From 13fd3e9611391742b4bea86cb2f4740534daf695 Mon Sep 17 00:00:00 2001
From: Oliver Wolff <oliver.wolff@theqtcompany.com>
Date: Wed, 2 Dec 2015 13:17:30 +0100
Subject: winrt: Fix application hang on sensor start/stop

If addition and removal are not done in the Xaml thread, the functions
might not return at all.

Task-number: QTBUG-49741
Change-Id: Iabdea2c7ee18bf851ab70adfeb28b09781b8b609
Reviewed-by: Andrew Knight <andrew.knight@intopalo.com>
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@theqtcompany.com>
---
 src/plugins/sensors/winrt/winrtgyroscope.cpp | 42 +++++++++++++++++-----------
 1 file changed, 26 insertions(+), 16 deletions(-)

(limited to 'src/plugins/sensors/winrt/winrtgyroscope.cpp')

diff --git a/src/plugins/sensors/winrt/winrtgyroscope.cpp b/src/plugins/sensors/winrt/winrtgyroscope.cpp
index e7910ab2..70d7980f 100644
--- a/src/plugins/sensors/winrt/winrtgyroscope.cpp
+++ b/src/plugins/sensors/winrt/winrtgyroscope.cpp
@@ -38,7 +38,9 @@
 #include "winrtcommon.h"
 
 #include <QtSensors/QGyroscope>
+#include <private/qeventdispatcher_winrt_p.h>
 
+#include <functional>
 #include <wrl.h>
 #include <windows.devices.sensors.h>
 using namespace Microsoft::WRL;
@@ -111,20 +113,24 @@ WinRtGyroscope::WinRtGyroscope(QSensor *sensor)
     : QSensorBackend(sensor), d_ptr(new WinRtGyroscopePrivate(this))
 {
     Q_D(WinRtGyroscope);
-    HStringReference classId(RuntimeClass_Windows_Devices_Sensors_Gyrometer);
-    ComPtr<IGyrometerStatics> factory;
-    HRESULT hr = RoGetActivationFactory(classId.Get(), IID_PPV_ARGS(&factory));
-    if (FAILED(hr)) {
-        qCWarning(lcWinRtSensors) << "Unable to initialize gyroscope sensor factory."
-                                  << qt_error_string(hr);
-        sensorError(hr);
-        return;
-    }
+    HRESULT hr = QEventDispatcherWinRT::runOnXamlThread([d]() {
+        HStringReference classId(RuntimeClass_Windows_Devices_Sensors_Gyrometer);
+        ComPtr<IGyrometerStatics> factory;
+        HRESULT hr = RoGetActivationFactory(classId.Get(), IID_PPV_ARGS(&factory));
+        if (FAILED(hr)) {
+            qCWarning(lcWinRtSensors) << "Unable to initialize gyroscope sensor factory."
+                                      << qt_error_string(hr);
+            return hr;
+        }
 
-    hr = factory->GetDefault(&d->sensor);
+        hr = factory->GetDefault(&d->sensor);
+        if (FAILED(hr)) {
+            qCWarning(lcWinRtSensors) << "Unable to get default gyroscope sensor."
+                                      << qt_error_string(hr);
+        }
+        return hr;
+    });
     if (FAILED(hr) || !d->sensor) {
-        qCWarning(lcWinRtSensors) << "Unable to get default gyroscope sensor."
-                                  << qt_error_string(hr);
         sensorError(hr);
         return;
     }
@@ -155,9 +161,11 @@ void WinRtGyroscope::start()
     if (d->token.value)
         return;
 
-    ComPtr<InclinometerReadingHandler> callback =
+    HRESULT hr = QEventDispatcherWinRT::runOnXamlThread([d]() {
+        ComPtr<InclinometerReadingHandler> callback =
             Callback<InclinometerReadingHandler>(d, &WinRtGyroscopePrivate::readingChanged);
-    HRESULT hr = d->sensor->add_ReadingChanged(callback.Get(), &d->token);
+        return d->sensor->add_ReadingChanged(callback.Get(), &d->token);
+    });
     if (FAILED(hr)) {
         qCWarning(lcWinRtSensors) << "Unable to attach to reading changed event."
                                   << qt_error_string(hr);
@@ -186,14 +194,16 @@ void WinRtGyroscope::stop()
     if (!d->token.value)
         return;
 
-    HRESULT hr = d->sensor->remove_ReadingChanged(d->token);
+    HRESULT hr = QEventDispatcherWinRT::runOnXamlThread([d]() {
+        return d->sensor->remove_ReadingChanged(d->token);
+    });
     if (FAILED(hr)) {
         qCWarning(lcWinRtSensors) << "Unable to detach from reading changed event."
                                   << qt_error_string(hr);
         sensorError(hr);
         return;
     }
-    d->sensor->put_ReportInterval(0);
+    hr = d->sensor->put_ReportInterval(0);
     if (FAILED(hr)) {
         qCWarning(lcWinRtSensors) << "Unable to reset report interval."
                                   << qt_error_string(hr);
-- 
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