C / C++ / MFC

10-Jan-05 22:50

Hello,

I need to create a form with multiple buttons instances. In C#, this
would look like this

static string[] strCaption={"Button A","Button B","Button C"};
Button[] btnShow=new Button[strCaption.Length];

for(int i=0 ; i < strCaption.Length ; i++)
{
btnShow[i]=new Button();
btnShow[i].Text=strCaption[i];
btnShow[i].Size=new Size(200,20);
btnShow[i].Location=new Point(10,35*i+20);
btnShow[i].Click+=new EventHandler(Button_Click);
btnShow[i].Tag=i.ToString();
this.Controls.Add(btnShow[i]);
}

I try to code this in C++, but I have a lot troubles setting the
identifiers.

This:
Button* btnShow[]
...
btnShow[i]=new Button();
...

Does not work. Any suggestions/code samples?

Thanks in advance,

Picander

KaЯl10-Jan-05 23:28

KaЯl

10-Jan-05 23:28

you should allocate first the size of your button array, either statically (Button *btnShow[10];) or dynamically ( Button **ppBtnShow; ppBtnShow = (Button **)calloc(10, sizeof(Button *)); [...] ppBtnShow[i] = new Button;). In the last case don't forget to free your data to avoid memory leaks!

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Cedric Moonen10-Jan-05 23:49

Cedric Moonen

10-Jan-05 23:49

I think it is better to have an array that contains directly the buttons and not the pointers to the buttons (otherwise you will need to destroy your buttons after use, ...).

So it looks like:
CButton* m_pButtonArray;

And to create for example 10 buttons:
m_pButtonArray = new CButton[10];

Then you will need to 'initialize' them using the Create method and then call ShowWindow(SW_SHOW) for all of them.

Hope this helps

Sohail_CSC11-Jan-05 0:56

Sohail_CSC

11-Jan-05 0:56

Hi Picander,
You forgot to attatch your code, and you didn't mention which compiler your are using VC6.0 or DOT net. Well I gave a try to do the same stuff you have tried, with MCF in VC6.0. You might take a look to it.

//---------------------------------------------------
char *strCaption[3]= {"Button A","Button B","Button C"};
char buffer[20];

int butt_width = 90,
butt_height = 30,
butt_pad = 10;

CButton *myButton = new CButton[3];

// Create a push button.
for(int i=1 ; i <= 3 ; i++)
{
myButton[i-1].Create(strCaption[i-1], WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON, CRect(10, 10 + butt_height * (i-1), 100, butt_height*i), this, 1);
//add code to populate variables
}
//--------------------------------------------------------

Good Day
Sohail

picander7711-Jan-05 3:49

11-Jan-05 3:49

Thanks for the reply Sohail!

I forgot to mention that I am developing a .NET windows forms application.

Button *myButton = new Button[3];

does not work...
gui\myForm.cpp(87) : error C2691: 'System::Windows::Forms::Button' : invalid type for __gc array element
gui\myForm.cpp(87) : error C3149: 'System::Windows::Forms::Button' : illegal use of managed type 'System::Windows::Forms::Button'; did you forget a '*'?
gui\myForm.cpp(87) : error C2691: 'System::Windows::Forms::Button __gc *' : invalid type for __gc array element

i have tried many other options, as other posted suggested and i still cannot get it working.
I cannot find on the net any similar code sample for c++.

Maximilien11-Jan-05 2:38

Maximilien

11-Jan-05 2:38

you need to reserve a range of continuous resource ID for your array of buttons; and manually create a ON_CONTROL_RANGE entry in the message map.

The problem with MFC is that you need to have a predefined ID range; you can't create the buttons with no defined ID and have it registered in the message map ( or I think so ).

ON_CONTROL_RANGEBN_CLICKED, id1, id2, OnButtonsClicked)

void YourMethod::OnButtonsClicked(UINT nCmdID)
{
  // nCmdID is the ID of the button you just clicked
  switch ( nCmdID )
  {
    case id1:
    ...
    case id2:
      break;
    default:
      break;
  }
}

One other way would be to create your own class of button that have callbacks that can be sent to the parent window.

Maximilien Lincourt
Your Head A Splode - Strong Bad

picander7711-Jan-05 4:09

Re: Array of Buttons SOLUTION

11-Jan-05 4:09

Thanks for all the replies! You are great folks!

Here is the combination of your suggestions:

Button* myButtons[];
myButtons= new Button *[20];
for (int i = 0; i < 20; i++)
myButtons[i] = new Button();

picander7711-Jan-05 4:10

Re: read data from line in

11-Jan-05 4:10

Thanks for all the replies! You are great folks!
For a .net managed c++ windows form application, here is the combination of your suggestions:

Button* myButtons[];
myButtons= new Button *[20];
for (int i = 0; i < 20; i++)
myButtons[i] = new Button();

rtf help

Mohammad Daba'an10-Jan-05 22:22

Mohammad Daba'an

10-Jan-05 22:22

hi all there, i want a code that help me to insert any file type in a rtf file, i need to insert by code not drag drop by mouse so plzzzzzzzzzzzzz help me .......

