Solved

Store picturebox.image in an imagelist in VB.NET

Posted on 2008-10-03
3
640 Views
Last Modified: 2010-04-21
Hi, experts -
I'm sure I'm just missing something ridiculously simple. I'm drawing a character in a picturebox, using Graphics objects associated with 2 pictureboxes (PB and PB2). After the character is drawn, I'm trying to put the picturebox image into an imagelist control. The imagelist is supposed to take an image of type "System.Drawing.Image" - which is what the picture box image should be (I assume). Yet in the line that is "IList1A.Images.Add (PB.Image)", I get an error saying that "Value can not be null" for PB.Image.

I just got through writing pixels on the bitmap of the PB, I don't see where it should be null. Can someone tell me what I'm doing wrong?

Thanks!

Dim g As Graphics = System.Drawing.Graphics.FromHwnd(PB.Handle)
                        Dim g1 As Graphics = System.Drawing.Graphics.FromHwnd(PB2.Handle)
 
                        For i = 1 To CellWidth
                            For l = Pointer1 + 1 To Pointer1 + 1 + CellHeight
                                'draw the '1's' as black
                                If Mid$(CellString(i), l, 1) = "1" Then
                                    g.DrawEllipse(Pens.Black, i - 1, CellHeight - (l - Pointer1), 1, 1)
                                    g1.DrawEllipse(Pens.Black, i - 1, CellHeight - (l - Pointer1), 1, 1)
                                Else
                                    g.DrawEllipse(Pens.Khaki, i - 1, CellHeight - (l - Pointer1), 1, 1)
                                    g1.DrawEllipse(Pens.DarkKhaki, i - 1, CellHeight - (l - Pointer1), 1, 1)
                                End If
                            Next l
                        Next i
 
                        ICount = ICount + 1
                        If j = 0 Then
                            IList1A.Images.Add(PB.Image)
                            IList1B.Images.Add(PB2.Image)

Open in new window

0
Comment
Question by:LongDave
  • 2
3 Comments
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 22638487
"I just got through writing pixels on the bitmap of the PB, I don't see where it should be null. Can someone tell me what I'm doing wrong?"

No, essentially what you did was draw on TOP of the PictureBox...sorta like drawing in the same layer that would draw its Border if that Style was enabled:

    Dim g As Graphics = System.Drawing.Graphics.FromHwnd(PB.Handle)

If you want to draw on the Image that the PictureBox is DISPLAYING, then you would need:

    Dim g As Graphics = System.Drawing.Graphics.FromImage(PB.Image)

*** BUT *** this assumes that you have actually ASSIGNED a valid Image to the PictureBoxes Image() Property!

By default, a PictureBox doesn't display anything and the Image() Property would return "Nothing"...
0
 
LVL 85

Accepted Solution

by:
Mike Tomlinson earned 500 total points
ID: 22638505
...what is the end goal here?...the nature of your code makes me wonder if you really need a PictureBox at all!  =\

You probably wanted something more like this:

    Dim bmp As New Bitmap(someWidth, someHeight)
    Dim G As Graphics = Graphics.FromImage(bmp)
    ' ... draw with "G" ...
    G.Dispose()
    IList1A.Images.Add(bmp)
0
 

Author Closing Comment

by:LongDave
ID: 31502937
Idle_Mind .... Not so Idle, m'man. Excellent suggestions - and it appears to work great! Many thanks .. all points are yours.
0

Featured Post

Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

1.0 - Introduction Converting Visual Basic 6.0 (VB6) to Visual Basic 2008+ (VB.NET). If ever there was a subject full of murkiness and bad decisions, it is this one!   The first problem seems to be that people considering this task of converting…
It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
Email security requires an ever evolving service that stays up to date with counter-evolving threats. The Email Laundry perform Research and Development to ensure their email security service evolves faster than cyber criminals. We apply our Threat…
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa…

828 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question