Replace viewerjs with optimized custom image viewer implementation

[Copilot]

Image zooming in viewerjs causes noticeable lag. This replaces it with a performant custom implementation and enhances the existing PhotoViewer component.

Changes

PhotoViewer.vue

• Replaced binary zoom toggle (fixed 1.5x) with continuous zoom (1x-4x)
• Added pinch-to-zoom, wheel zoom, and drag-to-pan
• Used CSS transforms with will-change: transform for GPU acceleration
• Disabled swiper touch events during image drag to prevent conflicts

New ImageViewer.vue

• Lightweight replacement for viewerjs library
• Same gesture support as PhotoViewer (pinch, wheel, drag, double-click)
• Removes ~50KB gzipped dependency

Implementation Example

// Transform state per image
const imageTransforms = ref<Map<number, ImageTransform>>(new Map());

interface ImageTransform {
  scale: number;      // 1x-4x range
  translateX: number; // Pan offset
  translateY: number;
}

// Smooth GPU-accelerated transforms
const imageStyle = computed(() => ({
  transform: `translate(${tx}px, ${ty}px) scale(${scale})`,
  transition: isDragging ? 'none' : 'transform 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94)',
  willChange: 'transform'
}));

All zoom/pan operations use CSS transforms to avoid layout recalculation.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>viewer js 实现的图片预览器进行图片缩放卡顿</issue_title>
<issue_description>是否存在性能优化的点？如果没有是否可以自己实现一个类似 viewer js 的库，功能是其子集即可</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes viewer js 实现的图片预览器进行图片缩放卡顿 #6

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Project	Deployment	Preview	Comments	Updated (UTC)
shellraining-blog	Error			Oct 26, 2025 5:42am

[shellRaining]

是 Viewer.vue 的滚动缩放效果不好