Private Function isopen() As AutoCAD.AcadApplication
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Try
dim CADapp_temp AutoCAD.AcadApplication = GetObject(, "AutoCAD.Application")
return CADapp_temp
Catch ex As Exception
Return Nothing
End Try
End Function
'调用上面的函数,如果为nothing表示没有打开,否则打开并返回对象
不用PictureBoxTest.Image属性,直接把图形绘制到PictureBoxTest上面就可以了。
Dim button As Integer = 0
Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles Button1.Click
Using g As Graphics = Graphics.FromHwnd(PictureBoxTest.Handle)
Dim penRed As Pen = New Pen(Color.Red, 1) '定义红色画笔
Dim penblue As Pen = New Pen(Color.Blue, 1) '定义蓝色画笔
If button = 0 Then
g.DrawLine(penRed, 0, 0, 100, 100)
button = 1
ElseIf button = 1 Then
g.DrawLine(penblue, 100, 100, 200, 200)
button = 0
End If
End Using
End Sub
VB.net与VB不同。
VB.net已经有专门绘图的类。
可以定义笔刷然后用Drawing类中的方法绘制。
Private Sub DrawEllipse()
Dim myPen As New System.Drawing.Pen(System.Drawing.Color.Red)
Dim formGraphics as System.Drawing.Graphics
formGraphics = Me.CreateGraphics()
formGraphics.DrawEllipse(myPen, New Rectangle(0,0,200,300))
myPen.Dispose()
formGraphics.Dispose()
End Sub
Private Sub DrawRectangle()
Dim myPen As New System.Drawing.Pen(System.Drawing.Color.Red)
Dim formGraphics as System.Drawing.Graphics
formGraphics = Me.CreateGraphics()
formGraphics.DrawRectangle(myPen, New Rectangle(0,0,200,300))
myPen.Dispose()
formGraphics.Dispose()
End Sub
Imports System.Drawing.Imaging
Public Class Form1
Dim imageName As String = "C:\Documents and Settings\...\1126.jpg "
Dim i As Image = Image.FromFile(imageName)
Dim g As Graphics = Graphics.FromImage(i) '此处从背景图创建Greaphics
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'划线
Dim BluePen As New Pen(Color.Blue, 5)
BluePen.DashStyle = Drawing2D.DashStyle.Solid
g.DrawLine(BluePen, 100.0F, 170, 500.0F, 170)
g.Dispose()
PictureBox1.Image = i
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
'退出
Me.Close()
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
'存盘
i.Save( "C:\testimage.jpg ", ImageFormat.Jpeg)
i.Dispose()
End Sub
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
PictureBox1.Image = i
End Sub
End Class
参考一下下面这段代码:
‘ 首先picturebox1 加载一张图像
FolderBrowserDialog1.Description = "选择图片文件夹导入图片"
FolderBrowserDialog1.ShowDialog()
path = FolderBrowserDialog1.SelectedPath()
If path = "" Then Return
strSrcFile = Dir(path "\*.tif")
PictureBox1.Image = Image.FromFile(path "\" strSrcFile)
’ 然后再在picturebox1中用graphic画图而不清空原图像
' 建立一个画图对象
Dim g As Graphics = Me.PictureBox1.CreateGraphics
‘ 定义画笔
Dim myPen As System.Drawing.Pen = New System.Drawing.Pen(Color.Blue)
’ 画出矩形框并且填充颜色(颜色保持50%的透明度,使得下面原来的图片背景能看得到)
g.DrawRectangle(myPen, New System.Drawing.Rectangle(50, 50, 30, 20))
g.FillRectangle(New SolidBrush(Color.FromArgb(50, Color.YellowGreen)), New System.Drawing.Rectangle(50, 50, 30, 20))
' 最后释放画图对象
g.Dispose()
效果大致如下图所示: