Visual Basic

Inserting a row using datagridview

7-Apr-06 11:26

Visual Studio comes with a free MSChart.ocx (ActiveX). However, I recommend that you steer clear of ActiveX controls in .NET. COM interop is slow and COM/ActiveX objects are very prone to DLL hell.

Instead, I recommend that you use a .NET graph control. Such as the ZedGraph[^] control which is free and way better than MSChart.

projectcode17-Apr-06 10:22

projectcode1

7-Apr-06 10:22

Hi All,

I am using datagridview control to display data in the datagrit. Datagridview is bound to a data source, nothing very complex. I want to insert data as I tab out of a new row( and data entered into that new row) and come to the next row. It should do it automatically.
Can any one please give me any ideas at to how I could do that?

Thanks a lot!!

CopyMemory VB.NET

chiragdanech7-Apr-06 9:26

7-Apr-06 9:26

Hi Everyone,

In VB.NET application, I want to copy a structure into a 2 dimensional array using CopyMemory.

just for your idea giving you the structure defination.

'for storing the pixel arrays...
_
Private Structure SAFEARRAYBOUND
Dim cElements As Integer
Dim lLbound As Integer
End Structure
_
Private Structure SAFEARRAY2D
Dim cDims As Short
Dim fFeatures As Short
Dim cbElements As Integer
Dim cLocks As Integer
Dim pvData As Integer
Dim Bounds() As SAFEARRAYBOUND
End Structure

I have gone through many forums but couldnt able to find the appropriate answer.

Expecting a solution soon.

Thanks

Chirag...

Joshua Quick7-Apr-06 12:07

7-Apr-06 12:07

Look at the System.Runtime.InteropServices.Marshal[^] class.

In particular, I think you'll need to use Marshal.StructToPtr[^] and Marshal.ReadByte[^].

I've never done this myself, so cross your fingers.

chiragdanech8-Apr-06 7:14

8-Apr-06 7:14

Hey thanks for you response. But I have tried that way too. but couldnt get success. Is there any other alternative......????

Chirag...

Joshua Quick8-Apr-06 9:18

8-Apr-06 9:18

By default, the compiler will "optimize" your structure by re-ordering its fields. Because of this, you'll need to define that your structure's fields be layed out sequentially in memory. You can do this via the StructLayout attribute as follows.

<System.Runtime.InteropServices.StructLayout(Runtime.InteropServices.LayoutKind.Sequential)> _
Public Structure SAFEARRAYBOUND
   Dim cElements As Integer
   Dim lLbound As Integer
End Structure

I've found an article on this website explaining how to do a CopyMemory call in VB.NET. It also goes over .NET marshalling too. Perhaps this will help you?
http://www.codeproject.com/vb/net/netcopymemorysample.asp[^]

chiragdanech8-Apr-06 9:22

8-Apr-06 9:22

that too i have done and also gone through the article.....but major problem is that i could not be able to convert this sequential structure into 2 dimensional array.......basically i need to covert this structure into 2 dimensional array which gives pixel information......and later on i will convert it into one dimensional long array.....thats wht my purpose....

Chirag...

Joshua Quick8-Apr-06 9:41

8-Apr-06 9:41

How is your 2 dimensional array defined?
How will it be used?

chiragdanech8-Apr-06 9:47

8-Apr-06 9:47

Public Function LongPixels() As Long()
'_____________________________________________________
'
' Purpose: converts the 2-dimensional 3/4 Byte DIB into a one-
' dimensional Long array, for easy summing of long int values.
' scans from left to right, then bottom to top.
' diblongarray(0) = lower left pixel.
' diblongarray(ubound) = upper right pixel.
' Assumptions: the DIB is 24-bit, the byte order of the pixels is
' r-g-b (not the common b-g-r)
' Affects:
' Inputs:
' Returns:
'_____________________________________________________

Dim bDibMag() As Byte '2 dimensional byte array holds pixels by row,col
Dim lX As Long, lY As Long 'x = pixel col, y = pixel row
Dim saDibMag As SAFEARRAY2D
Dim lXEnd As Long
Dim l As Long
Dim lCol As Long

