Rubberband in a PictureBox

Submitted by Dr Dave on Wednesday, November 20, 2013 - 05:42.

This program was created in Microsoft Visual Basic 2010 Express to demonstrate how to draw a rubberband rectangle in a picture box.

After creating a Windows Forms Applications, resize Form1 to 500 x 500. Add a PictureBox control to Form1 and resize to fill the Form workspace. Change the following PictureBox1 Properties

Anchor - select Top, Bottom, Left, & Right
BackColor - White

You will use the Form1 event Load to enter the initial properties of the Pen. In this example, the Rubberband will be a dashed black line with a line width of 1.5.

Picturebox1 events used are Mouseown, MouseMove, MouseUp and Resize. When you press the mouse button on the Picturebox the starting position will be saved in Xstart and Ystart. Picturebox1.Refresh is used to clear any previous drawings.

As the mouse is moved across the Picturebox, the location will be updated and a new rectangle is drawn using the DrawRectangle subroutine. Depending on the direction the mouse is moving with respect to the starting point will determine the values used in the RBrectangle variable.

When the mouse button is released, the process is stopped by setting bRB as false. You can add code in this area to do something with the area that is rubberbanded.

If you resize the Form, the boundaries of the Picturebox are updated. In order to keep the rectangle visible along the right and bottom edges, you will need to reduce the values of PBWidth and PBHeight by 1.

    Dim Xstart As Integer
    Dim Ystart As Integer
    Dim PBWidth As Integer
    Dim PBHeight As Integer
    Dim bRB As Boolean
    Dim RBPen As Pen
    Dim RBRectangle As Rectangle
 
    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        RBPen = New Pen(Color.Black, 1.5) 'Color, Width
        RBPen.DashStyle = Drawing2D.DashStyle.Dash
    End Sub
 
    Private Sub PictureBox1_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        PictureBox1.Refresh() 'erases previous rectangle
        Xstart = e.X
        Ystart = e.Y
        bRB = True
    End Sub
 
    Private Sub PictureBox1_MouseMove(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
        If bRB Then
            PictureBox1.Refresh() 'erases previous rectangle
 
            Select Case e.X
                Case Is < 0
                    RBRectangle.X = 0
                    RBRectangle.Width = Xstart
                Case 0 To Xstart
                    RBRectangle.X = e.X
                    RBRectangle.Width = Xstart - e.X
                Case Xstart To PBWidth
                    RBRectangle.X = Xstart
                    RBRectangle.Width = e.X - Xstart
                Case Is > PBWidth
                    RBRectangle.X = Xstart
                    RBRectangle.Width = PBWidth - Xstart
            End Select
 
            Select Case e.Y
                Case Is < 0
                    RBRectangle.Y = 0
                    RBRectangle.Height = Ystart
                Case 0 To Ystart
                    RBRectangle.Y = e.Y
                    RBRectangle.Height = Ystart - e.Y
                Case Ystart To PBHeight
                    RBRectangle.Y = Ystart
                    RBRectangle.Height = e.Y - Ystart
                Case Is > PBHeight
                    RBRectangle.Y = Ystart
                    RBRectangle.Height = PBHeight - Ystart
            End Select
 
            PictureBox1.CreateGraphics.DrawRectangle(RBPen, RBRectangle)
        End If
    End Sub
 
    Private Sub PictureBox1_MouseUp(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        If bRB Then
            bRB = False
            'Add code here
        End If
    End Sub
 
    Private Sub PictureBox1_Resize(sender As Object, e As System.EventArgs) Handles PictureBox1.Resize
        PBWidth = PictureBox1.Width - 1 'Right edge
        PBHeight = PictureBox1.Height - 1 'Bottom edge
    End Sub

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Rubberband in a PictureBox

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