iOS: protect OS sensors from being stopped when shared by several Qt sensors

When a Qt sensor is told to stop, it automatically stops the underlying
OS sensor as well. This caused a problem when several Qt sensors were
running, since stopping one would stop them all.

This patch will add a ref count for each affected sensor, so that we
keep track of when it's safe to start and stop the underlying OS sensor.

Task-number: QTBUG-54977
Change-Id: If06c4daac22916feef2f4c7bd521363d74f342a6
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Lorn Potter <lorn.potter@canonical.com>

8 files changed, 69 insertions, 14 deletions

diff --git a/src/plugins/sensors/ios/iosaccelerometer.h b/src/plugins/sensors/ios/iosaccelerometer.h
index 05de7a26..94a2ed8e 100644
--- a/src/plugins/sensors/ios/iosaccelerometer.h
+++ b/src/plugins/sensors/ios/iosaccelerometer.h
@@ -56,6 +56,8 @@ private:
     CMMotionManager *m_motionManager;
     QAccelerometerReading m_reading;
     int m_timer;
+
+    static int s_startCount;
 };
 QT_END_NAMESPACE
 
diff --git a/src/plugins/sensors/ios/iosaccelerometer.mm b/src/plugins/sensors/ios/iosaccelerometer.mm
index 570d58ba..dbeef017 100644
--- a/src/plugins/sensors/ios/iosaccelerometer.mm
+++ b/src/plugins/sensors/ios/iosaccelerometer.mm
@@ -40,6 +40,8 @@ char const * const IOSAccelerometer::id("ios.accelerometer");
 
 QT_BEGIN_NAMESPACE
 
+int IOSAccelerometer::s_startCount = 0;
+
 IOSAccelerometer::IOSAccelerometer(QSensor *sensor)
     : QSensorBackend(sensor)
     , m_motionManager([QIOSMotionManager sharedManager])
@@ -52,16 +54,24 @@ IOSAccelerometer::IOSAccelerometer(QSensor *sensor)
 
 void IOSAccelerometer::start()
 {
+    if (m_timer != 0)
+        return;
+
     int hz = sensor()->dataRate();
     m_timer = startTimer(1000 / (hz == 0 ? 60 : hz));
-    [m_motionManager startAccelerometerUpdates];
+    if (++s_startCount == 1)
+        [m_motionManager startAccelerometerUpdates];
 }
 
 void IOSAccelerometer::stop()
 {
-    [m_motionManager stopAccelerometerUpdates];
+    if (m_timer == 0)
+        return;
+
     killTimer(m_timer);
     m_timer = 0;
+    if (--s_startCount == 0)
+        [m_motionManager stopAccelerometerUpdates];
 }
 
 void IOSAccelerometer::timerEvent(QTimerEvent *)
diff --git a/src/plugins/sensors/ios/iosgyroscope.h b/src/plugins/sensors/ios/iosgyroscope.h
index f5c429d7..0b185233 100644
--- a/src/plugins/sensors/ios/iosgyroscope.h
+++ b/src/plugins/sensors/ios/iosgyroscope.h
@@ -56,6 +56,8 @@ private:
     CMMotionManager *m_motionManager;
     QGyroscopeReading m_reading;
     int m_timer;
+
+    static int s_startCount;
 };
 QT_END_NAMESPACE
 
diff --git a/src/plugins/sensors/ios/iosgyroscope.mm b/src/plugins/sensors/ios/iosgyroscope.mm
index fa051dac..0a4699c1 100644
--- a/src/plugins/sensors/ios/iosgyroscope.mm
+++ b/src/plugins/sensors/ios/iosgyroscope.mm
@@ -38,6 +38,8 @@ char const * const IOSGyroscope::id("ios.gyroscope");
 
 QT_BEGIN_NAMESPACE
 
+int IOSGyroscope::s_startCount = 0;
+
 IOSGyroscope::IOSGyroscope(QSensor *sensor)
     : QSensorBackend(sensor)
     , m_motionManager([QIOSMotionManager sharedManager])
@@ -50,16 +52,24 @@ IOSGyroscope::IOSGyroscope(QSensor *sensor)
 
 void IOSGyroscope::start()
 {
+    if (m_timer != 0)
+        return;
+
     int hz = sensor()->dataRate();
     m_timer = startTimer(1000 / (hz == 0 ? 60 : hz));
-    [m_motionManager startGyroUpdates];
+    if (++s_startCount == 1)
+        [m_motionManager startGyroUpdates];
 }
 
 void IOSGyroscope::stop()
 {
-    [m_motionManager stopGyroUpdates];
+    if (m_timer == 0)
+        return;
+
     killTimer(m_timer);
     m_timer = 0;
+    if (--s_startCount == 0)
+        [m_motionManager stopGyroUpdates];
 }
 
 void IOSGyroscope::timerEvent(QTimerEvent *)
diff --git a/src/plugins/sensors/ios/iosmagnetometer.h b/src/plugins/sensors/ios/iosmagnetometer.h
index f6430f5d..b8e611d2 100644
--- a/src/plugins/sensors/ios/iosmagnetometer.h
+++ b/src/plugins/sensors/ios/iosmagnetometer.h
@@ -60,6 +60,9 @@ private:
     QMagnetometerReading m_reading;
     int m_timer;
     bool m_returnGeoValues;
+
+    static int s_magnetometerStartCount;
+    static int s_deviceMotionStartCount;
 };
 QT_END_NAMESPACE
 
