C / C++ / MFC Discussion Boards

Rick York1-Jul-04 10:27

1-Jul-04 10:27

Make sure you use a touch screen with a driver that emulates a mouse. Then it becomes just a question of being able to press buttons and other controls with fingers. Try it yourself and you will quickly see the issues involved.

__________________________________________
a two cent stamp short of going postal.

Bitmap problem

JHAKAS30-Jun-04 22:14

JHAKAS

30-Jun-04 22:14

Hi

i am facing problem related to saving the contnt of the view as image in bitmap file.

http://www.codeguru.com/forum/showthread.php?s=&threadid=300550

Help reqd. urgently.

I want my memory device context variable to be member of my CMyView class.

Sandeep

Leave your mark wherever you go

allocating memory for pointers

30-Jun-04 22:12

I have tried to pass a pointer to a function and then with a copy of it's address, allocate a block of memory to it, expecting to be able to use it after the function call.

I know what the workarounds are so please don't just supply me with the function returning an address or allocating the memory before passing the pointer.

What i need is a good explanation of why this can't be done. I'm a bit puzzled because i expected 'new' to be able to use the memory address passed into the function, even if it is a copy.
thanks in advance

D'Oh! | :doh:

#include "<iostream>"

using namespace std;

void ChangeValue(char* p);

main()
{

char* pstr=0;

ChangeValue(pstr);

/*
Why doesn't pstr now point to the first block allocated by new?
If pstr has been passed in by value and a copy of it's memory address was used
by new to identify the starting address to be stored?

This has certainly got to do with scope but i would have thought this would work.
*/

cout<

Re: allocating memory for pointers

Graham Bradshaw30-Jun-04 22:23

Graham Bradshaw

30-Jun-04 22:23

This is the way the C and C++ languages work. If you pass a variable into a function, a copy of the variable is passed in, and however you modify the variable inside that function, it will have no effect on the "original" variable.

To achieve what you want to achieve, you could either pass a pointer to a pointer, or a reference to a pointer (the second is easier to "get your head around", as a rule.

As a pointer to a pointer

ChangeValue(&pstr); // pass in the address of the pointer, not the pointer itself

and

void ChangeValue(char** p)<br />
{<br />
cout <<"about to allocate";<br />
<br />
*p = new char[50]; <br />
strcpy(*p,"Test String");<br />
<br />
}

As a reference to a pointer

ChangeValue(pstr); // note, no change to your original code

and

void ChangeValue(char*& p)<br />
{<br />
cout <<"about to allocate";<br />
<br />
p = new char[50]; <br />
strcpy(p,"Test String");<br />
<br />
}

Re: allocating memory for pointers

Member 121044230-Jun-04 22:32

Member 1210442

30-Jun-04 22:32

thankyou for the response Graham, however i'm still a little puzzled.

When i pass a pointer into a function, even though a copy is made, i am
confident of being able to modify the 'Actual' variable the pointer points too. (after dereferencing it) Why doesn't pstr also point to the newly allocated mem? Is not p a copy of pstr's address?

Re: allocating memory for pointers

Graham Bradshaw30-Jun-04 22:41

Graham Bradshaw

30-Jun-04 22:41

randallcarl@hotmail.com wrote:
i am
confident of being able to modify the 'Actual' variable the pointer points too

You're quite right, you can do that. Trouble is, that's not what your code is doing. It's modifying the value of a copy of the original variable, which will leave the value of the original variable (pstr in your case) unchanged.

Re: allocating memory for pointers

Member 121044230-Jun-04 23:24

Member 1210442

30-Jun-04 23:24

Hmmm, thanks. I guess i thought both pointers contained the same address but upon printing them out i see the copy contains its own unique address.

I haven't seen the 'reference to a pointer' frag before, do you know of a good resource that deals well with this kind of stuff?
The books i have only scratch the surface.

thanks again.

