Fixing ImageScaleToFit() Invalid Size Errors In Earlier Versions Of Lucee CFML

test.cfm

<cfscript>

	img = imageNew(
		source = "",
		width = 16,
		height = 2000,
		canvasColor = "ff3366"
	);

	width = imageGetWidth( img );
	height = imageGetHeight( img );
	boxSize = 100;

	// When scaling the image, whichever dimension has the largest magnitude becomes
	// our limiting factor. This is the magnitude that drives the proportional scaling.
	sizeConstraint = max( width, height );

	// We only need to resize the image if some part of it doesn't fit inside the box.
	if ( sizeConstraint > boxSize ) {

		// CAUTION: In earlier versions of Lucee, this will not work because the
		// proportional scaling of the image will cause the WIDTH to be LESS THAN 1. As
		// such, the underlying Java code will try to create a canvas of WIDTH = 0, which
		// is invalid.
		imageScaleToFit( img, boxSize, boxSize, "highestPerformance" );

	}

	imageWrite( img, "./output-scaled.png" );

</cfscript>

test2.cfm

<cfscript>

	img = imageNew(
		source = "",
		width = 16,
		height = 2000,
		canvasColor = "ff3366"
	);

	width = imageGetWidth( img );
	height = imageGetHeight( img );
	boxSize = 100;

	// When scaling the image, whichever dimension has the largest magnitude becomes
	// our limiting factor. This is the magnitude that drives the proportional scaling.
	sizeConstraint = max( width, height );

	// We only need to resize the image if some part of it doesn't fit inside the box.
	if ( sizeConstraint > boxSize ) {

		// In order to get around the proportional scaling issues in earlier versions of
		// Lucee, we cannot rely on the auto-scaling of the image. Instead, we have to
		// explicitly calculate the dimensions and then use the imageResize() function
		// instead of the imageScaleToFit() function.
		scalingFactor = ( boxSize / sizeConstraint );

		// Make sure none of the scaled values drop below 1 - the scaled image has to
		// have non-zero dimensions.
		scaledWidth = max( fix( width * scalingFactor ), 1 );
		scaledHeight = max( fix( height * scalingFactor ), 1 );

		imageResize( img, scaledWidth, scaledHeight, "highestPerformance" );

	}

	imageWrite( img, "./output-resized.png" );

</cfscript>