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关于VB.NET画饼图的有关问题

2012-02-22 
关于VB.NET画饼图的问题我用VB.NET编了一个画饼图的程序,为什么运行以后,结果只显示了一下就消失了?程序如

关于VB.NET画饼图的问题
我用VB.NET编了一个画饼图的程序,为什么运行以后,结果只显示了一下就消失了?  

程序如下:  
Private   Sub   FormGraphics1_Load(ByVal   sender   As   System.Object,   ByVal   e   As   System.EventArgs)   Handles   MyBase.Load  

Dim   MyGraphics   As   Graphics   =   Me.PictureBox1.CreateGraphics  
Dim   MyBrush   As   New   SolidBrush(Color.Red)  
Dim   MyProportion   As   Single  
Dim   MyRect   As   New   Rectangle  
Dim   MyPoint   As   New   PointF  
Dim   R   As   Single  
Const   PI   =   3.1415926  
MyGraphics.Clear(PictureBox1.BackColor)  
Dim   MyStartAngel   As   Double  
Dim   MySweepAngel   As   Double  

R   =   Math.Min(Me.PictureBox1.Width,   Me.PictureBox1.Height)   /   2   -   15  
MyPoint.X   =   Me.PictureBox1.Width   /   2  
MyPoint.Y   =   Me.PictureBox1.Height   /   2  
MyRect.X   =   MyPoint.X   -   R  
MyRect.Y   =   MyPoint.Y   -   R  
MyRect.Width   =   R   *   2  
MyRect.Height   =   R   *   2  

MyStartAngel   =   0  
MyProportion   =   0.25  
MySweepAngel   =   360   *   MyProportion  
MyBrush.Color   =   Color.Red  
MyGraphics.FillPie(MyBrush,   MyRect,   MyStartAngel,   MySweepAngel)  

MyStartAngel   =   MyStartAngel   +   MySweepAngel  
MyProportion   =   0.75  
MySweepAngel   =   360   *   MyProportion  
MyBrush.Color   =   Color.Blue  
MyGraphics.FillPie(MyBrush,   MyRect,   MyStartAngel,   MySweepAngel)  

End   Sub  


[解决办法]
放在Pic的Paint事件中,否则每次切换重新绘制的时候,会造成图形的丢失;

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