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Webkit Image Effects with Masks

· Web Dev Zone

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Today’s article may seem short, but it describes some interesting features of webkit browsers, in particular, the animation of images using masks. I want to warn that these examples will only work in webkit browsers (Chrome and Safari). The idea to study the masks came to me when I saw the Chrome browser logo on a Google website. I liked this effect and I wanted to understand how it works. Well, what is a mask? Basically, it is an image (or gradient) where a transparent part will make your element invisible, non-transparent will make your element visible. These masks are similar to the ones in Photoshop.

To make our examples I used the -webkit-mask property (with different variations). This property is used to set individual mask property values for various elements. Now, please check our little demo (and download our sources), and I will explain how it works.

Live Demo

download the package


Step 1. HTML

Our HTML markup is really easy for today:

index.html

<div id="examples">
    <img class="type1" src="images/logo.png" />
    <img class="type2" src="images/logo2.png" />
    <img class="type3" src="images/logo3.png" />
    <img class="type4" src="images/logo4.png" />
</div>

There are only four images. Every image has own unique effect.

Step 2. JS

To make first two effects I had to use custom radial gradients. The main idea is to display expanding radial gradient (in a loop) until it reaches the end of image. It is nearly impossible to change the radial gradient params of -webkit-mask params with onle CSS3 (even using keyframes). This is why I had to use javascript here.

js/main.js

$(document).ready(function(){ 

    $('#examples img').hover(function () {
        var $imgObj = $(this);

        // class name
        var sClass = $(this).attr('class');

        // radius
        var iRad = 0;

        // interval
        var iInt;
        if (iInt) window.clearInterval(iInt);

        // loop until end
        iInt = window.setInterval(function() {
            var iWidth = $imgObj.width();
            var iHalfWidth = iWidth / 2;
            var iHalfHeight = $imgObj.height() / 2;

            if (sClass == 'type1') {
                $imgObj.css('-webkit-mask', '-webkit-gradient(radial, '+iHalfWidth+' '+iHalfHeight+', '+ iRad +', '+iHalfWidth+' '+iHalfHeight+', '+ (iRad + 30) +', from(rgb(0, 0, 0)), color-stop(0.5, rgba(0, 0, 0, 0.2)), to(rgb(0, 0, 0)))');
            } else if (sClass == 'type2') {
                $imgObj.css('-webkit-mask', '-webkit-gradient(radial, '+iHalfHeight+' '+iHalfHeight+', '+ iRad +', '+iHalfHeight+' '+iHalfHeight+', '+ (iRad + 30) +', from(rgb(0, 0, 0)), color-stop(0.5, rgba(0, 0, 0, 0.2)), to(rgb(0, 0, 0)))');
            }

            // when radius is more than our width - stop loop
            if (iRad > iWidth) {
                window.clearInterval(iInt);
            }

            iRad+=2;
        }, 10);
    });
});

As you see, in the ‘hover’ event handler it increases Radius of radial gradient in a loop

Step 3. CSS

To achieve the effects of another pair of images – it is sufficient to use only CSS3:

css/main.css

.type3 {
    -webkit-mask: url(../images/mask.png) no-repeat center center;
}
.type3:hover{
    -webkit-animation: loop_frames 1s ease-in-out infinite;
     -webkit-animation-direction:alternate;
     -webkit-mask-size: auto 100%;
}
@-webkit-keyframes loop_frames {
     0% { -webkit-mask-size: auto 100%; }
     100% { -webkit-mask-size: auto 70%; }
}

.type4 {
    -webkit-transition: -webkit-mask-position 0.5s ease;
    -webkit-mask-size: 400px 300px;
    -webkit-mask-image: -webkit-gradient(linear, left top, right top, color-stop(0.00, rgba(0,0,0,1)), color-stop(0.90, rgba(0,0,0,1)), color-stop(1.00, rgba(0,0,0,0)));
    -webkit-mask-position-x: 400px;
}
.type4:hover {
     -webkit-mask-position-x: 0;
}

As you can see, for the third effect we use the -webkit-mask-size property (to simulate some beats), for the fourth – we changed -webkit-mask-position-x param. We change both params using :hover selector (in case if we hover our images).


Live Demo

download the package


Conclusion

That’s all. I’ve just given you several examples of nice image effects using masks. I hope it will be very useful for you!

Make the transition to Node.js if you are Java, PHP, Rails or .NET developer with these resources to help jumpstart your Node.js knowledge plus pick up some development tips.  Brought to you in partnership with IBM.

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Published at DZone with permission of Andrey Prikaznov, DZone MVB. See the original article here.

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