How Do I Limit Dimensions Of An Upload Image?

Volitics

I am working on a script that will upload multiple files. The script will be used to upload .gif and .jpg images.

I've figured out how to limit the size of the uploaded file. I've also figured out how to check to make sure that the image is in the .gif or .jpg format. (Note: If anyone would like the script I will be happy to post the script here for everyone to copy - I've been working on it for a week - it works real good - please feel free to ask).

Anyway, what I'm now trying to figure out is how to limit the dimensions of the uploaded images. For example, I might want to limit the image to a maximum width of 250 pixels and a maximum height of 150 pixels.

I was thinking that I might have to put the limitations on the output page - and limit the output rather than limit the dimensions of the image as it is uploaded. For example, on the output page I might put a table there with the dimensions like so: <table width="250" height="150">, and then put the link to the image in another table, inside the larger table. The "inside" table could expand to accomodate the size of the image but could not expand further than a width of 250 pixels wide by 150 pixels high.

Does anyone have any other suggestions about how I might accomplish my task?

Thanks.

Volitics

majik-sheff

I don't think there's a way to check the size of an image as it's coming in, but you can do some things to it after it's received...

This is a cut-back version of a function I wrote a long time ago to do pretty much what you're talking about. It expects three arguments, an image resource (what was uploaded), and your maximum width and height (in this case 250 and 150 respectively).

It returns a new image resource containing the resized image. Hope this helps... 🙂

	function image_resize($im, $maxWidth, $maxHeight) {
		$maxAspect = $maxWidth / $maxHeight; //Figure out the aspect ratio of the desired limits
		$origWidth = imagesx($im); //Get the width of the uploaded image
		$origHeight = imagesy($im); //Get the height of the uploaded image
		$origAspect = $origWidth / $origHeight; //Get the aspect ratio of the uploaded image
		if (($origWidth > $maxWidth) || ($origHeight > $maxHeight)) { //See if we actually need to do anything
			if ($origAspect <= $maxAspect) { //If the aspect ratio of the uploaded image is less than or equal to the target size...
				$newWidth = $maxHeight * $origAspect; //Resize the image based on the height
				$newHeight = $maxHeight;
			} else { //If the ratio is greater...
				$newWidth = $maxWidth; //Resize based on width
				$newHeight = $maxWidth / $origAspect;
			}
			$om = imagecreatetruecolor($newWidth, $newHeight); //Create the target image
			imagecopyresampled($om, $im, 0, 0, 0, 0, $newWidth, $newHeight, $origWidth, $origHeight); //actually do the resizing
			return($om); //Return the result
		} else {
			return($im); //Or don't do anything and just return the input.
		}
	}

Volitics

majik-sheff;

Thank you for your kind help.

Best Regards;

Volitics

tekky

depending on how PHP reads the incoming data... if you have a filestream that you can sample.... I know gif images have the H/W dimensions in the first few bits of the file... jpeg should be similiar, you could possible sample the filestream and determine it that way.... (or wait till the files uploaded and the users wasted all that time (if its a slow connection) and then check the H/W via PHP and send a reject notice/delete the image if its out of allowable bounds...

Volitics

tekky;

Thanks you for your response. Below are examples of code that determine the file name, the file size, the temporary name for the file, and the file type.

The code at the very bottom is code from my script where I have incorporated the "_type" function into the script

//-----------------------------------------------
//I'm a little bit confused about how simply appending the "[COLOR=darkred]_name[/COLOR]", the
//"[COLOR=darkred]_size[/COLOR]", the "[COLOR=darkred]_tmp_name[/COLOR]", and the "[COLOR=darkred]_type[/COLOR]" functions to the end of the variables work
//- but they work - and I guess that that's all that matters.

$my_file_name (filename as uploaded)
$my_file_size (size of file)
$my_file_tmp_name (temp. name of file on server)
$my_file_type (file MIME type, such as image/gif)
//------------------------------------------------
//
//Here's how I incorporate the "_type" function into my code.
//The code below determines if the image is a .gif, .jpg, or other.

