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<td >Qt 5.9</td><td ><a href="qtcharts-index.html">Qt Charts</a></td><td ><a href="qtcharts-examples.html">Qt Charts Examples</a></td><td >Qml Weather</td></tr></table><table class="buildversion"><tr>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#running-the-example">Running the Example</a></li>
<li class="level1"><a href="#using-charts-in-qt-quick-applications">Using Charts in Qt Quick Applications</a></li>
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<h1 class="title">Qml Weather</h1>
<span class="subtitle"></span>
<!-- $$$qmlweather-description -->
<div class="descr"> <a name="details"></a>
<p class="centerAlign"><img src="images/examples_qmlweather.png" alt="" /></p><p>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.</p>
<p>For example:</p>
<pre class="cpp">
bin\qmlweather<span class="operator">.</span>exe <span class="number">1234567890abcdef123456</span>
</pre>
<a name="running-the-example"></a>
<h2 id="running-the-example">Running the Example</h2>
<p>To run the example from Qt Creator, open the <b>Welcome</b> mode and select the example from <b>Examples</b>. For more information, visit Building and Running an Example.</p>
<a name="using-charts-in-qt-quick-applications"></a>
<h2 id="using-charts-in-qt-quick-applications">Using Charts in Qt Quick Applications</h2>
<p>The example application uses a <a href="qml-qtcharts-chartview.html">ChartView</a> and a some series to visualize weather data:</p>
<pre class="qml">
<span class="type"><a href="qml-qtcharts-chartview.html">ChartView</a></span> {
<span class="name">id</span>: <span class="name">chartView</span>
<span class="name">title</span>: <span class="string">"Weather forecast"</span>
<span class="type"><a href="qml-qtcharts-barcategoryaxis.html">BarCategoryAxis</a></span> {
<span class="name">id</span>: <span class="name">barCategoriesAxis</span>
<span class="name">titleText</span>: <span class="string">"Date"</span>
}
<span class="type"><a href="qml-qtcharts-valueaxis.html">ValueAxis</a></span>{
<span class="name">id</span>: <span class="name">valueAxisY2</span>
<span class="name">min</span>: <span class="number">0</span>
<span class="name">max</span>: <span class="number">10</span>
<span class="name">titleText</span>: <span class="string">"Rainfall [mm]"</span>
}
<span class="type"><a href="qml-qtcharts-valueaxis.html">ValueAxis</a></span> {
<span class="name">id</span>: <span class="name">valueAxisX</span>
<span class="comment">// Hide the value axis; it is only used to map the line series to bar categories axis</span>
<span class="name">visible</span>: <span class="number">false</span>
<span class="name">min</span>: <span class="number">0</span>
<span class="name">max</span>: <span class="number">5</span>
}
<span class="type"><a href="qml-qtcharts-valueaxis.html">ValueAxis</a></span>{
<span class="name">id</span>: <span class="name">valueAxisY</span>
<span class="name">min</span>: <span class="number">0</span>
<span class="name">max</span>: <span class="number">15</span>
<span class="name">titleText</span>: <span class="string">"Temperature [&deg;C]"</span>
}
<span class="type"><a href="qml-qtcharts-lineseries.html">LineSeries</a></span> {
<span class="name">id</span>: <span class="name">maxTempSeries</span>
<span class="name">axisX</span>: <span class="name">valueAxisX</span>
<span class="name">axisY</span>: <span class="name">valueAxisY</span>
<span class="name">name</span>: <span class="string">"Max. temperature"</span>
}
<span class="type"><a href="qml-qtcharts-lineseries.html">LineSeries</a></span> {
<span class="name">id</span>: <span class="name">minTempSeries</span>
<span class="name">axisX</span>: <span class="name">valueAxisX</span>
<span class="name">axisY</span>: <span class="name">valueAxisY</span>
<span class="name">name</span>: <span class="string">"Min. temperature"</span>
}
<span class="type"><a href="qml-qtcharts-barseries.html">BarSeries</a></span> {
<span class="name">id</span>: <span class="name">myBarSeries</span>
