feature(b-icon): add animated icon options (closes #4720) (#4934)

Co-authored-by: Jacob Müller

Author: tmorehouse

docs/nuxt.config.js

@@ -276,7 +276,7 @@ module.exports = {
     'highlight.js/styles/atom-one-light.css',
     'codemirror/lib/codemirror.css',
     'bootstrap/dist/css/bootstrap.css',
-    '../scripts/build.scss', // BootstrapVue SCSS
+    '../scripts/index.scss', // BootstrapVue SCSS
     '@assets/css/docs.min.css',
     '@assets/scss/styles.scss'
   ]

scripts/build.sh

@@ -96,16 +96,16 @@ node-sass --output-style expanded \
           --source-map true \
           --source-map-contents true \
           --precision 6 \
-          scripts/build.scss \
+          scripts/index.scss \
           dist/bootstrap-vue.css
 postcss --config scripts/postcss.config.js \
         --replace dist/bootstrap-vue.css
-# Icons only CSS
+# BootstrapVue Icons only CSS
 node-sass --output-style expanded \
           --source-map true \
           --source-map-contents true \
           --precision 6 \
-          src/icons.scss \
+          scripts/icons.scss \
           dist/bootstrap-vue-icons.css
 postcss --config scripts/postcss.config.js \
         --replace dist/bootstrap-vue-icons.css

scripts/icons.scss

@@ -0,0 +1,11 @@
+/*!
+ * BootstrapVue Icons Custom CSS (https://bootstrap-vue.js.org)
+ */
+
+// Include Bootstrap functions, variables, and mixins
+@import "node_modules/bootstrap/scss/functions";
+@import "node_modules/bootstrap/scss/variables";
+@import "node_modules/bootstrap/scss/mixins";
+
+// Import BootstrapVue Icons custom SCSS
+@import "../src/icons.scss";

scripts/build.scss scripts/index.scssscripts/build.scss renamed to scripts/index.scss

@@ -59,6 +59,13 @@ $b-custom-file-height-inner-sm: calc(
   #{$b-custom-file-line-height-sm * 1em} + #{$b-custom-file-padding-y-sm * 2}
 ) !default;
 
+// --- Icons ---
+
+// Animations
+$b-icon-animation-spin-duration: 2s !default;
+$b-icon-animation-pulse-duration: 1s !default;
+$b-icon-animation-cylon-duration: 0.75s !default;
+
 // --- Tables ---
 
 // Table busy state

src/_variables.scss

@@ -222,4 +222,8 @@ label is provided. You can easily customize the role if required via prop `role`
 As well, when no label is provided, the spinner will automatically have the attribute
 `aria-hidden="true"` to hide the spinner from screen reader users.
 
+## See also
+
+An alternative to the `<b-spinner>` component are [animated icons](/docs/icons/#animated-icons).
+
 <!-- Component reference added automatically from component package.json -->

src/components/spinner/README.md

@@ -1,5 +1,8 @@
 // --- BootstrapVue Icons Custom SCSS ---
 
+// Include variables and utilities first
+@import "variables";
+@import "utilities";
+
 // Include custom SCSS for icons
-// Temporary until Bootstrap v5 (maybe)
 @import "icons/index";

