PHP display image with Header

Question

I m displaying images from outside my web root  like this   header  Content-type image png    readfile  fullpath     The content-type  image png is what confuses me   Someone else helped me out with this code  but I noticed that not all images are PNG   Many are jpg or gif  And still they are displayed successfully   does anyone know why

User · Answer

There is a better why to determine type of an image. with exif_imagetype

If you use this function, you can tell image's real extension.

_{with this function filename's extension is completely irrelevant, which is good.}

function setHeaderContentType(string $filePath): void
{
    $numberToContentTypeMap = [
        '1' => 'image/gif',
        '2' => 'image/jpeg',
        '3' => 'image/png',
        '6' => 'image/bmp',
        '17' => 'image/ico'
    ];

    $contentType = $numberToContentTypeMap[exif_imagetype($filePath)] ?? null;
    
    if ($contentType === null) {
        throw new Exception('Unable to determine content type of file.');
    }

    header("Content-type: $contentType");
}

You can add more types from the link.

Hope it helps.

User · Answer

The best solution would be to read in the file  then decide which kind of image it is and send out the appropriate header   filename   basename  file    file extension   strtolower substr strrchr  filename      1     switch   file extension         case  gif    ctype  image gif   break      case  png    ctype  image png   break      case  jpeg       case  jpg    ctype  image jpeg   break      case  svg    ctype  image svg xml   break      default     header  Content-type       ctype      Note  the correct content-type for JPG files is image jpeg

User · Answer

Though weirdly named  you can use the getimagesize   function  This will also give you mime information   Array        0    gt  295    width      1    gt  295    height      2    gt  3    http   php net manual en image constants php      3    gt  width  295  height  295     width and height as attr s      bits    gt  8      mime    gt  image png

User · Answer

Browsers make their best guess with the data they receive  This works for markup  which Websites often get wrong  and other media content  A program that receives a file can often figure out what its received regardless of the MIME content type it s been told   This isn t something you should rely on however  It s recommended you always use the correct MIME content

User · Answer

Browsers can often tell the image type by sniffing out the meta information of the image  Also  there should be a space in that header   header  Content-type  image png

User · Answer

if you know the  file name  but don t know the file extention you can use this function   public function showImage  name                   types                   gif   gt   image gif                 png   gt   image png                 jpeg   gt   image jpeg                 jpg   gt   image jpeg                         root path      var www my app     use your framework to get this properly             foreach  types as  type  gt  meta                if file exists  root path    uploads    name         type                     header  Content-type       meta                    readfile  root path    uploads    name        type                    return                                    Note  the correct content-type for JPG files is image jpeg

[php] PHP, display image with Header()

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