C / C++ / MFC

sawerr9-Sep-08 12:27

sawerr

9-Sep-08 12:27

OK. Understood.

But is there a way to send a text string to another application with SendMessage+WM_SETTEXT?
Because of lPararm is just a pointer, this way doesn't allow to send a buffer to another application i think. Or I couldn't find a way...

Mark Salsbery9-Sep-08 12:48

9-Sep-08 12:48

sawerr wrote:
is there a way to send a text string to another application with SendMessage+WM_SETTEXT?

No. You could use WM_COPYDATA or some other IPC mechanism[^] however.

Did you mention another application and I missed it?
I thought this was DLL to EXE...

Mark

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

sawerr9-Sep-08 13:00

sawerr

9-Sep-08 13:00

Yes, it is dll to exe. But dll calls SetWindowsHookEx. So it is loaded to all processes address spaces.
So it becomes exe to exe, as in the figure:
http://www.codeproject.com/KB/DLL/hooks.aspx[^]

I thought i could update textbox's text from dll as i tried to explain above.(In dll first get text with Sendmessage-WM_gettext and append new presssed key and send it to the application with SendMessage+WM_SETTEXT)

Mark Salsbery9-Sep-08 13:32

9-Sep-08 13:32

sawerr wrote:
So it becomes exe to exe, as in the figure:

Then I guess other options are to one of the IPC methods described
at the previous link or do something similar to what Joe does in his
article but post the WPARAM and LPARAM passed to the KeyboardProc to
a window in the exe process and let the EXE do the string stuff.

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

Mark Salsbery9-Sep-08 12:56

9-Sep-08 12:56

I just noticed this

sawerr wrote:
int textlength = SendMessage(hWndServer, WM_GETTEXTLENGTH, 0, 0) + 1 ;

You already added 1 ... I didn't see that, but this:

sawerr wrote:
TCHAR *td = new TCHAR(textlength+1);

is BAD! That should be

// Notice the square brackets!
TCHAR *td = new TCHAR[textlength];  // + 1 for NULL terminator already added above

The wrong brackets is probably the runrime error problem, since not enough
space is allocated for a string longer than 0 TCHARs if you use parenthesis. Smile | :)

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

how to get registry subkey value using c++

sawerr9-Sep-08 13:07

sawerr

9-Sep-08 13:07

Shame on me. OK. I see it.

But although these stupid errors, i think wm_settext+sendmessage could not send text as i tried to explain my previous post.

adhilingam9-Sep-08 6:14

adhilingam

9-Sep-08 6:14

Hi Am new to the registry concept in C++, I need help regarding registry subkey concepts. If possible please solve my issue with example source code to get registry subkey value.

Re: how to get registry subkey value using c++

Perspx9-Sep-08 6:59

Perspx

9-Sep-08 6:59

This article should help.

Regards,
--Perspx

Don't trust a computer you can't throw out a window

-- Steve Wozniak

Re: how to get registry subkey value using c++

vikas amin9-Sep-08 7:42

vikas amin

9-Sep-08 7:42

microsoft article
http://msdn.microsoft.com/en-us/library/ms838625.aspx[^]

Vikas Amin

My First Article on CP" Virtual Serial Port "[^]

modified on Thursday, July 24, 2008 5:33 PM

Re: how to get registry subkey value using c++

Hamid_RT9-Sep-08 8:10

Hamid_RT

9-Sep-08 8:10

Or see here[^].

DrawText is giving me garbage

thebeekeeper9-Sep-08 5:16

9-Sep-08 5:16

I'm losing my mind over some Unicode issue and hopefully someone can help me out. I haven't done a ton of MFC stuff before, so hopefully it's a simple problem.

