I have a js/css routine that I’d like to add to an image. When mouse (or touch, if someone is able to adapt the code) hovers the image, a circular magnified portion is displayed.
function magnify(imgID, zoom) {
var img, glass, w, h, bw;
img = document.getElementById(imgID);
/* Create magnifier glass: */
glass = document.createElement("DIV");
glass.setAttribute("class", "img-magnifier-glass");
/* Insert magnifier glass: */
img.parentElement.insertBefore(glass, img);
/* Set background properties for the magnifier glass: */
glass.style.backgroundImage = "url('" + img.src + "')";
glass.style.backgroundRepeat = "no-repeat";
glass.style.backgroundSize = (img.width * zoom) + "px " + (img.height * zoom) + "px";
bw = 3;
w = glass.offsetWidth / 2;
h = glass.offsetHeight / 2;
/* Execute a function when someone moves the magnifier glass over the image: */
glass.addEventListener("mousemove", moveMagnifier);
img.addEventListener("mousemove", moveMagnifier);
/*and also for touch screens:*/
glass.addEventListener("touchmove", moveMagnifier);
img.addEventListener("touchmove", moveMagnifier);
function moveMagnifier(e) {
var pos, x, y;
/* Prevent any other actions that may occur when moving over the image */
e.preventDefault();
/* Get the cursor's x and y positions: */
pos = getCursorPos(e);
x = pos.x;
y = pos.y;
/* Prevent the magnifier glass from being positioned outside the image: */
if (x > img.width - (w / zoom)) {x = img.width - (w / zoom); }
if (x < w / zoom) {x = w / zoom;}
if (y > img.height - (h / zoom)) {y = img.height - (h / zoom);}
//if (y < h / zoom) {y = h / zoom;}
if (y < h / zoom) {element = document.getElementByClassName('img-magnifier-glass'); element.remove();}
/* Set the position of the magnifier glass: */
glass.style.left = ((x+img.x) - w) + "px";
glass.style.top = (y - h) + "px";
/* Display what the magnifier glass "sees": */
glass.style.backgroundPosition = "-" + ((x * zoom) - w + bw) + "px -" + ((y * zoom) - h + bw) + "px";
}
function getCursorPos(e) {
var a, x = 0, y = 0;
e = e || window.event;
/* Get the x and y positions of the image: */
a = img.getBoundingClientRect();
/* Calculate the cursor's x and y coordinates, relative to the image: */
x = e.pageX - a.left;
y = e.pageY - a.top;
/* Consider any page scrolling: */
x = x - window.pageXOffset;
y = y - window.pageYOffset;
return {x : x, y : y};
}
}
Inspect the HTML blocs creates for the image bric and compare to the markup you have. You will be able to figure it out. You can adjust the code to suit your needs.
Add the event listener for hovering over images and let that call the function.
I would change the code to remove the need for IDs as if you are using an event listener on each one, it can just be relative to the elements you hover. Otherwise you need a ID for each one.
I’m not sure, but you probably need to destroy the mouse event listeners on mouseoff? Have a play.
This doesn’t do much when adding this to CodePen, But maybe does when you run it live on the site.
By the way are there any platforms that allow you to run HTML, CSS and JS live that actually work?
Input = Output. The entire purpose of these platforms is testing and development.
Codepen, JSFiddle and multitude of others like them all work, so as long as a person knows what they are doing. If something across the HTML / CSS / JS is not properly setup things will fail or falter, that should be easily understood. This appears to be where the code was derived from, so learn from there.
I improved the original script a bit and added a mouseout event listener to remove the magnifying glass when not hovering over the image and a querySelectorAll to be able to have multiple images on one page. The weekend has started early this week!
