图片压缩

核心压缩函数

// 核心压缩函数
function compressImage(file, options) {
    return new Promise((resolve, reject) => {
    const img = new Image();
    img.onload = () => {
        // 创建Canvas元素
        const canvas = document.createElement('canvas');
        const ctx = canvas.getContext('2d');

        // 计算调整后的尺寸
        let { width, height } = img;
        if (width > options.maxWidth || height > options.maxHeight) {
        const ratio = Math.min(
            options.maxWidth / width,
            options.maxHeight / height
        );
        width = Math.floor(width * ratio);
        height = Math.floor(height * ratio);
        }

        // 设置Canvas尺寸
        canvas.width = width;
        canvas.height = height;

        // 绘制图片到Canvas
        ctx.drawImage(img, 0, 0, width, height);

        // 转换为Blob
        canvas.toBlob(
        (blob) => {
            if (!blob) return reject(new Error('压缩失败'));
            resolve(blob);
        },
        'image/jpeg',  // 输出格式
        options.quality // 压缩质量
        );
    };

    img.onerror = reject;
    img.src = URL.createObjectURL(file);
    });
}

使用示例和效果