Re: allocating memory for pointers

palbano1-Jul-04 4:46

palbano

1-Jul-04 4:46

Tutorial at Cplusplus.com
This and many others can be found by Googling: C++ pass pointer by reference
Cool | :cool:

"No matter where you go, there your are." - Buckaroo Banzai

-pete

Registry editor Access in WinXP

syedi30-Jun-04 21:41

syedi

30-Jun-04 21:41

How can I read Registry subkey using Win API

Re: Registry editor Access in WinXP

Graham Bradshaw30-Jun-04 22:28

Graham Bradshaw

30-Jun-04 22:28

See these articles[^] for some ideas.

Navigation in visual studio using bookmarks

Muhammad Ahmed30-Jun-04 21:25

Muhammad Ahmed

30-Jun-04 21:25

Hello:
Navigation in visual studio seems a big prob when u are working on a big solution, the bookmarks provided in VS only help us navigate within the same file , what if we have to go from one file to another of different projects , can any one recommend me some solution
Thanks
Muhammad Ahmed

Ahmed

Re: Navigation in visual studio using bookmarks

P-Rex30-Jun-04 21:58

P-Rex

30-Jun-04 21:58

take a look at
Windowtabs[^]

Re: Navigation in visual studio using bookmarks

David Crow1-Jul-04 2:42

David Crow

1-Jul-04 2:42

I typically use a break point, not for the reason of breaking at that line of code, but for marking a line of code for later return. As a bonus, if the IDE is shut down, the break points are saved whereas bookmarks are not (they used to be in earlier versions of VC++).

"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen

get member var from App

JabraJabra30-Jun-04 21:24

JabraJabra

30-Jun-04 21:24

hi,
in my CXXXApp i got a member variable called myVar.
i want to get this member variable in other object, like a View.
i do :

<br />
tempVar = afxGetApp()->myVar;<br />

but the compiler won't let me,
what do u suggest for me to do?
obviously i cant create another object of CXXXApp...
is my syntax wrong? Unsure | :~

Re: get member var from App

jmkhael30-Jun-04 22:17

jmkhael

30-Jun-04 22:17

AfxGetApp will return a CWinApp*, and this one doesn't have a myVar memeber, but your application has.

So all you have to do, is to cast the returned pointer into your application

CMyApp * pxApp = (CMyApp *)AfxGetApp ();
if(pxApp)
{
// Do the dance...
pxApp->myVar;
}

Papa

while (TRUE)
Papa.WillLove ( Bebe ) ;

Re: get member var from App

JabraJabra30-Jun-04 23:43

JabraJabra

30-Jun-04 23:43

thanks , it worked!

ToolBar won't un-hide correctly.

zooosta30-Jun-04 21:13

zooosta

30-Jun-04 21:13

Hey all,

I'm trying to get my MDI application to load a tool bar at startup in the hidden mode and then on a button press display the hidden menu.

My results thus far are that I can hide the tool bar on start up but when I do my button press, the tool bar remains hidden until I drag and drop another tool bar currently docked to the bottom of my main window.

Code extract provided:

------------------
Tool Bar creation
------------------
if (!m_imageProcessingToolBar.Create(
this,
WS_CHILD |
WS_MINIMIZE |
CBRS_LEFT,
IDR_TICS_COMMANDS) ||
!m_imageProcessingToolBar.LoadToolBar(IDR_IMAGE_PROCESSING))

{
TRACE0("Failed to create image processing toolbar\n");
return -1; // fail to create
}

m_imageProcessingToolBar.SetSizes(button, image);

m_imageProcessingToolBar.SetBarStyle(
m_imageProcessingToolBar.GetBarStyle() |
CBRS_TOOLTIPS |
CBRS_FLYBY |
CBRS_SIZE_DYNAMIC);

m_imageProcessingToolBar.EnableDocking(CBRS_ALIGN_ANY);
EnableDocking(CBRS_ALIGN_ANY);
DockControlBar(&m_imageProcessingToolBar);

----------------
un-hide tool bar
----------------

void CMainFrame::OnImageManipulation()
{
m_imageProcessingToolBar.ShowWindow(SW_MAXIMIZE);
}

If anyone can see the error of my way, I'd thank you so much.

Regards.

