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Hi' how are you.
I'm having some trouble with an ActiveX Control which i use in a project i'm working on.
The Control has a method like this:
Ax.GetCurrentImage(ref variant image, ref variant size)
Where the image parameter is supposed to return a bitmap.
And the size parameter returns the size of the bitmap.
I've tryed going in the direction of using a variable of the type System.Object, but that doesen't work.
If anyone has some ideas on how to attack this problem i would be grateful.
I'll try and post some more concrete code and error messages tomorrow when i get to work.
Venlig hilsen / Regards
Steffen Otto Jensen
(Denmark)
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 Did you not use AxImp tool or use IDE to add the ActiveX control. Variants are automatically converted to objects.
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Hi' and thanks for your reply.
Yes i did import the control with the AxImp tool.
The code that is giving me trouble is the following:
object bmp = new System.Object();
object size = new System.Object();
ax.GetBMP(ref bmp, ref size);
** pictureBox1.Image = (Bitmap)bmp;
** The exception gets thrown on this line, and sounds like this:
an unhandled exception of type System.InvalidCastException occured in WindowsApplication2.exe
Additional information: Specified cast is not valid.
The "blueprint" for the method looks like this:
ax.GetBmp(ref object vimage, ref object vsize)
And in the documentation for the ActiveX Control the two parameters of the GetBMP method is listed af Variant types.
Holding that together with this table from the framework SDK i guess the variant type is not completely supported:
TypeCode COM variant type
----------------------------------------
TypeCode.Empty --> VT_EMPTY
TypeCode.Object --> VT_UNKNOWN
TypeCode.DBNull --> VT_NULL
TypeCode.Boolean --> VT_BOOL
TypeCode.Char --> VT_UI2
TypeCode.Sbyte --> VT_I1
TypeCode.Byte --> VT_UI1
TypeCode.Int16 --> VT_I2
TypeCode.UInt16 --> VT_UI2
TypeCode.Int32 --> VT_I4
TypeCode.UInt32 --> VT_UI4
TypeCode.Int64 --> VT_I8
TypeCode.UInt64 --> VT_UI8
TypeCode.Single --> VT_R4
TypeCode.Double --> VT_R8
TypeCode.Decimal --> VT_DECIMAL
TypeCode.DateTime --> VT_DATE
TypeCode.String --> VT_BSTR
Not supported. --> VT_INT
Not supported. --> VT_UINT
Not supported. --> VT_ARRAY
Not supported. --> VT_RECORD
Not supported. --> VT_CY
Not supported. --> VT_VARIANT
Or am i just confused..
I hope to get some input back
Venlig hilsen / Regards
Steffen Otto Jensen
(Denmark)
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Try to create an actual bitmap object and see if it works, like this:
Bitmap bmp = new System.Drawing.Bitmap();
int size = 0;
ax.GetBMP(ref bmp, ref size);
pictureBox1.Image = (Bitmap)bmp;
Gaul C. Ihenacho
Gaulles Technologies, Inc
http://www.gaulles.com
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Bad luck.
when i use your suggestion:
Bitmap bmp = new System.Drawing.Bitmap(352, 288);
int size = 0;
axImage1.GetBMP(ref bmp, ref size);
pictureBox1.Image = (Bitmap)bmp;
I get the folowing error messages:
* The best overloaded method match for 'AxATLCAMIMAGELib.AxCamImage.GetBMP(ref object, ref object)' has some invalid arguments
* Argument '1': cannot convert from 'ref System.Drawing.Bitmap' to 'ref object'
* Argument '2': cannot convert from 'ref int' to 'ref object'
But thanks for your help.
Im not sure what i should do now...
Venlig hilsen / Regards
Steffen Otto Jensen
(Denmark)
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I see that this problem is not yet solved.
What are you returning the Variant as VT_DISPATCH? Can you post a bit of implementation of your COM method GetImage.
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Unfortunatly i can't do that, as i didn't implement it, the control is supplied by the manufacturer of a camera.
The only documantation i have about it is the following:
GetBMP Method:
Description:
Returns the data and size of the current bitmap image.
Syntax:
CamImage.GetBMP Image, Size
Part Description
Image: Required. A variant containing the bitmap data.
Size: Required. Contains the size of the returned bitmap data.
Remarks:
Returns the data and size of the current bitmap image. The Display property has to be set to True when using the GetBMP method, otherwise the Jpeg images won’t be decompressed to bitmaps.
Example:
In this example a bitmap is captured with the GetBMP method and saved to a file.
Dim b As Variant
Dim Size As Variant
Dim a() As Byte
Call CamImage1.GetBMP(b, Size)
a() = b
Open "C:/Test.bmp" For Binary Access Write As #1
Put #1, , a()
Close #1
I hope this is helpfull!
I appreciate your help.
Venlig hilsen / Regards
Steffen Otto Jensen
(Denmark)
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This is what you do
object bmp = new System.Object();
object size = new System.Object();
ax.GetBMP(ref bmp, ref size);
System.IO.MemoryStream ms = new System.IO.MemoryStream((byte[])bmp);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(ms);
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Thanks Rama Krishna
The code you gave me was Paste'n'Run.
That helped me a lot!
Venlig hilsen / Regards
Steffen Otto Jensen
(Denmark)
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For those of you who've not seen it, I've uploaded part 1 of a chapter excerpt from my Inside C# book. This particular part is based on a topic I see frequently asked about - string handling in C# - and I believe covers many areas and issues not found in the online documentation and other texts.
