Reading EXIF Orientation And Auto-Orienting Images Using GraphicsMagick And Lucee CFML 5.2.9.31

<cfscript>

	param name="url.image" type="string" default="deer.jpg";

	startedAt = getTickCount();

	inputFilepath = expandPath( "../images/#url.image#" );

	// We can use the IDENTIFY command to read the Orientation header from the image's
	// EXIF (Exchangeable image file format) meta-data.
	result = gm([
		"identify",

		// Identify returns a String using a default format. We can use the "-format"
		// option to override this response. In this case, we want to return one of the
		// EXIF headers.
		"-format %[EXIF:Orientation]",

		// This is the image we are inspecting.
		applyReader( inputFilepath )
	]);

	// If the Orientation EXIF header is not available in the given photo, the result
	// will empty. We're expecting the result to be NUMERIC. As such, we can use val() to
	// coalesce undefined values to "0".
	// --
	// EXIF Orientation readings:
	// Taken from : https://sirv.com/help/articles/rotate-photos-to-be-upright/
	// -- 
	// 1 : 0 degrees - the correct orientation, no adjustment is required.
	// 2 : 0 degrees, mirrored - image has been flipped back-to-front.
	// 3 : 180 degrees - image is upside down.
	// 4 : 180 degrees, mirrored - image is upside down and flipped back-to-front.
	// 5 : 90 degrees - image is on its side.
	// 6 : 90 degrees, mirrored - image is on its side and flipped back-to-front.
	// 7 : 270 degrees - image is on its far side.
	// 8 : 270 degrees, mirrored - image is on its far side and flipped back-to-front.
	inputOrientation = val( result.trim() );

	// If the image has a non-correct orientation, let's use the CONVERT command to
	// auto-orient it as we copy it to the current directory (for the demo). This will
	// rotate the image so that it is correct-side-up.
	if ( inputOrientation > 1 ) {

		result = gm([
			"convert",

			// This is the image we are inspecting.
			applyReader( inputFilepath ),

			// Tell Graphicsmagick to use the image's EXIF data to automatically rotate
			// the image so that it is correct-side-upright.
			"-auto-orient",

			// Remove all profile and text-attribute data from the image. This can
			// reduce the file-size of the image (which is good for the web).
			"-strip",

			// CAUTION: Manipulating a JPG image is [almost never] LOSSLESS! When we
			// output the JPG, GraphicsMagick is defaulting to a quality of 75. As such,
			// auto-orienting may result in some degree of data loss.
			// --
			// "-quality 75",

			// Finally, write the file to the local directory.
			expandPath( "./out.jpg" )
		]);

	// If the image has the correct orientation - or if there is no orientation info -
	// let's just copy the file as-is to the current directory (for the demo).
	} else {

		fileCopy( inputFilepath, "./out.jpg" );

	}

	duration = ( getTickCount() - startedAt );

	// ------------------------------------------------------------------------------- //
	// ------------------------------------------------------------------------------- //

	/**
	* I prefix the given filepath with an explicit reader. We want to be EXPLICIT about
	* which input reader GraphicsMagick should use when reading in an image. If we leave
	* it up to "automatic detection", a malicious actor could fake the file-type and
	* potentially exploit a weakness in a given reader. As such, we want to align the
	* reader with the articulated file-type.
	* 
	* READ MORE: http://www.graphicsmagick.org/security.html
	* 
	* @filepath I am the filepath being decorated.
	*/
	public string function applyReader( required string filepath ) {

		switch ( listLast( filepath, "." ).lcase() ) {
			case "jpg":
			case "jpeg":
				var reader = "jpg";
			break;
			case "gif":
				var reader = "gif";
			break;
			case "png":
				var reader = "png";
			break;
			default:
				throw( type = "UnsupportedImageFileExtension" );
			break;
		}

		return( reader & ":""" & filepath & """" );

	}


	/**
	* I execute the given options against the GM (GraphicsMagick) command-line tool. If
	* there is an error, the error is dumped-out and the processing is halted. If there
	* is no error, the standard-output is returned.
	* 
	* NOTE: Options are flattened using a space (" ").
	* 
	* @options I am the collection of options to apply.
	* @timeout I am the timeout to use during the execution.
	*/
	public string function gm(
		required array options,
		numeric timeout = 5
		) {

		execute
			name = "gm"
			arguments = options.toList( " " )
			variable = "local.successResult"
			errorVariable = "local.errorResult"
			timeout = timeout
		;

		// If the error variable has been populated, it means the CFExecute tag ran into
		// an error - let's dump-it-out and halt processing.
		if ( local.keyExists( "errorVariable" ) && errorVariable.len() ) {

			dump( errorVariable );
			abort;

		}

		return( successResult ?: "" );

	}

</cfscript>
<cfoutput>

	<link rel="stylesheet" type="text/css" href="./demo.css">

	<h3>
		<strong>Orientation:</strong> #inputOrientation#

		<cfif ( inputOrientation gt 1 )>
			:: Applying "-auto-orient"
		</cfif>
	</h3>

	<p class="images">
		<img src="../images/#url.image#" width="315" />
		<img src="./out.jpg" width="315" />
	</p>

	<p>
		<strong>File Size:</strong>
		#numberFormat( getFileInfo( inputFilepath ).size )#
		&mdash;&gt;
		#numberFormat( getFileInfo( "./out.jpg" ).size )#
	</p>

	<p>
		<a href="#cgi.script_name#?image=deer.jpg">deer</a>,
		<a href="#cgi.script_name#?image=beach-small.jpg">beach-small</a>,
		<a href="#cgi.script_name#?image=bench.jpg">bench</a>
	</p>

	<p>
		Duration: #numberFormat( duration )# ms
	</p>

</cfoutput>