I've Unicode enabled in this project because I've got a 3rd party library that requires it. I've subclassed CListBox to get a list box that shows multiple lines per item. I'm overriding DrawItem and MeasureItem. In DrawItem I have the following lines for drawing text:

LPCTSTR lpszText = (LPCTSTR) lpDrawItemStruct->itemData;
...
dc.DrawText(lpszText, _tcslen(lpszText), &lpDrawItemStruct->rcItem, DT_LEFT | DT_TOP | DT_WORDBREAK);

In my main dialog class I add data to the list box like this:

m_ProductList.AddString((LPCTSTR)updates[i]->ToString().c_str());

And my text comes out looking like garbage. Usually Chinese characters. I can get the output to look correct if I do:

m_ProductList.AddString(TEXT("yoyoyoyoy\nzomgzomg\nblabla"));

I tried looking at what the TEXT macro does, but the farthest I can get is that is is an alias for L## which is difficult to google.

I've tried a lot of stuff and nothing has worked. I've tried: MultiByteToWideChar, CT2CW, A2W, and some other stuff.

My understanding of this issue is that I've got a UTF-8 encoded string from an XML file that's stored in a std::string. Then, since I'm using Unicode, DrawText is actually DrawTextW. So, I have to convert my string to Unicode, but nothing seems to be able to do that conversion.

Thanks,
Nick

Mark Salsbery9-Sep-08 5:30

9-Sep-08 5:30

Instead of trying a bunch of stuff, it may be easier to take a close
look at the type of the characters in your strings.

A good clue is the need for casts. You shouldn't need any casts.
If you do, then look at why.

For example:
m_ProductList.AddString((LPCTSTR)updates[i]->ToString().c_str());

Why the cast to LPCTSTR?

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

thebeekeeper9-Sep-08 5:37

9-Sep-08 5:37

I was a little confused about that part too. If I don't cast it, I get a compile error: cannont convert from const char* to LPCTSTR. I always thought those were the same thing.

Another odd part of this problem is that when I use a standard CListBox, I can correctly add items to it like this:

USES_CONVERSION;
CA2CT converted(updates[i]->ToString().c_str());
m_UpdateBox.AddString(converted)

Which makes it seem like I'm incorrectly calling DrawText in my subclass because when I add the same text to my list box I get bad data on the display.

Mark Salsbery9-Sep-08 5:45

9-Sep-08 5:45

thebeekeeper wrote:
I get a compile error: cannont convert from const char* to LPCTSTR. I always thought those were the same thing.

That's exactly what I'm talking about Smile | :)

That's a perfect example why
casting away problems is BAD. C++ is a strongly typed language - know
your data types!

No, LPCTSTR is NOT the same as a char *.

Here's the macro breakdown for LPCTSTR:
LP = long pointer
C = constant
T = generic-character-type (wchar_t for Unicode builds, else char)
STR = string

thebeekeeper wrote:
when I use a standard CListBox, I can correctly add items to it like this:

Yes, because you're converting the string to the type the
listbox is expecting.

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

thebeekeeper9-Sep-08 6:09

9-Sep-08 6:09

Thanks for that tip on data types. I never realized LPCTSTR was just an alias for the generic string type of the build.

I guess this is really what I don't understand. CA2CT converts ASCII to wchar_t since this is a Unicode build, right?

CListBox::AddItem expects LPCTSTR. But this is actually a LPCWSTR, right? So, why does converting with CA2CT work with the stock CListBox and not my subclass? CListBox::DrawItem has to be calling DrawTextW, which is the same thing I'm calling.

Mark Salsbery9-Sep-08 6:22

9-Sep-08 6:22

thebeekeeper wrote:
CA2CT converts ASCII to wchar_t since this is a Unicode build, right?

Right. A is ANSI, T is generic...A2T is ANSI to generic.

thebeekeeper wrote:
why does converting with CA2CT work with the stock CListBox and not my subclass?

Is the source string already a Unicode (wchar_t) string?

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

thebeekeeper9-Sep-08 6:36

9-Sep-08 6:36

No, it's coming out of std::string c_str(), so it's a const char*. There's no way that can be Unicode, right?

