计算轮廓矩形边界与重心

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　　轮廓矩形边界即轮廓的左边界、上边界、右边界和下边界。采用线段表可以方便求得，直接求线段端点在水平方向和垂直方向的最小值和最大值即可。需要注意一个概念上的区别，轮廓矩形边界不等于轮廓的最小外接四边形。
　　轮廓重心同样采用线段表进行计算，分别计算各线段在水平方向和垂直方向上的加权平均，其权重为线段长度。

#include <vector> typedef std::vector<POINT> ptLineTable; // 轮廓矩形边界 // 1. LineTable 线段表 bool ContourRect(ptLineTable LineTable, RECT *pRect) { ptLineTable::iterator i; if (LineTable.empty()) { pRect->left = 0; pRect->top = 0; pRect->right = 0; pRect->bottom = 0; } else { pRect->left = LineTable[0].x; pRect->top = LineTable[0].y; pRect->right = LineTable[0].x; pRect->bottom = LineTable[0].y; for (i = LineTable.begin(); i != LineTable.end(); i += 2) { if (pRect->left > i->x) pRect->left = i->x; if (pRect->top > i->y) pRect->top = i->y; if (pRect->right < (i + 1)->x) pRect->right = (i + 1)->x; if (pRect->bottom < i->y) pRect->bottom = i->y; } } return true; } // 轮廓重心 // 1. LineTable 线段表 bool ContourBarycenter(ptLineTable LineTable, POINT *pBarycenter) { long lLength = 0; long lArea = 0; ptLineTable::iterator i; pBarycenter->x = 0; pBarycenter->y = 0; for (ptLineTable::iterator i = LineTable.begin(); i != LineTable.end(); i += 2) { lLength = ((i + 1)->x - i->x + 1); pBarycenter->x += (lLength * ((i + 1)->x + i->x) / 2); pBarycenter->y += (lLength * i->y); lArea += lLength; } pBarycenter->x /= lArea; pBarycenter->y /= lArea; return true; }