document.observe("dom:loaded", function() { 

	//calculatebg();
		
});

function calculatebg (imgW, imgH) {
	//imgH = $('bgimage').getDimensions().height;
	//imgW = $('bgimage').getDimensions().width;
	
	//console.log(imgW);
	//console.log(imgH);
	
	portW = document.viewport.getDimensions().width;
	portH = document.viewport.getDimensions().height;
	
	factor = imgW/imgH;
	factorPort = portW/portH
		
	if(factorPort > factor){
		//hoger dan breed
		resizedImgH = portW/factor;
		spacerTop = (resizedImgH/2 - portH/2)*-1;
		
		imgH = resizedImgH;
		imgW = portW;
		spacerTop = spacerTop;
		spacerLeft = 0;
		
	}else{
	
		resizedImgW = portH*factor;
		
		spacerLeft = (resizedImgW/2 - portW/2)*-1;
		
		imgH = portH;
		imgW = resizedImgW;
		spacerTop = 0;
		spacerLeft = spacerLeft;
	
	}
	
	$('bgimage').style.width = imgW + 'px';
	$('bgimage').style.height = imgH + 'px';
	$('bgimage').style.top = spacerTop + 'px';	
	$('bgimage').style.left = spacerLeft + 'px';	
	
	

}
function preloadImage (fotoURL, w, h) {
	var bgPreloader = new Image();
	//breedte word niet juist doorgegeven bij preloaden
	//bgPreloader.onload = giveimage(bgPreloader.width, bgPreloader.height);
	bgPreloader.onload = giveimage(w, h);
	bgPreloader.src = fotoURL;
	//alert(w);
	
}
function giveimage (w, h) {
	
	//alert('preload');
	calculatebg(w, h);
	new Effect.Appear($('bgimage'), { duration: 0.5, from: 0.0, to: 0.5});
}