how to make a qr code code example

Example 1: qr code generator

<!DOCTYPE html>
<html lang="en">
<head>
<title>QR-Code Generator</title>
<style>
	* {
      margin: 0px; 
      padding: 0px;
      font-family: monospace, Arial, sans-serif;
  	}
	h1 {
      text-align: center; 
      text-shadow: 2px 2px 0px rgba(255,255,255,.7), 5px 7px 0px rgba(0, 0, 0, 0.1);  font-size:50px; margin-top:40px; color:#fff; 
  	}
    input[type=text] {
        width: 90%;
        padding: 12px 20px;
        margin: 8px 26px;
        display: inline-block;
        border: 1px solid #ccc;
        box-sizing: border-box;
        font-size:16px;
    }
    button {
        background-color: #4CAF50;
        color: white;
        padding: 14px 20px;
        margin: 8px 26px;
        border: none;
        cursor: pointer;
        width: 90%;
        font-size:20px;
    }
    button:hover {
        opacity: 0.8;
    }
</style>
<!--Jquery 3.2.1-->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
</head>
<body background="../background1.png">
<h1>QR-Code Generator</h1>
<div id="form-wrapper" style="width:46%; float:left; border:5px solid rgba(255,255,255,0.6); margin-top:20px; padding:10px">
    <form id="generator">     
        <label for="codeSize" style="font-size:20px; margin-right:20px; color:#fff;">Select QR Size:</label>
        <select id="codeSize" name="codeSize" style="width:260px; height:40px; ">
            <option value="75">Mini</option>
            <option value="155">Small</option>
            <option value="186">Medium</option>
            <option value="248" selected="selected">Large</option>
            <option value="300">XL</option>
            <option value="450">XXL</option>
        </select>
        <input type="text" onclick="myFunction()" id="codeData" name="codeData" size="50" placeholder="Enter a url or text" style="margin-top:20px" autocomplete="off"/ >
        <br>
        <button id="generate">generate</button>
    </form>
    <div id="alert" style="height:20px; text-align:center; margin:10px auto"></div>
</div>

  <div style="float:right;">
   <div id="image" style="margin:auto">Image will show here</div>
   <div id="link" style="margin-top:10px; text-align:center"></div>
  </div>
  
  <div id="code" style="float:left; width:100%; height:20px; text-align:center; margin-top:10px"></div>
<script>
function myFunction() {
     document.getElementById("alert").innerHTML = "";
	}
$("#generate").on("click", function () {
var data = $("#codeData").val();
var size = $("#codeSize").val();
if(data == "") {
    $("#alert").append("<p style='color:#fff;font-size:20px'>Please Enter A Url Or Text</p>"); // If Input Is Blank
    return false;
} else {
    if( $("#image").is(':empty')) {
		
	  //QR Code Image
      $("#image").append("<img src='http://chart.apis.google.com/chart?cht=qr&chl=" + data + "&chs=" + size + "' alt='qr' />");
	  
	  //This Provide An Image Download Link
      $("#link").append("<a style='color:#fff;' href='http://chart.apis.google.com/chart?cht=qr&chl=" + data + "&chs=" + size + "'>Download QR Code</a>");
	  
	  //This Provide the Image Link Path In Text
      $("#code").append("<p style='color:#fff;'><strong>Image Link:</strong> http://chart.apis.google.com/chart?cht=qr&chl=" + data + "&chs=" + size + "</p>");
      return false;
} else {
      $("#image").html("");
      $("#link").html("");
      $("#code").html("");
	  
      //QR Code Image
      $("#image").append("<img src='http://chart.apis.google.com/chart?cht=qr&chl=" + data + "&chs=" + size + "' alt='qr' />");
	  
	  //This Provide An Image Download Link
      $("#link").append("<a style='color:#fff;' href='http://chart.apis.google.com/chart?cht=qr&chl=" + data + "&chs=" + size + "'>Download QR Code</a>");
	  
	  //This Provide the Image Link Path In Text
      $("#code").append("<p style='color:#fff;'><strong>Image Link:</strong> http://chart.apis.google.com/chart?cht=qr&chl=" + data + "&chs=" + size + "</p>");
      return false;
    }
  }
});
</script>
</body>
</html>

Example 2: QR code in QT

#include "QrCode.hpp"

void paintQR(QPainter &painter, const QSize sz, const QString &data, QColor fg)
{

    qrcodegen::QrCode qr = qrcodegen::QrCode::encodeText(data.toUtf8().constData(), qrcodegen::QrCode::Ecc::LOW);
    const int s=qr.getSize()>0?qr.getSize():1;
    const double w=sz.width();
    const double h=sz.height();
    const double aspect=w/h;
    const double size=((aspect>1.0)?h:w);
    const double scale=size/(s+2);
   
    painter.setPen(Qt::NoPen);
    painter.setBrush(fg);
    for(int y=0; y<s; y++) {
        for(int x=0; x<s; x++) {
            const int color=qr.getModule(x, y);  // 0 for white, 1 for black
            if(0!=color) {
                const double rx1=(x+1)*scale, ry1=(y+1)*scale;
                QRectF r(rx1, ry1, scale, scale);
                painter.drawRects(&r,1);
            }
        }
    }
}

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