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Sorry, no harsh criticism intended; however I get upset when exceptions get ignored like that. They exist to signal a problem, so don't shut them out.
One more idea: Image.FromFile throws an OOM on a bad file, so I suggest you check which file fails; then try the sequence again, skipping the first half of the succeeding files.
Luc Pattyn
Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.
Local announcement (Antwerp region): Lange Wapper? Neen!
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Thanks Luc, you may have a good point there. I will skip the first files and see if I get the error.
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Nope, it went straight through and did the lot (40+ files) no problem. It definitely seems to stil at 66 files.
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Strange but true Luc, you sort of hit the nail!
I did this:
sr = New StreamReader(ImagePathName)
'sourceBitmap = New Bitmap(Image.FromFile(ImagePathName))
sourceBitmap = New Bitmap(Image.FromStream(sr.BaseStream))
Reading it into a stream first works - no memory errors!
Thanks for you assistance.(and tutoring )
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you're welcome.
sorry, having information in two threads got me confused.
It still is too expensive; I don't see why you copy the image, as
sourceBitmap = New Bitmap(Image.FromStream(sr.BaseStream))
creates two identical images, the first one is the result of FromStream and is a real Image (and also a Bitmap upcast to an Image), the second the result of your Bitmap constructor is a real Bitmap. And once more, the first never gets disposed of.
A simple Image.FromStream(sr.BaseStream) As Bitmap should do (or whatever the VB syntax is for casting from Image to Bitmap). This should halve your CPU and memory load.
FYI: the person you reply to normally gets an e-mail notification; as you seem to be replying a lot to yourself, you got lots of e-mails, and I only saw your replies by watching the forum. So I suggest you make sure you reply to (the last message of) the person you want to get the reply and notification...
Luc Pattyn
Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.
Local announcement (Antwerp region): Lange Wapper? Neen!
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Though I agree Luc could have been a little nicer, he's right on all four points.
1) If you know what the exception is, and are intentionally ignoring it (Not ideal, but sometimes unavoidable), you should at least catch the specific exception being triggered... For example, "Catch ex as FileNotFoundException", so you won't miss an unexpected one.
2) As he said, sleeping the thread won't help, but you realized that.
3) Yes, setting a local variable to nothing is meaningless, since it will go out of scope as soon as the method ends. This was needed back in VB6 when you didn't have a Dispose() method, but no longer.
4) Definitely put all disposes in Finally blocks, otherwise they'll be skipped if an exception occurs. If you want to keep things simple, define both disposables at the beginning of the method (Initialized to null), and only try to dispose if they're non-null. That way you don't need an extra try loop just for the graphics object.
Other suggestions:
5) Don't use "new IntPtr()"... Use IntPtr.Zero
6) From the MSDN article for GetThumbnailImage, in reference to the callback parameter: "In GDI+ version 1.0, the delegate is not used. Even so, you must create a delegate and pass a reference to that delegate in this parameter"... As we don't know how this is implemented (By Microsoft), this may or may not be the cause.
If none of these solve your problem, it may be elsewhere in your program... Just because this method does the heavy lifting, doesn't necessarily mean it's the only one that can leak.
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Ian, many thanks for your response. I understand what was being said now and yes the code was not the best! 
I have made all the changes that you and Luc suggested, but it still gives an Out of memory error after about 65 or so iterations.
I have had to leave Nothing in the callback as both Microsoft's example and the other example given in MSDN do not work for me. The Microsoft one gives the message "'System.Drawing.Image.GetThumbnailImageAbort' is a delegate type and requires a single 'addressof' expression as the only argument to the constructor." ?? What does that mean. I copied the code which was in c# and converted it to VB on Developer Fusion's web page and that was the result. Using the other example I get 'Value of type 'Boolean' cannot be converted to 'System.Drawing.Image.GetThumbnailImageAbort'
Nothing does not seem to cause any problems!!
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No problems on the surface, but maybe a memory leak internally... Graphics calls tend to have issues like that...
Basically it wants a delegate of a particular type, in this case a Image.GetThumbnailImageAbort delegate. As per MSDN, you need to create a dummy function, such as:
Private Function ThumbnailDummyFunc() as Boolean
End Function
new Image.GetThumbnailImageAbort(AddressOf ThumbnailDummyFunc)
(Sorry if my syntax is off... Been programming in C# all day, so it's tricky to switch mental modes)
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Hi Ian, I think I sussed out the delegate thing. I ended up with this:
Dim callback As New Image.GetThumbnailImageAbort(AddressOf ThumbnailCallback)
and
Public Function ThumbnailCallback() As Boolean
Return False
End Function
so my getthumbnailimage call looks like this now - but the error still occurs.
destBitmap = sourceBitmap.GetThumbnailImage(imgWidth, imgHeight, callback, IntPtr.Zero)
Looking at the list of errors there is one 'out of memory', then two 'Parameter is not valid' and then the rest are 'Out of Memory'.
I don't know where this 'Parameter is not valid' is coming from so I shall try and single step the whole thing (after the first error)
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It is this line
sourceBitmap = New Bitmap(Image.FromFile(ImagePathName))
This causes the Out Of Memory errors and the Parameter is not valid. When I get the parameter error, the file name is a valid existing file name and is a graphic. If I wait two minutes and then complete the list it works, in other words the file that seemed to cause an error, and all the subsequent files in the list, go through OK. 
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TheComputerMan wrote: sourceBitmap = New Bitmap(Image.FromFile(ImagePathName))
that is bad code! Image has a Dispose() method, so you should call it; by having two operations in one line, you don't have the first image reference and can't call Dispose. Split it into two statements, and dispose.
