function ContainElement(options) { var scaleFactor = 1; var element = document.getElementById(options.id); var elementWidth = options.width || element.offsetWidth; var elementHeight = options.height || element.offsetHeight; // Apply required attributes to the element and its parents element.style.position = 'absolute'; element.parentElement.style.overflow = 'hidden'; if (['relative', 'absolute', 'fixed'].indexOf(window.getComputedStyle(element.parentElement, null).getPropertyValue('position')) === -1) element.parentElement.style.position = 'relative'; function updateContain() { 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/center/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 center 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/center/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 center 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(updateContain, 30); } } // Run the scale function and bind it to various window-size-changing events updateContain(); // Add scale function to the library this.update = updateContain; }