使用鼠標在圖片框圖像上繪製vb.net

Question

如何在vb.net上使用鼠標在線上繪製圖片框圖片？

Answer 1

轉換a similar question從C＃到VB.NET，用線 - 測試工作：

Private _Previous As System.Nullable(Of Point) = Nothing 
Private Sub pictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown 
    _Previous = e.Location 
    pictureBox1_MouseMove(sender, e) 
End Sub 

Private Sub pictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove 
    If _Previous IsNot Nothing Then 
    If PictureBox1.Image Is Nothing Then 
     Dim bmp As New Bitmap(PictureBox1.Width, PictureBox1.Height) 
     Using g As Graphics = Graphics.FromImage(bmp) 
     g.Clear(Color.White) 
     End Using 
     PictureBox1.Image = bmp 
    End If 
    Using g As Graphics = Graphics.FromImage(PictureBox1.Image) 
     g.DrawLine(Pens.Black, _Previous.Value, e.Location) 
    End Using 
    PictureBox1.Invalidate() 
    _Previous = e.Location 
    End If 
End Sub 

Private Sub pictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp 
    _Previous = Nothing 
End Sub 

Answer 2

我已經修改了你的代碼放置在鼠標點擊一個「點」，它可以移動（覆蓋）

我需要的是用於多個「點」，比如說四個。

用戶從列表中選擇一個標記，並將它放置在圖片框上，然後他們選擇另一個並放置在不同的位置，但它會覆蓋上一個標記。

Marker = Lst_Markers.SelectedIndex + 1 
If _Previous IsNot Nothing Then 
    For i As Integer = 0 To Marker 
    Dim bmp As New Bitmap(PictureBox1.Width, PictureBox1.Height) 
    PictureBox1.Image = bmp 
    Next 
    Select Case Marker 
    Case 1 
     'PictureBox1.Image = bmp1 
     Using g As Graphics = Graphics.FromImage(PictureBox1.Image) 
     g.FillEllipse(Brushes.Red, e.X, e.Y, 10, 10) 
     End Using 
    Case 2 
     'PictureBox1.Image = bmp2 
     Using g As Graphics = Graphics.FromImage(PictureBox1.Image) 
     g.FillEllipse(Brushes.Yellow, e.X, e.Y, 10, 10) 
     End Using 
    Case 3 
     'PictureBox1.Image = bmp3 
     Using g As Graphics = Graphics.FromImage(PictureBox1.Image) 
     g.FillEllipse(Brushes.Green, e.X, e.Y, 10, 10) 
     End Using 
    Case 4 
     'PictureBox1.Image = bmp4 
     Using g As Graphics = Graphics.FromImage(PictureBox1.Image) 
     g.FillEllipse(Brushes.Blue, e.X, e.Y, 10, 10) 
     End Using 
    Case Else 
     MsgBox("Select a marker") 
    End Select 
    PictureBox1.Invalidate() 
    _Previous = e.Location 
End If