有关填充多边形的问题

[clever101]

使用CDC类填充一一些多边形，出现了一些黑边。然后查MSDN:
CDC::Polygon
BOOL Polygon( LPPOINT lpPoints, int nCount );

Return Value

Nonzero if the function is successful; otherwise 0.

Parameters

lpPoints

Points to an array of points that specifies the vertices of the polygon. Each point in the array is a POINT structure or a CPoint object.

nCount

Specifies the number of vertices in the array.

Remarks

Draws a polygon consisting of two or more points (vertices) connected by lines, using the current pen. The system closes the polygon automatically, if necessary, by drawing a line from the last vertex to the first.

我估计是The system closes the polygon automatically, if necessary, by drawing a line from the last vertex to the first. 造成的。请问 if necessary有哪些情况呢？还有组成多边形的点是否有顺序要求呢？如果有要求，是顺时针还是逆时针呢？

[fandh]

出现什么样的黑边？你把填充色与画笔的颜色设置成一样，然后将画笔配置到DC，再试试！

[clever101]

[Quote=引用 1 楼 fandh 的回复:]

出现什么样的黑边？你把填充色与画笔的颜色设置成一样，然后将画笔配置到DC，再试试！
[/Quote]

就是在多边形的边界中出现一些黑线，估计就是多边形的顶点连成的。