Re: Virtual Destructor - C / C++ / MFC Discussion Boards

kd834110-Mar-05 17:32

10-Mar-05 17:32

I am using visual studio .net and want to save a BMP file to JPG format. How to do this? Is there a sample code for reference?

Thanks.

Re: save BMP to JPG

V.10-Mar-05 21:09

10-Mar-05 21:09

if it's really just the file you'd like to convert manually (not code) just do it in Paint, but I'm not sure you can load jpg into the resources.

No hurries, no worries.

Re: save BMP to JPG

kd834111-Mar-05 4:15

kd8341

11-Mar-05 4:15

Sorry, I didn't express myself clearly, but I need to convert BMP to JPG in run time(within program). Is there any sample code in Visual studio?

Thanks a lot!

Re: save BMP to JPG

Mircea Puiu11-Mar-05 4:34

Mircea Puiu

11-Mar-05 4:34

Hi,

use the intel jpeg library (ijl15.dll)

SkyWalker

Re: save BMP to JPG

C^hris L^osinger11-Mar-05 6:18

C^hris L^osinger

11-Mar-05 6:18

MFC/Windows does not have this capability built-in.

you'll need to use a library like GDI+, CIXImage (available here on CP), ImgSource (my favorite Smile | :)

), or any of the other dozens of libraries out there.

Image Toolkits | Image Processing | Cleek

Virtual Destructor

Neelesh K J Jain10-Mar-05 17:09

Neelesh K J Jain

10-Mar-05 17:09

What is the main advantage of Virtual destructor?

Why don't we have virtual constructor when virtual destructor's are present?

Please help regarding this 2 questions.

Thanking you,

Neelesh K J Jain.

Re: Virtual Destructor

Serge Krynine10-Mar-05 17:25

Serge Krynine

10-Mar-05 17:25

1) See: http://www.parashift.com/c++-faq-lite/virtual-functions.html#faq-20.7[^]

2) See http://www.parashift.com/c++-faq-lite/virtual-functions.html#faq-20.8[^]

Serge

Re: Virtual Destructor

Cedric Moonen10-Mar-05 20:55

Cedric Moonen

10-Mar-05 20:55

Neelesh K J Jain wrote:
What is the main advantage of Virtual destructor?

Imagine you have one base class (CBase) and one derived class (CChild that inherits from CBase). Now look at this piece of code:

CBase* pPtr = new CChild;<br />
....<br />
// Do things with pPtr..<br />
...<br />
delete pPtr;

Now, what would happens if the destructor wasn't virtual ? The only destructor that will be called is the destructor of the base class (pPtr is a pointer of type CBase*) and so your object may be not completelly cleaned. So, if you make your destructor virtual, the destructor of CChild will be called.

Neelesh K J Jain wrote:
Why don't we have virtual constructor when virtual destructor's are present?

Because when you create an instance of an object (like in the piece of code before), you know exactly which kind of class (CChild or CBase) you want to create. In fact this line: CBase* pPtr = new CChild can be explained as: first create an object of type CChild (the compiler knows exactly that he will need to call the constructor of CChild) and then store this pointer in pPtr.
So, here, no need for virtual constructors...

Hope this helps

How to control mouse to select area ?

RobertHuang10-Mar-05 15:49

RobertHuang

10-Mar-05 15:49

dear all seniors:
I have a control about the use mouse to select an area , but I can't clear all the unselect area. There is some vestigital shadow when move the mouse from right to left.I don't have any idea to avoid this case. Please give me a hand, thank you very much. The code as beloow :