Thanks alot
Metal Man

read data from line in

gecool10-Jan-05 22:21

gecool

10-Jan-05 22:21

Hi. Can anyone help me on this: I need to read data from sound card on line in. All I want is to get the digitized data that represents the signal I apply to line in. If anyone could suggest me some docs, or anything related to this I would be thankful.

PLEASE HELP !!! Thank you.;)

KaЯl10-Jan-05 23:20

KaЯl

10-Jan-05 23:20

You could record this data using the Waveform-Audio Interface. You may find information on how to use this API to record audio data at the following address: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/multimed/htm/managingwaveformaudiorecording.asp[^].

HTH,

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increase the max length of SETWINDOWTEXT

Member 147966910-Jan-05 21:43

Member 1479669

10-Jan-05 21:43

hello,

I have a problem. the call SETWINDOWTEXT truncates the length of the displayed text to 259 characters (dialog based, ansi mode) (somebody else reported 159), i don't see any dots, also a lot of space is left on the bar. A getwindowtext will return the full original string.

I try to set a titlebar of my dialog with 3 strings which are left, center and right justified. I do this by inserting a lot of spaces between the strings

Things i can do, but don't wan't to:
- Change the active title bar font.
- Draw my own titlebar.

The following code will work on a 800x600 mode maximized dialog, but not on a 1600x1200.

<code>
void SetWindowText3(CWnd* TargetWnd, CString LeftText, CString MidText, CString RightText)
{
CRect Rect;
int CaptionWidth;
CFont font;
CDC dc;
NONCLIENTMETRICS ncm;
int LeftWidth;
int MidWidth;
int RightWidth;
int SpaceWidth;
int FillWidth;
int FillLeftWidth;
int FillRightWidth;
int PosCenter;
CString CaptionText;

/****************************************************************************
Figure out the maximum width of the caption text
****************************************************************************/
TargetWnd->GetWindowRect(Rect);
CaptionWidth = Rect.Width(); // get width of whole window
CaptionWidth -= 2*GetSystemMetrics(SM_CXBORDER); // Remove left and right the border width
CaptionWidth -= 2*GetSystemMetrics(SM_CXFRAME); // Remove left and right the frame width
if (TargetWnd->GetStyle() & WS_SYSMENU)
CaptionWidth -= 2*GetSystemMetrics(SM_CXSIZE); // Remove the icon and close button
else
CaptionWidth -= 5; // Remove extra edge if no close button
PosCenter = CaptionWidth/2;
if ( (TargetWnd->GetStyle() & WS_MAXIMIZEBOX)
|| (TargetWnd->GetStyle() & WS_MINIMIZEBOX) )
CaptionWidth -= (2*GetSystemMetrics(SM_CXSIZE)) - 1; // Remove the width of the minimizebutton

/****************************************************************************
Prepare the GetTextExtent function.
****************************************************************************/
ncm.cbSize = sizeof(NONCLIENTMETRICS); // i don't why this is used.
SystemParametersInfo(SPI_GETNONCLIENTMETRICS,
sizeof(NONCLIENTMETRICS), &ncm, 0); // get the pointer to the nonclientmetrics struct
font.CreateFontIndirect(&ncm.lfCaptionFont); // Create a copy of the font used title bar
dc.CreateCompatibleDC(NULL); // Create an DC
CFont* pOldFont = (CFont*)dc.SelectObject(&font); // Make sure that gettextextent uses the correct font.
dc.SetMapMode(MM_TEXT); // Make sure that gettextextent returns PIXELS.

/****************************************************************************
Get various width in pixels of the thext
****************************************************************************/
LeftWidth = dc.GetTextExtent(LeftText).cx; // Get the text width of the left text.
MidWidth = dc.GetTextExtent(MidText).cx; // Get the text width of the mid text.
RightWidth = dc.GetTextExtent(RightText).cx; // Get the text width of the right text.
SpaceWidth = dc.GetTextExtent(_T(" ")).cx; // How many pixels does a space take
FillWidth = (CaptionWidth - LeftWidth -
MidWidth - RightWidth)/SpaceWidth; // How much space is left on the title bar?

