Visual Basic

1-Sep-09 21:27

kjsl2k9 wrote:
Dim g As Graphics = MainPanel.CreateGraphics

g.DrawLine(Pens.Red, Convert.ToInt32(0), Convert.ToInt32(0), Convert.ToInt32(190), Convert.ToInt32(190))

All of this code is bad. Every last bit of it. Handle a paint event, never call CreateGraphics unless you're drawing a rubber band. Draw directly onto the form, not into a picture box, that's not what it's for. Use the graphics object passed into the paint event.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

connection

ihe1-Sep-09 18:54

ihe

1-Sep-09 18:54

Please I would like your help in the following questions,(Please supply code example.)
:

1. How can I make a program’s able to link with its database independent of location?

There is a program I am trying to create. It works fine only if the database is placed in a particular location. I would like the program to be such that a user can install the program in any location and my program can look for and locate the database.

In a multi-tier network application, let us assume the following conditions exist:

• The front –end is in VB.NET/ C# .NET. (I am at home with any of them so you can write the code in any of these languages) The back-end is an oracle database.

2. How can I link the two? The front-end is not in the same computer as the database.

3. How can I make my apps able to read/ write real-time data?
Thank you .

ihe

_Damian S_1-Sep-09 20:22

_Damian S_

1-Sep-09 20:22

ihe wrote:
1. How can I make a program’s able to link with its database independent of location?

You will need to have some sort of local data store (or registry entry etc) that records the location of your database. When your system opens, it attempts to connect to the database, if it fails, it prompts the user to locate the database and saves it to the data store (or registry entry etc).

ihe wrote:
2. How can I link the two?

Using Connections.

ihe wrote:
The front-end is not in the same computer as the database.

This is standard design.

ihe wrote:
3. How can I make my apps able to read/ write real-time data?

Write your application to get data from the database (through the connection) and display it to the user, then write data to the database when the user clicks update (or save, or do it, or whatever).

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ihe2-Sep-09 16:06

ihe

2-Sep-09 16:06

Please can you give sample codes?

ihe

Christian Graus1-Sep-09 21:28

1-Sep-09 21:28

Please don't cross post. Did you want VB or C# code ?

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

Error when drawing a bitmap

ihe2-Sep-09 16:03

ihe

2-Sep-09 16:03

Please in any (Vb.NET or C#.NET). I write in the two languages.

ihe

Sonhospa1-Sep-09 15:28

Sonhospa

1-Sep-09 15:28

Hello gurus,

I'd really need someone advanced in graphics since I have a weird error which I can't locate at all. I think it's connected with a piece of code that's supposed to display a grayscale image:

arrayImage = dpx.GS16ArrayFromRawArray(dpx.DPXPixelArray)
gch = GCHandle.Alloc(arrayImage, GCHandleType.Pinned)
Dim pBuf As IntPtr = gch.AddrOfPinnedObject
Dim stride As Integer = Width * 2
Me.CurrentBitmap = New Bitmap(Width, Height, stride, Imaging.PixelFormat.Format16bppGrayScale, pBuf)
gch.Free()

I might have to mention that I use the exact same process (with adapted parameters) to read an RGB image from a byte array (24bppRGB). The image data in this case are supplied as an array of UInt16 - and the values seem to fit. When stepping through the code, everything seems to be fine.... but a little bit later in connection with the update of a progressBar Confused | :confused:

, I get an InvalidArgumentException.

The stack trace leaves me the following:

bei System.Drawing.Graphics.CheckErrorStatus(Int32 status)
bei System.Drawing.Graphics.DrawImage(Image image, Int32 x, Int32 y, Int32 width, Int32 height)
bei System.Drawing.Graphics.DrawImage(Image image, Rectangle rect)
bei System.Windows.Forms.PictureBox.OnPaint(PaintEventArgs pe)
bei System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer, Boolean disposeEventArgs)
bei System.Windows.Forms.Control.WmPaint(Message& m)
bei System.Windows.Forms.Control.WndProc(Message& m)
bei System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
bei System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
bei System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
bei System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
bei System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
bei System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
bei System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
bei System.Windows.Forms.Application.Run(ApplicationContext context)
bei Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
bei Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
bei Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
bei HeadersTwo.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:Zeile 81.
bei System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
bei System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
bei Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
bei System.Threading.ThreadHelper.ThreadStart_Context(Object state)
bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
bei System.Threading.ThreadHelper.ThreadStart()

Does anyone of you probably have an idea where to start looking for the error?

