Function buildLabelLinePath

src/label/labelGuideHelper.ts:554–584

(path: CanvasRenderingContext2D, shape: Polyline['shape'])

}

function buildLabelLinePath(path: CanvasRenderingContext2D, shape: Polyline['shape']) {
    const smooth = shape.smooth as number;
    const points = shape.points;
    if (!points) {
        return;
    }
    path.moveTo(points[0][0], points[0][1]);
    if (smooth > 0 && points.length >= 3) {
        const len1 = vector.dist(points[0], points[1]);
        const len2 = vector.dist(points[1], points[2]);
        if (!len1 || !len2) {
            path.lineTo(points[1][0], points[1][1]);
            path.lineTo(points[2][0], points[2][1]);
            return;
        }

        const moveLen = Math.min(len1, len2) * smooth;

        const midPoint0 = vector.lerp([], points[1], points[0], moveLen / len1);
        const midPoint2 = vector.lerp([], points[1], points[2], moveLen / len2);

        const midPoint1 = vector.lerp([], midPoint0, midPoint2, 0.5);
        path.bezierCurveTo(midPoint0[0], midPoint0[1], midPoint0[0], midPoint0[1], midPoint1[0], midPoint1[1]);
        path.bezierCurveTo(midPoint2[0], midPoint2[1], midPoint2[0], midPoint2[1], points[2][0], points[2][1]);
    }
    else {
        for (let i = 1; i < points.length; i++) {
            path.lineTo(points[i][0], points[i][1]);
        }
    }
}

/**
 * Create a label line if necessary and set it's style.