discourse/app/assets/stylesheets/common/components/d-lightbox.scss

/* Main document */

html.has-lightbox {
  overflow: hidden;

  &::-webkit-scrollbar {
    display: none;
  }

  .profiler-results {
    display: none;
  }

  #main {
    padding-right: var(--document-scrollbar-width);
  }

  --carousel-item-size: clamp(6.5rem, 12vh, 15rem);
  --d-lightbox-primary: #ffffff;
  --d-lightbox-secondary: #000000;
  --d-lightbox-secondary-translucent: rgba(0, 0, 0, 0.25);
}

/* Lightbox element*/

// Grid

.d-lightbox {
  overscroll-behavior: contain;

  * {
    box-sizing: border-box;
  }

  &.is-visible {
    display: grid;
    place-items: stretch;
  }

  &__content {
    display: grid;
    place-items: stretch;
  }

  &.is-vertical &__content {
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr auto auto;

    grid-template-areas:
      "lightbox-header"
      "lightbox-body"
      "lightbox-carousel"
      "lightbox-footer";
  }

  &.is-horizontal &__content {
    grid-template-columns: auto 1fr;
    grid-template-rows: auto 1fr auto;
    grid-template-areas:
      "lightbox-carousel lightbox-header"
      "lightbox-carousel lightbox-body"
      "lightbox-carousel lightbox-footer";
  }

  &__header {
    grid-area: lightbox-header;
    justify-self: stretch;
    display: grid;
    place-items: center start;
    grid-template-areas: "preview-controls lightbox-header-buttons";
  }

  &__multi-item-controls {
    grid-area: preview-controls;
    place-self: center start;
    display: grid;
    gap: 0.5em;
    place-items: center start;
    grid-auto-flow: column;
    grid-template-areas: "lightbox-carousel-toggle lightbox-counter";

    .d-lightbox__carousel-button {
      grid-area: lightbox-carousel-toggle;
    }
  }

  &__counters {
    grid-area: lightbox-counter;
  }

  &__header-buttons {
    grid-area: lightbox-header-buttons;
    place-self: center end;
    display: grid;
    gap: 0 0.25em;
    place-items: center end;
    grid-auto-flow: column;
  }

  &__body {
    grid-area: lightbox-body;
    display: grid;
    place-items: center stretch;

    grid-auto-flow: column;
    grid-template-columns: auto 1fr auto;
    grid-template-areas: "lightbox-previous-button lightbox-main-image lightbox-next-button";
  }

  &__main-image,
  &__error-message,
  &__loading-spinner {
    grid-area: lightbox-main-image;
    place-self: center;
    display: grid;
    place-items: center;
    grid-auto-flow: column;
  }

  &__previous-button {
    grid-area: lightbox-previous-button;
    place-self: center start;
  }

  &__next-button {
    grid-area: lightbox-next-button;
    place-self: center end;
  }

  &.has-carousel &,
  &.is-rotated &,
  &.is-zoomed & {
    &__body {
      grid-auto-flow: row;
      grid-template-columns: 1fr;
      grid-template-areas: "lightbox-main-image";
    }
  }

  &__footer {
    grid-area: lightbox-footer;
    place-self: stretch;
    display: grid;
    grid-auto-flow: column;
    gap: 1.5em;
    grid-template-columns: 1fr auto;
    grid-template-areas: "lightbox-title lightbox-footer-buttons";
  }

  &__main-title {
    grid-area: lightbox-title;
    place-self: center start;
  }

  &__footer-buttons {
    grid-area: lightbox-footer-buttons;
    place-self: center end;
    display: grid;
    grid-auto-flow: column;
    gap: 0 0.25em;
    place-items: center;
  }

  &__carousel {
    grid-area: lightbox-carousel;
    display: grid;
    place-items: center;
  }

  &__carousel-items {
    grid-area: lightbox-preview-images;
    display: grid;
    gap: 1em;
    place-items: center;
  }

