Enhancement: return xoffset/yoffset when creating text image

Feature request

What are you trying to achieve?

I'm trying to align multiple texts at their baselines. Some cursory experimentation with pyvips suggests that it might be possible to do this if yoffset was available.

In sharp it is not:

let sharp = require('sharp');

(async function () {
	let image = sharp({
		text: {
		  text: 'Hello'
		}
	});

	console.log(await image.metadata());
})();

{
  format: 'raw',       
  width: 30,
  height: 10,
  space: 'b-w',        
  channels: 1,
  depth: 'uchar',      
  density: 72,
  isProgressive: false,
  hasProfile: false,   
  hasAlpha: false      
}

When you searched for similar feature requests, what did you find that might be related?

"yoffset" appeared in several issue but none were about yoffset.

What would you expect the API to look like?

(await image.metadata()).yoffset

What alternatives have you considered?

-

Please provide sample image(s) that help explain this feature

-

Start by tracing how the text input creates an image and how image metadata() is assembled, then compare the available libvips/pyvips xoffset and yoffset values. Done means metadata for text-created images exposes the requested offsets in the documented API, with coverage for the example case.