lubo_comment_query/resources/js/component/ocr_canvas.js

/**
 * 视频右侧栏 OCR 结果 canvas 复刻绘制。
 * 数据源：CDN 上的分P全量 JSON（{space:[w,h], recs:[[ts,[[x1,y1,x2,y2,text],...]],...]}）
 * 或服务器注入的单帧快照（{ts, lines:[[x1,y1,x2,y2,text],...]}）。
 */
(function () {
    // 按框坐标 1:1 复刻：黑底、黄框、白字，字号按框高自适应
    function drawFrame(canvas, space, lines) {
        const sw = space[0], sh = space[1];
        const cssWidth = canvas.clientWidth || 200;
        const scale = cssWidth / sw;
        const cssHeight = Math.max(1, Math.round(sh * scale));
        const dpr = window.devicePixelRatio || 1;
        canvas.width = Math.round(cssWidth * dpr);
        canvas.height = Math.round(cssHeight * dpr);
        canvas.style.height = cssHeight + "px";
        const ctx = canvas.getContext("2d");
        ctx.setTransform(dpr * scale, 0, 0, dpr * scale, 0, 0);
        ctx.fillStyle = "#000000";
        ctx.fillRect(0, 0, sw, sh);
        ctx.strokeStyle = "#eab308";
        ctx.fillStyle = "#ffffff";
        ctx.textBaseline = "middle";
        lines.forEach(function (line) {
            const x1 = line[0], y1 = line[1], x2 = line[2], y2 = line[3], text = line[4];
            ctx.lineWidth = 2 / scale;
            ctx.strokeRect(x1, y1, x2 - x1, y2 - y1);
            if (text) {
                ctx.font = Math.max(4, (y2 - y1) * 0.75) + "px sans-serif";
                ctx.fillText(text, x1 + 2 / scale, (y1 + y2) / 2, x2 - x1 - 4 / scale);
            }
        });
    }

    function formatHms(seconds) {
        seconds = Math.max(0, Math.floor(seconds));
        const h = Math.floor(seconds / 3600);
        const m = Math.floor((seconds % 3600) / 60);
        const s = seconds % 60;
        const pad = (n) => String(n).padStart(2, "0");
        return h + ":" + pad(m) + ":" + pad(s);
    }

    // 单帧 space：按本帧最大框坐标向上取整到 16 的倍数（与导出端一致）
    function frameSpace(lines) {
        let maxX = 0, maxY = 0;
        lines.forEach(function (line) {
            maxX = Math.max(maxX, line[2]);
            maxY = Math.max(maxY, line[3]);
        });
        return [Math.max(16, Math.ceil(maxX / 16) * 16), Math.max(16, Math.ceil(maxY / 16) * 16)];
    }

    // 稿件详情页：CDN 全量 + 进度条联动（展示 ts<=t 最近一条）
    function initPlayer(panel) {
        const urls = JSON.parse(panel.dataset.urls || "{}");
        const canvas = panel.querySelector("canvas");
        const slider = panel.querySelector("input[type=range]");
        const timeLabel = panel.querySelector("[data-ocr-time]");
        const status = panel.querySelector("[data-ocr-status]");
        const tabs = panel.querySelectorAll("[data-ocr-part]");
        let data = null;
        let loadSeq = 0;

        function showStatus(text) {
            if (status) {
                status.textContent = text;
                status.style.display = text ? "" : "none";
            }
        }

        function currentIndex(t) {
            // 二分：ts<=t 的最后一条；t 早于首条时展示首条
            const recs = data.recs;
            let lo = 0, hi = recs.length - 1, ans = 0;
            while (lo <= hi) {
                const mid = (lo + hi) >> 1;
                if (recs[mid][0] <= t) { ans = mid; lo = mid + 1; } else { hi = mid - 1; }
            }
            return ans;
        }

        function render() {
            if (!data || data.recs.length === 0) {
                return;
            }
            const t = parseFloat(slider.value);
            const idx = currentIndex(t);
            timeLabel.textContent = formatHms(t) + "（OCR @" + formatHms(data.recs[idx][0]) + "）";
            drawFrame(canvas, data.space, data.recs[idx][1]);
        }

        function load(partNum) {
            const seq = ++loadSeq;
            data = null;
            showStatus("加载中…");
            tabs.forEach(function (tab) {
                tab.classList.toggle("font-bold", tab.dataset.ocrPart === String(partNum));
            });
            fetch(urls[partNum])
                .then((response) => {
                    if (!response.ok) { throw new Error("HTTP " + response.status); }
                    return response.json();
                })
                .then((payload) => {
                    if (seq !== loadSeq) { return; }
                    data = payload;
                    slider.max = payload.recs.length ? Math.floor(payload.recs[payload.recs.length - 1][0]) : 0;
                    showStatus("");
                    render();
                })
                .catch(() => {
                    if (seq !== loadSeq) { return; }
                    showStatus("OCR 数据加载失败");
                });
        }

        slider.addEventListener("input", render);
        tabs.forEach(function (tab) {
            tab.addEventListener("click", function () {
                slider.value = 0;
                load(tab.dataset.ocrPart);
            });
        });
        const firstPart = Object.keys(urls)[0];
        if (firstPart !== undefined) {
            load(firstPart);
        }
    }

    // 节目详情页：服务器注入的单帧快照
    function initSnapshots(scope) {
        (scope || document).querySelectorAll("canvas[data-ocr-frame]").forEach(function (canvas) {
            const frame = JSON.parse(canvas.dataset.ocrFrame);
            drawFrame(canvas, frameSpace(frame.lines), frame.lines);
        });
    }

    window.OcrCanvas = {
        drawFrame: drawFrame,
        initPlayer: initPlayer,
        initSnapshots: initSnapshots,
    };
})();