phpqrcode修改代码使生成透明背景的二维码

其实还是比较简单的。找到phpqrcode/phpqrcode.php，大概997行开始：

private static function image($frame, $pixelPerPoint = 4, $outerFrame = 4) 
{
    $h = count($frame);
    $w = strlen($frame[0]);
    
    $imgW = $w + 2*$outerFrame;
    $imgH = $h + 2*$outerFrame;
    
    $base_image =ImageCreate($imgW, $imgH);
    
    $col[0] = ImageColorAllocate($base_image,255,255,255);
    $col[1] = ImageColorAllocate($base_image,0,0,0);

    //imagefill($base_image, 0, 0, $col[0]);//这一行注释掉，并在下面增加如下三行
    $bg = imagecolorallocatealpha($base_image , 0 , 0 , 0 , 127);
    imagealphablending($base_image, false);
    imagefill($base_image, 0, 0, $bg);

    for($y=0; $y<$h; $y++) {
        for($x=0; $x<$w; $x++) {
            if ($frame[$y][$x] == '1') {
                ImageSetPixel($base_image,$x+$outerFrame,$y+$outerFrame,$col[1]); 
            }
        }
    }