  &__carousel-previous-button {
    grid-area: lightbox-previous;
  }

  &__carousel-next-button {
    grid-area: lightbox-next;
  }

  &.is-vertical &__carousel {
    grid-auto-flow: column;
    grid-template-columns: auto 1fr auto;
    grid-template-areas: "lightbox-previous lightbox-preview-images lightbox-next";
  }

  &__carousel-items {
    grid-auto-flow: column;
  }
  &__carousel-item,
  &__carousel-item.is-current {
    height: var(--carousel-item-size);
  }

  &.is-horizontal &__carousel {
    max-height: 100vh;
    grid-template-rows: 1fr auto 1fr;
    place-items: center;
    grid-template-areas:
      "lightbox-previous"
      "lightbox-preview-images"
      "lightbox-next";
  }

  &.is-horizontal &__carousel-items {
    grid-auto-flow: row;
  }

  &__carousel-item,
  &__carousel-item.is-current {
    width: var(--carousel-item-size);
  }

  &__carousel-previous-button {
    place-self: self-end center;
  }

  &__carousel-next-button {
    place-self: self-start center;
  }
}

/* Base styles */

.d-lightbox {
  &.is-visible {
    position: fixed;
    top: 0;
    left: 0;
    height: 100dvh;
    width: 100%;
    z-index: z("max");
  }

  &__content {
    background-color: var(--d-lightbox-secondary);

    &:focus-visible {
      outline: none;
    }
  }
}

.d-lightbox {
  &__header {
    z-index: 1;
    padding: 0.25em 1px; // 1px for button outlines
    color: var(--d-lightbox-primary);
    background: linear-gradient(
      to right,
      var(--d-lightbox-secondary),
      transparent
    );

    position: relative;
  }
}

.d-lightbox {
  &__body {
    @include user-select(none);
    position: relative;
    outline: none;
  }

  &__loading-spinner,
  &__error-message,
  &__main-image {
    position: absolute;
    outline: none;
  }

  &__backdrop {
    position: fixed;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
    background-size: cover;
    background-position: center;
    filter: blur(15px) brightness(0.25);
    background-color: var(--d-lightbox-secondary);
    background-image: var(--d-lightbox-image-small-url);
  }

  &__main-image {
    aspect-ratio: var(--d-lightbox-image-aspect-ratio);
    background-color: var(--d-lightbox-image-dominant-color);
    box-sizing: border-box;
    max-height: 100%;
    max-width: 100%;
    box-shadow: shadow("card");
  }

  &__error-message {
    color: var(--d-lightbox-primary);
  }

  &__previous-button,
  &__next-button {
    z-index: 1;
    position: absolute;

    .d-icon {
      font-size: var(--font-up-2);
    }
  }
}

.d-lightbox {
  &__footer {
    z-index: 1;
    padding: 0.25em 1px;
    min-width: 0;
    box-sizing: border-box;
    color: var(--d-lightbox-primary);
    background: linear-gradient(
      to left,
      var(--d-lightbox-secondary),
      transparent
    );
    position: relative;
  }

  &__main-title {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 0 0.25em;
    word-break: break-word;
    max-width: 100%;
    // right/left padding to align with buttons
    padding: 0 0.65em;
    border: 1px solid transparent;
    width: 100%;
    min-width: 0;
    overflow: hidden;
    &:focus-visible {
      outline: none;
      border: 1px solid var(--tertiary);
      border-radius: 1px;
    }
  }

  &__item-title {
    display: block;
    @include ellipsis;
  }

  &__item-file-details {
    font-size: var(--font-down-2);
    color: var(--primary-600);
    white-space: nowrap;
  }
}

.d-lightbox {
  &__carousel {
    @include user-select(none);
    box-sizing: border-box;
    z-index: 1;
    position: relative;
    color: var(--d-lightbox-primary);
  }
  &__carousel-previous-button,
  &__carousel-next-button {
    z-index: 2;

    .d-icon {
      font-size: var(--font-up-2);
    }
  }
}

.d-lightbox {
  &__carousel-items {
    @extend %lightbox-scrollable;
    max-height: 100%;
    max-width: 100%;
    z-index: 0;
    box-sizing: border-box;
  }