Thanks a lot!
Mick

Christian Graus1-Sep-09 16:10

1-Sep-09 16:10

I am pretty sure your calculation of stride is wrong, unless it means something different to what it meant when I used the term in my image processing days. I am also surprised that a 16 bit conversion exists inside the framework, but I guess it looks like it does.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

Luc Pattyn2-Sep-09 1:05

Re: Error when drawing a bitmap [modified]

2-Sep-09 1:05

Hi,

yes you can construct an image/bitmap from raw data with one of its constructors.
However the documentation clearly states "The caller is responsible for allocating and freeing the block of memory specified by the scan0 parameter, however, the memory should not be released until the related Bitmap is released." so the way I understand it is you should not free the GCHandle right away, the raw data should not be allowed to move around for as long as your bitmap is alive.

Smile | :)

Luc Pattyn

Badger | [badger,badger,badger,badger...]

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.

Sonhospa2-Sep-09 8:12

Sonhospa

2-Sep-09 8:12

Aahhh - I see! I thought I had taken care of this issue by assigning the new bitmap to the Me.CurrentBitmap property, which is later used as the source of a picture box... I should have assigned a copy and then freed the original, right?

What do you say regarding Christian's hint about the stride parameter? Sniff | :^)

[EDIT:]
I just replaced the relevant lines with

Dim arrBmp As New Bitmap(Width, Height, stride, Imaging.PixelFormat.Format16bppGrayScale, pBuf)
Me.CurrentBitmap = New Bitmap(arrBmp, arrBmp.size)
gch.Free()

and now I'm receiving an ArgumentException in the second line.

modified on Wednesday, September 2, 2009 2:20 PM

Luc Pattyn2-Sep-09 8:33

2-Sep-09 8:33

Hi,

1. yes, a good approach would be to create the bitmap, make a copy, dispose of the original, then free the GCHandle. The bad thing is this temporarily takes twice the amount of memory.

2. MSDN says stride must be a multiple of 4, so width should be even (or rounded up, raw data permitting).

3. you have to look at Exception.ToString() to get all the available details. If still insufficient, experiment with different parameter combinations. And maybe after all, 16-bit isn't supported after all? the doc says it gets converted to some other format right away.

Smile | :)

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.

Sonhospa2-Sep-09 8:55

Sonhospa

2-Sep-09 8:55

Hi Luc,

I'll follow that approach. Btw it's been your own idea Wink | ;)

from an older thread.
Width is 1024, so I guess it should be allright.

Exception.ToString() shows a ArgumentException "Invalid Parameter". Finally it refers to the line where I try to assign the first bitmap to a new one... Does that tell you anything? Confused | :confused:

Since that happens when I try to assign the 16-bit-Grayscale format to a regular bitmap, I'm afraid it really might not be supported. Or - as the doc says - that it's converted to anything special that doesn't want to be converted to a normal thing...

Since I actually just want to display a grayscale, I could anyway live much better with 8-bit. BUT: There's no such PixelFormat as "8bppGrayscale", just indexed colours which loads (!) but shows a weird picture of course. Do you by any chance know which PixelFormat I'd have to choose for a simple grayscale image?

Thanks
Mick

Luc Pattyn2-Sep-09 9:32

VB6 Serial Comm Crashs Visual Studio

2-Sep-09 9:32

Michael Schäuble wrote:
your own idea Wink from an older thread.

yep. copying an image solves a file-locked problem in Image.FromFile; using FromStream does the same.