<span class="name">axisX</span>: <span class="name">barCategoriesAxis</span>
<span class="name">axisYRight</span>: <span class="name">valueAxisY2</span>
<span class="type"><a href="qml-qtcharts-barset.html">BarSet</a></span> {
<span class="name">id</span>: <span class="name">rainfallSet</span>
<span class="name">label</span>: <span class="string">"Rainfall"</span>
}
}
</pre>
<p>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.</p>
<pre class="qml">
<span class="comment">// Make HTTP GET request and parse the result</span>
var <span class="name">xhr</span> = new <span class="name">XMLHttpRequest</span>;
<span class="name">xhr</span>.<span class="name">open</span>(<span class="string">"GET"</span>,
<span class="string">"http://free.worldweatheronline.com/feed/weather.ashx?q=Jyv%c3%a4skyl%c3%a4,Finland&format=json&num_of_days=5&key="</span>
<span class="operator">+</span> <span class="name">weatherAppKey</span>);
<span class="name">xhr</span>.<span class="name">onreadystatechange</span> <span class="operator">=</span> <span class="keyword">function</span>() {
<span class="keyword">if</span> (<span class="name">xhr</span>.<span class="name">readyState</span> <span class="operator">==</span> <span class="name">XMLHttpRequest</span>.<span class="name">DONE</span>) {
var <span class="name">a</span> = <span class="name">JSON</span>.<span class="name">parse</span>(<span class="name">xhr</span>.<span class="name">responseText</span>);
<span class="name">parseWeatherData</span>(<span class="name">a</span>);
}
}
<span class="name">xhr</span>.<span class="name">send</span>();
</pre>
<p>The JSON response contains an array of forecast data:</p>
<pre class="qml">
<span class="comment">// Loop through the parsed JSON</span>
<span class="keyword">for</span> (<span class="keyword">var</span> <span class="name">i</span> in <span class="name">weatherData</span>.<span class="name">data</span>.<span class="name">weather</span>) {
var <span class="name">weatherObj</span> = <span class="name">weatherData</span>.<span class="name">data</span>.<span class="name">weather</span>[<span class="name">i</span>];
</pre>
<p>That is then used as input data for our series and a ListModel we use as a container for weather icon URLs:</p>
<pre class="qml">
<span class="comment">// Store temperature values, rainfall and weather icon.</span>
<span class="comment">// The temperature values begin from 0.5 instead of 0.0 to make the start from the</span>
<span class="comment">// middle of the rainfall bars. This makes the temperature lines visually better</span>
<span class="comment">// synchronized with the rainfall bars.</span>
<span class="name">maxTempSeries</span>.<span class="name">append</span>(<span class="name">Number</span>(<span class="name">i</span>) <span class="operator">+</span> <span class="number">0.5</span>, <span class="name">weatherObj</span>.<span class="name">tempMaxC</span>);
<span class="name">minTempSeries</span>.<span class="name">append</span>(<span class="name">Number</span>(<span class="name">i</span>) <span class="operator">+</span> <span class="number">0.5</span>, <span class="name">weatherObj</span>.<span class="name">tempMinC</span>);
<span class="name">rainfallSet</span>.<span class="name">append</span>(<span class="name">i</span>, <span class="name">weatherObj</span>.<span class="name">precipMM</span>);
<span class="name">weatherImageModel</span>.<span class="name">append</span>({"imageSource":<span class="name">weatherObj</span>.<span class="name">weatherIconUrl</span>[<span class="number">0</span>].<span class="name">value</span>});
</pre>
<p>Files:</p>
<ul>
<li><a href="qtcharts-qmlweather-qml-qmlweather-main-qml.html">qmlweather/qml/qmlweather/main.qml</a></li>
<li><a href="qtcharts-qmlweather-main-cpp.html">qmlweather/main.cpp</a></li>
<li><a href="qtcharts-qmlweather-qmlweather-pro.html">qmlweather/qmlweather.pro</a></li>
<li><a href="qtcharts-qmlweather-resources-qrc.html">qmlweather/resources.qrc</a></li>
</ul>
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<!-- @@@qmlweather -->
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