Managed C++/CLI

15-Aug-07 11:59

Hi, I'm using Visual Studio 2005 C++/CLI. I have some text and graphics that I both need to display and print. For the Form1 object I used 'graphics = this->CreateGraphics();' in the Form1 constructor and then used graphics->DrawString('aCharacter', drawFont, blackBrush, x_coord, y_coord) in various functions to output text characters onto the screen so that the information fits perfectly on the screen. What I have been reading about the GDI+ is that it was designed to insulate the programmer from a lot of the printer details by using the printer drivers. When I try to print or use print preview the graphics is scaled too large. Simply using 'e->Graphics->PageScale::set((float)0.85);' will get it to fit on the printed page but things (characters) are squished together. I figured out how to obtain the Font Metrics but they are read only. I have tried changing the printDocument1->DefaultPageSettings->PrinterResolution->X (and Y) with no effect. Tried changing margins too. Spending way too much time (20 hours so far) trying to figure this out. Any information that will point me in the right direction would be helpful.

Thanks,

Buck

Luc Pattyn15-Aug-07 12:10

15-Aug-07 12:10

Hi Buck, me again. If you haven't already, you should take a look at my approach
for this in the Sokoban article. It shows a board game that fits on a monitor,
and it fits on one printed page (whatever the print dimensions would be).
It does, however not really have text (except for a title line when printing).

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

this weeks tips:
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BuckBrown16-Aug-07 9:35

16-Aug-07 9:35

Thanks Luc,

I must have been really tired or hung over because the first time I looked over the Sokoban code I didn't see what you were doing. At least now I think I can replicate some of this but I am having a problem that may be a C++ vs. C# thing. In the Board.cs file there is a class called PrintableBoard. The first line of the constructor is 'this.board = board;' (this->board = board; in CLI). If I try to do this I get the following compiler error...

error C2582: 'operator =' function is unavailable in 'System::Windows::Forms::Form'

The next line is 'PrintPage += new PrintPageEventHandler(PrintableBoard_PrintPage);' or in CLI use PrintPage^ += gcnew PrintPageEventHandler(PrintableBoard_PrintPage). If I don't use the ^ then the compiler complains that the PrintPageEventHandler needs 2 arguments not just 1. If I do include the ^ then I get 'error C2059: syntax error : +='. Is this a C++ vs. C# issue?

Buck

Buck

Luc Pattyn16-Aug-07 10:41

16-Aug-07 10:41

Hi Buck,

the PrintableBoard class has a class member "private Board board;" in C#.
I believe you would need a "private: Board^ board;" in C++.

and then the "this->board=board;" should work AFAIK.
i.e. in C++, the way I understand it, all reference types need a ^ when defined
and good old -> where I gladly use a simple . in C#

Hope this helps.

Luc Pattyn [Forum Guidelines] [My Articles]

BuckBrown16-Aug-07 9:43

16-Aug-07 9:43

Hi Luc,

Actually there is a difference in the structure of the definition of 'PrintPage^ += gcnew PrintPageEventHandler(PrintableMap_PrintPage);' I did a search on the entire Sokoban solution for PrintPage and there was only the 1 occurrance. How and where is PrintPage defined?

Buck

Luc Pattyn16-Aug-07 10:34

16-Aug-07 10:34

Hi Buck,

When there is a PrintDocument that .NET wants to print, it does two things:
- it invokes OnPrintPage() which is empty by default, but you could override it;
- it fires the PrintPage event which is also empty, but you could add delegates
to it (with the += syntax in C# and C++).

BTW: the method that you should pass to the new delegate takes two arguments
(object sender, XXXeventArgs e) whereas the OnXXX method only takes the latter.

All the same is true for the Paint event of a Control; that's why you were looking for
an OnPaint() but did not find one in Sokoban, it has a Paint+=new ... statement instead.

This is a C++ example straight from MSDN:

pictureBox1->Paint += gcnew System::Windows::Forms::PaintEventHandler(
 this, &Form1::pictureBox1_Paint );

Hope this helps.

Luc Pattyn [Forum Guidelines] [My Articles]

BuckBrown16-Aug-07 11:17

16-Aug-07 11:17

I still can't get the SOB to compile. I get an...

error C3924: error in argument #2 of delegate constructor call 'System::Drawing::Printing::PrintPageEventHandler

I guess I'll have to take the next week (Ha! more like the next couple of months) and learn about delegates.

Buck

Luc Pattyn16-Aug-07 11:24

16-Aug-07 11:24

showing the code would give us a chance to suggest a fix.

Luc Pattyn [Forum Guidelines] [My Articles]

BuckBrown16-Aug-07 12:27

16-Aug-07 12:27

Yes, yes, yes! I have verified this by making a copy of the board.cs file and renaming it board.cpp. Then I included it into the VS solution and remarked out all of the code. The I unremarked the code compiling as I went. Propblems did not occur until the line...

PrintPage += gcnew PrintPageEventHandler(PrintableBoard_PrintPage);

I had tried ...
PrintPage += gcnew PrintPageEventHandler(PrintableBoard_PrintPage);
PrintPage += gcnew PrintPageEventHandler(this, PrintableBoard_PrintPage);
PrintPage += gcnew PrintPageEventHandler(&PrintableBoard_PrintPage);
PrintPage += gcnew PrintPageEventHandler(this, &PrintableBoard_PrintPage);
PrintPage += gcnew PrintPageEventHandler(Namespace::PrintableBoard::PrintableBoard_PrintPage);
PrintPage += gcnew PrintPageEventHandler(&Namespace::PrintableBoard::PrintableBoard_PrintPage);
PrintPage += gcnew PrintPageEventHandler(this, Namespace::PrintableBoard::PrintableBoard_PrintPage);

but I missed...

