It is quite difficult to use PHP language to generate QR codes, except for calling the interface to generate QR code images. If you write the code to generate it yourself, you really have no way to start. However, we can use phpqrcode, a ready-made class file and PHP QR code generation class library, to easily generate QR codes.

Preliminary preparation:

1.phpqrcode class file download, download address: https://sourceforge.net/projects/phpqrcode/
2. The PHP environment must enable GD2 extension library support (usually enabled)

Interpretation of method:

Download The class file that comes down is a compressed package, which contains many files and demonstration programs. We only need the phpqrcode.php file inside to generate the QR code. It is a collection file of multiple classes. We need to use the png() method (line 3090) of the QRcode class (line 2963) inside:

public static function png($text, $outfile = false, $level = QR_ECLEVEL_L, $size = 3, $margin = 4, $saveandprint=false)
{
  $enc = QRencode::factory($level, $size, $margin);
  return $enc->encodePNG($text, $outfile, $saveandprint=false);
}

The first parameter $text: The content contained in the QR code, which can be a link, text, json string, etc.;
The second parameter $outfile: The default is false, no file is generated, and only the QR code image is returned to the output; otherwise, the file name and path to store the generated QR code image need to be given;
The third parameter$level: The default is L , the values ??that can be passed by this parameter are L(QR_ECLEVEL_L, 7%), M(QR_ECLEVEL_M, 15%), Q(QR_ECLEVEL_Q, 25%), H(QR_ECLEVEL_H, 30%). This parameter controls the error tolerance rate of the QR code. Different parameters represent the percentage of the area that can be covered by the QR code, that is, the covered area can still be recognized;
The fourth parameter$size: controls the size of the generated image, the default is 4;
The 5th parameter$margin: Controls the size of the blank area for generating QR codes;
The 6th parameter$saveandprint: Saves the QR code image and displays it , $outfile must pass the image path;

Usage example:

1. Generate QR code (generate image file)

// 1. 生成原始的二維碼(生成圖片文件)
function scerweima($url=''){
  require_once 'phpqrcode.php';
  $value = $url;         //二維碼內(nèi)容
  $errorCorrectionLevel = 'L';  //容錯(cuò)級(jí)別
  $matrixPointSize = 5;      //生成圖片大小
  //生成二維碼圖片
  $filename = 'qrcode/'.microtime().'.png';
  QRcode::png($value,$filename , $errorCorrectionLevel, $matrixPointSize, 2);
  $QR = $filename;        //已經(jīng)生成的原始二維碼圖片文件
  $QR = imagecreatefromstring(file_get_contents($QR));
  //輸出圖片
  imagepng($QR, 'qrcode.png');
  imagedestroy($QR);
  return &#39;<img src="qrcode.png" alt="使用微信掃描支付">&#39;;
}
//調(diào)用查看結(jié)果
echo scerweima(&#39;https://www.baidu.com&#39;);

2. Add logo to the generated QR code (generate image file)

//2. 在生成的二維碼中加上logo(生成圖片文件)
function scerweima1($url=''){
  require_once 'phpqrcode.php';
  $value = $url;         //二維碼內(nèi)容
  $errorCorrectionLevel = 'H';  //容錯(cuò)級(jí)別
  $matrixPointSize = 6;      //生成圖片大小
  //生成二維碼圖片
  $filename = 'qrcode/'.microtime().'.png';
  QRcode::png($value,$filename , $errorCorrectionLevel, $matrixPointSize, 2);
  $logo = 'qrcode/logo.jpg'; //準(zhǔn)備好的logo圖片
  $QR = $filename;      //已經(jīng)生成的原始二維碼圖
  if (file_exists($logo)) {
    $QR = imagecreatefromstring(file_get_contents($QR));    //目標(biāo)圖象連接資源。
    $logo = imagecreatefromstring(file_get_contents($logo));  //源圖象連接資源。
    $QR_width = imagesx($QR);      //二維碼圖片寬度
    $QR_height = imagesy($QR);     //二維碼圖片高度
    $logo_width = imagesx($logo);    //logo圖片寬度
    $logo_height = imagesy($logo);   //logo圖片高度
    $logo_qr_width = $QR_width / 4;   //組合之后logo的寬度(占二維碼的1/5)
    $scale = $logo_width/$logo_qr_width;  //logo的寬度縮放比(本身寬度/組合后的寬度)
    $logo_qr_height = $logo_height/$scale; //組合之后logo的高度
    $from_width = ($QR_width - $logo_qr_width) / 2;  //組合之后logo左上角所在坐標(biāo)點(diǎn)
    //重新組合圖片并調(diào)整大小
    /*
     * imagecopyresampled() 將一幅圖像(源圖象)中的一塊正方形區(qū)域拷貝到另一個(gè)圖像中
     */
    imagecopyresampled($QR, $logo, $from_width, $from_width, 0, 0, $logo_qr_width,$logo_qr_height, $logo_width, $logo_height);
  }
  //輸出圖片
  imagepng($QR, 'qrcode.png');
  imagedestroy($QR);
  imagedestroy($logo);
  return &#39;<img src="qrcode.png" alt="使用微信掃描支付">&#39;;
}
//調(diào)用查看結(jié)果
echo scerweima1(&#39;https://www.baidu.com&#39;);

3. Generate QR code Code (does not generate image files)

//3. 生成原始的二維碼(不生成圖片文件)
function scerweima2($url=''){
  require_once 'phpqrcode.php';
  $value = $url;         //二維碼內(nèi)容
  $errorCorrectionLevel = 'L';  //容錯(cuò)級(jí)別
  $matrixPointSize = 5;      //生成圖片大小
  //生成二維碼圖片
  $QR = QRcode::png($value,false,$errorCorrectionLevel, $matrixPointSize, 2);
}
//調(diào)用查看結(jié)果
scerweima2('https://www.baidu.com');

The first two methods will generate a QR code image locally every time they are called. The third method does not generate file, the QR code will be output directly to the browser.

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