GraphPane pGraphPane=this.zedGraphControl1.GraphPane;//调用饼图类
pGraphPane.Title.Text = "重金属含量分析图";//饼图标题

//下面是饼图各个饼块的设置

PieItem segment1 = pGraphPane.AddPieSlice(20, Color.Navy, Color.White, 45f, 0, "North");
PieItem segment3 = pGraphPane.AddPieSlice(30, Color.Purple, Color.White, 45f, .0, "East");
PieItem segment4 = pGraphPane.AddPieSlice(10.21, Color.LimeGreen, Color.White, 45f, 0, "West");
PieItem segment2 = pGraphPane.AddPieSlice(40, Color.SandyBrown, Color.White, 45f, 0.2, "South");
PieItem segment6 = pGraphPane.AddPieSlice(250, Color.Red, Color.White, 45f, 0, "Europe");
PieItem segment7 = pGraphPane.AddPieSlice(50, Color.Blue, Color.White, 45f, 0.2, "Pac Rim");
PieItem segment8 = pGraphPane.AddPieSlice(400, Color.Green, Color.White, 45f, 0, "South America");
PieItem segment9 = pGraphPane.AddPieSlice(50, Color.Yellow, Color.White, 45f, 0.2, "Africa");

this.zedGraphControl1.AxisChange();//用于终断刷新

this.zedGraphControl1.Refresh();