/****************************************************************************
Bug Work around. Make sure text is never longer as 259 characters
****************************************************************************/
// if ((LeftText.GetLength()+MidText.GetLength()+RightText.GetLength()+FillWidth)>259)
// FillWidth = 259 - (LeftText.GetLength()+MidText.GetLength()+RightText.GetLength());

/****************************************************************************
Fill in the spaces between the text and write the text to the title bar
****************************************************************************/

FillLeftWidth = (PosCenter-LeftWidth-(MidWidth/2))/SpaceWidth; // Space (in characters) between left and middle
//FillLeftWidth = FillWidth/2; // Same as above, but midtext in middle of empty area
FillRightWidth = FillWidth - FillLeftWidth; // space (in characters) between middle and right

CaptionText = LeftText;

for (int loopy=0;loopy<FillLeftWidth;loopy++) // How many space are needed between left and middle?
CaptionText += _T(" "); // Add a space to the caption text

CaptionText += MidText; // Add the middle text to the caption text

for (int loopy=0;loopy<FillRightWidth;loopy++) // How many space are needed between middle and right?
CaptionText += _T(" "); // Add a space to the caption text

CaptionText += RightText; // Add the right text tot the caption text
TargetWnd->SetWindowText(CaptionText); // now actually set the windows text

/****************************************************************************
Delete temperary objects
****************************************************************************/
dc.SelectObject(pOldFont);
font.DeleteObject(); // Delete the font.
dc.DeleteDC(); // Delete the DC
}
</code>

Re: increase the max length of SETWINDOWTEXT

Roger Allen10-Jan-05 23:19

Roger Allen

10-Jan-05 23:19

You could take a look at this article http://www.codeproject.com/gdi/customcaption.asp[^] which shows how to do custom captions.

If you vote me down, my score will only get lower

CRectTracker and scrolling problems

Maverick10-Jan-05 21:38

Maverick

10-Jan-05 21:38

Hello! I've seen some sample programs on how to use CRectTracker properly, but i only have seen it on ordinary CViews...

I noticed the problem when i used CScrollViews and when I'm scrolling..

When I scroll the view, the CRectTracker also scrolls, thats fine.. But when I scroll all the way to the right, the CRectTracker is supposed to disappear, since its coordinates is out of the view already, and thats fine... But When I scroll back to its position, i expected to see it back, but i didn't.... I want the CRectTracker to be appearing again..

How do i solve this?

FIFO thread synchronizing

Menny Even Danan10-Jan-05 20:53

Menny Even Danan

10-Jan-05 20:53

Hello,
i'm programming a multithreaded communication application. Some of the communication operations are being hold in a a shared (for all threads) synchronized queue. the synchronized queue is using c++ 'CRITICAL_SECTION' handle (using the 'EnterCriticalSection' and 'LeaveCriticalSection' functions).

have three questions (actually it's two):
1) Is 'CRITICAL_SECTION' ensure FIFO threads access into the critial sections of code?
2) If not, what can i use to ensure FIFO access?
3) If yes, is there a better (less CPU time, less resources) way to ensure FIFO access to critical sections of code?

thanks

Blake Miller11-Jan-05 4:03

Blake Miller

11-Jan-05 4:03

1. Yes. This first thread to request critical section using EnterCriticalSection acquires it. The others must wait until the critical section is released with LeaveCriticalSection. I have seen some articles, posts, and other submissions here at the CodeProject site arguing that a class wrapper is a good idea in case you experience an exception - the critical section will not remain locked by a thread experiencing the exception. You can also look into TryEnterCriticalSection if you do not want your threads to block for some reason.

2. You can also use Mutex if your data is accessed by multiple threads from multiple processes. IF the data is only acessed by a single process, the critical section is generally the easiest and the quickest, without getting into interlocked element usage.

3. Not really. The critical section has been the recommended element for single-process multiple-thread protection of sections of code.

Menny Even Danan11-Jan-05 21:39

Menny Even Danan

11-Jan-05 21:39

Hello,
Are you sure that CRITICAL_SECTION handles the threads waiting in FIFO order?

MSDN does not reffer to it any where

could you point me to an article or something that talks about it?

thanks

Blake Miller12-Jan-05 5:00

Blake Miller

12-Jan-05 5:00

I misunderstood your initial question, and thought you were trying to implement a FIFO stack or similar queue.

This is what MSDN had to say about the critical section:
Platform SDK : DLLs, Processes, and Threads : Critical Section Objects ; Last updated: April 2004
"A critical section object provides synchronization similar to that provided by a mutex object, except that a critical section can be used only by the threads of a single process. Event, mutex, and semaphore objects can also be used in a single-process application, but critical section objects provide a slightly faster, more efficient mechanism for mutual-exclusion synchronization (a processor-specific test and set instruction). Like a mutex object, a critical section object can be owned by only one thread at a time, which makes it useful for protecting a shared resource from simultaneous access. There is no guarantee about the order in which threads will obtain ownership of the critical section, however, the system will be fair to all threads. Unlike a mutex object, there is no way to tell whether a critical section has been abandoned."