Enjoy and please feel free to drop me a line regarding the article/chapter and even how it can be improved!
Cheers,
Tom Archer
Author - Inside C#, Visual C++.NET Bible
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Thats good!
And helpful! Thank you man! 
Rickard Andersson@Suza Computing
ICQ#: 50302279 (Add me!)
E-mail: nikado@pc.nu
I'm from the winter country SWEDEN!
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When is Visual C++ .NET Bible available?
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Thanks for the interest, Albert!
That book is being "processed" now. In other words, I'm done with my work and the publisher is printing it. That usually takes about 2 months to get to the store.
Cheers,
Tom Archer
Author - Inside C#, Visual C++.NET Bible
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Cool!
So, should I buy it? Duh! I am asking the Author
Anything different from Step by Step Visual C++ .NET? How long it took you to write the book?
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Albert Pascual wrote:
So, should I buy it? Duh! I am asking the Author
Actually, I'm very forthcoming and will tell you exactly whether or not you should buy the book based on your needs. Remember, it doesn't do me any good to sell someone a book that they don't like, will probably return and certainly not have nice things to say about.
Having said that, it doesn't look like the book is for you as the book you're comparing it to is a managed extensions book and mine is an MFC book.
Therefore, if you're looking for a beginner-level managed extensions book, I'd recommend the Step by Step. I don't know of any decent intermediate-to-advanced managed extensions books. On the other hand, if you're looking for a really good MFC book, then I would recommend mine without hesitation.
Cheers,
Tom Archer
Author - Inside C#, Visual C++.NET Bible
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Thanks Tom,
Actually I am moving away from any MFC. I only use MC++ extensions and C# for UI (I use Inside C# as a reference)
Even that I think I am going to buy your book when it comes out, if is just as good as your Inside C# I am going to enjoy reading it!
Thanks
Al
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Albert Pascual wrote:
I use Inside C# as a reference
Thank you very much for the support. Have you seen the second edition yet?
Albert Pascual wrote:
Even that I think I am going to buy your book when it comes out, if is just as good as your Inside C# I am going to enjoy reading it!
Definitely the MFC book is very strong. While there will be a lot of beginner level material (no way a pub will let anyone write just an advanced MFC book for some reason), it also has tons of great material not found in any other MFC book. I think you'll get a lot out of it.
Cheers,
Tom Archer
Author - Inside C#, Visual C++.NET Bible
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Tom Archer wrote:
advanced MFC book for some reason
Tom , you are wrong 
What about MFC Internals ? Hehe ! I Catch you
Behaving like a spoiled brat
Cheers,
Joao Vaz
A person who is nice to you, but rude to the waiter, is not a nice person - Natalie Portman (Padme/Amidala of Star Wars)
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That book is about 7 years old, Joao I meant that the publishers I've spoken to won't allow you to write an advanced audience book only today :P
Cheers,
Tom Archer
Author - Inside C#, Visual C++.NET Bible
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Hehe , I guessed that you would come up with a good argument 
Cheers,
Joao Vaz
A person who is nice to you, but rude to the waiter, is not a nice person - Natalie Portman (Padme/Amidala of Star Wars)
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Tom Archer wrote:
Enjoy and please feel free to drop me a line regarding the article/chapter and even how it can be improved!
Again just an apology, I thought I had found something wrong when I had actually just been working way too long....
Great Article Tom ! 
Nick Parker
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Maybe a strange question...
Normally you know what variables you are using in your application, and what types they are.
But suppose we have to create a variabele depending on some input.
if (input == somevalue)
int i = new int();
else
string s = new string();
This won't work, because it's not possible to create a variabele in an if statement.
Anyone an idea?
Ludwig
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Hello Friends,
Before opening my main application I want to ask for password.
For which I've created one login form. After successful login my main appliocation should get open.
Now my problem is if I want to open LoginForm first, I've to supply its object in
Application.run(loginForm);
After user entering of password and my code checking of that password I want to open my main application
depending on the condition . I want to close LogonForm at this point wheather user successfully logged in or not.
For which I hope I have to call ite close method as
loginForm.close();
But if I close this form, my next main form will not get open, as LoginForm was open with Application.Run().
I dont want to make LoginForm invisible.I want to completly destroy it and then open my Main form.
Is anybody knows any way of solving this problem.
Thanks in advance.
Pranoti
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Create your LoginForm object in the Load_event (Idon't know what it's named) and call the show method (ShowDialog) and when the Load_event method returns your LoginForm object is destroyed!
Did I understand you right!?
Rickard Andersson@Suza Computing
ICQ#: 50302279 (Add me!)
E-mail: nikado@pc.nu
I'm from the winter country SWEDEN!
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Hi Rickard,
Thanks for prompt reply.
Actually, I'm making instance of Login Form in Main() class after performing certain checks.So, roughly...
public static void Main()
{
if(oneCheck)
{
if(anotherCheck)
{
LoginForm loginForm = new LoginForm();
Application.Run(loginForm);
}
else
{
//Some Code
}
}
else
{
//Some Code
}
Now in that LoginForm in the click event of OK button I'll check wheather
password is correct or not.
If password is correct My Main MDI form should open and if password is wrong one message box should open stating Password is wrong.
So in click event of OK button, LoginForm should be destroyed and either my main MDI application or message box should get open.
I hope now it should be preety clear now.
Thank you very much.
Pranoti
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