OCR 文字识别接入文档

{
  "token": "a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6",
  "imageBase64": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/..."
}

{
  "success": true,
  "count": 3,
  "data": [
    { "text": "传思网", "x": 120, "y":  50, "width": 180, "height": 36 },
    { "text": "OCR 文字识别", "x":  90, "y": 110, "width": 220, "height": 32 },
    { "text": "PP-OCRv4 引擎", "x":  85, "y": 168, "width": 240, "height": 30 }
  ]
}

// HTTP 400 - 参数错误
{ "success": false, "message": "缺少 token" }
{ "success": false, "message": "缺少 imageBase64" }
{ "success": false, "message": "imageBase64 不是合法的 base64 字符串" }
{ "success": false, "message": "图片大小不能超过 10MB" }

// HTTP 401 - Token 无效
{ "success": false, "message": "token 无效" }
{ "success": false, "message": "token 已过期，请重新换取" }
{ "success": false, "message": "token 不支持 OCR 服务" }

// HTTP 503 - 服务端模型未就绪
{ "success": false, "message": "OCR 模型未就绪，请检查服务器 models/ 目录" }

// HTTP 500 - 识别异常
{ "success": false, "message": "OCR 识别失败: ..." }

curl -X POST https://your-webapi.com/api/ocr/recognize \
  -H "Content-Type: application/json" \
  -d '{
    "token": "a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6",
    "imageBase64": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/..."
  }'

<input type="file" id="file" accept="image/*">
<button onclick="recognize()">识别</button>

<script>
function fileToBase64(file) {
    return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = () => resolve(reader.result); // 含 data: 前缀
        reader.onerror = reject;
        reader.readAsDataURL(file);
    });
}

async function recognize() {
    const file = document.getElementById('file').files[0];
    if (!file) return alert('请选择图片');

    const imageBase64 = await fileToBase64(file);
    const resp = await fetch('https://your-webapi.com/api/ocr/recognize', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
            token: 'a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6',
            imageBase64: imageBase64
        })
    });
    const result = await resp.json();
    if (result.success) {
        console.log('识别 ' + result.count + ' 项:', result.data);
        // result.data: [{ text, x, y, width, height }, ...]
    } else {
        alert(result.message);
    }
}
</script>

/**
 * 在浏览器端压缩图片，返回带 data: 前缀的 base64 字符串
 * @param {File|Blob} file        原始图片文件
 * @param {number}    maxSide     最长边像素，默认 1600
 * @param {number}    quality     JPEG 质量 0~1，默认 0.85
 * @returns {Promise<string>}     data:image/jpeg;base64,...
 */
function compressImage(file, maxSide = 1600, quality = 0.85) {
    return new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = () => {
            const img = new Image();
            img.onload = () => {
                const ratio = Math.min(1, maxSide / Math.max(img.width, img.height));
                const w = Math.round(img.width * ratio);
                const h = Math.round(img.height * ratio);
                const canvas = document.createElement('canvas');
                canvas.width = w; canvas.height = h;
                const ctx = canvas.getContext('2d');
                // 白色底色，避免透明区域被 JPEG 渲染成黑色
                ctx.fillStyle = '#fff';
                ctx.fillRect(0, 0, w, h);
                ctx.drawImage(img, 0, 0, w, h);
                resolve(canvas.toDataURL('image/jpeg', quality));
            };
            img.onerror = reject;
            img.src = reader.result;
        };
        reader.onerror = reject;
        reader.readAsDataURL(file);
    });
}

// 用法：
// const dataUrl = await compressImage(file, 1600, 0.85);
// fetch('/api/ocr/recognize', { ... body: JSON.stringify({ token, imageBase64: dataUrl }) });