Scaling An Image During A Draw Operation Using GraphicsMagick And Lucee CFML 5.2.9.31

index.cfm

<cfscript>

	param name="url.image" type="string" default="beach-small.jpg";

	startedAt = getTickCount();

	// CAUTION: For the sake of the demo, I am not validating the input image. However,
	// in a production setting, I would never allow an arbitrary filepath to be provided
	// by the user! Not without some sort of validation.
	inputFilename = url.image;
	inputFilepath = expandPath( "../images/#inputFilename#" );

	// As a first step, we need to figure out how large the input image is so that we can
	// calculate the display-scale of each paste operation. To do that, we can use the
	// Identify utility.
	inputDimensions = getImageDimensions( inputFilepath );
	inputWidth = inputDimensions.width;
	inputHeight = inputDimensions.height;

	// Setup the output filepath for our generated image.
	// --
	// NOTE: The file-extension of this output filename will be used by GraphicsMagick to
	// figure out how to encode the final image.
	outputFilename = "out.jpg";
	outputFilepath = expandPath( "./#outputFilename#" );

	// Define the dimensions of our demo image.
	outputWidth = 650;
	outputHeight = 300;

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

	// Before we execute our Convert command, let's calculate the "-draw" sub-commands
	// for each of the desired scaling sizes. These are the WIDTH dimensions at which we
	// want to paste the input image into the output image:
	drawWidths = [ 10, 50, 100, 200, 300 ];

	// As we draw the input image at different widths, we need to keep a running offset
	// for the X-coordinate of the operation (so that the different draw operations don't
	// overlap each other).
	runningX = 10;

	// Map the widths onto the actual "-draw" sub-commands.
	drawCommands = drawWidths.map(
		( drawWidth ) => {

			var drawScale = ( drawWidth / inputWidth );
			var drawHeight = ( inputHeight * drawScale );
			var drawX = runningX;
			var drawY = 10;

			// Update the running X-coordinate for the next iteration.
			runningX += ( drawWidth + 10 );

			// CAUTION: It is not possible to provide an explicit READER during a draw
			// operation. To avoid potential security issues, the input should be
			// sanitized ahead of time.
			// --
			// Read More: https://sourceforge.net/p/graphicsmagick/discussion/250738/thread/71a6a6a8e8/
			return( "-draw 'image over #drawX#,#drawY# #drawWidth#,#drawHeight# #inputFilepath#'" );

		}
	);

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

	// Now that we know where and at what sizes the input images are going to be pasted
	// into the output image, we can use the Convert utility to compose the various
	// image operations together.
	result = gm([
		"convert",

		// Start with a "blank" canvas with the desired output dimensions.
		"-size #outputWidth#x#outputHeight# xc:##fafafa",

		// Now, let's "spread" the "draw" sub-commands into the current Convert.
		drawCommands.toList( " " ),

		// And, finally, output our composite image!
		"-quality 75",
		outputFilepath
	]);

	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 return the Width and Height of the image at the given path.
	* 
	* @filepath I am the filepath being inspected.
	*/
	public struct function getImageDimensions( required string filepath ) {

		// NOTE: Trailing comma after -format being included on purposes. It delimits
		// multi-page images (like GIFs). While I don't have any GIFs in this demo, I am
		// leaving it in so I don't forget why I have it.
		var result = gm([
			"identify",
			"-format %w,%h,",
			applyReader( filepath )
		]);

		var dimensions = result.listToArray();

		return({
			width: dimensions[ 1 ],
			height: dimensions[ 2 ]
		});

	}


	/**
	* 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>

	<h1>
		Resizing The Image During The DRAW Command
	</h1>

	<p>
		<img
			src="./#outputFilename#"
			width="#outputWidth#"
			height="#outputHeight#"
			style="border: 1px solid ##aaaaaa ; border-radius: 4px ;"
		/>
	</p>

	<!--- List all of the images in the test directory. --->
	<p style="width: 650px ;">
		<cfloop query="#directoryList( path = '../images', listInfo = 'query', sort = 'name asc' )#">

			<a href="#cgi.script_name#?image=#encodeForHtmlAttribute( name )#">
				#encodeForHtml( name )#
			</a>,

		</cfloop>
	</p>

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

</cfoutput>

index2.cfm

<cfscript>

	param name="url.image" type="string" default="beach-small.jpg";

	startedAt = getTickCount();

