function containElement(options) { var scaleFactor = 1; var element = document.getElementById(options.id); var elementWidth = options.width ? options.width : element.offsetWidth; var elementHeight = options.height ? options.height : element.offsetHeight; // Apply required attributes to the element and its parents if they aren't already set if (element.style.position != 'absolute') element.style.position = 'absolute'; if (element.parentElement.style.overflow != 'hidden') element.parentElement.style.overflow = 'hidden'; if (element.parentElement.style.position != 'relative' && element.parentElement.style.position != 'absolute' && element.parentElement.style.position != 'fixed') element.parentElement.style.position = 'relative'; function scaleElement() { var parentWidth = element.parentElement.offsetWidth; var parentHeight = element.parentElement.offsetHeight; // Run the scale/position functionality if able to determine the document width and height if ((parentWidth) && (parentHeight)) { // Calculate the scale factor if (parentWidth > ((parentHeight / (elementHeight * scaleFactor)) * (elementWidth * scaleFactor))) scaleFactor = (parentWidth / elementWidth); else scaleFactor = (parentHeight / elementHeight); // Scale the element using the scale factor element.style.width = (elementWidth * scaleFactor) + 'px'; element.style.height = (elementHeight * scaleFactor) + 'px'; // Anchor the element horizontally to the left/middle/right if (parentWidth < (elementWidth * scaleFactor)) { switch(options.halign) { case 'left': // anchor horizontally to the left of the parent element element.style.left = 0 + 'px'; break; case 'right': // anchor horizontally to the right of the parent element element.style.left = (0 - ((elementWidth * scaleFactor) - parentWidth)) + 'px'; break; default: // anchor horizontally to the middle of the parent element element.style.left = (0 - (((elementWidth * scaleFactor) - parentWidth) / 2 )) + 'px'; } } else { element.style.left = 0 + 'px'; } // Anchor the element vertically to the top/middle/bottom if ((elementHeight * scaleFactor) > parentHeight) { switch(options.valign) { case 'top': // anchor vertically to the top of the parent element element.style.top = 0 + 'px'; break; case 'bottom': // anchor veritcally to the bottom of the parent element element.style.top = (0 - ((elementHeight * scaleFactor) - parentHeight)) + 'px'; break; default: // anchor vertically to the middle of the parent element element.style.top = (0 - (((elementHeight * scaleFactor) - parentHeight) / 2 )) + 'px'; } } else { element.style.top = 0 + 'px'; } } else { // Try again in 30ms if the document didn't load enough to determine its width and height yet window.setTimeout(scaleElement, 30); } } // Run the scale function and bind it to various window-size-changing events scaleElement(); window.onload = function(event) { scaleElement(); }; window.onresize = function(event) { scaleElement(); }; screen.addEventListener('orientationchange', function() { scaleElement(); }); }