场景-图片水印

Jimp

1. 上传时加水印

用户上传原始图片 --->服务器：保留原始图片以及水印图片

示例：

const path = require("path");
const jimp = require("jimp");

// 给一张图片加水印
async function mark(
    waterFile,
    originFile,
    targetFile,
    proportion = 10,
    marginProportion = 0.05
) {
    const [water, origin] = await Promise.all([
        jimp.read(waterFile),
        jimp.read(originFile),
    ]);
    // 对水印图片进行缩放
    const curProportion = origin.bitmap.width / water.bitmap.width;
    water.scale(curProportion / proportion);

    // 计算位置
    const right = origin.bitmap.width * marginProportion;
    const bottom = origin.bitmap.height * marginProportion;
    const x = origin.bitmap.width - right - water.bitmap.width;
    const y = origin.bitmap.height - bottom - water.bitmap.height;

    // 写入水印
    origin.composite(water, x, y, {
        mode: jimp.BLEND_SOURCE_OVER,
        opacitySource: 0.3,
    });
    await origin.write(targetFile);
}

async function test() {
    const waterPath = path.resolve(__dirname, "./water.jpg");
    const originPath = path.resolve(__dirname, "./origin.jpg");
    const targetPath = path.resolve(__dirname, "./new.jpg");
    await mark(waterPath, originPath, targetPath);
}

test();

2. 动态水印

用户上传原始图片 ---> 服务器：只保留原始图片

请求图片时，服务器动态加水印