Solved

Imagelist shows blank bitmaps

Posted on 2008-10-08
8
401 Views
Last Modified: 2012-05-05
This strikes me as odd - I create a small in-memory bitmap, and draw a single character with a background color on it. I then transfer this into an Imagelist control. However, when I transfer the imagelist.image(x) to a location in a picturebox, only the background color of the image shows up.

I know that the bitmap was created correctly, because if I use "bmp1.save(filename)" then take the file and read it into an image ("dim g as image = image.fromfile(filename)") then load g into the imagelist, it works great.

Can anyone tell me why it doesn't transfer properly to the imagelist unless I save it to disk and read it back?  Thanks!!


Dim bmp1 As New Bitmap(CellWidth, CellHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb)
 
For i = 1 To CellWidth
  For l = 1 To CellHeight
  'draw the '1's' as black
   If Mid$(CellString(i), l, 1) = "1" Then
     bmp1.SetPixel(i - 1, CellHeight - l, Color.Black)
   Else
     bmp1.SetPixel(i - 1, CellHeight - l, Color.DarkGoldenrod)
   End If
  Next l
Next i
 
IList1A.Images.Add(bmp1)

Open in new window

0
Comment
Question by:LongDave
  • 4
  • 3
8 Comments
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 22673239
try with the following:

yourImgList.ImageSize = new System.Drawing.Size(CellWidth, CellHeight)
yourImgList.Images.Add(bmp1)
yourImgList.TransparentColor = Color.DarkGoldenrod  'optional

0
 

Author Comment

by:LongDave
ID: 22673676
Nope - that didn't do it. The wierd thing is that it seems that saving the bmp to a file and then calling it back somehow transforms it so that it loads properly in the Imagelist control. Any other ideas?

0
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 22673845
Does this make a diff?
        Dim bmp1 As New Bitmap(cellWidth, cellHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb)
        Dim G As Graphics = Graphics.FromImage(bmp1)
        G.Clear(Color.Goldenrod)
        For i = 1 To cellWidth
            For l = 1 To cellHeight
                'draw the '1's' as black
                If Mid$(CellString(i), l, 1) = "1" Then
                    G.FillRectangle(Brushes.Black, New Rectangle(i - 1, cellHeight - l, 1, 1))
                End If
            Next l
        Next i
        G.Dispose()
        IList1A.Images.Add(bmp1)

Open in new window

0
DevOps Toolchain Recommendations

Read this Gartner Research Note and discover how your IT organization can automate and optimize DevOps processes using a toolchain architecture.

 

Author Comment

by:LongDave
ID: 22673947
OK!! That did it! But I still don't see why the use of the bmp directly to the imagelist didn't work properly. Any ideas? I'd really like to understand why. But I will issue you the points - I just didn't want to close the question before your answer.
0
 
LVL 85

Accepted Solution

by:
Mike Tomlinson earned 500 total points
ID: 22674055
I really don't have a TECHNICAL answer for you sorry...just haven't really seen anyone using Bitmap.SetPixel() and I knew that my method would work...   =\

0
 

Author Closing Comment

by:LongDave
ID: 31504403
Hi, Idle_Mind ... This is the 2nd time you've helped me. Thanks a lot! Your solution looks like it works fine - but I wish I knew WHY the other didn't!  :(
Oh, well!
0
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 22674227
A simple test using your original technique worked for me...not sure what you did wrong:
Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim CellWidth As Integer = 5
        Dim CellHeight As Integer = 5
 
        Dim pixels As String = "11111,00100,00100,00100,11111;10001,11011,10101,10001,10001"
        For Each charSig As String In pixels.Split(";")
            Dim bmp As New Bitmap(CellWidth, CellHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb)
            Dim rows() As String = charSig.Split(",")
            For y As Integer = 0 To rows.GetUpperBound(0)
                For x As Integer = 0 To rows(y).Length - 1
                    If rows(y).Substring(x, 1) = "1" Then
                        bmp.SetPixel(x, y, Color.Black)
                    Else
                        bmp.SetPixel(x, y, Color.DarkGoldenrod)
                    End If
                Next
            Next
            ImageList1.Images.Add(bmp)
        Next
        PictureBox1.Image = ImageList1.Images(0)
        PictureBox2.Image = ImageList1.Images(1)
    End Sub
 
End Class

Open in new window

IM-Chars.jpg
0
 

Author Comment

by:LongDave
ID: 22674270
Wierd - thanks for the input though. I was using the DrawImage function to place the chars in the picturebox, but I don't know why that would have made any difference (I'm sure it did not).

But thanks again - hope I don't have to bug you too often! :)
0

Featured Post

DevOps Toolchain Recommendations

Read this Gartner Research Note and discover how your IT organization can automate and optimize DevOps processes using a toolchain architecture.

Question has a verified solution.

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

The ECB site provides FX rates for major currencies since its inception in 1999 in the form of an XML feed. The files have the following format (reducted for brevity) (CODE) There are three files available HERE (http://www.ecb.europa.eu/stats/exch…
A long time ago (May 2011), I have written an article showing you how to create a DLL using Visual Studio 2005 to be hosted in SQL Server 2005. That was valid at that time and it is still valid if you are still using these versions. You can still re…
This Micro Tutorial will give you a basic overview how to record your screen with Microsoft Expression Encoder. This program is still free and open for the public to download. This will be demonstrated using Microsoft Expression Encoder 4.
Established in 1997, Technology Architects has become one of the most reputable technology solutions companies in the country. TA have been providing businesses with cost effective state-of-the-art solutions and unparalleled service that is designed…

815 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

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now