How TO - Image Magnifier Glass
Learn how to create an image magnifier glass.
Image Magnifier Glass
Mouse over the image:
Create an Image Magnifier Glass
Step 1) Add HTML:
Example
<div class="img-magnifier-container">
<img id="myimage" src="img_girl.jpg"
width="600" height="400" alt="Girl">
</div>
Step 2) Add CSS:
The container must have a "relative" positioning.
Example
* {box-sizing: border-box;}
.img-magnifier-container {
position:
relative;
}
.img-magnifier-glass {
position: absolute;
border:
3px solid #000;
border-radius: 50%;
cursor: none;
/*Set the size of the
magnifier glass:*/
width: 100px;
height: 100px;
}
Step 3) Add JavaScript:
Example
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;}
/* Set the position of the magnifier glass: */
glass.style.left = (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};
}
}
Step 4) Initiate the Magnify Function
Example
<script>
/* Execute the magnify function: */
magnify("myimage", 3);
/* Specify the id of the
image, and the strength of the magnifier glass: */
</script>
Try it Yourself »
