PHP GD Text with Transparency/Alpha background

问题

alright so im having a problem with getting my text layed over a partly transparent image. i want the text to be solid, but i want part of the background of the image to be transparent, and the part the text is over to be solid, which i have, the problem is the text is inheriting the transparent background of one of the previous layers. here is the code, and an example of the output, and under that output what i want it to look like. the image is laying on a light grey background so the light border around the image in between the darker grey is transparent but nothing else should be especially the text. it seems to be not the text its self but the background of the text blocks that is transparent. which as you can see isn't very desirable. please help, this is the only problem i have left to complete my project. :)

can't post images yet, so heres a link to the image of example output and desired outcome (orig):

<?php

$img = imagecreatetruecolor(200, 50);

$imageX = imagesx($img);
$imageY = imagesy($img);

imagealphablending($img, false);
imagesavealpha($img, true);

$transparent = imagecolorallocatealpha($img, 255,255,255, 127);
$white = imagecolorallocate($img, 255,255,255);
$grey = imagecolorallocate($img, 127,127,127);
imagefilledrectangle($img, 0, 0, $imageX, $imageY, $grey);
imagefilledrectangle($img, 2, 2, $imageX-4, $imageY-4, $transparent);

$font = "./arialbd.ttf";
$fontSize = 12;
$text = "THIS IS A TEST";

$textDim = imagettfbbox($fontSize, 0, $font, $text);
$textX = $textDim[2] - $textDim[0];
$textY = $textDim[7] - $textDim[1];

$text_posX = ($imageX / 2) - ($textX / 2);
$text_posY = ($imageY / 2) - ($textY / 2);

imagefilledrectangle($img, 10, 10, $imageX-10, $imageY-10, $grey);
imagettftext($img, $fontSize, 0, $text_posX, $text_posY, $white, $font, $text);

header("Content-Type: image/png");
imagepng($img);

?>

回答1:

hah i guess i didn't think hard enough on it. the solution was to turn imagealphablending back on before laying the text onto the image.

<?php

$img = imagecreatetruecolor(200, 50);

$imageX = imagesx($img);
$imageY = imagesy($img);

imagealphablending($img, false);
imagesavealpha($img, true);

$transparent = imagecolorallocatealpha($img, 255,255,255, 127);
$white = imagecolorallocate($img, 255,255,255);
$grey = imagecolorallocate($img, 127,127,127);
imagefilledrectangle($img, 0, 0, $imageX, $imageY, $grey);
imagefilledrectangle($img, 2, 2, $imageX-4, $imageY-4, $transparent);

$font = "./arialbd.ttf";
$fontSize = 12;
$text = "THIS IS A TEST";

$textDim = imagettfbbox($fontSize, 0, $font, $text);
$textX = $textDim[2] - $textDim[0];
$textY = $textDim[7] - $textDim[1];

$text_posX = ($imageX / 2) - ($textX / 2);
$text_posY = ($imageY / 2) - ($textY / 2);

imagefilledrectangle($img, 10, 10, $imageX-10, $imageY-10, $grey);
imagealphablending($img, true);
imagettftext($img, $fontSize, 0, $text_posX, $text_posY, $white, $font, $text);

header("Content-Type: image/png");
imagepng($img);

?>

来源：https://stackoverflow.com/questions/2134467/php-gd-text-with-transparency-alpha-background

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php

transparent

imagettftext