define("dojox/gfx/arc", ["./_base", "dojo/_base/lang", "./matrix"], function(g, lang, m){ var twoPI = 2 * Math.PI, pi4 = Math.PI / 4, pi8 = Math.PI / 8, pi48 = pi4 + pi8, curvePI4 = unitArcAsBezier(pi8); function unitArcAsBezier(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} }; } var arc = g.arc = { // summary: // This module contains the core graphics Arc functions. unitArcAsBezier: unitArcAsBezier, /*===== 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 }, =====*/ // curvePI4: Object // an object with properties of an arc around a unit circle from 0 to pi/4 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 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; // Array } }; return arc; });