Re: ToolBar won't un-hide correctly.

bneacetp30-Jun-04 23:58

bneacetp

30-Jun-04 23:58

Try:

void CMainFrame::OnImageManipulation() 
{
    m_imageProcessingToolBar.ShowWindow(SW_SHOW);
}

void CMainFrame::OnImageManipulation() 
{
   m_imageProcessingToolBar.ShowWindow(TRUE);
}

See if one of those snippets work. Best of luck in your programming efforts.

Happy Programming and God Bless!

"Your coding practices might be buggy, but your code is always right."

Internet::WWW::CodeProject::bneacetp

Re: ToolBar won't un-hide correctly.

zooosta1-Jul-04 13:05

zooosta

1-Jul-04 13:05

Thanks for the advice, but it's still not working.

I've tried all of the SW values that can go into the ShowWindow function and none of them make the toolbar re-appear without me having to drag and drop the default system toolbar.

Re: ToolBar won't un-hide correctly.

bneacetp1-Jul-04 13:25

bneacetp

1-Jul-04 13:25

Try coding your function like this:

ShowControlBar(&m_wndToolBar, 
	!m_wndToolBar.IsVisible(), FALSE);
// Reshuffle the frame layout. - You might want to remove this line.
RecalcLayout();

Sorry. I hope this suggestion helps.

Happy Programming and God Bless!

"Your coding practices might be buggy, but your code is always right."

Internet::WWW::CodeProject::bneacetp

Re: ToolBar won't un-hide correctly.

bneacetp1-Jul-04 13:28

bneacetp

1-Jul-04 13:28

The first example using ShowContolBar toggles the toolbar visibility. If you just want to show the toolbar, try coding your function like this:

ShowControlBar(&m_wndToolBar, TRUE, FALSE);
// Reshuffle the frame layout. - You might want to remove this line.
RecalcLayout();

Sorry. I hope this suggestion helps.

Happy Programming and God Bless!

"Your coding practices might be buggy, but your code is always right."

Internet::WWW::CodeProject::bneacetp

Re: ToolBar won't un-hide correctly.

zooosta1-Jul-04 13:35

zooosta

1-Jul-04 13:35

Pure genius ;0)

Thanks a million, that worked a treat.

The RecalcLayout() line wasn't needed to make this work, what purpose does it serve?

Cheers again.

Re: ToolBar won't un-hide correctly.

bneacetp1-Jul-04 13:53

bneacetp

1-Jul-04 13:53

Glad to help.

RecalcLayout is generally used to tell MFC to reshuffle the visible controlbars when a toolbar/controlbar is added or removed from being docked (top/bottom/left/right).

MSDN Describes it this way:
Called by the framework when the standard control bars are toggled on or off or when the frame window is resized.
-Remarks-
The default implementation of this member function calls the CWnd member function RepositionBars to reposition all the control bars in the frame as well as in the main client window (usually a CView or MDICLIENT).

Override this member function to control the appearance and behavior of control bars after the layout of the frame window has changed. For example, call it when you turn control bars on or off or add another control bar.

Hope this helps. Smile | :)

Happy Programming and God Bless!

"Your coding practices might be buggy, but your code is always right."

Internet::WWW::CodeProject::bneacetp

question related to system font

johnny,Kim30-Jun-04 20:26

johnny,Kim

30-Jun-04 20:26

I'm using Visual Studio 6..
But as you know we can not change font of some part such as classview pane..
It seem to be fixed to system font.. you guys might be able to see Sans serif font..
(I'm not pretty sure about that..)

Anyway My question is 'How can I change the system font?'
I'm actually using Korean Version Windows.
What I wanna use is the sans serif system font like what you guys using.

the System font that comes with Korean Edition Windows is not good looking...
I'd like to change it..
Does any know about that?

ps. sorry about that my question is out of programming topic..

Using SpinButtonCtrl

Shuang. Wu30-Jun-04 20:13

Shuang. Wu

30-Jun-04 20:13

To change the buttons' size of a SpinButton, I need to use CSpinButtonCtrl::Create() function. Now I added a SpinButton control on my dialog, what shall I do next?

|-|3llo Wo|2ld

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