Learning to use an API - C / C++ / MFC Discussion Boards

Santanu Lahiri24-Mar-03 20:20

24-Mar-03 20:20

You can open a com port as a file under Win32. With minor restrictions, you can specify Read or Write attributes when opening such files to read from or write to. You can even try opening the ports as CFile using MFC. There is an example on Microsoft's site showing how to do this, including creating CArchive objects based on these files. After they are open, you can use standard file read and write routines or the << and >> operators. Look at MSDN.

Here is a link to start you off. This goes through the theory, anyway, plus it is non-mfc. Can't recall the MFC link, but you can look at the VCTERM sample for specs on using the Communication control as well..

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnfiles/html/msdn_serial.asp

My personal experience: Do not try to do the copy in the same thread. Gets very messy. I spun off threads to read and write to and from the files. That worked well, except you now need synchronization between the threads.

Good Luck! Smile | :)

Message Handling in Controls instead of Dialog

brigham_young24-Mar-03 13:00

brigham_young

24-Mar-03 13:00

I've added message handlers for a ComboBox control to that combobox's class (a subclass of CComboBoxEx which I have defined) to handle messages such as WM_CHAR, etc. However, when I use that combobox in a Dialog, my message handlers are not triggered by the user interactions which they are supposed to respond to. Any ideas on what is going on or how i can solve this problem would be much appreciated.

Ben

Re: Message Handling in Controls instead of Dialog

bryce24-Mar-03 14:03

bryce

24-Mar-03 14:03

did you subclass it?

in the oninitdialog... or somewhere useful

m_myCombo.SubClassWindow(IDC_MYCOMBO, this);

Bryce

Re: Message Handling in Controls instead of Dialog

Alin Negru24-Mar-03 22:02

Alin Negru

24-Mar-03 22:02

As I understood you have your own class CComboBoxEx in which you have implemented a handler for WM_CHAR, right?
And more you want to use this combo in your dialog.
Then if this is correct then add a combobox to your dialog by dragging it from the resource editor and add a member variable to that combo of the type CComboBox. Then go where your variable was added and change the variable from type CComboBox to CComboBoxEx.
I hope I understood corectly your question...

Add Custom Controls To A Dialog???

brigham_young24-Mar-03 12:12

brigham_young

24-Mar-03 12:12

I have my own combo-box subclass (CMyCombo) that extends CComboBoxEx in order to add some specific features to all combo boxes in my program. However, I do not know how to display combo boxes of my type in Dialogs. Is there any way to add a combo box control to a dialog box in the resource editor, but use my subclass to implement it, rather than the default CComboBoxEx ?

Ben

Re: Add Custom Controls To A Dialog???

Dave Bryant24-Mar-03 12:17

Dave Bryant

24-Mar-03 12:17

Add it as a normal combo box to the template. Then in class wizard add a control member for the combo box (not a value). This adds a CComboBox member to the class definition - you can then replace CComboBox with CMyCombo.

Dave

Re: Add Custom Controls To A Dialog???

brigham_young24-Mar-03 12:18

brigham_young

24-Mar-03 12:18

Thank you!

Learning to use an API

trimtrom24-Mar-03 12:09

trimtrom

24-Mar-03 12:09

Hello,
I am a beginner trying to understand how to use an API (in this case HtmlHelp). I am not sure how to call an API method: I want to call a method HtmlHelp(...), which has four arguments, and I can see this in Intellisense if I put two colons before the methodname:

::HtmlHelp(HWND hwndCaller, LPCSTR pszFile, UINT uCommand, DWORD dwData) ;

However, all the examples I read show the method being called without the two colons, yet with four arguments. What does this mean?? Does this relate to namespaces?? When I take away the colons, the Intellisense shows only the CWinApp method:

virtual void HtmlHelp(DWORD_PTR dwData, UINT nCmd = 0x000F);

with two arguments. When I use the ::HtmlHelp(...) with four arguments, I get the following error message:

LPSEmail error LNK2019: unresolved external symbol _HtmlHelpA@16 referenced in function "public: int __thiscall CMainFrame::OnHelpInfo(struct tagHELPINFO *)" (?OnHelpInfo@CMainFrame@@QAEHPAUtagHELPINFO@@@Z)

I have placed the htmlhelp.lib file in the lib directory, and the htmlhelp.h at the top of this class. So what have I done wrong?? Do I need the colons??

Sincerely,
Trimtrom

Re: Learning to use an API

Dave Bryant24-Mar-03 12:15

Dave Bryant

24-Mar-03 12:15

The double colons force the compiler to look in the global namespace for the function - without them it will always look in the current class first, meaning that it finds the HtmlHelp() method rather than the global function.

To link with HtmlHelp.lib, you must add it to the list of libraries in the project settings (Project->Settings->Link) - it does not automatically link with all libraries in the lib directory.

Dave

When do I initialize a CListView?

Jonah Bishop24-Mar-03 11:51

Jonah Bishop

24-Mar-03 11:51

I'm creating an SDI application using the CListView class as the base view, and I'm having a problem knowing when I should do things like InsertColumn(). If I use the OnInitialUpdate() method, columns get inserted every time that a new document gets created. When I try to use the OnCreate() method, I get an exception stating that the main frame has not yet been created (note that I'm getting a pointer to the main frame object to set some window "snap" settings).