PrintPage += gcnew PrintPageEventHandler(this, &Namespace::PrintableBoard::PrintableBoard_PrintPage);

Which is the correct syntax because now it will compile. The other combinations just give similar error messages.

Thanks a lot, chances are that I would not have gone back and realized that there was one combination of arguments that I had not tried.

Buck

Luc Pattyn16-Aug-07 12:50

16-Aug-07 12:50

Hi Buck,

the fact is I never did any C++/CLI so I gave it a single try which obviously
failed, then read the MSDN page on Paint event, and copied what was in the example.

It is good to do some experiments, it is even better to combine them with
reading some documentation. And when new at a language it really pays to buy
and study a book on it (I have the book, just haven't read it yet).

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

BuckBrown20-Aug-07 6:26

20-Aug-07 6:26

Hi Luc,

Trust me, I spend half my day reading documentation. I do have a little issue that may be a circular dependency. Taking the Sokoban projects Board.cs file and modifying it to be C++ code I have remarked out the guts of the functions and everything compiles just fine. In the 'Board' class there is a function named

public: void Print() {
PrintDocument^ printDoc = gcnew PrintableBoard(this) // unremark out this one line
};

The class 'PrintableBoard' is defined after the 'Board' class. If I leave the single line in the Print() function I get an "error C2061: syntax error : identifier 'PrintableBoard'". Is this a C++ vs. C# issue?

Thanks

Buck

BuckBrown20-Aug-07 6:42

20-Aug-07 6:42

Okay, I had been trying to use a forward declaration with no luck but I must have gotten the location of the forward decalration in the right place because now it will compile.

Buck

Luc Pattyn20-Aug-07 13:12

20-Aug-07 13:12

So I can ignore both messages then?
I am unaware of any circular reference stuff, I never had such a problem in C#;
I do recall C needed forward declarations once in a while, I trust C++ is the same.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Luc Pattyn16-Aug-07 11:41

16-Aug-07 11:41

Hi Buck,

I just learned C++ needs two arguments ina delegate constructor, the first one
being "this".

The following code compiles:

namespace test3 {
	using namespace System;
	using namespace System::ComponentModel;
	using namespace System::Collections;
	using namespace System::Windows::Forms;
	using namespace System::Data;
	using namespace System::Drawing;
	using namespace System::Drawing::Printing;

	public ref class PD : public System::Drawing::Printing::PrintDocument {
	public:
		PD(void) {
			this->PrintPage+=gcnew PrintPageEventHandler(
				this, &test3::PD::pdm);
		}
 
		void pdm(Object^ sender, PrintPageEventArgs^e) {
		}
	};
}

That's my longest C++/CLI program ever. Hope it helps.

Luc Pattyn [Forum Guidelines] [My Articles]

HeapAlloc

miah alom15-Aug-07 11:13

15-Aug-07 11:13

Hi,

I have an application in C# which allocates 200MB of data from the unmanaged heap using the

[DllImport("kernel32")]
static extern void* HeapAlloc(int hHeap, int flags, int size);

I have another fucntion

[DllImport("cppwrapper.dll")]
private extern static int test(IntPtr DataOut, out string ErrorOut);

I want to pass the the pointer returned by HeapAlloc into the test function using the parameter DataOut instead of string as I run into OutofmemoryException randomly(There is a limitation on the managed heap). But I am constantly getting the system.accessviolation exception.

The body of test method looks like

SOME_API int test(LPSTR* DataOut, LPSTR* ErrorOut)
{
return _lpsomefunction(DataOut, ErrorOut);
}

Can someone guide me in the right direction...

Luc Pattyn15-Aug-07 11:23

15-Aug-07 11:23

Hi,

it would be more accurate to use:

[DllImport("kernel32")]<br />
static extern IntPtr HeapAlloc(IntPtr hHeap, int flags, int size);

since both hHeap and the return value are pointers (hence 4B on Win32 and 8B on Win64,
exactly what IntPtr gives you).

As such you can pass the return value to your test method.

But then I am puzzled as to why you would use HeapAlloc at all.
You could allocate a byte array of the same size, and use GCHandle class
to "pin" it in memory, then get its pointer (which is an IntPtr obviously).
That way you get managed memory that will not move, and will live until
you Free the GCHandle.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Mark Salsbery15-Aug-07 11:26

Mark Salsbery

15-Aug-07 11:26

Hi Luc,

Is this the C# board now?

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

miah alom15-Aug-07 11:50

15-Aug-07 11:50

Sorry if this bothered you. Since there was some C++ involved in the problem so I posted this question.

Mark Salsbery15-Aug-07 12:16

Mark Salsbery

15-Aug-07 12:16

No problem Smile | :)

I was just giving Luc a hard time.

Cheers,
Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Luc Pattyn15-Aug-07 11:55

15-Aug-07 11:55

Hi Mark,

no we are not colonizing the C++/CLI forum Laugh | :laugh:

; I just copied and improved two lines
of code from the OP and introduced some .NET stuff that exists for all CLR
languages AFAIK.

If, however I had known at that time that the identical question was posted
in the C# forum, I would have answered it there (identically). As it is, I told him
overthere not to duplicate stuff...

Please feel free to adjust whatever I may have messed up language wise.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Mark Salsbery15-Aug-07 12:16

Mark Salsbery

15-Aug-07 12:16

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

miah alom15-Aug-07 11:49

15-Aug-07 11:49

Thanks a lot for the reply.
I will try and see if it works.

miah alom15-Aug-07 11:59