Drawing on Mouse Click

[psmukilan]

Im developing a project with .Net framework 1.1 using VB.Net.
During runtime, on mouse click or mouse down event of the label1 i want to draw cross lines over the label1. I have tried with drawing2d to draw lines, but i want to handle that paint event of label1 during the mouse down or mouse click event. The function is given below to draw lines simply. But i have to draw the lines on the label.

Private Sub Label1_Click(ByVal sender As Object, ByVal e As System. EventArgs) Handles Label1.Click
Draw(da)
End Sub

Private Sub Draw(ByVal e As PaintEventArgs)
e.Graphics.DrawLine(Pens.Black, New Point(10, 10), New Point(100, 50))
End Sub

Please can anyone help me out to solve this problem. Thanks in Advance

Regards
Mukil

[HanneSThEGreaT]

Hello psmukilan!

Is there any specific reason as to why you need to draw on a label ¿
IMHO, drawing on a picturebox would make more sense, in that way, I could easily persist the drawing.

Seeing the fact that you want to draw on a label, have a look at this :

    Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click
        Dim daX As New Point(0, 50) 'declare point 
        Dim daY As New Point(50, 100) 'declare another point 

        Dim g As Graphics = Label1.CreateGraphics() 'enable drawing capabilities on label

        Dim pPen As New Pen(Color.Red) 'new pen
        pPen.Width = 5 'size of pen

        g.DrawLine(pPen, 1, 1, 50, 50) 'draw the line 

        g.DrawLine(pPen, daX, daY) 'draw another line using the points

    End Sub

You might want to have a look at GDI+ on MSDN

[psmukilan]

Thanks a lot for your reply, Its working fine on mouse click, but whne the form gets restored, lines are invisible, that is redraw is not taking place.

The code is written below. Please give me your suggestion. I have tried to redarw while the form is getting activated.

Private Sub Label1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseDown
DrawCrossLine(Label1)
ControlNames.Add(Label1.Name)
End Sub

Private Sub DrawCrossLine(ByVal ControlName As Control)
Dim daX As New Point(0, 50) 'declare point
Dim daY As New Point(850, 100) 'declare another point

Dim g As Graphics = ControlName.CreateGraphics()
'Dim g As Graphics = Label1.CreateGraphics() 'enable drawing capabilities on label

Dim pPen As New Pen(Color.Red) 'new pen
pPen.Width = 2 'size of pen

'g.DrawLine(pPen, 1, 1, 250, 50) 'draw the line
'g.DrawLine(pPen, 1, 50, 50, 1) 'draw the line

Dim pts() As Point
pts = New Point() {New Point(1, 5), New Point(108, 30), _
New Point(108, 1), New Point(1, 30)}
g.DrawPolygon(pPen, pts)

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
AddHandler Label1.Paint, AddressOf myClickHandler
End Sub

Private Sub myClickHandler(ByVal sender As System.Object, ByVal e As PaintEventArgs)
e.Graphics.DrawLine(Pens.Black, New Point(10, 10), New Point(100, 50))
End Sub

Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label2.Click
ControlNames.Add(Label2.Name)
DrawCrossLine(Label2)
End Sub

Private Sub Form1_Activated(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Activated
Static Done As Boolean = False
Dim i As Integer = 0
Dim name As String
If Not Done And ControlNames.Count > 0 Then
For Each ctrl As Control In Me.Controls
Select Case True
Case TypeOf ctrl Is Label
name = System.Convert.ToString(ControlNames.Item(i))
If ctrl.Name = name Then
DrawCrossLine(ctrl)
i = i + 1
End If
End Select
Next
End If
End Sub

Private Sub Label1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Label1.Paint
DrawCrossLine(Label1)
End Sub

Private Sub Label2_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Label2.Paint
DrawCrossLine(Label2)
End Sub
End Class

[HanneSThEGreaT]

Hello again psmukilan!

Your whole problem is the Form_Activate event.
Remember the Activate event also fiers when the form is busy loading. based on that, your Polygons should have been drawn when the form is first shown as well.

BTW, what is that select case True in your Form_Activate event - it should not be like that!

Personally, what I'd do here is just to do this in the Form_Click event :

Private Sub Form1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Click
DrawCrossLine(Label1)
DrawCrossLine(Label2)
End Sub

Your Activate event doesn't work. By doing the above, when the user clicks on the form, it will draw those lines again. It won't work with clicking the TitleBar though, but it should give you an idea of what to do

Are you Happy with this ¿

PS : Just remember using CODE tags when posting code, have a look in my signature to see how it is done.