How To Build An Expandable Accessible Gallery
About The Author
Silvestar Bistrović is a fearless web engineer, CSS developer, JAMstack enthusiast, WordPress theme specialist, author of the UI Dev Newsletter, and founder of …
In this article, we’ll be looking at how to set up a gallery that is expandable as well as accessible with a few tips and tricks along the way. Let’s get started!
One of the use cases for using CSS Grid is to display a gallery of images, but a gallery on its own may not be that exciting. We could, for example, add a click effect to enlarge the image without affecting the grid to make it a little bit more fun. And of course, as to not exclude anybody from enjoying this feature, we should make it accessible, too.
In this article, I’ll explain how to build an accessible expandable gallery with a few tips and tricks along the way. Here’s how the final result looks like:
See the Pen [How to build accessible expandable gallery](https://codepen.io/smashingmag/pen/PojxvJr) by Silvestar Bistrović.
First, we are going to set the HTML structure. Of course, we could always do it in various ways, but let us use a list of images wrapped in buttons.
Now, to make the gallery accessible, we need to make some adjustments:
Finally, let’s add a paragraph with helpful text on how to use the gallery, and wrap the whole code in a landmark (in this case, the
For the simplicity of the demo, I decided to use images wrapped with the
To define the grid layout, we could use CSS Grid. We’ll use
auto-fit so that items can fit into the available space, but restrict themselves from shrinking under a certain width. This means that we’ll see a different number of items on different viewports without writing too many media queries.
To preserve the correct aspect ratio of the image, we could use the property. To reset the button style, we could add the
all: initial declaration. We should also hide the overflow of the button.
To make the image fit right into the button, we’ll use
object-fit: cover declaration and set both
The expanding effect is done with the
scale transformation. The transition is enabled by default, but if the user does not prefer transitions and animations, we can use the
prefers-reduced-motion media query and set the
transition-duration property to
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Before we make the element expandable, we need to prepare and calculate a few things.
First, we’ll need to get the duration of the transition by reading the CSS Custom Property
Next, we’ll set the data attributes for the later calculation:
The first two are pretty straightforward. We could get the values from the computed CSS style.
To find the number of columns, we should iterate through each tile and compare the top position of each element. Once the top position changes, the item is in the new row, which gets us the number of items.
To achieve the expandable effect, we should make some checks and calculations first. First, we should check if the item is in the last row and at the end of the row. If the item is in the last row, it should expand to the top. That means it should have the
transform-origin property set to the
Important: If the element should expand to one direction, its
transform-origin property should be set to an “opposite” value. Note that vertical and horizontal values should be combined.
To enlarge the image without affecting the grid, we could use CSS transforms. In particular, we should use the scale transformation. I decided to make the image double in size, i.e. the factor is the ratio of the double width of the element plus grid-gap.
Users who navigate sites by using a keyboard should be able to use the gallery. Going through the list works by default when using key Tab. Emulating the click works by default by pressing the Enter key while the item is focused. To enhance the default behavior, we should add support for Esc and the arrow keys.
Once we expand the item, pressing Esc should revert it to its standard size. We could do it by checking the code of the pressed key. The same goes for arrow keys, but the action is different. When pressing arrow keys, we want to get the previous or next sibling and then emulate the click on that element.
To make the gallery element expanded, we should deactivate all other elements first. Then, if we click on the expanded element, it should revert to the standard size.
To prevent issues with
z-index and stacking context, we should use the timeout to delay the transform. That is the same timeout that we calculated in the preparation phase.
If the viewport changes the size, we need to recalculate defaults because we defined a fluid grid that allows items to fill the available space and move from row to row.
A Word About Accessibility And Credits
I had no problems building this demo except with the accessibility part. I was not sure what to do and which aria attributes to use at first. Even after figuring out which attributes to use, I could not be 100% sure it was right. So the first step was to test everything with a keyboard. That was the easy part. Then I used the VoiceOver application (since I am using a Mac) to test how it works for visually impaired persons. It sounded good enough to me.
However, even after all that testing, I was still not 100% sure. So I decided to ask for help. I am a part of one Slack community for designers and developers (BoagWorld), and I posted a question there. Fortunately, accessibility experts like Todd Libby helped me test the demo on different devices and correct the code. I also asked Manuel Matuzović for help and he helped me clean up the code.
I’m grateful to have the Internet and developer communities where we can all ask for help, get answers from professionals, and solve problems together. That is especially true with sensitive issues like accessibility. Accessibility is hard, and it does not take much to make it wrong. Less is more — at least it was in my case.
And finally, I wanted to share the greatest lesson:
(vf, yk, il)
This content was originally published here.