Adjust Loading Animations in Vaadin

By default, loading animations in Vaadin are already pretty awesome, though you might want to adjust them to make them fit better with your custom theme.

While tweaking around with the animations myself, I found that there wasn’t too much information to find about it around the web, so here’s me contributing.

It’s All CSS

To adjust the loading animations, there’s actually no need at all to fiddle in Java code. Everything can be easily set up in css. You only need to edit one file, which would be your custom theme’s scss file.

First of all, it is important to know that the styling for the animations is not located under the .v-app class. All the editing can be done top-level, right after the base theme include statement. For the Valo theme, this would be right after the following line: @include valo;.

Top Loading Indicator

In this example I will cover a minor tweak to the loading bar you see on the top of the page, which by default is blue. It is displayed upon page navigation.

To simply adjust the color you can use following code snippet, where all style attributes are just coppied from the default styling. The only property you’ll want to tweak will be the background-color one.

.v-loading-indicator {
    position: fixed !important;
    z-index: 99999;
    left: 0;
    right: auto;
    top: 0;
    width: 50%;
    opacity: 1;
    height: 4px;
    background-color: red;
    pointer-events: none;
    -webkit-transition: none;
    -moz-transition: none;
    transition: none;
    -webkit-animation: v-progress-start 1000ms 200ms both;
    -moz-animation: v-progress-start 1000ms 200ms both;
    animation: v-progress-start 1000ms 200ms both;

Connection Lost Spinner

Since we’re at it, we might as well adjust the color of the spinner that shows when the connection was lost. Once again, this snippet must be placed outside the .v-app class. Obviously, if you want to adjust all spinners application-wide, apply the styling to the .spinner class only.

The resulting box with spinner.
The resulting box with spinner.
.v-reconnect-dialog .spinner {
    border-top-color: red;
    border-right-color: red;

Centered Loading Spinner

Vaadin’s default spinner is shown upon page refresh, for instance. At least in the Valo theme, it is relatively small. Its’ styling is somewhat basic, so it might be good to give it a more customized touch, like the spinner below.

A custom loading spinner.
A custom loading spinner.

Right along the previously provided css snippet, another one can be placed. Following example shows how to replace the default spinner with our own.

.v-app-loading::before {
    opacity: .8; 
    filter: alpha(opacity=80); 
    width: 100px; height: 100px; 
    background: transparent url(../customtheme/img/spinner.gif); 

Update the Vaadin Theme

After these small tweaks in this one file you are all set and ready to check out the result of the applied changes.

Keep in mind that you will need to update the theme first. Vaadin has this Maven plugin com.vaadin:vaadin-maven-plugin:8.0.0, that you can add to your pom.xml. Once added, you can simply update and compile the theme and rebuild your project. Besides that, you will probably have to clear your browser’s cache before reloading your application. If you don’t do that, a previous version of your theme’s css file will be used.