ionic-framework/core/src/components/progress-bar/progress-bar.scss

@import "../../themes/ionic.globals";

// Progress bar
// --------------------------------------------------
// Host has no background by default - this will be added to the progress-buffer-bar

:host {
  /**
  * @prop --background:  Same as --buffer-background when using a determinate progress bar, otherwise it styles the background of the ion-progress-bar itself.
  * @prop --progress-background: Color of the progress bar
  * @prop --buffer-background: Color of the buffer bar
  */
  --background: #{ion-color(primary, base, 0.2)};
  --progress-background: #{ion-color(primary, base)};
  --buffer-background: var(--background);
  display: block;

  position: relative;

  width: 100%;

  contain: strict;

  direction: ltr;
  overflow: hidden;
}

:host(.ion-color) {
  --progress-background: #{current-color(base)};
  --buffer-background: #{current-color(base, 0.2)};
}

// indeterminate has no progress-buffer-bar, so it will be added to the host
:host(.progress-bar-indeterminate) {
  background: var(--buffer-background);
}

.progress,
.progress-indeterminate,
.indeterminate-bar-primary,
.indeterminate-bar-secondary,
.progress-buffer-bar,
.progress-buffer-bar:before,
.buffer-circles {
  @include position(0, 0, 0, 0);

  position: absolute;

  width: 100%;
  height: 100%;
}

// Determinate progress bar
// --------------------------------------------------

.progress,
.progress-buffer-bar {
  /* stylelint-disable-next-line property-blacklist */
  transform-origin: left top;

  transition: transform 150ms linear;
}

// Progress and background bar
// --------------------------------------------------

.progress,
.progress-indeterminate {
  background: var(--progress-background);

  z-index: 2;
}

.progress-buffer-bar {
  // It's currently here because --buffer-background has an alpha
  // Otherwise the buffer circles would be seen through
  background: #fff;

  z-index: 1; // Make it behind the progress

  &:before {
    background: var(--buffer-background);

    content: "";
  }
}

// MD based animation on indeterminate type
// --------------------------------------------------

.indeterminate-bar-primary {
  /* stylelint-disable property-blacklist */
  top: 0;
  right: 0;
  bottom: 0;
  left: -145.166611%;
  /* stylelint-enable property-blacklist */

  animation: primary-indeterminate-translate 2s infinite linear;

  .progress-indeterminate {
    animation: primary-indeterminate-scale 2s infinite linear;
    animation-play-state: inherit;
  }
}

.indeterminate-bar-secondary {
  /* stylelint-disable property-blacklist */
  top: 0;
  right: 0;
  bottom: 0;
  left:  -54.888891%;
  /* stylelint-enable property-blacklist */

  animation: secondary-indeterminate-translate 2s infinite linear;

  .progress-indeterminate {
    animation: secondary-indeterminate-scale 2s infinite linear;
    animation-play-state: inherit;
  }
}

// Buffer style
// --------------------------------------------------

.buffer-circles {
  background: radial-gradient(ellipse at center, var(--buffer-background) 0%, var(--buffer-background) 30%, transparent 30%) repeat-x 5px center;
  background-size: 10px 10px;

  z-index: 0;
  animation: buffering 450ms infinite linear;
}

// If reversed is set to true, the animation will be reversed
// and the bars starting at the top right
// --------------------------------------------------

:host(.progress-bar-reversed) {
  .progress,
  .progress-buffer-bar {
    /* stylelint-disable-next-line property-blacklist */
    transform-origin: right top;
  }

  .buffer-circles,
  .indeterminate-bar-primary,
  .indeterminate-bar-secondary,
  .progress-indeterminate {
    animation-direction: reverse;
  }
}

// Progress paused
// --------------------------------------------------

:host(.progress-paused) {
  .indeterminate-bar-secondary,
  .indeterminate-bar-primary,
  .buffer-circles {
    animation-play-state: paused;
  }
}

// Animation Keyframes
// --------------------------------------------------
// Source: https://github.com/material-components/material-components-web/blob/master/packages/mdc-linear-progress/_keyframes.scss

@keyframes primary-indeterminate-translate {
  0% {
    transform: translateX(0);
  }

  20% {
    animation-timing-function: cubic-bezier(.5, 0, .701732, .495819);

    transform: translateX(0);
  }

  59.15% {
    animation-timing-function: cubic-bezier(.302435, .381352, .55, .956352);

    transform: translateX(83.67142%);
  }

  100% {
    transform: translateX(200.611057%);
  }
}

@keyframes primary-indeterminate-scale {
  0% {
    transform: scaleX(.08);
  }

  36.65% {
    animation-timing-function: cubic-bezier(.334731, .12482, .785844, 1);

    transform: scaleX(.08);
  }

  69.15% {
    animation-timing-function: cubic-bezier(.06, .11, .6, 1);

    transform: scaleX(.661479);
  }

  100% {
    transform: scaleX(.08);
  }
}

@keyframes secondary-indeterminate-translate {
  0% {
    animation-timing-function: cubic-bezier(.15, 0, .515058, .409685);

    transform: translateX(0);
  }

  25% {
    animation-timing-function: cubic-bezier(.31033, .284058, .8, .733712);

    transform: translateX(37.651913%);
  }

  48.35% {
    animation-timing-function: cubic-bezier(.4, .627035, .6, .902026);

    transform: translateX(84.386165%);
  }

  100% {
    transform: translateX(160.277782%);
  }
}

@keyframes secondary-indeterminate-scale {
  0% {
    animation-timing-function: cubic-bezier(.205028, .057051, .57661, .453971);

    transform: scaleX(.08);
  }

  19.15% {
    animation-timing-function: cubic-bezier(.152313, .196432, .648374, 1.004315);

    transform: scaleX(.457104);
  }

  44.15% {
    animation-timing-function: cubic-bezier(.257759, -.003163, .211762, 1.38179);

    transform: scaleX(.72796);
  }

  100% {
    transform: scaleX(.08);
  }
}

@keyframes buffering {
  to {
    transform: translateX(-10px);
  }
}