画一些线上的一个图像老鼠移动

Question 1

我想画一些线上的一个图像使用鼠标在移动vb.net. 我的问题是，当我开始绘画下一条线，前线消失！任何人都可以帮我吗？我把我的代码连同照片的我的项目

Dim st, en As New Point
Dim p As Pen
Private mouseButtonPressed As Boolean = False

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
    p = New Pen(Color.Black, 2)
    Dim g As Graphics = e.Graphics
    g.DrawLine(p, st, en)
End Sub

Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp
    mouseButtonPressed = False
End Sub

Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
    If mouseButtonPressed Then
        PictureBox1.Invalidate()
        en = e.Location
    End If
End Sub

Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown
    If e.Button = MouseButtons.Left Then
        st = New Point(e.X, e.Y)
        mouseButtonPressed = True
    End If
End Sub

GIF of my run project

Question 2

可存储在一个列表，因为他们得到完成，然后提请所有前线的时候你画的生活的一个

Private st, en As New Point
Private mouseButtonPressed As Boolean = False

Private lines As New List(Of (st As Point, en As Point))

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
    Dim p = New Pen(Color.Black, 2)
    Dim g As Graphics = e.Graphics
    g.DrawLine(p, st, en)
    For Each line In lines
        g.DrawLine(p, line.st, line.en)
    Next
End Sub

Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp
    mouseButtonPressed = False
    lines.Add((st, en))
End Sub

Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
    If mouseButtonPressed Then
        PictureBox1.Invalidate()
        en = e.Location
    End If
End Sub

Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown
    If e.Button = MouseButtons.Left Then
        st = New Point(e.X, e.Y)
        mouseButtonPressed = True
    End If
End Sub

列表中拥有 Tuple(of Point, Point)

djv · Answer 1 · 2021-11-23T15:48:51

可存储在一个列表，因为他们得到完成，然后提请所有前线的时候你画的生活的一个

Private st, en As New Point
Private mouseButtonPressed As Boolean = False

Private lines As New List(Of (st As Point, en As Point))

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
    Dim p = New Pen(Color.Black, 2)
    Dim g As Graphics = e.Graphics
    g.DrawLine(p, st, en)
    For Each line In lines
        g.DrawLine(p, line.st, line.en)
    Next
End Sub

Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp
    mouseButtonPressed = False
    lines.Add((st, en))
End Sub

Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
    If mouseButtonPressed Then
        PictureBox1.Invalidate()
        en = e.Location
    End If
End Sub

Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown
    If e.Button = MouseButtons.Left Then
        st = New Point(e.X, e.Y)
        mouseButtonPressed = True
    End If
End Sub

列表中拥有 Tuple(of Point, Point)

画一些线上的一个图像老鼠移动

的问题

最好的答案

其他语言

此页面有其他语言版本

受欢迎的此类别

流行的问题，在这个类别