Scrolling in a panel

[Rob T]

To keep my example simple, let's say I have a windows application form with
a panel in it. For this example, I want to draw a single line in the panel,
which is larger than the size of the panel. Is there a way to get the
scrollbars to show up?

Also....If I were to put a control (like a button) into the panel, the
scrollbars are there...but my line doesn't redraw properly.

How should I be doing this? Thanks.

PS. here's code snip of what I'm trying to do....

Private components As System.ComponentModel.IContainer



Friend WithEvents Panel1 As System.Windows.Forms.Panel

<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

Me.Panel1 = New System.Windows.Forms.Panel

Me.SuspendLayout()

'

'Panel1

'

Me.Panel1.Anchor = CType((((System.Windows.Forms.AnchorStyles.Top Or
System.Windows.Forms.AnchorStyles.Bottom) _

Or System.Windows.Forms.AnchorStyles.Left) _

Or System.Windows.Forms.AnchorStyles.Right),
System.Windows.Forms.AnchorStyles)

Me.Panel1.AutoScroll = True

Me.Panel1.BackColor = System.Drawing.Color.White

Me.Panel1.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D

Me.Panel1.Location = New System.Drawing.Point(112, 56)

Me.Panel1.Name = "Panel1"

Me.Panel1.Size = New System.Drawing.Size(472, 344)

Me.Panel1.TabIndex = 0

'

'Preview

'

Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)

Me.ClientSize = New System.Drawing.Size(592, 413)

Me.Controls.Add(Me.Panel1)

Me.Name = "Preview"

Me.Text = "Preview"

Me.ResumeLayout(False)

End Sub

Private Sub DrawIt(ByVal g As Graphics)

g.DrawLine(New Pen(Color.Black), 2, 2, 500, 400)

End Sub

Private Sub Panel1_Paint(ByVal sender As Object, ByVal e As
System.Windows.Forms.PaintEventArgs) Handles Panel1.Paint

DrawIt(e.Graphics)

End Sub

 

[VBen]

You should use AutoScrollMinSize and AutoScrollMargin to let the control
know that your area has a certain size, whether it has other controls in it
or not.
To redraw the line, you should capture the OnAutoScroll event (I don't
remember the exact name, but it's something like that) and call
[MyControl].Invalidate() or even [MyForm].Invalidate(true)...
With this, .Net calls the Paint event for your MyControl or your MyForm
(invalidating all children controls).
I'm not sure it's not called automatically if you set the drawing styles of
your control... Try your code with the AutoScrollMinSize and Margin set, and
do the scrolling to see if your line gets redrawn...
Hope this helps...
VBen.

 

[Bob Powell [MVP]]

See the article in Windows Forms Tips and Tricks that explains autoscroll

--
Bob Powell [MVP]
Visual C#, System.Drawing

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http://www.bobpowell.net/tipstricks.htm

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http://www.bobpowell.net/faqmain.htm

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[Rob T]

Thanks. That worked great. I couln't find any events that were like
OnAutoScroll...but when I scrolled, it refreshed on it's own anyway.
Perhaps it triggers the paint event automatically...

You should use AutoScrollMinSize and AutoScrollMargin to let the control
know that your area has a certain size, whether it has other controls in
it
or not.
To redraw the line, you should capture the OnAutoScroll event (I don't
remember the exact name, but it's something like that) and call
[MyControl].Invalidate() or even [MyForm].Invalidate(true)...
With this, .Net calls the Paint event for your MyControl or your MyForm
(invalidating all children controls).
I'm not sure it's not called automatically if you set the drawing styles
of
your control... Try your code with the AutoScrollMinSize and Margin set,
and
do the scrolling to see if your line gets redrawn...
Hope this helps...
VBen.

To keep my example simple, let's say I have a windows application form with
a panel in it. For this example, I want to draw a single line in the panel,
which is larger than the size of the panel. Is there a way to get the
scrollbars to show up?

Also....If I were to put a control (like a button) into the panel, the
scrollbars are there...but my line doesn't redraw properly.

How should I be doing this? Thanks.

PS. here's code snip of what I'm trying to do....

Private components As System.ComponentModel.IContainer



Friend WithEvents Panel1 As System.Windows.Forms.Panel

<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

Me.Panel1 = New System.Windows.Forms.Panel

Me.SuspendLayout()

'

'Panel1

'

Me.Panel1.Anchor = CType((((System.Windows.Forms.AnchorStyles.Top Or
System.Windows.Forms.AnchorStyles.Bottom) _

Or System.Windows.Forms.AnchorStyles.Left) _

Or System.Windows.Forms.AnchorStyles.Right),
System.Windows.Forms.AnchorStyles)

Me.Panel1.AutoScroll = True

Me.Panel1.BackColor = System.Drawing.Color.White

Me.Panel1.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D

Me.Panel1.Location = New System.Drawing.Point(112, 56)

Me.Panel1.Name = "Panel1"

Me.Panel1.Size = New System.Drawing.Size(472, 344)

Me.Panel1.TabIndex = 0

'

'Preview

'

Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)

Me.ClientSize = New System.Drawing.Size(592, 413)

Me.Controls.Add(Me.Panel1)

Me.Name = "Preview"

Me.Text = "Preview"

Me.ResumeLayout(False)

End Sub

Private Sub DrawIt(ByVal g As Graphics)

g.DrawLine(New Pen(Color.Black), 2, 2, 500, 400)

End Sub

Private Sub Panel1_Paint(ByVal sender As Object, ByVal e As
System.Windows.Forms.PaintEventArgs) Handles Panel1.Paint

DrawIt(e.Graphics)

End Sub

 

[Rob T]

Thanks for the tip on using the matrix...works great!

 

[Gabriele G. Ponti]

You may also be interested in this post:
http://blogs.msdn.com/rickbrew/archive/2004/06/24/165493.aspx