add nice zoom controls

frontend/src/viewer/components/ImageViewer.jsx

@@ -1,24 +1,219 @@
 import AuthImage from '../../components/AuthImage'
 import { getServerUrl } from '../../hooks/getConstants'
-import { useState, useEffect } from 'react'
-import { Loader2 } from 'lucide-react'
+import { useState, useEffect, useRef, useCallback } from 'react'
+import { Loader2, ZoomIn, ZoomOut } from 'lucide-react'
+
+const MIN_SCALE = 1
+const MAX_SCALE = 8
 
 export default function ImageViewer({ albumId, mediaId, token, title }) {
     const src = `${getServerUrl()}/api/media/${albumId}/${mediaId}`
     const [loaded, setLoaded] = useState(false)
+    const [scale, setScale] = useState(1)
+    const [position, setPosition] = useState({ x: 0, y: 0 })
+    const [isDragging, setIsDragging] = useState(false)
+    const [zoomControlVisible, setZoomControlVisible] = useState(false)
+
+    const containerRef = useRef(null)
+    const scaleRef = useRef(1)
+    const positionRef = useRef({ x: 0, y: 0 })
+    const draggingRef = useRef(false)
+    const dragOrigin = useRef({ x: 0, y: 0 })
+    const lastTouchDist = useRef(null)
+
+    // Keep refs in sync with state
+    useEffect(() => { scaleRef.current = scale }, [scale])
+    useEffect(() => { positionRef.current = position }, [position])
+
+    // Reset on image change
+    useEffect(() => {
+        setScale(1)
+        setPosition({ x: 0, y: 0 })
+        scaleRef.current = 1
+        positionRef.current = { x: 0, y: 0 }
+        setLoaded(false)
+    }, [mediaId])
+
+    const clamp = useCallback((pos, s) => {
+        if (!containerRef.current) return pos
+        const { clientWidth: w, clientHeight: h } = containerRef.current
+        const maxX = (w * (s - 1)) / 2
+        const maxY = (h * (s - 1)) / 2
+        return {
+            x: Math.max(-maxX, Math.min(maxX, pos.x)),
+            y: Math.max(-maxY, Math.min(maxY, pos.y)),
+        }
+    }, [])
+
+    // Zoom towards a specific point (ox, oy) in container-local coordinates
+    const zoomTowards = useCallback((newScale, ox, oy) => {
+        const s = Math.max(MIN_SCALE, Math.min(MAX_SCALE, newScale))
+        const factor = s / scaleRef.current
+        const { clientWidth: w, clientHeight: h } = containerRef.current
+        const cx = ox - w / 2
+        const cy = oy - h / 2
+        const newPos = s === MIN_SCALE
+            ? { x: 0, y: 0 }
+            : clamp({
+                x: positionRef.current.x * factor + cx * (1 - factor),
+                y: positionRef.current.y * factor + cy * (1 - factor),
+            }, s)
+        scaleRef.current = s
+        positionRef.current = newPos
+        setScale(s)
+        setPosition(newPos)
+    }, [clamp])
+
+    // Wheel zoom
+    useEffect(() => {
+        const container = containerRef.current
+        if (!container) return
+        const onWheel = (e) => {
+            e.preventDefault()
+            const rect = container.getBoundingClientRect()
+            const ox = e.clientX - rect.left
+            const oy = e.clientY - rect.top
+            const factor = e.deltaY < 0 ? 1.15 : 1 / 1.15
+            zoomTowards(scaleRef.current * factor, ox, oy)
+        }
+        container.addEventListener('wheel', onWheel, { passive: false })
+        return () => container.removeEventListener('wheel', onWheel)
+    }, [zoomTowards])
+
+    // Mouse drag
+    const handleMouseDown = useCallback((e) => {
+        if (scaleRef.current <= 1 || e.button !== 0) return
+        draggingRef.current = true
+        setIsDragging(true)
+        dragOrigin.current = {
+            x: e.clientX - positionRef.current.x,
+            y: e.clientY - positionRef.current.y,
+        }
+        e.preventDefault()
+    }, [])
+
+    const handleMouseMove = useCallback((e) => {
+        if (!draggingRef.current) return
+        const newPos = clamp(
+            { x: e.clientX - dragOrigin.current.x, y: e.clientY - dragOrigin.current.y },
+            scaleRef.current,
+        )
+        positionRef.current = newPos
+        setPosition(newPos)
+    }, [clamp])
+
+    const handleMouseUp = useCallback(() => {
+        draggingRef.current = false
+        setIsDragging(false)
+    }, [])
+
+    const handleDoubleClick = useCallback(() => {
+        scaleRef.current = 1
+        positionRef.current = { x: 0, y: 0 }
+        setScale(1)
+        setPosition({ x: 0, y: 0 })
+    }, [])
+
+    // Touch handlers — touchmove must be non-passive to call preventDefault
+    const handleTouchStart = useCallback((e) => {
+        if (e.touches.length === 2) {
+            draggingRef.current = false
+            setIsDragging(false)
+            const dx = e.touches[0].clientX - e.touches[1].clientX
+            const dy = e.touches[0].clientY - e.touches[1].clientY
+            lastTouchDist.current = Math.sqrt(dx * dx + dy * dy)
+        } else if (e.touches.length === 1 && scaleRef.current > 1) {
+            draggingRef.current = true
+            setIsDragging(true)
+            dragOrigin.current = {
+                x: e.touches[0].clientX - positionRef.current.x,
+                y: e.touches[0].clientY - positionRef.current.y,
+            }
+        }
+    }, [])
+
+    useEffect(() => {
+        const container = containerRef.current
+        if (!container) return
+        const onTouchMove = (e) => {
+            e.preventDefault()
+            if (e.touches.length === 2) {
+                const dx = e.touches[0].clientX - e.touches[1].clientX
+                const dy = e.touches[0].clientY - e.touches[1].clientY
+                const dist = Math.sqrt(dx * dx + dy * dy)
+                if (lastTouchDist.current) {
+                    const rect = container.getBoundingClientRect()
+                    const ox = (e.touches[0].clientX + e.touches[1].clientX) / 2 - rect.left
+                    const oy = (e.touches[0].clientY + e.touches[1].clientY) / 2 - rect.top
+                    zoomTowards(scaleRef.current * (dist / lastTouchDist.current), ox, oy)
+                }
+                lastTouchDist.current = dist
+            } else if (e.touches.length === 1 && draggingRef.current) {
+                const newPos = clamp(
+                    { x: e.touches[0].clientX - dragOrigin.current.x, y: e.touches[0].clientY - dragOrigin.current.y },
+                    scaleRef.current,
+                )
+                positionRef.current = newPos
+                setPosition(newPos)
+            }
+        }
+        container.addEventListener('touchmove', onTouchMove, { passive: false })
+        return () => container.removeEventListener('touchmove', onTouchMove)
+    }, [zoomTowards, clamp])
+
+    const handleTouchEnd = useCallback(() => {
+        lastTouchDist.current = null
+        draggingRef.current = false
+        setIsDragging(false)
+    }, [])
+
+    const zoomIn = useCallback(() => {
+        if (!containerRef.current) return
+        const { clientWidth: w, clientHeight: h } = containerRef.current
+        zoomTowards(scaleRef.current * 1.5, w / 2, h / 2)
+    }, [zoomTowards])
+
+    const zoomOut = useCallback(() => {
+        if (!containerRef.current) return
+        const { clientWidth: w, clientHeight: h } = containerRef.current
+        zoomTowards(scaleRef.current / 1.5, w / 2, h / 2)
+    }, [zoomTowards])
+
+    useEffect(() => {
+        // while zooming, show the zoom control
+        setZoomControlVisible(true)
+        if (isDragging) return
+        const timer = setTimeout(() => {
+            setZoomControlVisible(false)
+        }, 1000)
+        return () => clearTimeout(timer)
+    }, [scale, isDragging])
 
