PHP调整大小图像给出黑色背景 [英] PHP Resize image gives black background
本文介绍了PHP调整大小图像给出黑色背景的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在使用此代码来调整大小:
I am using this code for resizing:
<?php
// Function for resizing any jpg, gif, or png image files
function ak_img_resize($target, $newcopy, $w, $h, $ext) {
list($w_orig, $h_orig) = getimagesize($target);
$scale_ratio = $w_orig / $h_orig;
if (($w / $h) > $scale_ratio) {
$w = $h * $scale_ratio;
} else {
$h = $w / $scale_ratio;
}
$img = "";
$ext = strtolower($ext);
if ($ext == "gif"){
$img = imagecreatefromgif($target);
} else if($ext =="png"){
$img = imagecreatefrompng($target);
} else {
$img = imagecreatefromjpeg($target);
}
$tci = imagecreatetruecolor($w, $h);
// imagecopyresampled(dst_img, src_img, dst_x, dst_y, src_x, src_y, dst_w, dst_h, src_w, src_h)
imagecopyresampled($tci, $img, 0, 0, 0, 0, $w, $h, $w_orig, $h_orig);
imagejpeg($tci, $newcopy, 80);
}
?>
但是,每次我上传透明的png图像时,结果都是黑色背景.如何防止这种情况发生并保持透明的背景?
But everytime I upload a transparant png image it turns out with a black background. How do I prevent this from happening and maintain the transparant background?
推荐答案
在重新进行图像复制采样之前尝试此操作,添加alpha混合,然后保存Alpa
try this before imagecopyresampled, added alpha blending, and then save alpa
imagealphablending($tci, false);
imagesavealpha($tci,true);
$transparent = imagecolorallocatealpha($tci, 255, 255, 255, 127);
imagefilledrectangle($tci, 0, 0, $w, $h, $transparent);
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