/**
 * 图片优化CSS
 * 优化图片加载体验，包括加载动画、过渡效果等
 */

/* 图片容器基础样式 */
.img-wrapper {
    position: relative;
    overflow: hidden;
    background-color: #f5f5f5;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

/* 图片加载状态 */
.img-wrapper.loading {
    background-color: #f0f0f0;
}

.img-wrapper.loading::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: loading 1.5s infinite;
}

@keyframes loading {
    0% {
        background-position: 200% 0;
    }
    100% {
        background-position: -200% 0;
    }
}

/* 图片加载完成状态 */
.img-wrapper.loaded {
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0.7;
    }
    to {
        opacity: 1;
    }
}

/* 图片悬停效果 */
.img-wrapper:hover {
    transform: scale(1.03);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

/* 圆形图片 */
.img-wrapper.circle {
    border-radius: 50%;
}

/* 带边框的图片 */
.img-wrapper.bordered {
    border: 2px solid #eee;
    border-radius: 4px;
}

/* 响应式图片 */
.img-wrapper.responsive {
    width: 100%;
    height: 0;
    padding-bottom: 56.25%; /* 16:9 比例 */
}

.img-wrapper.responsive.square {
    padding-bottom: 100%; /* 1:1 比例 */
}

.img-wrapper.responsive.portrait {
    padding-bottom: 125%; /* 4:5 比例 */
}

/* 懒加载占位符 */
.lazyload-placeholder {
    background-color: #f5f5f5;
    background-image: linear-gradient(45deg, #f0f0f0 25%, transparent 25%), 
                      linear-gradient(-45deg, #f0f0f0 25%, transparent 25%), 
                      linear-gradient(45deg, transparent 75%, #f0f0f0 75%), 
                      linear-gradient(-45deg, transparent 75%, #f0f0f0 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
}

/* Swiper轮播图中的图片优化 */
.swiper-slide .img-wrapper {
    width: 100%;
    height: 100%;
}

.swiper-slide .img-wrapper.loading {
    background-color: #222;
}

.swiper-slide .img-wrapper.loading::before {
    background: linear-gradient(90deg, #222 25%, #333 50%, #222 75%);
    background-size: 200% 100%;
}

/* 图片错误状态 */
.img-wrapper.error {
    background-color: #f8f8f8;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #999;
    font-size: 14px;
}

.img-wrapper.error::before {
    content: "图片加载失败";
    display: block;
    text-align: center;
}

/* 图片加载优化 - 针对移动设备 */
@media (max-width: 768px) {
    .img-wrapper {
        transform: translateZ(0); /* 启用硬件加速 */
        backface-visibility: hidden; /* 防止闪烁 */
    }
    
    /* 减少移动设备上的动画 */
    .img-wrapper.loading::before {
        animation-duration: 2s; /* 稍微减慢动画速度，减少CPU使用 */
    }
}

/* 针对慢速连接的优化 */
@media (prefers-reduced-data: reduce) {
    .img-wrapper.loading::before {
        display: none; /* 禁用加载动画 */
    }
    
    .img-wrapper {
        transition: none; /* 禁用过渡效果 */
    }
}

/* 针对偏好减少动画的用户的优化 */
@media (prefers-reduced-motion: reduce) {
    .img-wrapper {
        transition: none;
    }
    
    .img-wrapper.loading::before {
        animation: none;
    }
    
    .img-wrapper.loaded {
        animation: none;
    }
}

/* 图片容器内部的内容样式 */
.img-wrapper .overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0);
    transition: background 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.img-wrapper:hover .overlay {
    background: rgba(0, 0, 0, 0.3);
}

/* 图片加载进度条 */
.img-wrapper .progress-bar {
    position: absolute;
    bottom: 0;
    left: 0;
    height: 3px;
    width: 0;
    background-color: #4285f4;
    transition: width 0.3s ease;
}

/* 图片懒加载淡入效果 */
.lazyload {
    opacity: 0;
    transition: opacity 0.3s;
}

.lazyload.loaded {
    opacity: 1;
}

/* 图片容器内的文本样式 */
.img-wrapper .img-text {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: 10px;
    background: linear-gradient(to top, rgba(0,0,0,0.7) 0%, rgba(0,0,0,0) 100%);
    color: white;
    font-size: 14px;
    text-align: center;
    box-sizing: border-box;
}

/* 图片优化 - 针对高DPI屏幕 */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
    .img-wrapper {
        image-rendering: -webkit-optimize-contrast;
        image-rendering: crisp-edges;
    }
}

/* 图片优化 - 针对暗色主题 */
@media (prefers-color-scheme: dark) {
    .img-wrapper.loading {
        background-color: #333;
    }
    
    .img-wrapper.loading::before {
        background: linear-gradient(90deg, #333 25%, #444 50%, #333 75%);
        background-size: 200% 100%;
    }
    
    .img-wrapper.error {
        background-color: #222;
        color: #aaa;
    }
}