Fix QML API for sensor ranges

Previously the QQmlListProperties were constructed on stack-allocated
lists, which immediately turned into dangling pointers on return. Also,
none of the sensor ranges was ever deleted.

Keep the sensor ranges in persistent lists in the private object, parent
them to the main QmlSensor object, and add some tests for them.

Fixes: QTBUG-79224
Change-Id: Ie61d0aaeaaaf998c1d1f46f60c81848ae48659d6
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
(cherry picked from commit f6b550ea5eae80124576766fe1a9609ae5aba1e3)

5 files changed, 177 insertions, 26 deletions

diff --git a/src/imports/sensors/qmlsensor.cpp b/src/imports/sensors/qmlsensor.cpp
index 84eea6f..e0a6958 100644
--- a/src/imports/sensors/qmlsensor.cpp
+++ b/src/imports/sensors/qmlsensor.cpp
@@ -40,9 +40,39 @@
 #include "qmlsensor.h"
 #include <QtSensors/QSensor>
 #include <QDebug>
+#include <QtCore/private/qobject_p.h>
 
 QT_BEGIN_NAMESPACE
 
+class QmlSensorPrivate : public QObjectPrivate
+{
+    Q_DECLARE_PUBLIC(QmlSensor)
+public:
+
+    QList<QmlSensorRange *> availableRanges;
+    QList<QmlSensorOutputRange *> outputRanges;
+};
+
+template<typename Item>
+int readonlyListCount(QQmlListProperty<Item> *p)
+{
+    return static_cast<const QList<Item *> *>(p->data)->count();
+}
+
+template<typename Item>
+Item *readonlyListAt(QQmlListProperty<Item> *p, int idx)
+{
+    return static_cast<const QList<Item *> *>(p->data)->at(idx);
+};
+
+template<typename Item>
+QQmlListProperty<Item> readonlyListProperty(const QObject *o, const QList<Item *> *list)
+{
+    // Unfortunately QQmlListProperty won't accept a const object, even on the readonly ctor.
+    return QQmlListProperty<Item>(const_cast<QObject *>(o), const_cast<QList<Item *> *>(list),
+                                  readonlyListCount<Item>, readonlyListAt<Item>);
+}
+
 /*!
     \qmltype Sensor
     \instantiates QmlSensor
@@ -59,7 +89,7 @@ QT_BEGIN_NAMESPACE
 */
 
 QmlSensor::QmlSensor(QObject *parent)
-    : QObject(parent)
+    : QObject(*(new QmlSensorPrivate), parent)
     , m_parsed(false)
     , m_active(false)
     , m_reading(0)
@@ -193,19 +223,10 @@ void QmlSensor::setSkipDuplicates(bool skipDuplicates)
 
     Please see QSensor::availableDataRates for information about this property.
 */
-
 QQmlListProperty<QmlSensorRange> QmlSensor::availableDataRates() const
 {
-    QList<QmlSensorRange*> ret;
-    ret.reserve(sensor()->availableDataRates().size());
-    foreach (const qrange &r, sensor()->availableDataRates()) {
-        QmlSensorRange *range = new QmlSensorRange;
-        //QQmlEngine::setObjectOwnership(range, QQmlEngine::JavaScriptOwnership);
-        range->setMinumum(r.first);
-        range->setMaximum(r.second);
-        ret << range;
-    }
-    return QQmlListProperty<QmlSensorRange>(const_cast<QmlSensor*>(this), ret);
+    Q_D(const QmlSensor);
+    return readonlyListProperty<QmlSensorRange>(this, &d->availableRanges);
 }
 
 /*!
@@ -237,17 +258,8 @@ void QmlSensor::setDataRate(int rate)
 
 QQmlListProperty<QmlSensorOutputRange> QmlSensor::outputRanges() const
 {
-    QList<QmlSensorOutputRange*> ret;
-    ret.reserve(sensor()->outputRanges().size());
-    foreach (const qoutputrange &r, sensor()->outputRanges()) {
-        QmlSensorOutputRange *range = new QmlSensorOutputRange;
-        //QQmlEngine::setObjectOwnership(range, QQmlEngine::JavaScriptOwnership);
-        range->setMinimum(r.minimum);
-        range->setMaximum(r.maximum);
-        range->setAccuracy(r.accuracy);
-        ret << range;
-    }
-    return QQmlListProperty<QmlSensorOutputRange>(const_cast<QmlSensor*>(this), ret);
+    Q_D(const QmlSensor);
+    return readonlyListProperty<QmlSensorOutputRange>(this, &d->outputRanges);
 }
 