I have used this code:

byte[] bytes=new byte[32*1024];
GCHandle handle=GCHandle.Alloc(bytes, GCHandleType.Pinned);
IntPtr ptr=handle.AddrOfPinnedObject();
// no exceptions:   Format16bppArgb1555, Format16bppRgb565, Format16bppRgb555,
//          Format1bppIndexed, Format8bppIndexed, Format32bppRgb
// exceptions:      Format16bppGrayScale
Bitmap bm1=new Bitmap(16, 16, 1024, PixelFormat.Format8bppIndexed, ptr);
log("bm1 OK");
Bitmap bm4=new Bitmap(1000, 1000);
Graphics g=Graphics.FromImage(bm4);
g.DrawImage(bm1, 0, 0);
log("bm4 drawn");
Bitmap bm2=new Bitmap(bm1);
bm1.Dispose();
handle.Free();
Bitmap bm3=new Bitmap(bm2);
bm2.Dispose();
log("size ="+bm3.Size);
bm3.Dispose();

to experiment and find out which formats are acceptable; it seems Format16bppGrayScale is the
odd one out: .NET is willing to construct a bitmap (bm1) but refuses to use it (either in bm4 or in bm2)

Work arounds:

1.
Format1bppIndexed is the one closest to what you could use, but I have no idea on how to install an appropriate lookup table.

2.
What is bound to work is convert the raw data to a format that will be understood, such as Format32bppRgb
All it takes is replacing each 16-bit value X by a new value Y where Y equals something like X/4 * 0x1010101 which assumes X has 10 significant bits, so 2 bits need to be thrown out, and the gray value gets copied to all bytes (that's what the multiplication does when using unsigned arithmetic).

Smile | :)

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.

modified on Wednesday, September 2, 2009 3:59 PM

suguimoto1-Sep-09 12:02

suguimoto

1-Sep-09 12:02

Hello everyone,

I got a really strange problem. I could make 2 computers to communicate to each other through hyperterminal, 115200,8,n,1 Hardware(CTS,RTS).

Then I decide to make a VB6 program in one of those (with the same parameters). Sending data from VB6 is just fine (the hyperterminal in the other computer shows the same data), but when it receives any data the program crashes and the program manager shows 99% of the cpu is beings used by VB6 Confused | :confused:

Note.: There´re no infinite loops neither "OnComm" function is avaible in the algorithm.

Did anyone have this problem? Or knows how to solve it?

Thanks Wink | ;)

Christian Graus1-Sep-09 14:26

1-Sep-09 14:26

Why would you use VB6 ? It's out of date, and was always rubbish.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

suguimoto1-Sep-09 16:20

suguimoto

1-Sep-09 16:20

Well, it´s easy to program and does not need the whole .net framework to run with.

I know it´s out of date, but it´s still reliable for simple tasks and even really old pcs can run.

Thanks but...

Does anyone have a clue about it?

Mycroft Holmes1-Sep-09 16:05

Mycroft Holmes

1-Sep-09 16:05

STOP throw out what you have started, download VB.net express and start again. You are using a tool that is no longer supported.

Luc Pattyn2-Sep-09 1:11

Calculate the origin and radius of a circle

2-Sep-09 1:11

No matter how obsolete and outdated your chosen language is, Windows always has and always will require you to not touch controls from any thread other than the one that created the control, and my best guess is you are trying to receive and somehow display incoming serial data on a different thread (most asynchronous operations run on some other thread automatically).

This little article[^] describes the problem and solution in .NET (using C# examples); I don't know how it looks in ancient VB.

Smile | :)

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.

keithp08231-Sep-09 10:21

keithp0823

1-Sep-09 10:21

My trig skills are lacking, please assist if possible.

Given the coordinates of three points of an arc, how do I calculate the origin and radius of the arc or circle.

Dim s As String() = Split("a 100 100 76 110 50 100", " ")

Dim x1 As Integer = CInt(s(1))
Dim y1 As Integer = CInt(s(2))

Dim x2 As Integer = CInt(s(3))
Dim y2 As Integer = CInt(s(4))

Dim x3 As Integer = CInt(s(5))
Dim y3 As Integer = CInt(s(6))

e.Graphics.DrawArc(Pens.Green, x, y, width, height, angle1, angle2)

Re: Calculate the origin and radius of a circle

Luc Pattyn1-Sep-09 13:58