AVFoundation: fix QCameraInfo::availableCameras() on OS X.

Cameras can be dynamically added or removed on OS X. Make sure
the cache is updated often enough so QCameraInfo::availableCameras()
return an up to date list.

Task-number: QTBUG-39708
Change-Id: Id806d52278e1a29163fcc6707da7f86c0f3e7c0d
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>

1 files changed, 36 insertions, 23 deletions

diff --git a/src/plugins/avfoundation/camera/avfcamerasession.mm b/src/plugins/avfoundation/camera/avfcamerasession.mm
index a72ef5041..4d4b2f657 100644
--- a/src/plugins/avfoundation/camera/avfcamerasession.mm
+++ b/src/plugins/avfoundation/camera/avfcamerasession.mm
@@ -52,14 +52,14 @@
 
 #include <QtCore/qdatetime.h>
 #include <QtCore/qurl.h>
+#include <QtCore/qelapsedtimer.h>
 
 #include <QtCore/qdebug.h>
 
 QT_USE_NAMESPACE
 
-QByteArray AVFCameraSession::m_defaultCameraDevice;
-QList<QByteArray> AVFCameraSession::m_cameraDevices;
-QMap<QByteArray, AVFCameraInfo> AVFCameraSession::m_cameraInfo;
+int AVFCameraSession::m_defaultCameraIndex;
+QList<AVFCameraInfo> AVFCameraSession::m_cameraDevices;
 
 @interface AVFCameraSessionObserver : NSObject
 {
@@ -172,45 +172,55 @@ AVFCameraSession::~AVFCameraSession()
     [m_captureSession release];
 }
 
-const QByteArray &AVFCameraSession::defaultCameraDevice()
+int AVFCameraSession::defaultCameraIndex()
 {
-    if (m_cameraDevices.isEmpty())
-        updateCameraDevices();
-
-    return m_defaultCameraDevice;
+    updateCameraDevices();
+    return m_defaultCameraIndex;
 }
 
-const QList<QByteArray> &AVFCameraSession::availableCameraDevices()
+const QList<AVFCameraInfo> &AVFCameraSession::availableCameraDevices()
 {
-    if (m_cameraDevices.isEmpty())
-        updateCameraDevices();
-
+    updateCameraDevices();
     return m_cameraDevices;
 }
 
 AVFCameraInfo AVFCameraSession::cameraDeviceInfo(const QByteArray &device)
 {
-    if (m_cameraDevices.isEmpty())
-        updateCameraDevices();
+    updateCameraDevices();
 
-    return m_cameraInfo.value(device);
+    Q_FOREACH (const AVFCameraInfo &info, m_cameraDevices) {
+        if (info.deviceId == device)
+            return info;
+    }
+
+    return AVFCameraInfo();
 }
 
 void AVFCameraSession::updateCameraDevices()
 {
-    m_defaultCameraDevice.clear();
+#ifdef Q_OS_IOS
+    // Cameras can't change dynamically on iOS. Update only once.
+    if (!m_cameraDevices.isEmpty())
+        return;
+#else
+    // On OS X, cameras can be added or removed. Update the list every time, but not more than
+    // once every 500 ms
+    static QElapsedTimer timer;
+    if (timer.isValid() && timer.elapsed() < 500) // ms
+        return;
+#endif
+
+    m_defaultCameraIndex = -1;
     m_cameraDevices.clear();
-    m_cameraInfo.clear();
 
     AVCaptureDevice *defaultDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
-    if (defaultDevice)
-        m_defaultCameraDevice = QByteArray([[defaultDevice uniqueID] UTF8String]);
-
     NSArray *videoDevices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
     for (AVCaptureDevice *device in videoDevices) {
-        QByteArray deviceId([[device uniqueID] UTF8String]);
+        if (defaultDevice && [defaultDevice.uniqueID isEqualToString:device.uniqueID])
+            m_defaultCameraIndex = m_cameraDevices.count();
 
         AVFCameraInfo info;
+        info.deviceId = QByteArray([[device uniqueID] UTF8String]);
         info.description = QString::fromNSString([device localizedName]);
 
         // There is no API to get the camera sensor orientation, however, cameras are always
@@ -235,9 +245,12 @@ void AVFCameraSession::updateCameraDevices()
             break;
         }
 
-        m_cameraDevices << deviceId;
-        m_cameraInfo.insert(deviceId, info);
+        m_cameraDevices.append(info);
     }
+
+#ifndef Q_OS_IOS
+    timer.restart();
+#endif
 }
 
 void AVFCameraSession::setVideoOutput(AVFVideoRendererControl *output)