:self selector:@selector(screenDisconnected:)
+            name:UIScreenDidDisconnectNotification object:nil];
+    [center addObserver:self selector:@selector(screenModeChanged:)
+            name:UIScreenModeDidChangeNotification object:nil];
+}
+
++ (void)screenConnected:(NSNotification*)notification
+{
+    QIOSIntegration *integration = QIOSIntegration::instance();
+    Q_ASSERT_X(integration, Q_FUNC_INFO, "Screen connected before QIOSIntegration creation");
+
+    integration->addScreen(new QIOSScreen([notification object]));
+}
+
++ (void)screenDisconnected:(NSNotification*)notification
+{
+    QIOSScreen *screen = qtPlatformScreenFor([notification object]);
+    Q_ASSERT_X(screen, Q_FUNC_INFO, "Screen disconnected that we didn't know about");
+
+    delete screen;
+}
+
++ (void)screenModeChanged:(NSNotification*)notification
+{
+    QIOSScreen *screen = qtPlatformScreenFor([notification object]);
+    Q_ASSERT_X(screen, Q_FUNC_INFO, "Screen changed that we didn't know about");
+
+    screen->updateProperties();
+}
+
+@end
+
+// -------------------------------------------------------------------------
+
 @interface QIOSOrientationListener : NSObject {
     @public
     QIOSScreen *m_screen;
@@ -99,6 +157,8 @@
 
 @end
 
+// -------------------------------------------------------------------------
+
 /*!
     Returns the model identifier of the device.
 
@@ -118,27 +178,31 @@ static QString deviceModelIdentifier()
     return QString::fromLatin1(value);
 }
 
-QIOSScreen::QIOSScreen(unsigned int screenIndex)
+QIOSScreen::QIOSScreen(UIScreen *screen)
     : QPlatformScreen()
-    , m_uiScreen([[UIScreen screens] count] > screenIndex
-        ? [[UIScreen screens] objectAtIndex:screenIndex]
-        : [UIScreen mainScreen])
+    , m_uiScreen(screen)
     , m_orientationListener(0)
 {
-    QString deviceIdentifier = deviceModelIdentifier();
+    if (screen == [UIScreen mainScreen]) {
+        QString deviceIdentifier = deviceModelIdentifier();
 
-    if (deviceIdentifier == QStringLiteral("iPhone2,1") /* iPhone 3GS */
-        || deviceIdentifier == QStringLiteral("iPod3,1") /* iPod touch 3G */) {
-        m_depth = 18;
+        if (deviceIdentifier == QStringLiteral("iPhone2,1") /* iPhone 3GS */
+            || deviceIdentifier == QStringLiteral("iPod3,1") /* iPod touch 3G */) {
+            m_depth = 18;
+        } else {
+            m_depth = 24;
+        }
+
+        if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad
+            && !deviceIdentifier.contains(QRegularExpression("^iPad2,[567]$")) /* excluding iPad Mini */) {
+            m_unscaledDpi = 132;
+        } else {
+            m_unscaledDpi = 163; // Regular iPhone DPI
+        }
     } else {
+        // External display, hard to say
         m_depth = 24;
-    }
-
-    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad
-        && !deviceIdentifier.contains(QRegularExpression("^iPad2,[567]$")) /* excluding iPad Mini */) {
-        m_unscaledDpi = 132;
-    } else {
-        m_unscaledDpi = 163; // Regular iPhone DPI
+        m_unscaledDpi = 96;
     }
 
     connect(qGuiApp, &QGuiApplication::focusWindowChanged, this, &QIOSScreen::updateStatusBarVisibility);