 /*!
@@ -466,12 +478,31 @@ void QmlSensor::componentComplete()
     if (oldOutputRange != outputRange())
         Q_EMIT outputRangeChanged();
 
+    Q_D(QmlSensor);
+    const auto available = sensor()->availableDataRates();
+    d->availableRanges.reserve(available.size());
+    for (const qrange &r : available) {
+        auto *range = new QmlSensorRange(this);
+        range->setMinumum(r.first);
+        range->setMaximum(r.second);
+        d->availableRanges.append(range);
+    }
+    const auto output = sensor()->outputRanges();
+    d->outputRanges.reserve(output.size());
+    for (const qoutputrange &r : output) {
+        auto *range = new QmlSensorOutputRange(this);
+        range->setMinimum(r.minimum);
+        range->setMaximum(r.maximum);
+        range->setAccuracy(r.accuracy);
+        d->outputRanges.append(range);
+    }
+
     // meta-data should become non-empty
     if (!description().isEmpty())
         Q_EMIT descriptionChanged();
-    if (sensor()->availableDataRates().count())
+    if (available.count())
         Q_EMIT availableDataRatesChanged();
-    if (sensor()->outputRanges().count())
+    if (output.count())
         Q_EMIT outputRangesChanged();
 
     _update();
diff --git a/src/imports/sensors/qmlsensor.h b/src/imports/sensors/qmlsensor.h
index e46278b..3ac8269 100644
--- a/src/imports/sensors/qmlsensor.h
+++ b/src/imports/sensors/qmlsensor.h
@@ -40,6 +40,7 @@
 #ifndef QMLSENSOR_H
 #define QMLSENSOR_H
 
+#include <QObject>
 #include <QQmlParserStatus>
 #include <QQmlListProperty>
 #include "qmlsensorrange.h"
@@ -51,9 +52,11 @@ class QSensorReading;
 
 class QmlSensorReading;
 
+class QmlSensorPrivate;
 class QmlSensor : public QObject, public QQmlParserStatus
 {
     Q_OBJECT
+    Q_DECLARE_PRIVATE(QmlSensor)
     Q_ENUMS(AxesOrientationMode)
     Q_INTERFACES(QQmlParserStatus)
     Q_PROPERTY(QString identifier READ identifier WRITE setIdentifier NOTIFY identifierChanged)
diff --git a/src/imports/sensors/sensors.pro b/src/imports/sensors/sensors.pro
index d627916..7d15ec9 100644
--- a/src/imports/sensors/sensors.pro
+++ b/src/imports/sensors/sensors.pro
@@ -1,4 +1,4 @@
-QT += qml sensors sensors-private
+QT += core-private qml sensors sensors-private
 
 HEADERS += \
     qmlsensor.h \
diff --git a/tests/auto/sensors2qmlapi/sensors2qmlapi.pro b/tests/auto/sensors2qmlapi/sensors2qmlapi.pro
index 3d5e237..7438866 100644
--- a/tests/auto/sensors2qmlapi/sensors2qmlapi.pro
+++ b/tests/auto/sensors2qmlapi/sensors2qmlapi.pro
@@ -5,12 +5,16 @@ CONFIG += testcase
 QT = core testlib sensors-private qml
 
 SOURCES += tst_sensors2qmlapi.cpp \
+           ./../../../src/imports/sensors/qmlsensor.cpp \
            ./../../../src/imports/sensors/qmlsensorgesture.cpp \
+           ./../../../src/imports/sensors/qmlsensorrange.cpp \
            qtemplategestureplugin.cpp \
            qtemplaterecognizer.cpp
 
 HEADERS += \
+           ./../../../src/imports/sensors/qmlsensor.h \
            ./../../../src/imports/sensors/qmlsensorgesture.h \
+           ./../../../src/imports/sensors/qmlsensorrange.h \
            qtemplategestureplugin.h \
            qtemplaterecognizer.h
 
diff --git a/tests/auto/sensors2qmlapi/tst_sensors2qmlapi.cpp b/tests/auto/sensors2qmlapi/tst_sensors2qmlapi.cpp
index d007414..51007fc 100644
--- a/tests/auto/sensors2qmlapi/tst_sensors2qmlapi.cpp
+++ b/tests/auto/sensors2qmlapi/tst_sensors2qmlapi.cpp
@@ -29,10 +29,14 @@
 #include <QtTest/QtTest>
 #include <QtTest/QSignalSpy>
 #include <QtCore/QDebug>
+
+#include "../../../src/imports/sensors/qmlsensor.h"
 #include "../../../src/imports/sensors/qmlsensorgesture.h"
+
 #include "qtemplategestureplugin.h"
 #include "qtemplaterecognizer.h"
 #include <qsensorgesturemanager.h>
+#include <qsensorbackend.h>
 #include "qsensormanager.h"
 
