|
| 1 | +<script lang="ts"> |
| 2 | + import { createEventDispatcher } from 'svelte'; |
| 3 | +
|
| 4 | + export let url = ''; |
| 5 | + export let alt = ''; |
| 6 | + export let referrerpolicy: ReferrerPolicy | undefined = undefined; |
| 7 | +
|
| 8 | + const dispatch = createEventDispatcher<{ close: void }>(); |
| 9 | + const minScale = 1; |
| 10 | + const maxScale = 5; |
| 11 | + const tapMovementThreshold = 8; |
| 12 | +
|
| 13 | + let viewerElement: HTMLDivElement; |
| 14 | + let scale = 1; |
| 15 | + let translateX = 0; |
| 16 | + let translateY = 0; |
| 17 | + let lastUrl = ''; |
| 18 | + let lastDistance = 0; |
| 19 | + let lastCenter = { x: 0, y: 0 }; |
| 20 | + let tapStart = { x: 0, y: 0 }; |
| 21 | + let moved = false; |
| 22 | + let pointers = new Map<number, { x: number; y: number }>(); |
| 23 | +
|
| 24 | + $: if (url && url !== lastUrl) { |
| 25 | + lastUrl = url; |
| 26 | + resetZoom(); |
| 27 | + } |
| 28 | +
|
| 29 | + $: imageTransform = `translate3d(${translateX}px, ${translateY}px, 0) scale(${scale})`; |
| 30 | +
|
| 31 | + function close() { |
| 32 | + dispatch('close'); |
| 33 | + } |
| 34 | +
|
| 35 | + function resetZoom() { |
| 36 | + scale = 1; |
| 37 | + translateX = 0; |
| 38 | + translateY = 0; |
| 39 | + lastDistance = 0; |
| 40 | + lastCenter = { x: 0, y: 0 }; |
| 41 | + pointers = new Map(); |
| 42 | + moved = false; |
| 43 | + } |
| 44 | +
|
| 45 | + function pointerDown(event: PointerEvent) { |
| 46 | + viewerElement?.setPointerCapture?.(event.pointerId); |
| 47 | + pointers.set(event.pointerId, { x: event.clientX, y: event.clientY }); |
| 48 | + moved = false; |
| 49 | +
|
| 50 | + if (pointers.size === 1) { |
| 51 | + tapStart = { x: event.clientX, y: event.clientY }; |
| 52 | + } else if (pointers.size === 2) { |
| 53 | + event.preventDefault(); |
| 54 | + lastDistance = pointerDistance(); |
| 55 | + lastCenter = pointerCenter(); |
| 56 | + } |
| 57 | + } |
| 58 | +
|
| 59 | + function pointerMove(event: PointerEvent) { |
| 60 | + if (!pointers.has(event.pointerId)) return; |
| 61 | + const previous = pointers.get(event.pointerId) ?? { x: event.clientX, y: event.clientY }; |
| 62 | + pointers.set(event.pointerId, { x: event.clientX, y: event.clientY }); |
| 63 | +
|
| 64 | + if (Math.hypot(event.clientX - tapStart.x, event.clientY - tapStart.y) > tapMovementThreshold) moved = true; |
| 65 | +
|
| 66 | + if (pointers.size >= 2) { |
| 67 | + event.preventDefault(); |
| 68 | + const nextDistance = pointerDistance(); |
| 69 | + const nextCenter = pointerCenter(); |
| 70 | + if (lastDistance > 0) zoomAround(nextCenter, scale * (nextDistance / lastDistance)); |
| 71 | + translateX += nextCenter.x - lastCenter.x; |
| 72 | + translateY += nextCenter.y - lastCenter.y; |
| 73 | + constrainPan(); |
| 74 | + lastDistance = nextDistance; |
| 75 | + lastCenter = nextCenter; |
| 76 | + return; |
| 77 | + } |
| 78 | +
|
| 79 | + if (scale > minScale) { |
| 80 | + event.preventDefault(); |
| 81 | + translateX += event.clientX - previous.x; |
| 82 | + translateY += event.clientY - previous.y; |
| 83 | + constrainPan(); |
| 84 | + } |
| 85 | + } |
| 86 | +
|
| 87 | + function pointerUp(event: PointerEvent) { |
| 88 | + viewerElement?.releasePointerCapture?.(event.pointerId); |
| 89 | + const wasTap = !moved && pointers.size === 1 && Math.hypot(event.clientX - tapStart.x, event.clientY - tapStart.y) <= tapMovementThreshold; |
| 90 | + pointers.delete(event.pointerId); |
| 91 | +
|
| 92 | + if (pointers.size < 2) { |
| 93 | + lastDistance = 0; |
