if (!dojo._hasResource["dojox.gfx.arc"]) { // _hasResource checks added by // build. Do not use _hasResource // directly in your code. dojo._hasResource["dojox.gfx.arc"] = true; dojo.provide("dojox.gfx.arc"); dojo.require("dojox.gfx.matrix"); (function() { var m = dojox.gfx.matrix, unitArcAsBezier = function(alpha) { // summary: return a start point, 1st and 2nd control points, and an // end point of // a an arc, which is reflected on the x axis // alpha: Number: angle in radians, the arc will be 2 * angle size var cosa = Math.cos(alpha), sina = Math.sin(alpha), p2 = { x : cosa + (4 / 3) * (1 - cosa), y : sina - (4 / 3) * cosa * (1 - cosa) / sina }; return { // Object s : { x : cosa, y : -sina }, c1 : { x : p2.x, y : -p2.y }, c2 : p2, e : { x : cosa, y : sina } }; }, twoPI = 2 * Math.PI, pi4 = Math.PI / 4, pi8 = Math.PI / 8, pi48 = pi4 + pi8, curvePI4 = unitArcAsBezier(pi8); dojo.mixin(dojox.gfx.arc, { unitArcAsBezier : unitArcAsBezier, curvePI4 : curvePI4, arcAsBezier : function(last, rx, ry, xRotg, large, sweep, x, y) { // summary: calculates an arc as a series of Bezier curves // given the last point and a standard set of SVG arc // parameters, // it returns an array of arrays of parameters to form a series // of // absolute Bezier curves. // last: Object: a point-like object as a start of the arc // rx: Number: a horizontal radius for the virtual ellipse // ry: Number: a vertical radius for the virtual ellipse // xRotg: Number: a rotation of an x axis of the virtual ellipse // in degrees // large: Boolean: which part of the ellipse will be used (the // larger arc if true) // sweep: Boolean: direction of the arc (CW if true) // x: Number: the x coordinate of the end point of the arc // y: Number: the y coordinate of the end point of the arc // calculate parameters large = Boolean(large); sweep = Boolean(sweep); var xRot = m._degToRad(xRotg), rx2 = rx * rx, ry2 = ry * ry, pa = m .multiplyPoint(m.rotate(-xRot), { x : (last.x - x) / 2, y : (last.y - y) / 2 }), pax2 = pa.x * pa.x, pay2 = pa.y * pa.y, c1 = Math .sqrt((rx2 * ry2 - rx2 * pay2 - ry2 * pax2) / (rx2 * pay2 + ry2 * pax2)); if (isNaN(c1)) { c1 = 0; } var ca = { x : c1 * rx * pa.y / ry, y : -c1 * ry * pa.x / rx }; if (large == sweep) { ca = { x : -ca.x, y : -ca.y }; } // the center var c = m.multiplyPoint( [m.translate((last.x + x) / 2, (last.y + y) / 2), m.rotate(xRot)], ca); // calculate the elliptic transformation var elliptic_transform = m.normalize([m.translate(c.x, c.y), m.rotate(xRot), m.scale(rx, ry)]); // start, end, and size of our arc var inversed = m.invert(elliptic_transform), sp = m .multiplyPoint(inversed, last), ep = m.multiplyPoint( inversed, x, y), startAngle = Math.atan2(sp.y, sp.x), endAngle = Math .atan2(ep.y, ep.x), theta = startAngle - endAngle; // size // of // our // arc // in // radians if (sweep) { theta = -theta; } if (theta < 0) { theta += twoPI; } else if (theta > twoPI) { theta -= twoPI; } // draw curve chunks var alpha = pi8, curve = curvePI4, step = sweep ? alpha : -alpha, result = []; for (var angle = theta; angle > 0; angle -= pi4) { if (angle < pi48) { alpha = angle / 2; curve = unitArcAsBezier(alpha); step = sweep ? alpha : -alpha; angle = 0; // stop the loop } var c1, c2, e, M = m.normalize([elliptic_transform, m.rotate(startAngle + step)]); if (sweep) { c1 = m.multiplyPoint(M, curve.c1); c2 = m.multiplyPoint(M, curve.c2); e = m.multiplyPoint(M, curve.e); } else { c1 = m.multiplyPoint(M, curve.c2); c2 = m.multiplyPoint(M, curve.c1); e = m.multiplyPoint(M, curve.s); } // draw the curve result.push([c1.x, c1.y, c2.x, c2.y, e.x, e.y]); startAngle += 2 * step; } return result; // Object } }); })(); }