Also, if I use OutputDebugString, it works after I use the CA2W conversion and looks correct in the output window. So, I've got this:

USES_CONVERSION;
CA2W converted(updates[i]->ToString().c_str());
// CListBox -- looks right
m_UpdateBox.AddString(converted);
// CMyListBox -- looks wrong
m_ProductList.AddString(converted);
// Output window -- looks right
OutputDebugString(converted);

I'm starting to think I'm pulling out bad data in my DrawItem method, but I copied that code from MSDN, so it can't be wrong OMG | :OMG:

Mark Salsbery9-Sep-08 7:09

9-Sep-08 7:09

thebeekeeper wrote:
it's coming out of std::string c_str(), so it's a const char*. There's no way that can be Unicode, right?

Right, but a deeper question is why are you using a string
type hardwired to char in a Unicode environment?

I recommend using generic string types everywhere in
an MFC app. MFC does, so it works out nice when we do.
Using all generics makes any code you write compilable in
both Unicode and non-Unicode builds, just like MFC. Plus
you don't need to do all those string conversions, which are
inefficient.

If you must use STL strings, you could make your own generic
string class:

typedef std::basic_string<TCHAR, char_traits<TCHAR>,
	allocator<TCHAR>>  genericstdstring;

Use genericstdstring in place of std::string.

thebeekeeper wrote:
but I copied that code from MSDN, so it can't be wrong

Umm...if you say so Smile | :)

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

thebeekeeper9-Sep-08 6:59

9-Sep-08 6:59

AHA! I just figured out that I'm doing the conversion correctly (maybe), the problem is I have bad data to convert.

I inspected the memory location that lpDrawItemStruct->itemData was pointing to, and it looked like garbage. So, I added a method to my class where I can send text and store it in a vector. Then, in DrawItem I just look in my own vector for strings to draw, and everything works fine.

I guess this works for now, but I'd really like to know how to get my string out of itemData so I can use AddString on my list box like a normal person.

The only idea that I have right now is that my initial cast in DrawItem is bad.

LPCTSTR lpszText = (LPCTSTR) lpDrawItemStruct->itemData;

I don't see how this could be bad since that's exactly what I'm passing to AddString. The strange this is that it works when I pass in a literal with TEXT("..."), but not a converted const char* from string.c_str().

Thanks for your help!

Mark Salsbery9-Sep-08 7:17

9-Sep-08 7:17

thebeekeeper wrote:
The only idea that I have right now is that my initial cast in DrawItem is bad.

That cast is valid and necessary, since
DRAWITEMSTRUCT.itemData is a ULONG_PTR.

I'm not sure why you're getting garbage there...

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

Mark Salsbery9-Sep-08 7:19

9-Sep-08 7:19

thebeekeeper wrote:
The strange this is that it works when I pass in a literal with TEXT("..."), but not a converted const char* from string.c_str().

Ooops I missed that part Smile | :)

What conversion are you using there?
Are you sure that conversion is succeeding?
I'm thinking no Smile | :)

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

thebeekeeper9-Sep-08 7:25

9-Sep-08 7:25

I'm using the same CA2W conversion that I use on a const char* from c_str(). And no, it doesn't work, but the strange thing is that it's like the data is going bad when I pass it into CMyList::AddString().

So, if I create a LPCWSTR hello = TEXT("hello") and pass it into CListBox and CMyList::AddString everything works fine.

But! If I do a CA2W conversion and pass it into both of those same methods, it works for CListBox, but now for CMyList. Dead | X|

Mark Salsbery9-Sep-08 7:31

9-Sep-08 7:31

thebeekeeper wrote:
I'm using the same CA2W conversion

Why did you switch to CA2W, when the generic CA2CT was the
appropriate conversion?

Again, why is the conversion even necessary? Do you really
need to use char type strings anywhere? char has been pretty much
obsolete for a decade Smile | :)

Mixing hardwired character types and generic types causes
problems like these, which is why I recommend using the
generic types.

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