src/icons.scss

@@ -297,7 +297,7 @@ With the use of Bootstrap's border and background
 <!-- icons-styling.vue -->
 ```
 
-## Transforms
+## SVG transforms
 
 BootstrapVue icons provide several props for applying basic SVG transforms to the `<svg>`. All
 transforms can be combined for added effect. Note that the transforms are applied to the `<svg>`
@@ -428,6 +428,64 @@ Shifting is applied after any rotation transforms. As with scaling, backgrounds
 affected. If you need to shift the border/background with the icon, use Bootstrap's margin
 [spacing utility classes](/docs/reference/utility-classes).
 
+## Animated icons
+
+<span class="badge badge-info small">v2.7.0+</span>
+
+BootstrapVue includes two spinning animation options for icons: `spin` and `pulse`. Both animations
+spin the icon clockwise, but pulse uses a stepped spin. A third animation called `cylon` is also
+provided.
+
+To use the spin animation, set the `animation` prop to one of the animation names `'spin'`,
+`'pulse'` or `'cylon'`.
+
+```html
+<template>
+  <div>
+    <p>Spinning animation:</p>
+    <b-icon icon="arrow-clockwise" animation="spin" font-scale="4"></b-icon>
+
+    <p class="mt-3">Pulsing animation:</p>
+    <b-icon icon="arrow-clockwise" animation="pulse" font-scale="4"></b-icon>
+
+    <p class="mt-3">Cylon animation:</p>
+    <b-icon icon="three-dots" animation="cylon" font-scale="4"></b-icon>
+  </div>
+</template>
+
+<!-- b-icon-spin-aminations.vue -->
+```
+
+Note with the `cylon` animation, the left-right movement extends past the icon's bounding box by
+`25%`, so you may need to adjust padding or margins to compensate for your use case.
+
+As the animations are CSS based, they are applied _after_ any SVG transforms have taken place:
+
+```html
+<template>
+  <div class="p-4">
+    <b-icon icon="clock" animation="spin" font-scale="4" shift-v="8"></b-icon>
+  </div>
+</template>
+
+<!-- b-icon-spin-aminations-transforms.vue -->
+```
+
+The BootstrapVue defined icon animation effects require BootstrapVue's custom CSS. The `animation`
+prop translates to the class name `b-icon-animation-{animationName}`.
+
+Need a different style animation? Just create a custom class defining the animation, and apply that
+class to the icon component, or create a new animation class in the form of
+`b-icon-animation-{animationName}` and pass the custom animation name to the `animation` prop.
+
+**Note:** The BootstrapVue defined animation effects of this component is dependent on the
+`prefers-reduced-motion` media query. See the
+[reduced motion section of our accessibility documentation](/docs/reference/accessibility) for
+additional details.
+
+Side note: the `cylon` animation gets its name from the "eye" of the Cylons from the _original_
+[1978 Battlestar Galactica TV series](https://www.youtube.com/watch?v=5a5bEIf0UaU).
+
 ## Stacking icons
 
 <span class="badge badge-info small">v2.3.0+</span>
@@ -492,6 +550,8 @@ Stacked icon notes:
 - The `font-scale` prop cannot be used on the inner icon components
 - The `width` and `height` attributes cannot be applied to the inner icon components
 - Stacked icons **cannot** be stacked inside another `<b-iconstack>`
+- Note the animation props on the child icons will have no effect, however you _can_ use the
+  animation props on the `<b-iconstack>` component.
 
 ## Using in components
 

src/icons/README.md

@@ -9,6 +9,47 @@
     // Perhaps this values should be SASS variables?
     vertical-align: -0.15em;
   }
+
+  &.b-icon-animation-spin {
+    animation: $b-icon-animation-spin-duration infinite linear b-icon-animation-spin;
+    @media (prefers-reduced-motion: reduce) {
+      animation: none;
+    }
+  }
+
+  &.b-icon-animation-pulse {
+    animation: $b-icon-animation-pulse-duration infinite steps(8) b-icon-animation-spin;
+    @media (prefers-reduced-motion: reduce) {
+      animation: none;
+    }
+  }
+
+  &.b-icon-animation-cylon {
+    animation: $b-icon-animation-cylon-duration infinite ease-in-out alternate
+      b-icon-animation-cylon;
+    @media (prefers-reduced-motion: reduce) {
+      animation: none;
+    }
+  }
+}
+
+// Animation for spinning icons
+@keyframes b-icon-animation-spin {
+  0% {
+    transform: rotate(0deg);
+  }
+  100% {
+    transform: rotate(359deg);
+  }
+}
+
+@keyframes b-icon-animation-cylon {
+  0% {
+    transform: translateX(-25%);
+  }
+  100% {
+    transform: translateX(25%);
+  }
 }
 
 // Make icons slightly larger in buttons, nav-links, dropdowns, and input-group-text

src/icons/_icons.scss

@@ -37,6 +37,10 @@ export const commonIconProps = {
   shiftV: {
     type: [Number, String],
     default: 0
+  },
+  animation: {
+    type: String,
+    default: null
   }
 }
 
@@ -73,6 +77,7 @@ export const BVIconBase = /*#__PURE__*/ Vue.extend({
     const shiftV = toFloat(props.shiftV) || 0
     const flipH = props.flipH
     const flipV = props.flipV
+    const animation = props.animation
     // Compute the transforms
     // Note that order is important as SVG transforms are applied in order from
     // left to right and we want flipping/scale to occur before rotation
@@ -116,7 +121,10 @@ export const BVIconBase = /*#__PURE__*/ Vue.extend({
       mergeData(
         {
           staticClass: 'b-icon bi',
-          class: { [`text-${props.variant}`]: !!props.variant },
+          class: {
+            [`text-${props.variant}`]: !!props.variant,
+            [`b-icon-animation-${animation}`]: !!animation
+          },
           attrs: baseAttrs,
           style: isStacked ? {} : { fontSize: fontScale === 1 ? null : `${fontScale * 100}%` }
         },