It seems the renderWith() in my init() is being overidden by the default tempalte for the page type. WHen I check ?showtempalte=1 that shows the correct template, but the one rendered is incorrect.

class Artwork_Controller extends Page_Controller {
	
	private static $allowed_actions = array (
	);

	public function init() {
		parent::init();
		
		$image = $this->OrderedImages()->first();
		
		if($image && $ratio = $image->getRatio()) {
			
			if($ratio > 1.2 ) {
				$this->renderWith("ArtworkWide");
			} elseif ($ratio < 0.8) {
				$this->renderWith("ArtworkNarrow");
			} else {
				$this->renderWith("Artwork");
			}
			
		}
		
	}
	
}

I believe you'll have better luck overriding index() instead, as the parent's index is still having a chance to run w/ SS conventions.

And you'll want to return $this->renderWith instead of just calling it (per Pyro @ irc).

Thanks. I really need more sleep. I shoudl have seen that

catcher is correct, this should not be done in init.
The default executed action is index

public function index(){ //executed (if present) on page access without action

And yes, also as mentioned renderWith returns data, it doesn't immediately pump to output.

But another caveat you should be aware of is template convention, and that renderWith technically takes an array to specify both 'main' AND 'Layout' templates.
At the moment if your template is templates/Layout/Artwork.ss (and derivatives) then this is all the page will render. ie. (presumably) no header, footer, maybe sidebar, etc.

so

$returnValue = $this->renderWith(['Artwork', 'Page']);