PHP dynamically adds transparency gradient effect to images_PHP tutorial

Today, due to temporary needs, I need to dynamically add a transparency gradient effect to the image. I searched for an algorithm on the Internet for a long time without corresponding functions....

I wrote one myself:

The following is the quoted content:

以下为引用的内容：

////$strimgsrc = file_get_contents("http://127.0.0.1/5307754.jpg");
////$imgsrc = imagecreatefromstring($strimgsrc);
$imgsrc = imagecreatefromjpeg("5307754.jpg");
$imgsrcw = imagesx($imgsrc);
$imgsrch = imagesy($imgsrc);

$width = 30;
$x1 = 2;
$x2 = $imgsrcw - $x1 - 20;
$y1 = ($imgsrch - $width) - 2;
$y2 = $y1 + $width;

$steps = $x2 - $x1;
for($i = 0; $i < $steps; $i ++)
{
$alphax = round($i/($steps/127))+60;
if($alphax >= 128)
                $alphax = 127;
        $alpha = imagecolorallocatealpha($imgsrc, 255, 255, 255, $alphax);
        imagefilledrectangle($imgsrc, ($i+$x1), $y1, ($i+$x1+1), $y2, $alpha);
}

header(content-type: image/jpeg);

imagejpeg($imgsrc);
imagedestroy($imgsrc);
?>

////$strimgsrc = file_get_contents("http://127.0.0.1/5307754.jpg");

////$imgsrc = imagecreatefromstring($strimgsrc);

$imgsrc = imagecreatefromjpeg("5307754.jpg");

$imgsrcw = imagesx($imgsrc);$imgsrch = imagesy($imgsrc); $width = 30;$x1 = 2;$x2 = $imgsrcw - $x1 - 20;$y1 = ($imgsrch - $width) - 2;$ y2 = $y1 + $width; $steps = $x2 - $x1; for($i = 0; $i < $steps; $i ++){     $alphax = round($i/( $steps/127))+60;

if($alphax >= 128) $alphax = 127; $alpha = imagecolorallocatealpha($imgsrc, 255, 255, 255, $alphax) ;

imagefilledrectangle($imgsrc, ($i+$x1), $y1, ($i+$x1+1), $y2, $alpha);

} header(content-type: image/jpeg); imagejpeg($imgsrc);imagedestroy($imgsrc);?>

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