BTW: If the copy is there to avoid file lock problems, the cheaper solution is to use Image.FromStream, like so (using C# syntax):
stream=File.OpenRead(ImagePathName));
Bitmap bm=Image.FromStream(stream);
stream.Dispose();
Luc Pattyn
Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.
Local announcement (Antwerp region): Lange Wapper? Neen!
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Hi Luc, yes the stream thingy sorted it. I replied this to you on the other bit of the thread. Thanks for all your help.
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Hi Ian, thanks for your assistance. I resolved it!!!!  See my reply to Luc
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TheComputerMan wrote: This code is stupid: whatever goes wrong you choose to just ignore it; and then wonder what is going wrong and post a question here?
1. A completely erroneous assumption
No, it's not erroneous. You said you know what THE (assuming one) exception is, but you chose to capture ALL exceptions and eat them. Catch the ONE exception you know is going to come and handle it appropriately, log all the rest so you can see any other errors that show up.
TheComputerMan wrote: 3. Is it useless??? Are you sure about that. I have experience of it kicking off the garbage collector in another app which was not kicking off after a dispose was performed
The garbage collector doesn't wait for you app to pause. It'll pause your app for you and run when it needs to. Just throwing a sleep in doesn't kick off nor does it allow to run the GC. The GC runs when it wants to, regardless of what your app says. If you're doing this to "get the GC to run", you've got another problem in your code that this code just happens to work around. I really wouldn't call it a production quality fix.
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Hi,
Is there any way to trap all the events, function/procedure calls fired and log it without modifying code for each function/event.
Regards,
Praveen
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Nope. What are you trying to accomplish with this?
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In my client places, a record is missing occassionally and we could not reproduce it in our systems. I would like to track the events/function calls in the client's place with event log.
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Then you're going to have to instrument the code to log what you want. There's no real way to do it without changing the code.
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I want something that is similar to vb code profiler which takes exe instead of .vbp and log the events.
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Seeing as VB6 is a dead language, support for it is getting more and more sparse. Try looking through this[^] list for some options.
Good luck with that!
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Hi,
I'm having problems adding multiple rows to a DataGridView, on the Load-event of a Windows Application Form.
Adding one record doesn't cause a problem, but when adding the second record (using the identical code), an Exception is thrown.
Here's my code so far (VB.NET 2008):
Private Sub BWMFPForm_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim dgvRow As New DataGridViewRow
Dim dgvCell As DataGridViewCell
Dim dgvButton As DataGridViewImageColumn
Dim column As DataGridViewColumn
'Disable sorting for all Columns
For Each column In DataGridViewBrochures.Columns
column.SortMode = DataGridViewColumnSortMode.NotSortable
Next
'Add Record
'Column 1: Machine
dgvCell = New DataGridViewTextBoxCell()
dgvCell.Value = "Aficio MP 4000 / Aficio MP 5000"
dgvRow.Cells.Add(dgvCell)
'Column 2: Speed
dgvCell = New DataGridViewTextBoxCell()
dgvCell.Value = "40 PPM / 50 PPM"
dgvRow.Cells.Add(dgvCell)
'Column 3: Language
dgvCell = New DataGridViewTextBoxCell()
dgvCell.Value = "Nederlands"
dgvRow.Cells.Add(dgvCell)
'Column 4: Image Print
dgvButton = New DataGridViewImageColumn
dgvButton.Image = Drawing.Image.FromFile("D:\DEVPROJECTS\MarketingTouchScreen\TouchScreen\images\Print_Icon.jpg")
dgvButton.ReadOnly = True
dgvButton.ImageLayout = DataGridViewImageCellLayout.Normal
DataGridViewBrochures.Columns.Add(dgvButton)
'Add the Row
DataGridViewBrochures.Rows.Add(dgvRow)
'Add Record
'Column 1: Machine
dgvCell = New DataGridViewTextBoxCell()
dgvCell.Value = "Aficio MP 4000 / Aficio MP 5000"
dgvRow.Cells.Add(dgvCell)
'Column 2: Speed
dgvCell = New DataGridViewTextBoxCell()
dgvCell.Value = "40 PPM / 50 PPM"
dgvRow.Cells.Add(dgvCell)
'Column 3: Language
dgvCell = New DataGridViewTextBoxCell()
dgvCell.Value = "Nederlands"
dgvRow.Cells.Add(dgvCell)
'Column 4: Image Print
dgvButton = New DataGridViewImageColumn
dgvButton.Image = Drawing.Image.FromFile("D:\DEVPROJECTS\MarketingTouchScreen\TouchScreen\images\Print_Icon.jpg")
dgvButton.ReadOnly = True
dgvButton.ImageLayout = DataGridViewImageCellLayout.Normal
DataGridViewBrochures.Columns.Add(dgvButton)
'Add the Row
DataGridViewBrochures.Rows.Add(dgvRow)
End Sub
Anyone can help me here?
Kindly Yours
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When adding your second record you are still using the same DataGridViewRow as for the first record. You will need to use the new keyword on dgvRow before adding cells to it.
Also, in future it is helpful if you include any error messages in your post
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Hi Liqz,
Thanks!
That did the trick.
I'll keep in mind that next time, I'll include the error message.
Cheers.
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You're welcome
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For future reference, adding the text of the exception is always helpful. However from you're code I'm guessing it's something like "...row already exists in grid." ...or something like that. You're adding the same row object to the grid twice. You need a new row object the second time around. Otherwise all you are doing is updating the data in the first row you added.
Hope this helps.
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