Warn about severe weather conditions

autotests/weathertest.cpp

@@ -60,6 +60,7 @@ private Q_SLOTS:
         QCOMPARE((*it).precipitation(), 0.0f);
         QCOMPARE((*it).symbolType(), WeatherForecast::Clear);
         QCOMPARE((*it).windSpeed(), 1.6f);
+        QCOMPARE((*it).isSevere(), false);
     }
 
     void testWeatherSymbol()

src/app/WeatherForecastDelegate.qml

@@ -22,7 +22,7 @@ Kirigami.AbstractCard {
         id: headerBackground
         Kirigami.Theme.colorSet: Kirigami.Theme.Complementary
         Kirigami.Theme.inherit: false
-        color: Kirigami.Theme.backgroundColor
+        color: weatherForecast.isSevere ? Kirigami.Theme.negativeBackgroundColor : Kirigami.Theme.backgroundColor
         radius: Kirigami.Units.smallSpacing
         implicitWidth: icon.implicitWidth + Kirigami.Units.largeSpacing * 2
         Layout.minimumHeight: implicitWidth

src/app/WeatherForecastPage.qml

@@ -27,6 +27,7 @@ Kirigami.Page {
         Kirigami.AbstractListItem {
             readonly property var fc: model.weatherForecast
             highlighted: false
+            backgroundColor: fc.isSevere ? Kirigami.Theme.negativeBackgroundColor : "transparent"
             Row {
                 spacing: Kirigami.Units.largeSpacing
                 Kirigami.Icon {

src/weather/weatherforecast.cpp

@@ -213,3 +213,30 @@ void WeatherForecast::setTile(WeatherTile tile)
     d.detach();
     d->m_tile = tile;
 }
+
+bool WeatherForecast::isSevere() const
+{
+    // heat: https://en.wikipedia.org/wiki/Heat_index
+    // TODO to do this properly we need the humidity value as well
+    if (d->m_maxTemp > 35.0) {
+        return true;
+    }
+
+    // cold
+    if (d->m_minTemp < -20.0) {
+        return true;
+    }
+
+    // precipitation: https://de.wikipedia.org/wiki/Unwetter
+    if ((d->m_precipitation / d->m_range) > 25.0 || (d->m_precipitation > 35.0 && d->m_range >= 6)) {
+        return true;
+    }
+
+    // wind: https://en.wikipedia.org/wiki/Beaufort_scale
+    if (d->m_windSpeed > 17.5) {
+        return true;
+    }
+
+
+    return false;
+}

src/weather/weatherforecast.h

@@ -28,6 +28,7 @@ class WeatherForecast
     Q_PROPERTY(float windSpeed READ windSpeed CONSTANT)
     Q_PROPERTY(QString symbolIconName READ symbolIconName CONSTANT)
     Q_PROPERTY(int range READ range CONSTANT)
+    Q_PROPERTY(bool isSevere READ isSevere STORED false)
 
 public:
     enum SymbolFlag : uint16_t {
@@ -86,6 +87,10 @@ public:
     // internal for weighting different forecast elements
     int range() const;
     void setRange(int hours);
+
+    /** Severe weather conditions. */
+    bool isSevere() const;
+
     // internal for computing the day/night icons
     WeatherTile tile() const;
     void setTile(WeatherTile tile);