将文本应用于png透明度问题PHP

Question

I am trying to write text onto a png, however when I do it puts a dark border around it, I am not sure why.

The original image:

The processed image:

Code:

// Load the image
$im = imagecreatefrompng("admin/public/images/map/order/wally.png");

// If there's an error, gtfo
if(!$im) {
    die("");
}
$textColor = imagecolorallocate($im, 68, 68, 68);

$width = imagesx($im);
$height = imagesy($im);

$fontSize = 5; 
$text = "AC";
// Calculate the left position of the text
$leftTextPos = ($width - imagefontwidth($fontSize)*strlen($text)) / 2;
// Write the string
imagestring($im, $fontSize, $leftTextPos, $height-28, $text, $textColor);
// Output the image
header('Content-type: image/png');
imagepng($im);
imagedestroy($im);

Answer 1

I've had this issue several times, let me find the answer...

Ok, found something:

imagesavealpha($im, true);
imagealphablending($im, true);

Write that before imagepng .

Answer 2

Yes, saving with alpha is important but loading it is important as well. Your PNG image might have transparency but it is good practice to account for that as well.

You'd need to create true color image, set alpha color and then draw your loaded image with text over it. So something like this:

// create true color image
$img = imagecreatetruecolor($width, $height);
$transparent_color = imagecolorallocatealpha($img, 255, 255, 255, 0);

imagealphablending($img, false);
imagefillrectangle($img, 0, 0, $width, $height, $transparent_color);
imagealphablending($img, true);

// draw previously loaded PNG image
imagecopy($img, $loaded_img, 0, 0, 0, 0, $width, $height);

// draw your text

// save the whole thing
imagesavealpha($img, true);
imagepng($img, $file);