import EdgeBase from './EdgeBase' /** * The Base Class for all Bezier edges. Bezier curves are used to model smooth * gradual curves in paths between nodes. * * @extends EdgeBase */ class BezierEdgeBase extends EdgeBase { /** * @param {Object} options * @param {Object} body * @param {Label} labelModule */ constructor(options, body, labelModule) { super(options, body, labelModule); } /** * This function uses binary search to look for the point where the bezier curve crosses the border of the node. * * @param {Node} nearNode * @param {CanvasRenderingContext2D} ctx * @param {Node} viaNode * @returns {*} * @private */ _findBorderPositionBezier(nearNode, ctx, viaNode = this._getViaCoordinates()) { var maxIterations = 10; var iteration = 0; var low = 0; var high = 1; var pos, angle, distanceToBorder, distanceToPoint, difference; var threshold = 0.2; var node = this.to; var from = false; if (nearNode.id === this.from.id) { node = this.from; from = true; } while (low <= high && iteration < maxIterations) { var middle = (low + high) * 0.5; pos = this.getPoint(middle, viaNode); angle = Math.atan2((node.y - pos.y), (node.x - pos.x)); distanceToBorder = node.distanceToBorder(ctx, angle); distanceToPoint = Math.sqrt(Math.pow(pos.x - node.x, 2) + Math.pow(pos.y - node.y, 2)); difference = distanceToBorder - distanceToPoint; if (Math.abs(difference) < threshold) { break; // found } else if (difference < 0) { // distance to nodes is larger than distance to border --> t needs to be bigger if we're looking at the to node. if (from === false) { low = middle; } else { high = middle; } } else { if (from === false) { high = middle; } else { low = middle; } } iteration++; } pos.t = middle; return pos; } /** * Calculate the distance between a point (x3,y3) and a line segment from * (x1,y1) to (x2,y2). * http://stackoverflow.com/questions/849211/shortest-distancae-between-a-point-and-a-line-segment * @param {number} x1 from x * @param {number} y1 from y * @param {number} x2 to x * @param {number} y2 to y * @param {number} x3 point to check x * @param {number} y3 point to check y * @param {Node} via * @returns {number} * @private */ _getDistanceToBezierEdge(x1, y1, x2, y2, x3, y3, via) { // x3,y3 is the point let minDistance = 1e9; let distance; let i, t, x, y; let lastX = x1; let lastY = y1; for (i = 1; i < 10; i++) { t = 0.1 * i; x = Math.pow(1 - t, 2) * x1 + (2 * t * (1 - t)) * via.x + Math.pow(t, 2) * x2; y = Math.pow(1 - t, 2) * y1 + (2 * t * (1 - t)) * via.y + Math.pow(t, 2) * y2; if (i > 0) { distance = this._getDistanceToLine(lastX, lastY, x, y, x3, y3); minDistance = distance < minDistance ? distance : minDistance; } lastX = x; lastY = y; } return minDistance; } /** * Draw a bezier curve between two nodes * * The method accepts zero, one or two control points. * Passing zero control points just draws a straight line * * @param {CanvasRenderingContext2D} ctx * @param {Object} values | options for shadow drawing * @param {Object|undefined} viaNode1 | first control point for curve drawing * @param {Object|undefined} viaNode2 | second control point for curve drawing * * @protected */ _bezierCurve(ctx, values, viaNode1, viaNode2) { var hasNode1 = (viaNode1 !== undefined && viaNode1.x !== undefined); var hasNode2 = (viaNode2 !== undefined && viaNode2.x !== undefined); ctx.beginPath(); ctx.moveTo(this.fromPoint.x, this.fromPoint.y); if (hasNode1 && hasNode2) { ctx.bezierCurveTo(viaNode1.x, viaNode1.y, viaNode2.x, viaNode2.y, this.toPoint.x, this.toPoint.y); } else if (hasNode1) { ctx.quadraticCurveTo(viaNode1.x, viaNode1.y, this.toPoint.x, this.toPoint.y); } else { // fallback to normal straight edge ctx.lineTo(this.toPoint.x, this.toPoint.y); } // draw a background this.drawBackground(ctx, values); // draw shadow if enabled this.enableShadow(ctx, values); ctx.stroke(); this.disableShadow(ctx, values); } /** * * @returns {*|{x, y}|{x: undefined, y: undefined}} */ getViaNode() { return this._getViaCoordinates(); } } export default BezierEdgeBase;