Created
September 20, 2014 15:43
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gets jpeg size without fully download
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// Retrieve JPEG width and height without downloading/reading entire image. | |
function getjpegsize($img_loc) { | |
$handle = fopen($img_loc, "rb") or die("Invalid file stream."); | |
$new_block = NULL; | |
if(!feof($handle)) { | |
$new_block = fread($handle, 32); | |
$i = 0; | |
if($new_block[$i]=="\xFF" && $new_block[$i+1]=="\xD8" && $new_block[$i+2]=="\xFF" && $new_block[$i+3]=="\xE0") { | |
$i += 4; | |
if($new_block[$i+2]=="\x4A" && $new_block[$i+3]=="\x46" && $new_block[$i+4]=="\x49" && $new_block[$i+5]=="\x46" && $new_block[$i+6]=="\x00") { | |
// Read block size and skip ahead to begin cycling through blocks in search of SOF marker | |
$block_size = unpack("H*", $new_block[$i] . $new_block[$i+1]); | |
$block_size = hexdec($block_size[1]); | |
while(!feof($handle)) { | |
$i += $block_size; | |
$new_block .= fread($handle, $block_size); | |
if($new_block[$i]=="\xFF") { | |
// New block detected, check for SOF marker | |
$sof_marker = array("\xC0", "\xC1", "\xC2", "\xC3", "\xC5", "\xC6", "\xC7", "\xC8", "\xC9", "\xCA", "\xCB", "\xCD", "\xCE", "\xCF"); | |
if(in_array($new_block[$i+1], $sof_marker)) { | |
// SOF marker detected. Width and height information is contained in bytes 4-7 after this byte. | |
$size_data = $new_block[$i+2] . $new_block[$i+3] . $new_block[$i+4] . $new_block[$i+5] . $new_block[$i+6] . $new_block[$i+7] . $new_block[$i+8]; | |
$unpacked = unpack("H*", $size_data); | |
$unpacked = $unpacked[1]; | |
$height = hexdec($unpacked[6] . $unpacked[7] . $unpacked[8] . $unpacked[9]); | |
$width = hexdec($unpacked[10] . $unpacked[11] . $unpacked[12] . $unpacked[13]); | |
return array($width, $height); | |
} else { | |
// Skip block marker and read block size | |
$i += 2; | |
$block_size = unpack("H*", $new_block[$i] . $new_block[$i+1]); | |
$block_size = hexdec($block_size[1]); | |
} | |
} else { | |
return FALSE; | |
} | |
} | |
} | |
} | |
} | |
return FALSE; | |
} |
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