Qml Weather#

../_images/examples_qmlweather.png

This is a basic demonstration showing how to use the different chart types by using qml.

By default the application uses static test data to mimic a weather forecast. You can also obtain an application id from http://www.worldweatheronline.com/ to get access to weather API provided by World Weather Online. You can then give your application id as a parameter to the Qml Weather executable to make it use live data.

For example:

bin\qmlweather.exe 1234567890abcdef123456

Running the Example#

To run the example from Qt Creator , open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Using Charts in Qt Quick Applications#

The example application uses a ChartView and a some series to visualize weather data:

ChartView {
    id: chartView
    title: "Weather forecast"        BarCategoryAxis {
    id: barCategoriesAxis
    titleText: "Date"
}

ValueAxis{
    id: valueAxisY2
    min: 0
    max: 10
    titleText: "Rainfall [mm]"
}

ValueAxis {
    id: valueAxisX
    // Hide the value axis; it is only used to map the line series to bar categories axis
    visible: false
    min: 0
    max: 5
}

ValueAxis{
    id: valueAxisY
    min: 0
    max: 15
    titleText: "Temperature [°C]"
}

LineSeries {
    id: maxTempSeries
    axisX: valueAxisX
    axisY: valueAxisY
    name: "Max. temperature"
}

LineSeries {
    id: minTempSeries
    axisX: valueAxisX
    axisY: valueAxisY
    name: "Min. temperature"
}

BarSeries {
    id: myBarSeries
    axisX: barCategoriesAxis
    axisYRight: valueAxisY2
    BarSet {
        id: rainfallSet
        label: "Rainfall"
    }
}

To get data with weather forecast data, we make an HTTP GET request to World Weather Online. We request the response in JSON data format.

// Make HTTP GET request and parse the result
var xhr = new XMLHttpRequest;
xhr.open("GET",
         "http://free.worldweatheronline.com/feed/weather.ashx?q=Jyv%c3%a4skyl%c3%a4,Finland&format=json&num_of_days=5&key="
         + weatherAppKey);
xhr.onreadystatechange = function() {
    if (xhr.readyState == XMLHttpRequest.DONE) {
        var a = JSON.parse(xhr.responseText);
        parseWeatherData(a);
    }
}
xhr.send();

The JSON response contains an array of forecast data:

// Loop through the parsed JSON
for (var i in weatherData.data.weather) {
    var weatherObj = weatherData.data.weather[i];

That is then used as input data for our series and a ListModel we use as a container for weather icon URLs:

// Store temperature values, rainfall and weather icon.
// The temperature values begin from 0.5 instead of 0.0 to make the start from the
// middle of the rainfall bars. This makes the temperature lines visually better
// synchronized with the rainfall bars.
maxTempSeries.append(Number(i) + 0.5, weatherObj.tempMaxC);
minTempSeries.append(Number(i) + 0.5, weatherObj.tempMinC);
rainfallSet.append(i, weatherObj.precipMM);
weatherImageModel.append({"imageSource":weatherObj.weatherIconUrl[0].value});

Example project @ code.qt.io