diff --git a/src/plugins/sensors/ios/iosmagnetometer.mm b/src/plugins/sensors/ios/iosmagnetometer.mm
index 6c4fbaad..5326a762 100644
--- a/src/plugins/sensors/ios/iosmagnetometer.mm
+++ b/src/plugins/sensors/ios/iosmagnetometer.mm
@@ -38,6 +38,9 @@ QT_BEGIN_NAMESPACE
 
 char const * const IOSMagnetometer::id("ios.magnetometer");
 
+int IOSMagnetometer::s_magnetometerStartCount = 0;
+int IOSMagnetometer::s_deviceMotionStartCount = 0;
+
 IOSMagnetometer::IOSMagnetometer(QSensor *sensor)
     : QSensorBackend(sensor)
     , m_motionManager([QIOSMotionManager sharedManager])
@@ -55,24 +58,37 @@ IOSMagnetometer::IOSMagnetometer(QSensor *sensor)
 
 void IOSMagnetometer::start()
 {
+    if (m_timer != 0)
+        return;
+
     int hz = sensor()->dataRate();
     m_timer = startTimer(1000 / (hz == 0 ? 60 : hz));
     m_returnGeoValues = static_cast<QMagnetometer *>(sensor())->returnGeoValues();
 
-    if (m_returnGeoValues)
-        [m_motionManager startDeviceMotionUpdates];
-    else
-        [m_motionManager startMagnetometerUpdates];
+    if (m_returnGeoValues) {
+        if (++s_deviceMotionStartCount == 1)
+            [m_motionManager startDeviceMotionUpdates];
+    } else {
+        if (++s_magnetometerStartCount == 1)
+            [m_motionManager startMagnetometerUpdates];
+    }
 }
 
 void IOSMagnetometer::stop()
 {
-    if (m_returnGeoValues)
-        [m_motionManager stopDeviceMotionUpdates];
-    else
-        [m_motionManager stopMagnetometerUpdates];
+    if (m_timer == 0)
+        return;
+
     killTimer(m_timer);
     m_timer = 0;
+
+    if (m_returnGeoValues) {
+        if (--s_deviceMotionStartCount == 0)
+            [m_motionManager stopDeviceMotionUpdates];
+    } else {
+        if (--s_magnetometerStartCount == 0)
+            [m_motionManager stopMagnetometerUpdates];
+    }
 }
 
 void IOSMagnetometer::timerEvent(QTimerEvent *)
diff --git a/src/plugins/sensors/ios/iosproximitysensor.h b/src/plugins/sensors/ios/iosproximitysensor.h
index 147bc230..5a6b38ca 100644
--- a/src/plugins/sensors/ios/iosproximitysensor.h
+++ b/src/plugins/sensors/ios/iosproximitysensor.h
@@ -58,6 +58,8 @@ public:
 private:
     ProximitySensorCallback *m_proximitySensorCallback;
     QProximityReading m_reading;
+
+    static int s_startCount;
 };
 QT_END_NAMESPACE
 
diff --git a/src/plugins/sensors/ios/iosproximitysensor.mm b/src/plugins/sensors/ios/iosproximitysensor.mm
index 6905e5cc..0d673d12 100644
--- a/src/plugins/sensors/ios/iosproximitysensor.mm
+++ b/src/plugins/sensors/ios/iosproximitysensor.mm
@@ -39,6 +39,8 @@ char const * const IOSProximitySensor::id("ios.proximitysensor");
 
 QT_BEGIN_NAMESPACE
 
+int IOSProximitySensor::s_startCount = 0;
+
 @interface ProximitySensorCallback : NSObject
 {
     IOSProximitySensor *m_iosProximitySensor;
@@ -104,8 +106,12 @@ IOSProximitySensor::~IOSProximitySensor()
 
 void IOSProximitySensor::start()
 {
+    if (m_proximitySensorCallback)
+        return;
+
     m_proximitySensorCallback = [[ProximitySensorCallback alloc] initWithQIOSProximitySensor:this];
-    [UIDevice currentDevice].proximityMonitoringEnabled = YES;
+    if (++s_startCount == 1)
+        [UIDevice currentDevice].proximityMonitoringEnabled = YES;
 }
 
 void IOSProximitySensor::proximityChanged(bool close)
@@ -117,9 +123,13 @@ void IOSProximitySensor::proximityChanged(bool close)
 
 void IOSProximitySensor::stop()
 {
-    [UIDevice currentDevice].proximityMonitoringEnabled = NO;
+    if (!m_proximitySensorCallback)
+        return;
+
     [m_proximitySensorCallback release];
     m_proximitySensorCallback = 0;
+    if (--s_startCount == 0)
+        [UIDevice currentDevice].proximityMonitoringEnabled = NO;
 }
 
 QT_END_NAMESPACE