     return (
-        <div className="flex-1 flex items-center justify-center bg-black relative overflow-hidden">
+        <div
+            ref={containerRef}
+            className="flex-1 flex items-center justify-center bg-black relative overflow-hidden select-none"
+            style={{ cursor: scale > 1 ? (isDragging ? 'grabbing' : 'grab') : 'default', touchAction: 'none' }}
+            onMouseDown={handleMouseDown}
+            onMouseMove={handleMouseMove}
+            onMouseUp={handleMouseUp}
+            onMouseLeave={handleMouseUp}
+            onTouchStart={handleTouchStart}
+            onTouchEnd={handleTouchEnd}
+        >
             <AuthImage
                 src={src}
                 token={token}
                 alt={title}
                 className={`max-w-full max-h-full object-contain absolute ${loaded ? 'block' : 'hidden'}`}
-                onLoad={() => {
-                    setLoaded(true)
+                style={{
+                    transform: `translate(${position.x}px, ${position.y}px) scale(${scale})`,
+                    transformOrigin: 'center',
+                    willChange: 'transform',
                 }}
+                onLoad={() => setLoaded(true)}
+                draggable={false}
             />
-            {/* loading image */}
             {!loaded && (
                 <div className="absolute top-0 left-0 w-full h-full bg-black/50 flex items-center justify-center">
                     <AuthImage
@@ -30,7 +225,34 @@ export default function ImageViewer({ albumId, mediaId, token, title }) {
                     <Loader2 className="w-10 h-10 text-white animate-spin absolute bottom-5 right-5" />
                 </div>
             )}
+            <div
+                className="absolute bottom-4 right-4 flex items-center gap-1 bg-[#222]/50 rounded-full px-2 py-1.5 backdrop-blur-sm "
+                onMouseEnter={() => setZoomControlVisible(true)}
+                onMouseLeave={() => setZoomControlVisible(false)}
+                style={{ opacity: zoomControlVisible ? 1 : 0, transition: 'opacity 0.2s ease-in-out' }}
+                onMouseDown={e => e.stopPropagation()}
+            >
+                <button
+                    onClick={zoomOut}
+                    disabled={scale <= MIN_SCALE}
+                    className="text-white/80 hover:text-white disabled:opacity-30 disabled:cursor-not-allowed transition-colors p-1.5 cursor-pointer"
+                >
+                    <ZoomOut size={16} />
+                </button>
+                <button
+                    onClick={handleDoubleClick}
+                    className="text-white/60 hover:text-white transition-colors text-xs font-mono w-10 text-center cursor-pointer"
+                >
+                    {Math.round(scale * 100)}%
+                </button>
+                <button
+                    onClick={zoomIn}
+                    disabled={scale >= MAX_SCALE}
+                    className="text-white/80 hover:text-white disabled:opacity-30 disabled:cursor-not-allowed transition-colors p-1.5 cursor-pointer"
+                >
+                    <ZoomIn size={16} />
+                </button>
+            </div>
         </div>
     )
 }
-