  &__carousel-item,
  &__carousel-item.is-current {
    border: 1px solid transparent;
    box-shadow: 0 0 2px -1px var(--d-lightbox-primary);
    border-radius: 5px;
    cursor: pointer;
    user-select: none;
    transition: all var(--d-lightbox-image-animation-duration) ease-in-out;
    background-color: var(--dominant-color);
    aspect-ratio: var(--aspect-ratio);
    filter: saturate(0.5);

    &:focus {
      outline: none;
    }
  }

  &__carousel-item.is-current {
    border-color: var(--tertiary);
    pointer-events: none;
    filter: initial;
  }
}

.d-lightbox {
  &.is-vertical &__carousel {
    position: relative;
    background-color: var(--d-lightbox-secondary-translucent);
    &:before,
    &:after {
      content: "";
      position: absolute;
      display: block;
      z-index: 1;
      pointer-events: none;
      height: 100%;
      width: 20%;
    }

    &:before {
      left: 0;
      top: 0;
      background: var(--d-lightbox-secondary);
      -webkit-mask-image: linear-gradient(
        90deg,
        var(--d-lightbox-secondary),
        transparent
      );
      mask-image: linear-gradient(
        90deg,
        var(--d-lightbox-secondary),
        transparent
      );
    }

    &:after {
      right: 0;
      bottom: 0;
      background: var(--d-lightbox-secondary);
      -webkit-mask-image: linear-gradient(
        -90deg,
        var(--d-lightbox-secondary),
        transparent
      );
      mask-image: linear-gradient(
        -90deg,
        var(--d-lightbox-secondary),
        transparent
      );
    }

    .rtl & {
      &:before {
        left: auto;
        right: 0;
      }

      &:after {
        left: 0;
        right: auto;
      }
    }
  }

  &.is-vertical &__carousel-items {
    padding: 1em 2em;
  }

  &__carousel-previous-button,
  &__carousel-next-button {
    position: absolute;
  }
}

.d-lightbox {
  &.is-horizontal &__carousel {
    position: relative;
    &:before,
    &:after {
      content: "";
      position: absolute;
      display: block;
      z-index: 1;
      pointer-events: none;
      height: 20%;
      width: 100%;
    }

    &:before {
      left: 0;
      top: 0;
      background: var(--d-lightbox-secondary);
      -webkit-mask-image: linear-gradient(
        180deg,
        var(--d-lightbox-secondary),
        transparent
      );
      mask-image: linear-gradient(
        180deg,
        var(--d-lightbox-secondary) 20%,
        transparent 100%
      );
    }

    &:after {
      right: 0;
      bottom: 0;
      background: var(--d-lightbox-secondary);
      -webkit-mask-image: linear-gradient(
        0,
        var(--d-lightbox-secondary),
        transparent
      );
      mask-image: linear-gradient(
        0,
        var(--d-lightbox-secondary) 20%,
        transparent 100%
      );
    }
  }

  &.is-horizontal &__carousel-items {
    padding: 50% 1em;
  }

  &__carousel-previous-button,
  &__carousel-next-button {
    transform: rotate(90deg);

    .rtl & {
      transform: rotate(-90deg);
    }
  }
}

.d-lightbox {
  .btn-flat {
    .d-icon {
      margin: 0;
    }

    &:focus {
      background: transparent;
      outline: none;

      .d-icon {
        color: var(--d-lightbox-primary);
      }
    }

    &:focus-visible {
      outline: 1px solid var(--tertiary);
      border-radius: 1px;
      .d-icon {
        color: var(--tertiary);
      }
    }

    @include hover {
      .d-icon {
        color: var(--tertiary);
      }
    }
  }
}

.d-lightbox {
  &__focus-trap,
  &__screen-reader-announcer {
    position: absolute;
    left: -100%;
    top: -100%;
  }
}

/* State styles */

// Carousel
.d-lightbox {
  &.has-carousel {
    .d-lightbox__content {
      gap: 2em 0;
    }

