在圖片框中的鼠標位置放置圓圈

Question

我已經完成了大量搜索並找不到所需的幫助。

我需要能夠放置一些直徑爲140像素的圓形圖片在圖片框中的圖片的某些部分。在圖像上單擊鼠標時應出現圓圈。我需要將圓的中心放置在鼠標點擊位置。用戶還應該能夠將圓圈放置在圖像上時將其拖動到其他位置。

任何人都可以給我一些指導如何做到這一點？

在此先感謝！

Answer 1

這可能會啓動你。借鑑PictureBox.Click

Private Sub PictureBox1_Click(sender As System.Object, e As MouseEventArgs) Handles PictureBox1.Click 

    Dim myBrush As New System.Drawing.SolidBrush(System.Drawing.Color.Red) 
    Dim formGraphics As System.Drawing.Graphics 
    formGraphics = sender.CreateGraphics() 
    formGraphics.FillEllipse(myBrush, New Rectangle(e.X/2, e.Y/2, 70 , 70)) 
    myBrush.Dispose() 
    formGraphics.Dispose() 
End Sub 

編輯 一個簡單的紅色圓圈看起來exaclty像你正在尋找 http://www.dreamincode.net/forums/topic/59049-simple-drawing-selection-shape-or-rubberband-shape/

Answer 2

我的解決辦法：`

Private Sub PictureBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown 
    'start creating circle when the mouse is clicked 

    PictureBox1.Refresh() 'erases previous rectangle 
    Xstart = e.X 
    Ystart = e.Y 


    bRB = True 
End Sub 

Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove 
    'drag the circle over the seclected area 

    If bRB Then 
     PictureBox1.Refresh() 'erases previous rectangle 

     Select Case e.X 
      Case Is < 0 
       RBRectangle.X = 0 
       ' RBRectangle.Width = Xstart 
       RBRectangle.Width = 140 

      Case 0 To Xstart 
       RBRectangle.X = e.X 
       'RBRectangle.Width = Xstart - e.X 
       RBRectangle.Width = 140 

      Case Xstart To PBWidth 
       RBRectangle.X = Xstart 
       'RBRectangle.Width = e.X - Xstart 
       RBRectangle.Width = 140 
      Case Is > PBWidth 
       RBRectangle.X = Xstart 
       'RBRectangle.Width = PBWidth - Xstart 
       RBRectangle.Width = 140 
     End Select 

     Select Case e.Y 
      Case Is < 0 
       RBRectangle.Y = 0 
       'RBRectangle.Height = Ystart 
       RBRectangle.Height = 140 

      Case 0 To Ystart 
       RBRectangle.Y = e.Y 
       'RBRectangle.Height = Ystart - e.Y 
       RBRectangle.Height = 140 
      Case Ystart To PBHeight 
       RBRectangle.Y = Ystart 
       'RBRectangle.Height = e.Y - Ystart 
       RBRectangle.Height = 140 
      Case Is > PBHeight 
       RBRectangle.Y = Ystart 
       'RBRectangle.Height = PBHeight - Ystart 
       RBRectangle.Height = 140 
     End Select 

     PictureBox1.CreateGraphics.DrawEllipse(RBPen, RBRectangle) 
    End If 
End Sub 

Private Sub PictureBox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp 
    'show the area in the rectangle as a new image 
    Dim CroppedBm As Bitmap 
    If bRB Then 
     bRB = False 



     CroppedBm = New Bitmap(RBRectangle.Width, _ 
     RBRectangle.Height) 



    End If 
End Sub 

Answer 3

試試這個：

Dim g As Graphics 
Dim md As Boolean 
Private Sub Form1_Load() Handles MyBase.Load 
    g = PictureBox1.CreateGraphics 
End Sub 

Private Sub PictureBox1_MouseClick(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseClick 
    PictureBox1.Refresh() 
    g.DrawEllipse(Pens.Red, New Rectangle(e.X - 35, e.Y - 35, 70, 70)) 
End Sub 

Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown 
    md = True 
End Sub 

Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove 
    If md Then 
     PictureBox1.Refresh() 
     g.DrawEllipse(Pens.Red, New Rectangle(e.X - 35, e.Y - 35, 70, 70)) 
    End If 
End Sub 

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