如何在OpenCV.js中获取轮廓角点的坐标？

// 假设你已经加载了OpenCV.js库并且有一个canvas元素用于显示图像

// 加载图像到canvas
let img = cv.imread('canvasInput');
let gray = new cv.Mat();
cv.cvtColor(img, gray, cv.COLOR_RGBA2GRAY);

// 使用Canny边缘检测
let edges = new cv.Mat();
cv.Canny(gray, edges, 50, 150);

// 查找轮廓
let contours = new cv.MatVector();
let hierarchy = new cv.Mat();
cv.findContours(edges, contours, hierarchy, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE);

// 遍历每个轮廓
for (let i = 0; i < contours.size(); ++i) {
    let contour = contours.get(i);
    let approxCurve = new cv.Mat();
    let epsilon = 0.02 * cv.arcLength(contour, true);
    cv.approxPolyDP(contour, approxCurve, epsilon, true);

    // 获取角点坐标
    for (let j = 0; j < approxCurve.rows; ++j) {
        let point = approxCurve.ptr(j, 0);
        console.log(`Contour ${i}, Corner ${j}: (${point[0]}, ${point[1]})`);
    }

    approxCurve.delete();
}

// 清理内存
edges.delete();
gray.delete();
contours.delete();
hierarchy.delete();
img.delete();