add shape fitting

src/graphics/image/fitBezier.js

@@ -0,0 +1,60 @@
+/**
+ * @file 曲线拟合成二次bezier曲线
+ * @author mengke01(kekee000@gmail.com)
+ */
+
+
+define(
+    function (require) {
+
+        var fitCurve = require('./fitCurve');
+        var bezierCubic2Q2 = require('math/bezierCubic2Q2');
+
+        /**
+         * 三次bezier曲线点拟合点集
+         *
+         * @param  {Array} points 点集合
+         * @param  {number} scale  当前点的scale
+         *
+         * @return {Array}  结果点集
+         */
+        function fitBezier(points, scale) {
+            scale = scale || 1;
+            var size = points.length;
+            var maxError = size < 16 ? 4 * scale : (size ) * scale;
+
+            var cubicBezier = fitCurve(points, maxError);
+            var start = points[0];
+            var result = [];
+            for (var i = 0, l = cubicBezier.length; i < l; i += 3) {
+                var quadBezier = bezierCubic2Q2(start, cubicBezier[i], cubicBezier[i + 1], cubicBezier[i + 2]);
+                // 三次bezier曲线可能转成1条二次bezier曲线
+                if (quadBezier.length === 1) {
+                    quadBezier[0][2].onCurve = true;
+                    result.push(quadBezier[0][1]);
+                    result.push(quadBezier[0][2]);
+                }
+                else {
+                    quadBezier[0][2].onCurve = true;
+                    result.push(quadBezier[0][1]);
+                    result.push(quadBezier[0][2]);
+                    quadBezier[1][2].onCurve = true;
+                    result.push(quadBezier[1][1]);
+                    result.push(quadBezier[1][2]);
+                }
+                start = cubicBezier[i + 2];
+            }
+
+            return result.map(function (p) {
+                return {
+                    x: p.x,
+                    y: p.y,
+                    onCurve: !!p.onCurve
+                };
+            });
+        }
+
+
+        return fitBezier;
+    }
+);

src/graphics/image/fitCurve.js

@@ -512,7 +512,7 @@ define(
 
 
         /**
-         * 三次bezier曲线点拟合点集
+         * 三次bezier曲线点拟合点集，返回的结果不包含起始点和结束点
          *
          * @param  {Array} points 点集合
          * @param  {number} error  最大错误距离