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换成form1的Load事件就不能画图了:
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是因为form1在Load的时候,它还不能创建图形界面,也就不能执行 Me.CreateGraphics
分类: 电脑/网络 程序设计 其他编程语言
问题描述:
VB6中的form1.circle (100,200),rgb(0,255,0)的语句如何在VB中使用啊？
急用啊！！！！！！！！
解析:
VB与VB不同。
VB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
项目中要用图形来显示一个阀门的开度，以及控制阀的开度。本来是要用什么公司买的控件中的饼图之类的实现，不过我觉得也是麻烦，就想，还是自己画吧。
首先添加一个TrackBar，名字是“TrackBar1”，一个label，名字是“L_A_SHANG”，一个GroupBox，名字是“GB_RIGHT”,，然后添加拉动滚动条时的处理函数
'上位机控制
Dim m_start As Integer
Dim RcDraw As System.Drawing.Rectangle
Private Sub TrackBar1_Scroll(ByVal sender As Object, ByVal e As System.EventArgs) Handles TrackBar1.Scroll
m_start = (100 - TrackBar1.Value)
Me.L_A_SHANG.Text = Me.TrackBar1.Value.ToString
GB_RIGHT.Invalidate() '重画GB_RIGHT
End Sub
添加GB_RIGHT重画时的处理函数
Private Sub GB_RIGHT_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles GB_RIGHT.Paint
RcDraw.X = TrackBar1.Location.X - 40
RcDraw.Y = 20
RcDraw.Height = 100
RcDraw.Width = 20
e.Graphics.DrawRectangle(New Pen(Color.Blue, 5), RcDraw)
Dim i = TrackBar1.Location.X - 40
For i = TrackBar1.Location.X - 40 To TrackBar1.Location.X - 20
e.Graphics.DrawLine(New Pen(Color.Blue, 5), i, m_start + 20, i, 120)
Next
Me.L_A_SHANG.Text = Me.TrackBar1.Value.ToString + "%"
End Sub
到此以及可以实现拉动条的时候，图像跟着变化，并显示百分比。
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