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Clipping, Clipping, and More Clipping!

October 8th, 2019

There are so many things you can do with clipping paths. I’ve been exploring them for quite some time and have come up with different techniques and use cases for them — and I want to share my findings with you! I hope this will spark new ideas for fun things you can do with the CSS clip-path property. Hopefully, you’ll either put them to use on your projects or play around and have fun with them.

 

Before we dive in, it’s worth mentioning that this is my third post here on CSS-Tricks about clip paths. You might want to check those out for a little background:

This article is full of new ideas!

Idea 1: The Double Clip

One neat trick is to use clipping paths to cut content many times. It might sound obvious, but I haven’t seen many people using this concept.

For example, let’s look at an expanding menu:

See the Pen The more menu by Mikael Ainalem (@ainalem) on CodePen.

Clipping can only be applied to a DOM node once. A node cannot have several active instances of the same CSS rule, so that means one clip-path per instance. Yet, there is no upper limit for how many times you can combine clipped nodes. We can, for example, place a clipped <div> inside another clipped <div> and so on. In the ancestry of DOM nodes, we can apply as many separate cuts as we want.

That’s exactly what I did in the demo above. I let a clipped node fill out another clipped node. The parent acts as a boundary, which the child fills up while zooming in. This creates an unusual effect where a rounded menu appears. Think of it as an advanced method of overflow: hidden.

You can, of course, argue that SVGs are better suited for this purpose. Compared to clipping paths, SVG is capable of doing a lot more. Among other things, SVG provides smooth scaling. If clipping fully supported Bézier curves, the conversation would be different. This is not the case at the time of writing. Regardless, clipping paths are very convenient. One node, one CSS rule and you’re good to go. As far as the demo above is concerned, clipping paths do a good job and thus are a viable option.

I put together short video that explains the inner workings of the menu:

Idea 2: Zooming Clip Paths

Another (less obvious) trick is to use clipping paths for zooming. We can actually use CSS transitions to animate clipping paths!

The transition system is quite astonishing in how it’s built. In my opinion, its addition to the web is one of the biggest leaps that the web has taken in recent years. It supports transitions between a whole range of different values. Clipping paths are among the accepted values we can animate. Animation, in general, means interpolation between two extremes. For clipping, this translates to an interpolation between two complete, different paths. Here’s where the web’s refined animation system shows its strength. It doesn’t only work with single values — it also works when animating sets of values.

When animating clipping paths specifically, each coordinate gets interpolated separately. This is important. It makes clipping path animations look coherent and smooth.

Let’s look at the demo. Click on an image to restart the effect:

See the Pen Brand cut zoom by Mikael Ainalem (@ainalem) on CodePen.

I’m using clip-path transitions in this demo. It’s used to zoom in from one clipping path covering a tiny region going into another huge one. The smallest version of the clipping path is much smaller than the resolution — in other words, it’s invisible to the eye when applied. The other extreme is slightly bigger than the viewport. At this zoom level, no cuts are visible since all clipping takes place outside the visible area. Animating between these two different clipping paths creates an interesting effect. The clipped shape seems to reveal the content behind it as it zooms in.

As you may have noticed, the demo uses different shapes. In this case, I’m using logos of popular shoe brands. This gives you an idea of what the effect would look like when used in a more realistic scenario.

Again, here’s a video that walks through the technical stuff in fine detail:

Idea 3: A Clipped Overlay

Another idea is to use clipping paths to create highlight effects. For example, let’s say we want to use clipping paths to create an active state in a menu.

See the Pen Skewed stretchy menu by Mikael Ainalem (@ainalem) on CodePen.

The clipped path above stretches between the different menu options when it animates. Besides, we’re using an interesting shape to make the UI stand out a bit.

The demo uses an altered copy of the same content where the duplicate copy sits on top of the existing content. It’s placed in the exact same position as the menu and serves as the active state. In essence, it appears like any other regular active state for a menu. The difference is that it’s created with clipping paths rather than fancy CSS styles on HTML elements.

Using clipping enables creating some unusual effects here. The skewed shape is one thing, but we also get the stretchy effect as well. The menu comes with two separate cuts — one on the left and one on the right — which makes it possible to animate the cuts with different timing using transition delays. The result is a stretchy animation with very little effort. As the default easing is non-linear, the delay causes a slight rubber band effect.

The second trick here is to apply the delays depending on direction. If the active state needs to move to the right, then the right side needs to start animating first, and vice versa. I get the directional awareness by using a dash of JavaScript to apply the correct class accordingly on clicks.

Idea 4: Slices of the Pie

How often do you see a circular expanding menu on the web? Preposterous, right!? Well, clipping paths not only make it possible but fairly trivial as well.

See the Pen The circular menu by Mikael Ainalem (@ainalem) on CodePen.

We normally see menus that contain links ordered in a single line or even in dropdowns, like the first trick we looked at. What we’re doing here instead is placing those links inside arcs rather than rectangles. Using rectangles would be the conventional way, of course. The idea here is to explore a more mobile-friendly interaction with two specific UX principles in mind:

  • A clear target that is comfortable to tap with a thumb
  • Change takes place close to the focal point — the place where your visual focus is at the moment

The demo is not specifically about clipping paths. I just happen to use clipping paths to create the pen. Again, like the expandable menu demo earlier, it’s a question of convenience. With clipping and a border-radius of 50%, I get the arcs I need in no time.

Idea 5: The Toggle

Toggles never cease to amaze web developers like us. It seems like someone introduces a new interpretation of a toggle every week. Well, here’s mine:

See the Pen Inverted toggle by Mikael Ainalem (@ainalem) on CodePen.
The demo is a remake of this dribble shot by Oleg Frolov. It combines all three of the techniques we covered in this article. Those are:

  • The double clip
  • Zooming clip paths
  • A clipped overlay

All these on/off switches seem to have one thing in common. They consist of an oval background and a circle, resembling real mechanical switches. The way this toggle works is by scaling up a circular clipping path inside a rounded container. The container cuts the content by overflow: hidden, i.e. double clipping.

Another key part of the demo is having two alternating versions in markup. They are the original and its yin-yang inverted mirrored copy. Using two versions instead of one is, at risk of being repetitive, a matter of convenience. With two, we only need to create a transition for the first version. Then, we can reuse most of it for the second. At the end of the transition the toggle switches over to the opposite version. As the inverted version is identical to the previous end state, it’s impossible to spot the shift. The good thing about this technique is reusing parts of the animation. The drawback is the jank we get when interrupting the animation. What happens when the user punches the toggle before the animation has completed.

Let’s again have look under the hood:

Closing words

You might think: Exploration is one thing, but what about production? Can I use clipping paths on a site I’m currently working on? Is it ready for prime time?

Well, that question doesn’t have a straightforward answer. There are, among other things, two problems to take a closer look at:

1. Browser support
2. Performance

At the time of writing there is, according to caniuse, about 93% browser support. I’d say we’re on the verge of mass adoption. Note, this number takes the WebKit prefix into account.

There’s also always the IE argument but it’s really no argument to me. I can’t see that it’s worthwhile to go the extra mile for IE. Should you create workarounds for an insecure browser? Your users are better off with a modern browser. There are, of course, a few rare cases where legacy is a must. But you probably won’t consider modern CSS at all in those cases.

How about performance then? Well, performance gets tricky as things mount up, but nothing that I’d say would prevent us from using clipping paths today. It’s always measured performance that counts. It’s probable that clipping, on average, causes a bigger performance hit than other CSS rules. But remember that the practices we’ve covered here are recommendations, not law. Treat them as such. Make a habit out of measuring performance.

Go on, cut your web pages in pieces. See what happens!