 QT_USE_NAMESPACE
@@ -46,6 +50,7 @@ class tst_Sensors2QMLAPI : public QObject
 private slots:
     void initTestCase();
     void testGesture();
+    void testSensorRanges();
 };
 
 void tst_Sensors2QMLAPI::initTestCase()
@@ -169,6 +174,114 @@ void tst_Sensors2QMLAPI::testGesture()
     QCOMPARE(spy2_detected.count(), 1);
 }
 
+class QDummySensorBackend : public QSensorBackend
+{
+    Q_OBJECT
+public:
+    QDummySensorBackend(QSensor *sensor) : QSensorBackend(sensor)
+    {
+        addDataRate(2, 3);
+        addDataRate(5, 7);
+        addOutputRange(100, 200, 1);
+        addOutputRange(600, 700, 10);
+        addOutputRange(0, 1, 2);
+    }
+
+    void start() override {}
+    void stop() override {}
+};
+
+class QDummySensorReading : public QSensorReading
+{
+    Q_OBJECT
+public:
+    QDummySensorReading(QObject *parent) : QSensorReading(parent, nullptr) {}
+};
+
+class QmlDummySensorReading : public QmlSensorReading
+{
+    Q_OBJECT
+public:
+    QmlDummySensorReading(QSensor *sensor) :
+        QmlSensorReading(sensor),
+        m_reading(new QDummySensorReading(this))
+    {}
+
+    QSensorReading *reading() const override { return m_reading; }
+    void readingUpdate() override {}
+
+private:
+    QSensorReading *m_reading = nullptr;
+};
+
+class QmlDummySensor : public QmlSensor
+{
+    Q_OBJECT
+public:
+    QmlDummySensor(QObject *parent = nullptr) :
+        QmlSensor(parent),
+        m_sensor(new QSensor("dummy", this))
+    {
+        QDummySensorBackend b(m_sensor);
+        Q_UNUSED(b);
+    }
+
+    QSensor *sensor() const override { return m_sensor; }
+    QmlSensorReading *createReading() const override { return new QmlDummySensorReading(m_sensor); }
+
+    void componentComplete() override { QmlSensor::componentComplete(); }
+
+private:
+    QSensor *m_sensor = nullptr;
+};
+
+void tst_Sensors2QMLAPI::testSensorRanges()
+{
+    QScopedPointer<QmlDummySensor> qmlSensor(new QmlDummySensor);
+    qmlSensor->componentComplete();
+
+    auto ranges = qmlSensor->availableDataRates();
+    QCOMPARE(ranges.count(&ranges), 2);
+
+    const auto range0 = ranges.at(&ranges, 0);
+    QCOMPARE(range0->minimum(), 2);
+    QCOMPARE(range0->maximum(), 3);
+    QSignalSpy range0Spy(range0, SIGNAL(destroyed()));
+
+    const auto range1 = ranges.at(&ranges, 1);
+    QCOMPARE(range1->minimum(), 5);
+    QCOMPARE(range1->maximum(), 7);
+    QSignalSpy range1Spy(range1, SIGNAL(destroyed()));
+
+    auto outputs = qmlSensor->outputRanges();
+    QCOMPARE(outputs.count(&outputs), 3);
+
+    const auto output0 = outputs.at(&outputs, 0);
+    QCOMPARE(output0->minimum(), 100);
+    QCOMPARE(output0->maximum(), 200);
+    QCOMPARE(output0->accuracy(), 1);
+    QSignalSpy output0Spy(output0, SIGNAL(destroyed()));
+
+    const auto output1 = outputs.at(&outputs, 1);
+    QCOMPARE(output1->minimum(), 600);
+    QCOMPARE(output1->maximum(), 700);
+    QCOMPARE(output1->accuracy(), 10);
+    QSignalSpy output1Spy(output1, SIGNAL(destroyed()));
+
+    const auto output2 = outputs.at(&outputs, 2);
+    QCOMPARE(output2->minimum(), 0);
+    QCOMPARE(output2->maximum(), 1);
+    QCOMPARE(output2->accuracy(), 2);
+    QSignalSpy output2Spy(output2, SIGNAL(destroyed()));
+
+    qmlSensor.reset();
+    QCOMPARE(range0Spy.count(), 1);
+    QCOMPARE(range1Spy.count(), 1);
+    QCOMPARE(output0Spy.count(), 1);
+    QCOMPARE(output1Spy.count(), 1);
+    QCOMPARE(output2Spy.count(), 1);
+}
+
 QT_END_NAMESPACE
 
 QTEST_MAIN(tst_Sensors2QMLAPI)