On Error GoTo Cleanup

'structure the 2-dimensional safearray
With saDibMag
.cbElements = 1 'bytes to an element
.cDims = 2 'dimensions
.Bounds(0).lLbound = 0 'lbound of 1st dim
.Bounds(0).cElements = Height '# rows = height in pixels
.Bounds(1).lLbound = 0 'lbound of 2nd dim
.Bounds(1).cElements = LineByteWidth() 'calculate width with 24/32 row pad
.pvData = lPtrDibMag 'pointer to the DIBits
End With

'HH: MoveMemory is not available in Windows API but in Win32 API, similar command in current API is CopyMemory
'for MoveMemory, it's definition: Sub MoveMemory(pDest As Any, pSource As Any, ByteLen As Long)
'it moves a block of memory from one location to another.
'VarPtr: retrieves the memory handle of an object.
'ATTN: while calling using ByVal, it transfer the the source's memory handle
'if calling byRef(default), it instead transfer the tempoary variable that stores the souce's memory handle
'in a simple way, the following command is a quicker way, if there's a bunch of data, to pass values
'of source variable to destination variable

MoveMemory ByVal VarPtrArray(bDibMag()), VarPtr(saDibMag), 4 'copy safe array to bDibMag

lXEnd = (Width - 1) * 3
l = 0

ReDim lColor(Width * Height - 1) '4 MB
'HH: FOLLWING LOOP READS TWO DIMENSIONAL VALUE AND STORE THEM INTO A ONE-DIMENSION LONG ARRAY
'HH: READS VALUE FROM BOTTOM TO TOP
For lY = 0 To biDibMag.bmiHeader.biHeight - 1
DoEvents
'HH: FOR EACH ROW, READS VALUE FROM LEFT TO RIGHT
For lX = 0 To lXEnd Step 3
MoveMemory lCol, bDibMag(lX, lY), 3
lColor(l) = lCol
lCol = 0
MoveMemory ByVal VarPtr(lCol), 0&, 3
l = l + 1
Next lX
Next lY

LongPixels = lColor

lPix = l 'store pixelcount

'zero out the moved memory, so as to avoid
'a pacman-like memory-use situation
MoveMemory ByVal VarPtrArray(bDibMag), 0&, 4

Cleanup:

Erase saDibMag.Bounds
Erase lColor
Erase bDibMag

If err.Number <> 0 Then WriteLog "MAGRAS ERROR In Procedure LongPixels, #" _
& err.Number & ": " & err.Description

err.Clear

End Function

this is the VB function which i need to convert to VB.NET...this is the way i have defined the two dimensional array in VB.NET project..

Dim bDibMag(,) As Long '2 dimensional byte array holds pixels by row,col

Thanks again for taking interest in this problem..

Chirag...
chirag.danech@gmail.com

Joshua Quick9-Apr-06 10:49

9-Apr-06 10:49

After looking at your code, the only reason MoveMemory() is called is for performance reasons. Maybe in VB6 this was faster, but in VB.NET I doubt it. The reason is because a call to MoveMemory() is a call to unmanaged code, requiring a P/Invoke, which is a performance hit in .NET. I suggest that you make it easy on yourself, remove all of the MoveMemory() calls, and just iterate through the 2d array and directly copy the color values into your 1d array. You can look into boosting performance after you get it working.

Also, there appears to be a lot of legacy VB6 calls in your VB.NET code. You may just want to rewrite the whole thing.
You should replace your "On Error Goto" with Try/Catch.
You should replace "DoEvents" with "Application.DoEvents()".
Do a "Return lColors" instead of "LongPixels = lColors", and perhaps return an empty array on error.

chiragdanech9-Apr-06 10:55

9-Apr-06 10:55

Yeah I totally agree with you. Eventhough I have started to thinking to discard all the MoveMemory call. But as you have told just iterate through the 2d array and directly copy the color values into 1stD array. Yeah so for that the question is that..How can i get the 2D array from the structure. I mean once I get the 2D array I can easily convert it into the 1D array.

And Yeah whatever changes you have mentioned I have already made on my new .NET Code.

I appriciate If you can solve this too.

Thanks
chirag.danech@gmail.com

Chirag...

Joshua Quick9-Apr-06 12:12