@patternfly/pfe-sass

PFE SASS

Helper tools for building PatternFly Elements web components.

Broadcast variables

Containers & broadcast vars

If the container allows changes to background colors should influence the children: pfe-set-broadcasted function

Notes on using broadcast colors in components

1. Try to map CSS properties such as color only once. If updates to that property are needed, those should be done by updating the local variable.
2. Set the value equal to local variable: color: var(--pfe-local--Color);. Note that no fallback is defined at this level as that is done when the local variable is declared.
3. In the pfe-component, do not set value of the broadcasted variables unless the component is influencing the background color; instead, set local variables to look for the value of a broadcasted variable, followed by a fallback color. This provides a hook for containers to influence the color of the typography in the component so that it remains readable.
   • --pfe-local--Color: var(--pfe-broadcasted--text, #444);
   • If a component sets it's own background color, it can and should update the value of the broadcasted variables.
4. Reset local variable values as needed for attribute overrides.

CSS Example

Let's use the pfe-cta as an example. We can start by defining local variables, namespaced for this component, and then updating the values of those variables as we go.

    // 1. set up local vars equal to theme vars & fallbacks
    :host {
      --pfe-cta--Color: var(theme--link, #06c);
    }

    // 2. Use color property once, map to local var value
    :host(:not([priority]) {
      ::slotted(a) {
         // color: blue; CSS compiler will print this for IE11
         color: var(--pfe-cta--Color, blue) !important;
      }
    }

    // 3. Use broadcasted variables as needed, with theme fallback after other declarations
    :host {
      --pfe-cta--Color: var(broadcasted--link, var(theme--link, #06c));   
    }

    // 4. Override broadcasted last
    :host([color="accent"]) {
      --pfe-cta--BackgroundColor: var(theme--surface--accent);
      --pfe-cta--Color: var(theme--surface-accent--link);
    }