<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<!-- examples-qmlweather.qdoc -->
<title>Qml Weather | Qt Charts 5.12.6</title>
<link rel="stylesheet" type="text/css" href="style/offline-simple.css" />
<script type="text/javascript">
document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css");
// loading style sheet breaks anchors that were jumped to before
// so force jumping to anchor again
setTimeout(function() {
var anchor = location.hash;
// need to jump to different anchor first (e.g. none)
location.hash = "#";
setTimeout(function() {
location.hash = anchor;
}, 0);
}, 0);
</script>
</head>
<body>
<div class="header" id="qtdocheader">
<div class="main">
<div class="main-rounded">
<div class="navigationbar">
<table><tr>
<td >Qt 5.12</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>
<td id="buildversion" width="100%" align="right"><a href="qtcharts-index.html">Qt Charts | Commercial or GPLv3</a></td>
</tr></table>
</div>
</div>
<div class="content">
<div class="line">
<div class="content mainContent">
<div class="sidebar">
<div class="toc">
<h3><a name="toc">Contents</a></h3>
<ul>
<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>
</ul>
</div>
<div class="sidebar-content" id="sidebar-content"></div></div>
<h1 class="title">Qml Weather</h1>
<span class="subtitle"></span>
<!-- $$$qmlweather-brief -->
<p>This is a basic demonstration showing how to use the different chart types by using qml.</p>
<!-- @@@qmlweather -->
<!-- $$$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">
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"
}
}
</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">
// 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();
</pre>
<p>The JSON response contains an array of forecast data:</p>
<pre class="qml">
// Loop through the parsed JSON
for (var i in weatherData.data.weather) {
var weatherObj = weatherData.data.weather[i];
</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">
// 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});
</pre>
<p>Files:</p>
<ul>
<li><a href="qtcharts-qmlweather-main-cpp.html">qmlweather/main.cpp</a></li>
<li><a href="qtcharts-qmlweather-qml-qmlweather-main-qml.html">qmlweather/qml/qmlweather/main.qml</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>
</div>
<!-- @@@qmlweather -->
</div>
</div>
</div>
</div>
</div>
<div class="footer">
<p>
<acronym title="Copyright">©</acronym> 2019 The Qt Company Ltd.
Documentation contributions included herein are the copyrights of
their respective owners.<br/> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br/> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property
of their respective owners. </p>
</div>
</body>
</html>