    .btn-flat.d-lightbox__carousel-button .d-icon {
      color: var(--tertiary);

      @include hover {
        color: var(--tertiary);
      }
    }
  }
}

// expanded title
.d-lightbox {
  &.has-expanded-title {
    .d-lightbox__content {
      gap: 2em;
    }

    .d-lightbox__main-title {
      overflow: visible;
      white-space: normal;
      text-overflow: unset;
    }
  }
}

// Zoom
.d-lightbox {
  &.can-zoom {
    .d-lightbox__body {
      @extend %lightbox-scrollable;

      overflow: auto;
      height: 100%;
      width: 100%;
      position: absolute;
    }

    .d-lightbox__main-image {
      cursor: zoom-in;
    }
  }

  &.is-zoomed {
    .d-lightbox__content {
      gap: 0;
    }

    .d-lightbox {
      &__body {
        @extend %lightbox-scrollable;
        overflow: auto;
        height: 100%;
        width: 100%;
        position: absolute;
      }

      &__zoomed-image-container {
        cursor: zoom-out;
        background-image: var(--d-lightbox-image-full-size-url);
        background-repeat: no-repeat;
        backface-visibility: hidden;
        background-position: center;

        .mobile-view & {
          width: var(--d-lightbox-image-width);
          height: var(--d-lightbox-image-height);
        }

        .desktop-view & {
          width: 100%;
          height: 100%;
        }
      }
    }

    .btn-flat.d-lightbox__zoom-button .d-icon {
      color: var(--tertiary);

      @include hover {
        color: var(--tertiary);
      }
    }
  }
}

// Rotate
.d-lightbox {
  &.is-rotated {
    .d-lightbox__body {
      gap: 0;
    }
    .d-lightbox__main-image,
    .d-lightbox__zoomed-image-container {
      transform: rotate(var(--d-lightbox-image-rotation));
    }

    .btn-flat.d-lightbox__rotate-button .d-icon {
      color: var(--tertiary);
      transform: rotate(var(--d-lightbox-image-rotation));

      @include hover {
        color: var(--tertiary);
      }
    }
  }
}

// Full screen
.d-lightbox {
  &.is-fullscreen {
    .btn-flat.d-lightbox__full-screen-button .d-icon {
      color: var(--tertiary);

      @include hover {
        color: var(--tertiary);
      }
    }
  }
}

/* Animations */

.d-lightbox {
  &.is-visible &__content {
    @extend %lightbox-animation-base;
    @media (prefers-reduced-motion: no-preference) {
      animation-name: lightbox-fade-in-scale;
    }
  }

  &__backdrop,
  &__main-image,
  &__loading-spinner,
  &__zoomed-image-container,
  &__carousel,
  &__main-title {
    @extend %lightbox-animation-base;
    animation-name: lightbox-fade-in;
    @media (prefers-reduced-motion) {
      animation-duration: 0s;
    }
  }

  &__loading-spinner {
    animation-delay: var(--d-lightbox-image-animation-duration);
    opacity: 0;
  }

  &.will-close &__content {
    animation-name: lightbox-fade-out;
    @media (prefers-reduced-motion) {
      animation-duration: 0s;
    }
  }
}

%lightbox-animation-base {
  animation-duration: 150ms;
  animation-fill-mode: forwards;
  backface-visibility: hidden;
  will-change: opacity;
  animation-timing-function: linear;
}

%lightbox-scrollable {
  backface-visibility: hidden;

  // MOZ
  scrollbar-width: none;
  overflow: auto;
  // Webkit
  overflow: overlay;
  &::-webkit-scrollbar {
    display: none;
  }
}

@keyframes lightbox-fade-out {
  0% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}

@keyframes lightbox-fade-in {
  0% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}

@keyframes lightbox-fade-in-scale {
  0% {
    opacity: 0;
    transform: scale(0.85);
  }

  100% {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes lightbox-fade-out-scale {
  0% {
    opacity: 1;
    transform: scale(1);
  }

  100% {
    opacity: 0;
    transform: scale(0.85);
  }
}