我想在向用户显示该图像之前在图像中嵌入用户名。就像我有一个图像文件，现在我想把用户名放在图像里面，就像嵌入而不仅仅是放置文本一样。所以文字成为图像的实际部分？你们能不能建议我一个出路，输出schould是一个base64文件，这样我就可以通过api流式传输数据。谢谢。
1 回答
手掌心
TA贡献1942条经验 获得超3个赞
您没有指定您的API服务器正在运行的软件，所以我为您的客户端水印需求编写了此内容。它仅适用于没有透明度的图像。
它是 LSB（最低有效位）编码的实现。
索引.html
<!DOCTYPE html>
<script src="index.js"></script>
<body>
</body>
<script>
(async () => {
const base64 = `data:image/png;base64,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`;
const watermark = await createWatermark(base64, 'John Doe');
const image = new Image();
image.src = watermark;
document.body.appendChild(image); // displays watermarked image on screen
const hiddenText = await readWatermark(watermark, 8);
console.log(hiddenText); // John Doe
})();
</script>
</html>
索引.js
function stringToBits(string) {
return string.split('')
.map(char => char.charCodeAt(0))
.map(int => (int).toString(2).padStart(8, '0').split(''))
.flat()
.map(n => +n);
}
function bitsToString(bits) {
bits = [...bits.map(n => getBit(n, 0))];
return String.fromCharCode(...Array(Math.ceil(bits.length / 8))
.fill()
.map(() => bits.splice(0, 8))
.map(arr => parseInt(arr.join(''), 2)));
}
function setBit(number, bitPosition, sign) {
if (sign) return number | (1 << bitPosition);
const mask = ~(1 << bitPosition);
return number & mask;
}
function getBit(number, bitPosition) {
return (number & (1 << bitPosition)) === 0 ? 0 : 1;
}
function createWatermark(imageAsBase64, text) {
return new Promise(resolve => {
const image = new Image();
image.src = imageAsBase64;
image.onload = () => {
const canvas = document.createElement('canvas');
canvas.width = image.width;
canvas.height = image.height;
const context = canvas.getContext('2d');
context.drawImage(image, 0, 0);
const imageData = context.getImageData(0, 0, canvas.width, canvas.height);
const bits = stringToBits(text);
for (let i = 0; i < text.length * 8; i += 4) {
imageData.data[i] = setBit(imageData.data[i], 0, bits[i]);
imageData.data[i + 1] = setBit(imageData.data[i + 1], 0, bits[i + 1]);
imageData.data[i + 2] = setBit(imageData.data[i + 2], 0, bits[i + 2]);
imageData.data[i + 3] = setBit(imageData.data[i + 3], 0, bits[i + 3]);
}
context.putImageData(imageData, 0, 0);
resolve(canvas.toDataURL());
}
});
}
function readWatermark(base64, textLength) {
return new Promise(resolve => {
const image = new Image();
image.src = base64;
image.onload = () => {
const canvas = document.createElement('canvas');
canvas.width = image.width;
canvas.height = image.height;
const context = canvas.getContext('2d');
context.drawImage(image, 0, 0);
const imageData = context.getImageData(0, 0, canvas.width, canvas.height);
const bits = imageData.data.slice(0, textLength * 8);
resolve(bitsToString(bits));
}
});
}
添加回答
举报
0/150
提交
取消