Paste_Image.png

imagecolorallocatealpha

其值從 0 到 127。0 表示完全不透明，127 表示完全透明。

test.php

$filename = 'images/1.jpg';
$fileInfo = getimagesize($filename);
$mime = $fileInfo['mime'];
$createFun = str_replace('/', 'createfrom', $mime);
$outFun = str_replace('/', null, $mime);
$image = $createFun($filename);
$red = imagecolorallocatealpha($image, 255, 0, 0, 40);
$fontfile = 'fonts/couri.ttf';
imagettftext($image, 30, 0, 80, 80, $red, $fontfile, 'King...');
header('content-type:' . $mime);
$outFun($image);
imagedestroy($image);

Paste_Image.png