Add ALT badges to media that has alternative text in web UI (#24782)

app/javascript/mastodon/components/media_gallery.jsx

@@ -81,12 +81,10 @@ class Item extends React.PureComponent {
   render () {
     const { attachment, lang, index, size, standalone, displayWidth, visible } = this.props;
 
+    let badges = [], thumbnail;
+
     let width  = 50;
     let height = 100;
-    let top    = 'auto';
-    let left   = 'auto';
-    let bottom = 'auto';
-    let right  = 'auto';
 
     if (size === 1) {
       width = 100;
@@ -96,45 +94,13 @@ class Item extends React.PureComponent {
       height = 50;
     }
 
-    if (size === 2) {
-      if (index === 0) {
-        right = '2px';
-      } else {
-        left = '2px';
+    if (attachment.get('description')?.length > 0) {
+      badges.push(<span key='alt' className='media-gallery__gifv__label'>ALT</span>);
     }
-    } else if (size === 3) {
-      if (index === 0) {
-        right = '2px';
-      } else if (index > 0) {
-        left = '2px';
-      }
-
-      if (index === 1) {
-        bottom = '2px';
-      } else if (index > 1) {
-        top = '2px';
-      }
-    } else if (size === 4) {
-      if (index === 0 || index === 2) {
-        right = '2px';
-      }
-
-      if (index === 1 || index === 3) {
-        left = '2px';
-      }
-
-      if (index < 2) {
-        bottom = '2px';
-      } else {
-        top = '2px';
-      }
-    }
-
-    let thumbnail = '';
 
     if (attachment.get('type') === 'unknown') {
       return (
-        <div className={classNames('media-gallery__item', { standalone })} key={attachment.get('id')} style={{ left: left, top: top, right: right, bottom: bottom, width: `${width}%`, height: `${height}%` }}>
+        <div className={classNames('media-gallery__item', { standalone, 'media-gallery__item--tall': height === 100, 'media-gallery__item--wide': width === 100 })} key={attachment.get('id')}>
           <a className='media-gallery__item-thumbnail' href={attachment.get('remote_url') || attachment.get('url')} style={{ cursor: 'pointer' }} title={attachment.get('description')} lang={lang} target='_blank' rel='noopener noreferrer'>
             <Blurhash
               hash={attachment.get('blurhash')}
@@ -184,6 +150,8 @@ class Item extends React.PureComponent {
     } else if (attachment.get('type') === 'gifv') {
       const autoPlay = this.getAutoPlay();
 
+      badges.push(<span key='gif' className='media-gallery__gifv__label'>GIF</span>);
+
       thumbnail = (
         <div className={classNames('media-gallery__gifv', { autoplay: autoPlay })}>
           <video
@@ -201,14 +169,12 @@ class Item extends React.PureComponent {
             loop
             muted
           />
-
-          <span className='media-gallery__gifv__label'>GIF</span>
         </div>
       );
     }
 
     return (
-      <div className={classNames('media-gallery__item', { standalone })} key={attachment.get('id')} style={{ left: left, top: top, right: right, bottom: bottom, width: `${width}%`, height: `${height}%` }}>
+      <div className={classNames('media-gallery__item', { standalone, 'media-gallery__item--tall': height === 100, 'media-gallery__item--wide': width === 100 })} key={attachment.get('id')}>
         <Blurhash
           hash={attachment.get('blurhash')}
           dummy={!useBlurhash}
@@ -216,7 +182,14 @@ class Item extends React.PureComponent {
             'media-gallery__preview--hidden': visible && this.state.loaded,
           })}
         />
+
         {visible && thumbnail}
+
+        {badges && (
+          <div className='media-gallery__item__badges'>
+            {badges}
+          </div>
+        )}
       </div>
     );
   }

app/javascript/styles/mastodon/components.scss

@@ -6330,30 +6330,25 @@ a.status-card.compact:hover {
   z-index: 9999;
 }
 
-.media-gallery__gifv__label {
-  display: block;
+.media-gallery__item__badges {
   position: absolute;
-  color: $primary-text-color;
-  background: rgba($base-overlay-background, 0.5);
   bottom: 6px;
   inset-inline-start: 6px;
-  padding: 2px 6px;
-  border-radius: 2px;
-  font-size: 11px;
-  font-weight: 600;
-  z-index: 1;
-  pointer-events: none;
-  opacity: 0.9;
-  transition: opacity 0.1s ease;
-  line-height: 18px;
+  display: flex;
+  gap: 2px;
 }
 
-.media-gallery__gifv {
-  &:hover {
 .media-gallery__gifv__label {
-      opacity: 1;
-    }
-  }
+  display: block;
+  color: $white;
+  background: rgba($black, 0.65);
+  padding: 2px 6px;
+  border-radius: 4px;
+  font-size: 11px;
+  font-weight: 700;
+  z-index: 1;
+  pointer-events: none;
+  line-height: 18px;
 }
 
 .attachment-list {
@@ -6428,17 +6423,28 @@ a.status-card.compact:hover {
   position: relative;
   width: 100%;
   min-height: 64px;
+  display: grid;
+  grid-template-columns: 50% 50%;
+  grid-template-rows: 50% 50%;
+  gap: 2px;
 }
 
 .media-gallery__item {
   border: 0;
   box-sizing: border-box;
   display: block;
-  float: left;
   position: relative;
   border-radius: 4px;
   overflow: hidden;
 
+  &--tall {
+    grid-row: span 2;
+  }
+
+  &--wide {
+    grid-column: span 2;
+  }
+
   &.standalone {
     .media-gallery__item-gifv-thumbnail {
       transform: none;