vb.net 画线再画保留以前画得
Public Class Form1
Dim qq As Boolean
Dim x1, x2, y1, y2 As Single
Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
qq = True
x1 = e.X
y1 = e.Y
End Sub
Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
x2 = e.X
y2 = e.Y
If qq = True Then
PictureBox1.Refresh()
PictureBox1.CreateGraphics.DrawRectangle(Pens.Red, x1, y1, x2, y2)
End If
End Sub
Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
PictureBox1.CreateGraphics.DrawRectangle(Pens.Red, x1, y1, x2, y2)
qq = False
End Sub
End Class 展开
可以把所有画的线都保存在一个列表中，画的时候全部画出即可。如下：
Public Class Form1
Class Line '直线类
Public Point1, Point2 As Point '成员，直线的两个端点
Sub New(p1 As Point, p2 As Point) '构造方法
Point1 = p1
Point2 = p2
End Sub
Public Sub Draw(g As Graphics) '绘制方法
g.DrawLine(Pens.Black, Point1, Point2)
End Sub
End Class
Private Lines As New List(Of Line) '列表用于保存所有画下的直线
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
BackColor = Color.White
DoubleBuffered = True '开启双缓冲可有效避免闪烁
End Sub
Private Sub Form1_MouseDown(sender As Object, e As MouseEventArgs) Handles Me.MouseDown
Lines.Add(New Line(e.Location, e.Location)) '在直线列表中添加直线
End Sub
Private Sub Form1_MouseMove(sender As Object, e As MouseEventArgs) Handles Me.MouseMove
If e.Button <> Windows.Forms.MouseButtons.Left Then Return '左键未按下
'鼠标拖动时改变列表最后一条直线（也即当前直线的第二个端点）
Lines(Lines.Count - 1).Point2 = e.Location
Refresh() '刷新窗体
End Sub
'在Form的Paint事件中绘制所有直线，每次Form1重绘时都会触发Paint事件
'PS: 也可以通过重写OnPaint方法来达到类似的效果
Private Sub Form1_Paint(sender As Object, e As PaintEventArgs) Handles Me.Paint
e.Graphics.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias '开启抗锯齿
For Each l In Lines '遍历所有直线
l.Draw(e.Graphics) '调用绘制方法，传入的参数可以理解为画布
Next
End Sub
End Class
运行效果：
图像控制图像性能，然后以图片相关联的图像
上画线
图像保存到一个文件中
< / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
暗淡MYBITMAP作为图象
MYBITMAP =新的Bitmap（300，150）
PictureBox0.Image：= MYBITMAP
点心作为图形的
走势图= Graphics.FromImage（PictureBox0.image）的
走势图走势图。 drawLine的（Pens.Blue，0,0,111,111）
picturebox0.image.save（“C：\ aaa.jpg”）
/ / / / / / / / / / / / / / / / / /我一直在使用这个方法/ / / / / / / / / / / / / / / / / / /
保存为文件，绝对是你画的线......
Dim mybitmap As Bitmap
Dim Graph As Graphics
下面的可以放在new里面
mybitmap = New Bitmap(300, 150)
PictureBox1.Image = mybitmap
Graph = Graphics.FromImage(PictureBox1.Image)
PictureBox1_MouseUp里面改成下面的
Graph.DrawRectangle(Pens.Red, x1, y1, x2, y2)
PictureBox1.Image.Save("D:/1.jpg")
qq = False
刷新了，去掉这一句看看。
我输得不是假的， 这是VB.net的源代码。 你不知道VB.net吗？
