✨(frontend) add ScreenShareZoomControls toolbar component

Bottom-right toolbar with zoom, fit-to-window and fullscreen buttons.

src/frontend/src/features/rooms/livekit/components/ScreenShareZoomControls.tsx

@@ -0,0 +1,168 @@
+import { css } from '@/styled-system/css'
+import { HStack } from '@/styled-system/jsx'
+import { Button } from '@/primitives'
+import {
+  RiFullscreenExitLine,
+  RiFullscreenLine,
+  RiZoomInLine,
+  RiZoomOutLine,
+} from '@remixicon/react'
+import { useTranslation } from 'react-i18next'
+import { useCallback, useEffect, useState } from 'react'
+import { useScreenReaderAnnounce } from '@/hooks/useScreenReaderAnnounce'
+
+interface ScreenShareZoomControlsProps {
+  containerRef: React.RefObject<HTMLDivElement | null>
+  isZoomed: boolean
+  zoomPercentage: number
+  canZoomIn: boolean
+  canZoomOut: boolean
+  onZoomIn: () => void
+  onZoomOut: () => void
+  onResetZoom: () => void
+}
+
+export const ScreenShareZoomControls = ({
+  containerRef,
+  isZoomed,
+  zoomPercentage,
+  canZoomIn,
+  canZoomOut,
+  onZoomIn,
+  onZoomOut,
+  onResetZoom,
+}: ScreenShareZoomControlsProps) => {
+  const { t } = useTranslation('rooms', { keyPrefix: 'screenShareZoom' })
+  const announce = useScreenReaderAnnounce()
+
+  const [isFullscreen, setIsFullscreen] = useState(false)
+  const [isFullscreenAvailable] = useState(
+    () => typeof document !== 'undefined' && document.fullscreenEnabled
+  )
+
+  // Covers Esc and browser UI exits, not just the toolbar button.
+  useEffect(() => {
+    const onChange = () => {
+      const entered = !!document.fullscreenElement
+      setIsFullscreen(entered)
+      announce(
+        entered ? t('fullScreenEntered') : t('fullScreenExited'),
+        'assertive'
+      )
+    }
+    document.addEventListener('fullscreenchange', onChange)
+    return () => document.removeEventListener('fullscreenchange', onChange)
+  }, [announce, t])
+
+  const toggleFullScreen = useCallback(async () => {
+    try {
+      if (document.fullscreenElement) {
+        await document.exitFullscreen()
+      } else {
+        // Tile container so zoom controls stay visible in fullscreen.
+        await containerRef.current?.requestFullscreen()
+      }
+    } catch (error) {
+      console.error('Error toggling fullscreen:', error)
+    }
+  }, [containerRef])
+
+  return (
+    <div
+      className={css({
+        position: 'absolute',
+        bottom: '12px',
+        right: '12px',
+        zIndex: 2,
+        pointerEvents: 'auto',
+      })}
+    >
+      <HStack
+        gap={0}
+        role="toolbar"
+        aria-label={t('toolbarLabel')}
+        className={css({
+          backgroundColor: 'primaryDark.50',
+          borderRadius: '2rem',
+          padding: '0.25rem',
+          opacity: 0.7,
+          transition: 'opacity 200ms linear',
+          _hover: {
+            opacity: 0.95,
+          },
+        })}
+      >
+        {isZoomed && (
+          <>
+            <Button
+              size="sm"
+              variant="primaryTextDark"
+              square
+              tooltip={t('fitToWindow')}
+              aria-label={t('fitToWindow')}
+              onPress={onResetZoom}
+            >
+              <RiFullscreenExitLine size={18} />
+            </Button>
+            <Button
+              size="sm"
+              variant="primaryTextDark"
+              square
+              tooltip={t('zoomOut')}
+              aria-label={t('zoomOut')}
+              isDisabled={!canZoomOut}
+              onPress={onZoomOut}
+            >
+              <RiZoomOutLine size={18} />
+            </Button>
+            {/* Visual only - zoom level is announced via useScreenReaderAnnounce. */}
+            <span
+              aria-hidden="true"
+              className={css({
+                color: 'white',
+                fontSize: '0.75rem',
+                fontWeight: 500,
+                minWidth: '3rem',
+                textAlign: 'center',
+                userSelect: 'none',
+                display: 'flex',
+                alignItems: 'center',
+                justifyContent: 'center',
+                padding: '0 0.25rem',
+              })}
+            >
+              {zoomPercentage} %
+            </span>
+          </>
+        )}
+        <Button
+          size="sm"
+          variant="primaryTextDark"
+          square
+          tooltip={t('zoomIn')}
+          aria-label={t('zoomIn')}
+          isDisabled={!canZoomIn}
+          onPress={onZoomIn}
+        >
+          <RiZoomInLine size={18} />
+        </Button>
+        {isFullscreenAvailable && (
+          <Button
+            size="sm"
+            variant="primaryTextDark"
+            square
+            tooltip={isFullscreen ? t('exitFullScreen') : t('fullScreen')}
+            aria-label={isFullscreen ? t('exitFullScreen') : t('fullScreen')}
+            onPress={toggleFullScreen}
+          >
+            {isFullscreen ? (
+              <RiFullscreenExitLine size={18} />
+            ) : (
+              <RiFullscreenLine size={18} />
+            )}
+          </Button>
+        )}
+      </HStack>
+    </div>
+  )
+}