<br />
// testmouseView.h : interface of the CTestmouseView class<br />
//<br />
/////////////////////////////////////////////////////////////////////////////<br />
<br />
#if !defined(AFX_TESTMOUSEVIEW_H__25EE68BB_BD4B_4C4E_8731_90C45792A08E__INCLUDED_)<br />
#define AFX_TESTMOUSEVIEW_H__25EE68BB_BD4B_4C4E_8731_90C45792A08E__INCLUDED_<br />
<br />
#if _MSC_VER > 1000<br />
#pragma once<br />
#endif // _MSC_VER > 1000<br />
<br />
<br />
class CTestmouseView : public CView<br />
{<br />
protected: // create from serialization only<br />
	CTestmouseView();<br />
	DECLARE_DYNCREATE(CTestmouseView)<br />
<br />
// Attributes<br />
public:<br />
	CTestmouseDoc* GetDocument();<br />
	CRect SelectArea,DisSelectArea;<br />
	<br />
// Operations<br />
public:<br />
<br />
// Overrides<br />
	// ClassWizard generated virtual function overrides<br />
	//{{AFX_VIRTUAL(CTestmouseView)<br />
	public:<br />
	virtual void OnDraw(CDC* pDC);  // overridden to draw this view<br />
	virtual BOOL PreCreateWindow(CREATESTRUCT& cs);<br />
	protected:<br />
	virtual BOOL OnPreparePrinting(CPrintInfo* pInfo);<br />
	virtual void OnBeginPrinting(CDC* pDC, CPrintInfo* pInfo);<br />
	virtual void OnEndPrinting(CDC* pDC, CPrintInfo* pInfo);<br />
	//}}AFX_VIRTUAL<br />
<br />
// Implementation<br />
public:<br />
	virtual ~CTestmouseView();<br />
#ifdef _DEBUG<br />
	virtual void AssertValid() const;<br />
	virtual void Dump(CDumpContext& dc) const;<br />
#endif<br />
<br />
protected:<br />
<br />
// Generated message map functions<br />
protected:<br />
	//{{AFX_MSG(CTestmouseView)<br />
	afx_msg void OnLButtonDown(UINT nFlags, CPoint point);<br />
	afx_msg void OnLButtonUp(UINT nFlags, CPoint point);<br />
	afx_msg void OnMouseMove(UINT nFlags, CPoint point);<br />
	//}}AFX_MSG<br />
	DECLARE_MESSAGE_MAP()<br />
};<br />
<br />
#ifndef _DEBUG  // debug version in testmouseView.cpp<br />
inline CTestmouseDoc* CTestmouseView::GetDocument()<br />
   { return (CTestmouseDoc*)m_pDocument; }<br />
#endif<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
<br />
//{{AFX_INSERT_LOCATION}}<br />
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.<br />
<br />
#endif // !defined(AFX_TESTMOUSEVIEW_H__25EE68BB_BD4B_4C4E_8731_90C45792A08E__INCLUDED_)<br />

