如何将方行的按纽改变为其他的形状

下面的代码为如何生成一个圆形的按纽的方法 ,主要功能的实现为调用了一系列的API来实现的.

[System.Runtime.InteropServices.DllImport("gdi32")]
  private static extern IntPtr BeginPath(IntPtr hdc);
  [System.Runtime.InteropServices.DllImport("gdi32")]
  private static extern int SetBkMode(IntPtr hdc,int nBkMode);  
  const int TRANSPARENT=1;
  [System.Runtime.InteropServices.DllImport("gdi32")]     
  private static extern IntPtr EndPath(IntPtr hdc);
  [System.Runtime.InteropServices.DllImport("gdi32")]
  private static extern IntPtr PathToRegion(IntPtr hdc);
  [System.Runtime.InteropServices.DllImport("gdi32")]
  private static extern int Ellipse(IntPtr hdc,int x1,int y1,int x2,int y2);
  [System.Runtime.InteropServices.DllImport("user32")]
  private static extern IntPtr SetWindowRgn(IntPtr hwnd,IntPtr hRgn,bool bRedraw);
  [System.Runtime.InteropServices.DllImport("user32")]
  private static extern IntPtr GetDC(IntPtr hwnd);
  public Class7()
  {   
  }
  public void MakeToPictureBoxsToCircle(PictureBox[] pb)
  {
   IntPtr dc;
   IntPtr region;
   for(int i=0;i
   {
    dc=GetDC(pb[i].Handle);
    BeginPath(dc);
    SetBkMode(dc,TRANSPARENT);
    Ellipse(dc,0,0,pb[i].Width-3,pb[i].Height-2);
    EndPath(dc);
    region=PathToRegion(dc);
    SetWindowRgn(pb[i].Handle,region,false);
   }