Is there a method for a view that gets called only once upon program startup, but after all the windows have finished their creation state? I basically want to know where I should insert columns and do other, one-time initialization stuff.

Any ideas?

Thanks,

Jonah Bishop
Visit JGB Productions

Re: When do I initialize a CListView?

Ravi Bhavnani24-Mar-03 12:04

Ravi Bhavnani

24-Mar-03 12:04

How about just using a flag bListCtrlInitialized in OnInitialUpdate() to ensure it gets done just once?

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

Re: When do I initialize a CListView?

Jonah Bishop24-Mar-03 15:00

Jonah Bishop

24-Mar-03 15:00

Yes - I've thought of that, and it certainly would work. But it just seems so cheap... Smile | :)

Jonah Bishop
Visit JGB Productions

color palette

mstacey24-Mar-03 11:43

mstacey

24-Mar-03 11:43

I am trying to create a color palette that will allow someone to pick what color of text they want. I can't seem to find anything to help me out on this. Any ideas?

Re: color palette

_Theo_24-Mar-03 22:25

_Theo_

24-Mar-03 22:25

Use the ChooseColor function to create a dialog box where you can pick a color.

String replace

act_x24-Mar-03 11:42

act_x

24-Mar-03 11:42

I have a string that is :

string myString ="Appliance.Oven.Heater";<br />
string commandString="Run:appladdr:TurnOn:150seconds";

In commandString I want to replace "appladdr" with myString .
for the final string to be
Run:Appliance.Oven.Heater:TurnOn:150seconds

I was getting a memory error using CString .
when I did

CString finalString = commandString.c_str();<br />
finalString.replace("appladdr",myString.c_str());

What am i doing wrong ?
I would like to do this using STL itself.

Re: String replace

Nick Parker24-Mar-03 12:09

Nick Parker

24-Mar-03 12:09

act_x wrote:
What am i doing wrong ?
I would like to do this using STL itself.

My good deed of the day: Wink | ;)

#include <iostream.h>
#include <string>

using namespace std;

void main()
{

	string myString ="Appliance.Oven.Heater";
	string commandString="Run:appladdr:TurnOn:150seconds";
	commandString.insert(4, myString.c_str());
	commandString.replace(24, 8, "");
	cout << commandString.c_str() << endl;


}

-Nick Parker

The true measure of a man is how he treats someone who can do him absolutely no good. - Samuel Johnson

Re: String replace

Dave Bryant24-Mar-03 12:13

Dave Bryant

24-Mar-03 12:13

Using STL:

int nPos = commandString.find( "appladdr" );
if ( nPos != string::npos ) {
commandString.replace( nPos, strlen("appladdr"), myString );
}

The MFC code looks right though - what exactly is the memory error that you are getting, and on which line?

Dave

Re: String replace

act_x25-Mar-03 4:15

act_x

25-Mar-03 4:15

I am doing all of the MFC in thread functions . I do not know if that is a problem . I am getting memory read errors .

Re: String replace

Dave Bryant25-Mar-03 9:04

Dave Bryant

25-Mar-03 9:04

Are you sharing the string objects between threads? MFC objects should never be used in more than one thread, and the default STL string implementation provided with VC6 is not threadsafe for reading.

Dave

CHTMLWebBrowser ActiveX is not appearing in a property page!

Anonymous24-Mar-03 9:05

Anonymous

24-Mar-03 9:05

Hello CPIAN_GURUS! Cool | :cool:

I've placed a WebBrowser2 control (the active x that comes with VC++6 (Project >> Add To Project >> Components & Controls >>...)) In a dialog and in an array of property pages...

The one that is in the dialog works perfectly, but the one that is in the array of property pages don't appear... the strange thing is that I hear the sound of the page loaded (the 'click' that sounds when a page has been loaded completely) but I cannot see the control... Eek! | :eek:

Any idea?

Do you think I'm missing something?

TYIA!!!

Re: CHTMLWebBrowser ActiveX is not appearing in a property page!

Ravi Bhavnani24-Mar-03 9:25

Ravi Bhavnani

24-Mar-03 9:25

Perhaps the one on the property page is incorrectly positioned/sized?

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

CComboBox and scrollbars.

ns24-Mar-03 7:36

24-Mar-03 7:36

I have varying widthg content that will populate the CCombobox. I checked autoHSCrollin rthe design view but it doesnt develop the horiz scrollbars when necessary> How can I get the horiz scroll functionality?

Appreciate your help,
ns

Re: CComboBox and scrollbars.

Ravi Bhavnani24-Mar-03 8:25

Ravi Bhavnani

24-Mar-03 8:25

I don't know, but this[^] article shows to craft a combobox whose droplist is always wide enough to display the widest string in the combobox.

/ravi

Let's put "civil" back in "civilization"
http://www.ravib.com
ravib@ravib.com

thanks

ns24-Mar-03 8:31

24-Mar-03 8:31

sounds promising...

Appreciate your help,
ns

Re: CComboBox and scrollbars.

PJ Arends24-Mar-03 10:35

PJ Arends

24-Mar-03 10:35

CComboBox::SetHorizontalExtent()

Sonork 100.11743 Chicken Little

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

Within you lies the power for good - Use it!

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.