我有一个 php 页面，它获取用户图像并将其上传到我的网络服务器。
我刚刚注意到，如果我有一个透明背景的png，然后上传它，背景就会变成白色。
例如，我在 Photoshop 中创建一个具有透明背景的新图像，然后在页面上添加一个彩色圆圈。我将图像保存为 png 并通过 ftp 上传到服务器，然后图像在网页上显示为一个圆圈，因为背景是透明的。
如果我使用带有文件输入框的 php 上传图像，图像将变为白色。
我尝试使用 imagealphablending、imagecolorallocatealpha、imagefill 和 imagesavealpha 来保留透明背景，但它只是将 bg 更改为黑色。
任何线索？
这是我的php代码
<?php
$path = "../userfiles/orig/";
$userpath="../".$_REQUEST['userpath']."/";
function getExtension($str) {
$i = strrpos($str,".");
if (!$i) { return ""; }
$l = strlen($str) - $i;
$ext = substr($str,$i+1,$l);
return $ext;
}
$valid_formats = array("jpg", "png", "gif", "bmp","jpeg","PNG","JPG","JPEG","GIF","BMP");
if(isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST"){
$name = $_FILES['photoimg']['name'];
$size = $_FILES['photoimg']['size'];
if(strlen($name)){
$ext = getExtension($name);
if(in_array($ext,$valid_formats)){
if($size<(2048*2048)){
$time1=time();
$actual_image_name =$time1."_".str_replace(" ", "_", $name);
$tmp = $_FILES['photoimg']['tmp_name'];
if(move_uploaded_file($tmp, $path.$actual_image_name)){
$image=$actual_image_name;
/*--------resize image-----------*/
$size = 320; // the imageheight
$filedir = '../userfiles/orig/'; // the directory for the original image
$thumbdir = $userpath; // the directory for the resized image
$prefix = $time1.'_'; // the prefix to be added to the original name
$maxfile = '20000000';
$mode = '0666';
$userfile_name =str_replace(" ", "", $_FILES['photoimg']['name']);
$userfile_tmp = str_replace(" ", "", $_FILES['photoimg']['tmp_name']);
$userfile_size =$_FILES['photoimg']['size'];
$userfile_type = $_FILES['photoimg']['type'];
if (isset($_FILES['photoimg']['name'])){
$prod_img = $filedir.$actual_image_name;
$prod_img_thumb = $thumbdir.$prefix.$userfile_name;
move_uploaded_file($userfile_tmp, $prod_img);
chmod ($prod_img, octdec($mode));
$sizes = getimagesize($prod_img);
$aspect_ratio = $sizes[1]/$sizes[0];
if ($sizes[1] <= $size){
$new_width = $sizes[0];
$new_height = $sizes[1];
}else{
$new_height = $size;
$new_width = abs($new_height/$aspect_ratio);
}
$destimg=ImageCreateTrueColor($new_width,$new_height)
or die('Problem In Creating image');
switch($ext){
case "jpg":
case "jpeg":
case "JPG":
case "JPEG":
$srcimg=ImageCreateFromJPEG($prod_img)or die('Problem In opening Source Image');
break;
case "PNG":
case "png":
$srcimg = imageCreateFromPng($prod_img)or die('Problem In opening Source Image');
imagealphablending($destimg, false);
$colorTransparent = imagecolorallocatealpha($destimg, 0, 0, 0x7fff0000);
imagefill($destimg, 0, 0, $colorTransparent);
imagesavealpha($destimg, true);
break;
case "BMP":
case "bmp":
$srcimg = imageCreateFromBmp($prod_img)or die('Problem In opening Source Image');
break;
case "GIF":
case "gif":
$srcimg = imageCreateFromGif($prod_img)or die('Problem In opening Source Image');
break;
default:
$srcimg=ImageCreateFromJPEG($prod_img)or die('Problem In opening Source Image');
}
if(function_exists('imagecopyresampled')){
imagecopyresampled($destimg,$srcimg,0,0,0,0,$new_width,$new_height,imagesX($srcimg),imagesY($srcimg))
or die('Problem In resizing');
}else{
Imagecopyresized($destimg,$srcimg,0,0,0,0,$new_width,$new_height,imagesX($srcimg),imagesY($srcimg))
or die('Problem In resizing');
}
ImageJPEG($destimg,$prod_img_thumb,90)
or die('Problem In saving');
}
unlink($prod_img);
echo "<img src='".$prod_img_thumb."'>";
}else{
echo "Fail upload folder with read access.";
}
}else{
echo "Image file size max 3 MB";
}
}else{
echo "Invalid file format..";
}
}else{
echo "Please select image..!";
}
exit;
}
?>