Jcrop and imagemagic final piece of puzzle - express

Question

I have set up on client Jcrop and on Server a imagemagick (express.js).
Image is uploaded to server first, and then shown to the client. Client makes crop, and the following information is sent to server:
function showCoords(c)
{
// variables can be accessed here as
// c.x, c.y, c.x2, c.y2, c.w, c.h
};
I have the image stored on server ready to be cropped. Question is, if using imagemagick... how do I use those variables? Image magick has resize and crop (it has other options as well) that seem to be relevant... but it seems that I have more variables then the IM accepts.
What is going on?

Answer 1

You can ignore point2 (c.x2,x.y2). Jcrop is just being helpful by giving you a rectangles size (c.w,c.h), starting point (c.x,c.y), and ending point (c.x2,c.y2).
ImageMagick has it's own Image Geometry format, so you just need the size & offset (starting point).
function showCoords(c)
{
var IMGeometry = String.concat(c.w,"x",c.y,"+",c.x,"+",c.y);
//=> "175x125+50+50"
// Assuming you are using node-imagemagick
im.convert(["source.jpg","-crop",IMGeometry,"out.jpg"],function(err, stdout){
// Callback
});
}