$SetFormatFileType = "fileup".$Number."_type";//Set format for the file/image type.
$TypeFile = $$SetFormatFileType;//Assigns the type of the file to the $TypeFile variable.

Do you have any pointers about how I might go about checking the filestream in the .gif or .jpg files?

Thanks.

Volitics

tekky

whats the actual upload procedure look like?

thats where you would have to pick off data from the filestream....

Volitics

$Admin[UploadNum] = "10";  // Number of upload feilds to put on the html page
$Admin[Directory] = "/site/pictures/uploads";  // The directory the files will be uploaded to (must be chmoded to 777)
if($FileUpload) {
for ($Number = 1; $Number <= $Admin[UploadNum]; $Number++){
$SetFormatPicture = "fileup".$Number."_name";//Set the format for variable $OriginalFileName
$OriginalFileName = $$SetFormatPicture;//Assigns the name of the file to the $OriginalFileName variable.
$SetFormatTempFile = "fileup".$Number;//Set the format for variable $TemporaryFile
$TemporaryFile = $$SetFormatTempFile;//Assigns the name of the file to the $TemporaryFile variable.
$SetFormatFileType = "fileup".$Number."_type";//Set format for the file/image type.
$TypeFile = $$SetFormatFileType;//Assigns the type of the file to the $TypeFile variable.
if($TemporaryFile != "none") {
	echo "$OriginalFileName<br>";//For testing purposes only.
	echo "$TemporaryFile<br>";//For testing purposes only.
	echo "$TypeFile<p>";//For testing purposes only.
//----------------------------
if ($TypeFile == "image/gif"){//Check to see if it's a .gif image.
$gif = TRUE;
}else{
$gif = FALSE;
}
//---------------------------
if ($TypeFile == "image/jpeg"){//Check to see if it's a .jpeg image (must have the .jpg suffix).
$jpg = TRUE;
}else{
$jpg = FALSE;
}//---------------------------


if ($gif OR $jpg){
	$FileSizeBtyes = filesize($TemporaryFile);//Extract the size of the file.
	if ($FileSizeBtyes > 50000) { //Check the size of the file.
	$Message[] = "File size exceeds 50000 kb for file $Number<BR>";
	}elseif (file_exists("$Admin[Directory]/$OriginalFileName")){//Check to see if the file already exists
	$Message[] = "File name already exists for file $Number with file name $OriginalFileName<BR>";
	}else {
	copy ($TemporaryFile, "$Admin[Directory]/$OriginalFileName");//If everything checks out upload the file.
	$Message[] = "File Reference Number $Number, $OriginalFileName, has been uploaded<BR>";	
	}
}else{
$Message[] = "Wrong file type. Files must have one of the following suffixes: \".gif\",  \".jpeg\",  \".jpg\",  \".tif\",  or \".bmp\" .<BR>";
}
}
//--------------------------------
}
//---- echo messages.
if ($Message) {
	foreach ($Message as $Key => $Value) {
		echo "$Value <br>\n";	
	}
}
exit();
//------------------
} else {
echo "<form enctype=\"multipart/form-data\" action=\"$PHP_SELF\" method=\"post\">\n";
echo "<center><table width=\"450\" border=\"1\" cellspacing=\"5\" cellpadding=\"5\">\n";	
for ($Number = 1; $Number <= $Admin[UploadNum]; $Number++){
echo "<tr><td width=\"25%\">File $Number:</FONT></td><td width=\"75%\"><input name=\"fileup"."$Number\" type=\"file\" size=\"25\"></td></tr>\n";    

}
echo "</table></center>";
echo "<center><input name=\"FileUpload\" type=\"submit\" value=\"Upload Files\">\n";
exit();
}

tekky

hmmm judging by that... its not possible to intercept the filestream.... prior to it being completely uploaded

majik-sheff

To the best of my knowledge, PHP does not even see the data until the web server has finished receiving it and assembling it.. Doing an in-process analysis with PHP is not possible. Your best bet is to combine your file size limitation with an automatic resize of images that are too large.