为什么调整大小后的imagepng会创建一个黑色图像? [英] why imagepng after resize create a black image?
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问题描述
我尝试使用代码调整图片大小:
i m trying to resize a image using code:
list($width,$height,$type,$attr)= getimagesize($_FILES['upload'.$num]['name']);
$source = imagecreatefrompng($_FILES['upload'.$num]['name']);
$thumb = imagecreatetruecolor(445,320);
imagealphablending($thumb, false);
imagesavealpha($thumb, true);
imagecopyresampled($thumb,$source,0,0,0,0,445,320,$width,$height);
imagepng($thumb,"../public/img/".$Nome,8);
but the output is always a black image.. anyone know why?
谢谢
推荐答案
$ _ FILES ['upload'。$ num] ['name']
只是上传的文件名,如flower.jpg,不是文件的完整路径。
$_FILES['upload'.$num]['name']
is just filename of uploaded like "flower.jpg" not full path to file.
$ _ FILES ['upload'。$ num] ['tmp_name']
是实际文件的真正绝对路径上传到您的服务器(临时目录中的某个地方)
$_FILES['upload'.$num]['tmp_name']
is real absolute path to real file uploaded on your server (somewhere in temp directory)
您的代码应如下所示:
list($width,$height,$type,$attr)= getimagesize($_FILES['upload'.$num]['tmp_name']);
$source = imagecreatefrompng($_FILES['upload'.$num]['tmp_name']);
始终尝试调试您的第一个。使用 print_r($ _ FILES)
, var_dump($ _ FILES)
等函数调试变量。
除了 $ _ FILES
变量的问题,你的代码应该可以正常工作:演示
except issue with $_FILES
variable, your code should works fine: Demo
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