| 94 | + lastCenter = { x: 0, y: 0 }; |
| 95 | + } |
| 96 | +
|
| 97 | + if (scale <= minScale) { |
| 98 | + resetZoom(); |
| 99 | + if (wasTap) close(); |
| 100 | + } |
| 101 | + } |
| 102 | +
|
| 103 | + function pointerCancel(event: PointerEvent) { |
| 104 | + viewerElement?.releasePointerCapture?.(event.pointerId); |
| 105 | + pointers.delete(event.pointerId); |
| 106 | + if (pointers.size < 2) lastDistance = 0; |
| 107 | + } |
| 108 | +
|
| 109 | + function wheelZoom(event: WheelEvent) { |
| 110 | + if (!event.ctrlKey && Math.abs(event.deltaY) < 20) return; |
| 111 | + event.preventDefault(); |
| 112 | + const zoomFactor = event.deltaY < 0 ? 1.12 : 0.88; |
| 113 | + zoomAround({ x: event.clientX, y: event.clientY }, scale * zoomFactor); |
| 114 | + constrainPan(); |
| 115 | + } |
| 116 | +
|
| 117 | + function zoomAround(point: { x: number; y: number }, requestedScale: number) { |
| 118 | + const nextScale = clamp(requestedScale, minScale, maxScale); |
| 119 | + if (!viewerElement || nextScale === scale) return; |
| 120 | + const rect = viewerElement.getBoundingClientRect(); |
| 121 | + const originX = point.x - rect.left - rect.width / 2; |
| 122 | + const originY = point.y - rect.top - rect.height / 2; |
| 123 | + const ratio = nextScale / scale; |
| 124 | + translateX = originX - (originX - translateX) * ratio; |
| 125 | + translateY = originY - (originY - translateY) * ratio; |
| 126 | + scale = nextScale; |
| 127 | + if (scale <= minScale) resetZoom(); |
| 128 | + } |
| 129 | +
|
| 130 | + function pointerDistance() { |
| 131 | + const [first, second] = [...pointers.values()]; |
| 132 | + if (!first || !second) return 0; |
| 133 | + return Math.hypot(second.x - first.x, second.y - first.y); |
| 134 | + } |
| 135 | +
|
| 136 | + function pointerCenter() { |
| 137 | + const [first, second] = [...pointers.values()]; |
| 138 | + if (!first || !second) return { x: first?.x ?? 0, y: first?.y ?? 0 }; |
| 139 | + return { x: (first.x + second.x) / 2, y: (first.y + second.y) / 2 }; |
| 140 | + } |
| 141 | +
|
| 142 | + function constrainPan() { |
| 143 | + if (!viewerElement || scale <= minScale) return; |
| 144 | + const rect = viewerElement.getBoundingClientRect(); |
| 145 | + const maxX = (rect.width * (scale - 1)) / 2 + 80; |
| 146 | + const maxY = (rect.height * (scale - 1)) / 2 + 80; |
| 147 | + translateX = clamp(translateX, -maxX, maxX); |
| 148 | + translateY = clamp(translateY, -maxY, maxY); |
| 149 | + } |
| 150 | +
|
| 151 | + function clamp(value: number, min: number, max: number) { |
| 152 | + return Math.min(max, Math.max(min, value)); |
| 153 | + } |
| 154 | +</script> |
| 155 | + |
| 156 | +<div class="dialog-backdrop image-viewer-backdrop" role="presentation" tabindex="-1" on:click={(event) => event.target === event.currentTarget && close()}> |
| 157 | + <div |
| 158 | + bind:this={viewerElement} |
| 159 | + class="image-viewer" |
| 160 | + class:zoomed={scale > 1} |
| 161 | + role="dialog" |
| 162 | + aria-modal="true" |
| 163 | + aria-label="Image preview" |
| 164 | + tabindex="0" |
| 165 | + on:pointerdown={pointerDown} |
| 166 | + on:pointermove={pointerMove} |
| 167 | + on:pointerup={pointerUp} |
| 168 | + on:pointercancel={pointerCancel} |
| 169 | + on:wheel={wheelZoom} |
| 170 | + on:keydown={(event) => event.key === 'Escape' && close()} |
| 171 | + > |
| 172 | + <img src={url} alt={alt} {referrerpolicy} style:transform={imageTransform} draggable="false" /> |
| 173 | + </div> |
| 174 | +</div> |
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