sigma/rendering/canvas/edge-label.js

A JavaScript library dedicated to graph drawing.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
function drawEdgeLabel(context, edgeData, sourceData, targetData, settings) {
    var size = settings.edgeLabelSize, font = settings.edgeLabelFont, weight = settings.edgeLabelWeight, label = edgeData.label;
    context.fillStyle = edgeData.color;
    context.font = weight + " " + size + "px " + font;
    var textWidth = context.measureText(label).width;
    var cx = (sourceData.x + targetData.x) / 2;
    var cy = (sourceData.y + targetData.y) / 2;
    var dx = targetData.x - sourceData.x;
    var dy = targetData.y - sourceData.y;
    var d = Math.sqrt(dx * dx + dy * dy);
    var angle;
    if (dx > 0) {
        if (dy > 0)
            angle = Math.acos(dx / d);
        else
            angle = Math.asin(dy / d);
    }
    else {
        if (dy > 0)
            angle = Math.acos(dx / d) + Math.PI;
        else
            angle = Math.asin(dx / d) + Math.PI / 2;
    }
    context.save();
    context.translate(cx, cy);
    context.rotate(angle);
    context.fillText(label, -textWidth / 2, edgeData.size / 2 + size);
    context.restore();
}
exports.default = drawEdgeLabel;