<br />
// testmouseView.cpp : implementation of the CTestmouseView class<br />
//<br />
<br />
#include "stdafx.h"<br />
#include "testmouse.h"<br />
<br />
#include "testmouseDoc.h"<br />
#include "testmouseView.h"<br />
<br />
#ifdef _DEBUG<br />
#define new DEBUG_NEW<br />
#undef THIS_FILE<br />
static char THIS_FILE[] = __FILE__;<br />
#endif<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CTestmouseView<br />
<br />
IMPLEMENT_DYNCREATE(CTestmouseView, CView)<br />
<br />
BEGIN_MESSAGE_MAP(CTestmouseView, CView)<br />
	//{{AFX_MSG_MAP(CTestmouseView)<br />
	ON_WM_LBUTTONDOWN()<br />
	ON_WM_LBUTTONUP()<br />
	ON_WM_MOUSEMOVE()<br />
	//}}AFX_MSG_MAP<br />
	// Standard printing commands<br />
	ON_COMMAND(ID_FILE_PRINT, CView::OnFilePrint)<br />
	ON_COMMAND(ID_FILE_PRINT_DIRECT, CView::OnFilePrint)<br />
	ON_COMMAND(ID_FILE_PRINT_PREVIEW, CView::OnFilePrintPreview)<br />
END_MESSAGE_MAP()<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CTestmouseView construction/destruction<br />
<br />
CTestmouseView::CTestmouseView()<br />
{<br />
	// TODO: add construction code here<br />
	SelectArea = CRect(0,0,0,0);<br />
	DisSelectArea = SelectArea;<br />
}<br />
<br />
CTestmouseView::~CTestmouseView()<br />
{<br />
}<br />
<br />
BOOL CTestmouseView::PreCreateWindow(CREATESTRUCT& cs)<br />
{<br />
	// TODO: Modify the Window class or styles here by modifying<br />
	//  the CREATESTRUCT cs<br />
<br />
	return CView::PreCreateWindow(cs);<br />
}<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CTestmouseView drawing<br />
<br />
void CTestmouseView::OnDraw(CDC* pDC)<br />
{<br />
	CTestmouseDoc* pDoc = GetDocument();<br />
	ASSERT_VALID(pDoc);<br />
	// TODO: add draw code for native data here<br />
	//CRect rectWaveEditArea = CRect(Begin.x,Begin.y,End.x,Begin.y+50);<br />
	CBrush WhiteBrush(RGB(255,255,255));<br />
	CBrush LightGaryBrush(RGB(225,225,225));<br />
	CBrush *OldBrush;<br />
<br />
	if(DisSelectArea.Width() != 0)<br />
	{<br />
		OldBrush = pDC->SelectObject(&WhiteBrush);<br />
		pDC->FillRect(DisSelectArea,&WhiteBrush);<br />
		pDC->SelectObject(OldBrush);<br />
	}<br />
	if(SelectArea.Width() != 0)<br />
	{<br />
		OldBrush = pDC->SelectObject(&LightGaryBrush);<br />
		pDC->FillRect(SelectArea,&LightGaryBrush);<br />
		pDC->SelectObject(OldBrush);<br />
	}<br />
}<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CTestmouseView printing<br />
<br />
BOOL CTestmouseView::OnPreparePrinting(CPrintInfo* pInfo)<br />
{<br />
	// default preparation<br />
	return DoPreparePrinting(pInfo);<br />
}<br />
<br />
void CTestmouseView::OnBeginPrinting(CDC* /*pDC*/, CPrintInfo* /*pInfo*/)<br />
{<br />
	// TODO: add extra initialization before printing<br />
}<br />
<br />
void CTestmouseView::OnEndPrinting(CDC* /*pDC*/, CPrintInfo* /*pInfo*/)<br />
{<br />
	// TODO: add cleanup after printing<br />
}<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CTestmouseView diagnostics<br />
<br />
#ifdef _DEBUG<br />
void CTestmouseView::AssertValid() const<br />
{<br />
	CView::AssertValid();<br />
}<br />
<br />
void CTestmouseView::Dump(CDumpContext& dc) const<br />
{<br />
	CView::Dump(dc);<br />
}<br />
<br />
CTestmouseDoc* CTestmouseView::GetDocument() // non-debug version is inline<br />
{<br />
	ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CTestmouseDoc)));<br />
	return (CTestmouseDoc*)m_pDocument;<br />
}<br />
#endif //_DEBUG<br />
<br />
/////////////////////////////////////////////////////////////////////////////<br />
// CTestmouseView message handlers<br />
<br />
void CTestmouseView::OnLButtonDown(UINT nFlags, CPoint point) <br />
{<br />
	// TODO: Add your message handler code here and/or call default<br />
	SetCapture();<br />
	SelectArea.left = point.x;<br />
	SelectArea.top = point.y;<br />
	SelectArea.right = point.x;<br />
	SelectArea.bottom = point.y+ 50;<br />
	//CView::OnLButtonDown(nFlags, point);<br />
}<br />
<br />
void CTestmouseView::OnMouseMove(UINT nFlags, CPoint point) <br />
{<br />
	// TODO: Add your message handler code here and/or call default<br />
	if(nFlags == MK_LBUTTON)<br />
	{<br />
		if(point.x >= SelectArea.left)<br />
		{<br />
			if( point.x >= SelectArea.right)<br />
			{<br />
				SelectArea.right = point.x;<br />
			}<br />
			else if( point.x < SelectArea.right)<br />
			{<br />
				DisSelectArea.left = point.x;<br />
				DisSelectArea.top = SelectArea.top;<br />
				DisSelectArea.right = SelectArea.right;<br />
				DisSelectArea.bottom = SelectArea.bottom;<br />
				SelectArea.right = point.x;<br />
			}<br />
		}<br />
		else if(point.x < SelectArea.left)<br />
		{<br />
			if(point.x < SelectArea.right)<br />
			{<br />
				SelectArea.right = point.x;<br />
			}<br />
			else if(point.x > SelectArea.right)<br />
			{<br />
				DisSelectArea.left = point.x;<br />
				DisSelectArea.top = SelectArea.top;<br />
				DisSelectArea.right =SelectArea.right;<br />
				DisSelectArea.bottom = SelectArea.bottom;<br />
				SelectArea.right = point.x;<br />
			}<br />
		}<br />
	}<br />
	InvalidateRect(DisSelectArea,FALSE);<br />
	InvalidateRect(SelectArea,FALSE);<br />
	UpdateWindow();<br />
	//CView::OnMouseMove(nFlags, point);<br />
}<br />
void CTestmouseView::OnLButtonUp(UINT nFlags, CPoint point) <br />
{<br />
	// TODO: Add your message handler code here and/or call default<br />
	ReleaseCapture();<br />
	SelectArea.right = point.x;<br />
	//CView::OnLButtonUp(nFlags, point);<br />
}<br />

