coldfusion imageDraw java.lang.Double cannot be cast to java.lang.String

Question

I am working with imageDraw and getting an odd error. If I just plugin values and don't try to use the ones I am retrieving from elsewhere, it works, but I have to draw the values for the margins and line height from other places and calculate stuff.

 x = 50;
 y = 800;
 newImg = imageNew("", x, y);
 imageSetAntialiasing(newImg, true);
 setup['size'] = lineHeight*dpi;
 setup['font'] = "Arial";
 imageDrawText(newImg,img.text,topMargin,leftMargin,setup);

When I put each element in imageDrawText on a separate line, the error points to the attribute collection (setup). I did try this

setup['size'] = "#lineHeight*dpi#";

but it didn't work either.

The full error message at the top of the debug:

Error Occurred While Processing Request

Error casting an object of type java.lang.Double cannot be cast to java.lang.String to an incompatible type. This usually indicates a programming error in Java, although it could also mean you have tried to use a foreign object in a different way than it was designed. java.lang.Double cannot be cast to java.lang.String

Answer 1

There is something about asking for help that opens up channels for me. Found a solution. The issue was indeed the setup.size part of the attribute collection. Here is what worked:

setup['size'] = toString(int(lineHeight*dpi));

Don't know why it wants that to be a string specifically. Seems kind of dumb because we are using it as a number.

Answer 2

That's a bug in older ColdFusion versions (before ColdFusion 2016), because the size attribute is explicitly casted: (String)size. And even if you pass the value as String, your value may not contain decimal places, because ColdFusion attempts to parse the value as Integer: Integer.parseInt((String)size)

// works
setup['size'] = "12";

// works, because literal numbers are casted to String
setup['size'] = 12;

// DOES NOT work, because any math calculation results into a Double
setup['size'] = 12 * 1;

// DOES NOT work, because this is a Double
setup['size'] = 12.1;

Your solution using setup['size'] = toString(int(...)); is the correct workaround for this bug. int() to make sure you end up without decimal places (preventing NumberFormatException) and toString() to make sure you are passing a String (preventing ClassCastException).

(This post is more like a remark, but too long for a comment. Feel free to accept your own answer.)