	// CAUTION: For the sake of the demo, I am not validating the input image. However,
	// in a production setting, I would never allow an arbitrary filepath to be provided
	// by the user! Not without some sort of validation.
	inputFilename = url.image;
	inputFilepath = expandPath( "../images/#inputFilename#" );

	// As a first step, we need to figure out how large the input image is so that we can
	// calculate the display-scale for each intermediary, scaled image. To do that, we
	// can use the Identify utility.
	inputDimensions = getImageDimensions( inputFilepath );
	inputWidth = inputDimensions.width;
	inputHeight = inputDimensions.height;

	// Setup the output filepath for our generated image.
	// --
	// NOTE: The file-extension of this output filename will be used by GraphicsMagick to
	// figure out how to encode the final image.
	outputFilename = "out.jpg";
	outputFilepath = expandPath( "./#outputFilename#" );

	// Define the dimensions of our demo image.
	outputWidth = 650;
	outputHeight = 300;

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

	// Before we execute our Convert command, let's calculate the "-draw" sub-commands
	// for each of the desired scaling sizes. These are the WIDTH dimensions at which we
	// want to paste the input image into the output image:
	drawWidths = [ 10, 50, 100, 200, 300 ];

	// As we draw the input image at different widths, we need to keep a running offset
	// for the X-coordinate of the operation (so that the different draw operations don't
	// overlap each other).
	runningX = 10;

	// Map the widths onto the actual "-draw" sub-commands.
	drawCommands = drawWidths.map(
		( drawWidth ) => {

			var drawX = runningX;
			var drawY = 10;
			// NOTE: For the temporary image, I'm using MIFF - the lossless Magick Image
			// File Format. This way, we don't lose quality from the intermediary image.
			var tempFilepath = expandPath( "./temp-#drawWidth#.miff" );

			// In this approach, rather than pasting an image at a scaled dimension,
			// we're going to create an intermediary image at the desired dimensions.
			// This gives us more control over how the input image is treated (such as
			// changing the colorspace or using a specified resize algorithm).
			gm([
				"convert",
				applyReader( inputFilepath ),
				"-resize #drawWidth#x",
				"-colorspace RGB",
				tempFilepath
			]);

			// Update the running X-coordinate for the next iteration.
			runningX += ( drawWidth + 10 );

			// This time, since we've generated an intermediary, scaled image, we don't
			// have to specify the DIMENSIONS of the paste operation. Instead, we can use
			// "0,0" to tell GraphicsMagick to use the natural dimensions of the
			// temporary image we just generated.
			return( "-draw 'image over #drawX#,#drawY# 0,0 #tempFilepath#'" );

		}
	);

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

	// Now that we know where and at what sizes the input images are going to be pasted
	// into the output image, we can use the Convert utility to compose the various
	// image operations together.
	result = gm([
		"convert",

		// Start with a "blank" canvas with the desired output dimensions.
		"-size #outputWidth#x#outputHeight# xc:##fafafa",

		// Now, let's "spread" the "draw" sub-commands into the current Convert.
		drawCommands.toList( " " ),

		// And, finally, output our composite image!
		"-quality 75",
		outputFilepath
	]);

	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 return the Width and Height of the image at the given path.
	* 
	* @filepath I am the filepath being inspected.
	*/
	public struct function getImageDimensions( required string filepath ) {

		// NOTE: Trailing comma after -format being included on purposes. It delimits
		// multi-page images (like GIFs). While I don't have any GIFs in this demo, I am
		// leaving it in so I don't forget why I have it.
		var result = gm([
			"identify",
			"-format %w,%h,",
			applyReader( filepath )
		]);

		var dimensions = result.listToArray();

		return({
			width: dimensions[ 1 ],
			height: dimensions[ 2 ]
		});

	}


	/**
	* 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>

	<h1>
		Resizing The Image Using An Intermediary File
	</h1>

	<p>
		<img
			src="./#outputFilename#"
			width="#outputWidth#"
			height="#outputHeight#"
			style="border: 1px solid ##aaaaaa ; border-radius: 4px ;"
		/>
	</p>

	<!--- List all of the images in the test directory. --->
	<p style="width: 650px ;">
		<cfloop query="#directoryList( path = '../images', listInfo = 'query', sort = 'name asc' )#">

			<a href="#cgi.script_name#?image=#encodeForHtmlAttribute( name )#">
				#encodeForHtml( name )#
			</a>,

		</cfloop>
	</p>

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

</cfoutput>