用vb點虐 繪圖在Button1_Click可以畫出一條線。但是換成form1的Load事件就不能畫圖了，為什么？

換成form1的Load事件就不能畫圖了:

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是因為form1在Load的時候,它還不能創(chuàng)建圖形界面,也就不能執(zhí)行 Me.CreateGraphics

VB點虐 中如何畫圖？

分類: 電腦/網絡 程序設計 其他編程語言

問題描述:

VB6中的form1.circle (100,200),rgb(0,255,0)的語句如何在VB中使用??？

急用?。。。。。。。?！

解析:

VB與VB不同。

VB已經有專門繪圖的類。

可以定義筆刷然后用Drawing類中的方法繪制。

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

VB.Net如何實現(xiàn)摳圖并繪圖

項目中要用圖形來顯示一個閥門的開度，以及控制閥的開度。本來是要用什么公司買的控件中的餅圖之類的實現(xiàn)，不過我覺得也是麻煩，就想，還是自己畫吧。

首先添加一個TrackBar，名字是“TrackBar1”，一個label，名字是“L_A_SHANG”，一個GroupBox，名字是“GB_RIGHT”,，然后添加拉動滾動條時的處理函數(shù)

'上位機控制

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() '重畫GB_RIGHT

End Sub

添加GB_RIGHT重畫時的處理函數(shù)

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

到此以及可以實現(xiàn)拉動條的時候，圖像跟著變化，并顯示百分比。

關于vb點虐 中繪圖并保存圖片的問題

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) '此處從背景圖創(chuàng)建Greaphics

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

'劃線

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

'存盤

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