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在PictureBox1上画红色的实心圆：
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Private Sub DrawCircle(ByVal cp As Point, ByVal radius As Integer, ByVal color As Brush)
Dim gr As Graphics
gr = PictureBox1.CreateGraphics
Dim rect As Rectangle = New Rectangle(cp.X - radius, cp.Y - radius, 2 * radius, 2 * radius)
gr.DrawEllipse(Pens.Black, rect)
gr.FillEllipse(color, rect)
End Sub
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
DrawCircle(New Point(120, 100), 80, Brushes.Red)
End Sub
在窗体上拉一个Timer控件，enabled设为true，Interval设为20。完整代码如下： Dim myPen As New System.Drawing.Pen(System.Drawing.Color.Red)
Dim formGraphics As System.Drawing.Graphics
Dim num As Integer = 1
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Me.Refresh() '清屏
formGraphics = Me.CreateGraphics()
formGraphics.DrawEllipse(myPen, New Rectangle(100, 100, num, num)) '在坐标(100,100)的位置画圆
If num 200 Then '如果大于200则停止画圆
myPen.Dispose()
formGraphics.Dispose()
Timer1.Enabled = False
Else
num = num + 1
End If
End Sub
下面的例子通过重载Form 窗体的OnPaint()方法绘制GDI图形Protected Overrides Sub onpaint(ByVal e As System Windows Forms PaintEventArgs)注释 /////////////绘制任意直线Dim g As Graphics = e GraphicsDim mypen As Pen = New Pen(Color Red )g DrawLine(mypen )注释 /////////////绘制矩形(任意直线构成的封闭图形)Dim point As PointF = New PointF( F F)Dim point As PointF = New PointF( F F)Dim point As PointF = New PointF( F F)Dim point As PointF = New PointF( F F)Dim curvepoints As PointF() = {point point point point }g DrawPolygon(New Pen(Color Blue ) curvepoints)注释 ////////////文本表示Dim FFamily As FontFamily = New FontFamily( Arial )Dim font As Font = New Font(FFamily FontStyle Bold FontStyle Italic GraphicsUnit Pixel)Dim text As String = I love you! Dim solidbrush As SolidBrush = New SolidBrush(Color Red)Dim pr As PointF = New PointF( )e Graphics DrawString(text font solidbrush pr)注释 ////////////平面绘制Dim rec As RectangleF = New RectangleF( )g DrawPie(mypen rec )注释 ///////////封闭图形 应该是个圆g DrawClosedCurve(mypen curvepoints Drawing Drawing D FillMode Alternate)注释 ///////////大家自己试试看吧g DrawArc(mypen )g DrawCurve(mypen curvepoints)g DrawBezier(mypen )g DrawBeziers(mypen curvepoints)注释 //////////这可是一个圆Dim rec As RectangleF = New RectangleF( )g DrawEllipse(mypen rec )注释 //////////这是一个椭圆Dim rec As RectangleF = New RectangleF( )g DrawEllipse(mypen rec )End Sub 这些是我自己试验出来的 当然了 还有好多 我只是开了一个头 大家要是发现什么好东东 别忘了通知一下 ） lishixinzhi/Article/program/net/201311/11800
窗体上添加一个按钮，在该按钮的单击事件里编写代码如下：
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'声明窗体的Me.CreateGraphics对象
Dim MyGraphics As Graphics = Me.CreateGraphics
Dim Cx As Integer = 150 '圆心的X坐标
Dim Cy As Integer = 150 '圆心的Y坐标
Dim R As Integer '圆的半径
'绘制半径为R的圆
For R = 5 To 100 Step 5
MyGraphics.DrawEllipse(Pens.Black, New Rectangle(Cx - R, Cy - R, 2 * R, 2 * R))
Next
End Sub
‘用黑色画笔绘制一组同心圆，半径从5开始，增量为5。
说明：
DrawEllipse是VB.Net的Graphics类的绘制椭圆的方法；他有几种格式，上面使用的是一种；
DrawEllipse（画笔的颜色，绘制椭圆所需要的矩形区域）
其中：绘制椭圆所需要的矩形区域，如果被定义为正方形，就演变成绘制圆，定义该区域由死个数值确定，第1个数值，确定该区域左上角的X坐标，第2个数值，确定该区域左上角的Y坐标，第3个数值，确定该区域的宽度，第4个数值，确定该区域的高度。
例如1：
DrawEllipse(Pens.Black, New Rectangle(150, 150, 50, 50))
就是以圆心坐标为（100,100），绘制半径为50 的圆。其实在VB.NET中，是告诉系统在以左上角坐标（150,150），边长为50的正方形里绘制内切圆。理解了是在正方形里绘制内切圆，就可以通过数学计算，知道如何绘制了。
同理例如2：
DrawEllipse(Pens.Black, New Rectangle(150, 150, 100, 50))
就是以圆心坐标为（100,100），绘制半径为50 的圆。其实在VB.NET中，是告诉系统在以左上角坐标（150,150），长轴为100，短轴为50的内切椭圆。