OleLoadFromStream??

Anonymous10-Mar-05 11:09

Anonymous

10-Mar-05 11:09

I am trying to extract an embedded object from a RTF file.
I can extract the embedded object tag and corresponding data from the original RTF file, but I don't know how to make that into its own object outside of the RTF.

Any help would be appreciated.

please help me

ali elba10-Mar-05 10:57

ali elba

10-Mar-05 10:57

how can i use file dll in visual c++ and open it to use it's contents

Re: please help me

David Crow11-Mar-05 4:59

David Crow

11-Mar-05 4:59

Are you wanting to know how to use exported functions or classes from the DLL?

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Re: please help me

Anonymous11-Mar-05 6:57

Anonymous

11-Mar-05 6:57

yes please......
by visual c++

Re: please help me

David Crow11-Mar-05 7:25

David Crow

11-Mar-05 7:25

You would need to load the DLL using LoadLibrary(). With the returned handle, you would then make a call to GetProcAddress() to get the address of the exported function. See here for an example.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

Visual C++.Net

jogodo10-Mar-05 10:16

jogodo

10-Mar-05 10:16

How can I use colors to make text of the console application look pretty with VC++.Net?

Re: Visual C++.Net

Serge Krynine10-Mar-05 12:49

Serge Krynine

10-Mar-05 12:49

Here’s the easiest way to set the default console foreground and background colors from a .NET console application:

Serge

#include "stdafx.h"

int _tmain(int argc, _TCHAR* argv[])
{
// paint in red on black:
::system("COLOR 04");
std::cout << "Hello, World!" << std::endl;

return 0;
}

/*
C:>color /?
Sets the default console foreground and background colors.

COLOR [attr]

attr Specifies color attribute of console output

Color attributes are specified by TWO hex digits -- the first
corresponds to the background; the second the foreground. Each digit
can be any of the following values:

0 = Black 8 = Gray
1 = Blue 9 = Light Blue
2 = Green A = Light Green
3 = Aqua B = Light Aqua
4 = Red C = Light Red
5 = Purple D = Light Purple
6 = Yellow E = Light Yellow
7 = White F = Bright White

If no argument is given, this command restores the color to what it was
when CMD.EXE started. This value either comes from the current console
window, the /T command line switch or from the DefaultColor registry
value.

The COLOR command sets ERRORLEVEL to 1 if an attempt is made to execute
the COLOR command with a foreground and background color that are the
same.

Example: "COLOR fc" produces light red on bright white
*/

Hiw can I make "Visual C++ 6 Components"?

Behzad Ebrahimi10-Mar-05 9:55

Behzad Ebrahimi

10-Mar-05 9:55

I want to make "Visual C++ Components" for VC++ 6.
Like: predefined "Pop-up Menu"

Thanks

popupmenu language

coolice200210-Mar-05 9:05

coolice2002

10-Mar-05 9:05

Hi !

I have a problem. I had created a service with a trayicon which has a popupmenu. The popupmenu items generated dinamically.

My problem that I need to set the language of the popupmenu. What I mean under the language, what I can retrieve with : GetKeyboardLayout.

I can set it in case of a form with : LoadKeyboardLayout , but for some reason it is NOT working for the popupmenu.

Could somebody help me please ?

Thanks a lot in advance,

Moore

Re: popupmenu language

Mircea Puiu11-Mar-05 4:44

Mircea Puiu

11-Mar-05 4:44

The pop-up menu has nothing to do with the KeyboardLayout.
Make different string resources, one for each language you want to use, and use the
appropriate one (depending on the language selection).

SkyWalker

Use of Registry WriteProfileString

jerry1211a10-Mar-05 8:37

jerry1211a

10-Mar-05 8:37

Hello.

I am using the registry for a program in the following manner:
sprintf(szBuffer, "%f", Value)
AfxGetApp()->WriteProfileString("NAME", "SECTION", szBuffer)

Value in the sprintf call is a double. I have to allocate space with szBuffer as:
char szBuffer[sizeof(double)*2], in order to get the program to run properly.

But, I have a run time error if I try:
char szBuffer[sizeof(float)]

I dont understand why I get the error. Can anyone help me out?
All I want to do is to save Value as a string and read it back as a string.

Thanks,
Jerry

Re: Use of Registry WriteProfileString

Chris Meech10-Mar-05 9:05

Chris Meech

10-Mar-05 9:05

You have to allocate enough space to hold the representation of the double or float. Not the size of a double or float. eg. Suppose the value is 1234, then you need five bytes. But if the value is 1234567890.1234567890, you will need twenty two bytes.

Chris Meech

I am Canadian. [heard in a local bar]

Gently arching his fishing rod back he moves the tip forward in a gentle arch releasing the line.... kersplunk [Doug Goulden]

Nice sig! [Tim Deveaux on Matt Newman's sig with a quote from me]

Re: Use of Registry WriteProfileString

David Crow10-Mar-05 10:00

David Crow

10-Mar-05 10:00

jerry1211a wrote:
sprintf(szBuffer, "%f", Value)

Use MFC constructs when available:

CString strBuffer;
strBuffer.Format("%f", Value);

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

MFC Open Dialog

Anonymous10-Mar-05 8:00

Anonymous

10-Mar-05 8:00

How can I force the open dialog to open with a specific path every time?

thanks,

Re: MFC Open Dialog

Steen Krogsgaard 210-Mar-05 8:08

Steen Krogsgaard 2

10-Mar-05 8:08

Set the lpstrInitialDir field of the m_ofn member of CFileDialog prior to calling CFileDialog::DoModal. If you want the dialog that is shown when the user uses the Open item on the File menu in a standard MFC program you have to dig into the doc/view architechture. There was a post about this earlier, that was about the Save dialog buts it's the same story.

cheers
Steen

I'm puzzled

g3e10-Mar-05 7:57

g3e

10-Mar-05 7:57

I've implemented a wizard using the CPropertySheet and CPropertyPage classes.
When i'm in a particular page of the wizard, when i click the "Cancel" button or press ESC or close the page by clicking on the "X" in the right top corner, the CANCEL message gets fired and control comes to the OnCancel command handler. At this point the PSN_WIZFINISH notification is not sent.

void CMyPropertyPage::OnCancel()
{
ASSERT(m_pSheet != NULL);
m_pSheet->EndDialog(IDCANCEL);
}

Now I have a scenario where i have to forcefully close the wizard by sending
SendMessage(WM_COMMAND,IDCANCEL);
Now after the CANCEL message being sent, the PSN_WIZFINISH notification is also sent . Confused | :confused:

In my class, i've overridden the OnWizardFinish to do some functionality.. So when i do a "SendMessage" i dont want the PSN_WIZFINISH to be sent ..

why does it work this way and how do i avoid it ?

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