C / C++ / MFC

Re: Want to find Rightmost top point from the CPoint List

9-Jun-11 10:32

The first thing you need to decide is whether the horizontal or vertical axis has precedence. After that is a simple matter of selecting the largest value in either set.

The best things in life are not things.

CPallini9-Jun-11 22:09

CPallini

9-Jun-11 22:09

As already noted by Richard, you have to choose the sorting order (first Y-axis or first X-axis?) otherwise the problem is ambiguous. On the other hand, if you instead need to find the 'bounding rectangle' top-right point, then the problem is well-defined but such point doesn't necessary match one of the given set.
Smile | :)

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-- Alfonso the Wise, 13th Century King of Castile.

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Re: Want to find Rightmost top point from the CPoint List

Stefan_Lang15-Jun-11 2:46

Stefan_Lang

15-Jun-11 2:46

If I understand you correctly, you want to find the point that is the farthest ina a particular direction. By the way you ask I assume you are not looking for the rightmost or topmost point, but a point that is 'closest to the top right corner', or something like that.

I am thinking what you need is to define the direction you are looking at as a vector (in a geometrical sense), and then use vector algebra to determine which of the points is farthest in the direction denoted by that vector. To do this, you use that direction to define a line, and project all points onto that line, then determine its distance to the lines origin. It doesn't really matter where that origin lies as long as you differentiate which side of the origin your projected point comes to lie by using a signed distance value; for sake of simplicity just use (0,0) as origin.

A line through (0,0) in the direction of D can be defined by L(t)=t*D. Calculating the projection Q of a point P on this line can be done like this: Q = (P*D / |D|) * D / |D| = (P*D)*D / (D*D). Basically this formula defines the parameter t for the peojected point Q to be t(Q)=(P*D)/(D*D). For the purpose of looking for the point 'farthest' in the direction of D, you can just compare the values of t(Q). And since the denominator (D*D) is a constant, you can just ignore it. Instead just calculate P*D for each point P and determine the point with the largest result:

struct point2 {
   int x;
   int y;
}
int operator*(const point2& p1, const point2& p2) {
   return p1.x*p2.x + p1.y*p2.y;
}
void test() {
   
   std::list<point2> pointlist;
   point2 P;
   P.x = 1258;
   P.y = 263;
   pointlist.push_back(P);
   P.x = 1263;
   P.y = 260;
   pointlist.push_back(P);

   point2 D;
   D.x = 1;
   D.y = 1;

   std::list<point2>::iterator it = pointlist.begin()
   double farthest_value = (*it) * D;
   std::list<point2>::iterator farthest_point = it;
   while (++it != pointlist.end()) {
      double value = (*it) * D;
      if (value > farthest_value) {
          farthest_value = value;
          farthest_point = it;
      }
   }

   std::cout << "farthest point is (" << farthest_point.x << "," << farthest_point.y << ")" << std::endl;
}

Using C# in C++

Chris_Green8-Jun-11 23:54

Chris_Green

8-Jun-11 23:54

Hi,

I have a sample project where I am using a C# library in a C++ test program. I'm doing this by COM, using the tlb and project reference.

C#

<br />
    [ComVisible(true)]<br />
    [ClassInterface(ClassInterfaceType.AutoDual)]<br />
    public class Math<br />
    {<br />
        public int Add(int x, int y)<br />
        {<br />
            return x + y;<br />
        }<br />
<br />
        public static int Subtract(int x, int y)<br />
        {<br />
            return x - y;<br />
        }<br />
    }<br />

C++

<br />
#include "stdafx.h"<br />
#include <iostream><br />
<br />
#import "..\\CSharpUsefulLibrary.tlb" raw_interfaces_only<br />
<br />
int _tmain(int argc, _TCHAR* argv[])<br />
{<br />
    CoInitialize(0);<br />
<br />
    CSharpUsefulLibrary::_MathPtr math(__uuidof(CSharpUsefulLibrary::Math));<br />
<br />
    long value;<br />
    math->Add(1, 2, &value);<br />
    std::wcout << "The value is " << value;<br />
<br />
    CoUninitialize();<br />
	return 0;<br />
}<br />

So this works fine, I'm able to call the add method in my C# library from C++. The question is, how do I call the static subtract method?

CPallini9-Jun-11 0:24

CPallini

9-Jun-11 0:24

I'm afraid you cannot do it: There's no trace of the static Subtract method in the tlh generated file.

Chris_Green9-Jun-11 0:54

Chris_Green

9-Jun-11 0:54

Yeah, in VS I did File->Open on the tlb and indeed couldn't find it. Looks like we'll need a wrapper to expose static funcitons. Thanks

Rolf Kristensen9-Jun-11 8:43

Rolf Kristensen

9-Jun-11 8:43

You could create a singleton object in C# project, that could provide access to the static methods.

CPallini9-Jun-11 22:03

CPallini

9-Jun-11 22:03

There's no need, I suppose, since he already has a class. He has simply to wrap the static method with an instance one.
Smile | :)

ThatsAlok13-Jun-11 21:14

ThatsAlok

13-Jun-11 21:14

newkie wrote:
The question is, how do I call the static subtract method?

afaik, and my weak knowledge in COM, i haven't seen STATIC method being exported by COM model

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Font Size Problem in Edit Control [SOLVED]

ThatsAlok13-Jun-11 21:16

ThatsAlok

13-Jun-11 21:16

just a FAQ on COM :- http://com-faq.blogspot.com/[^]

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
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vishalgpt8-Jun-11 19:37

8-Jun-11 19:37

Hi to all,
I am facing a strange problem, i had asked for help in the forum few days before. But due to certain delays i was unable to show the code. Here is the code. My Problem is with hindi fonts.

When i substitute the the LOGFONT.lfHeight with 0(Zero) then everything works fine, But when i change the size of lfHeight to anything greater or lesser than zero, the Hindi fonts is displayed very small. How to solve this issue.

case WM_INITDIALOG:
	LOGFONT lf;
		
	HFONT cFont;
	HWND target = GetDlgItem(hwnd,IDC_STATIC1);
	HFONT hFont = (HFONT)GetStockObject(DEFAULT_GUI_FONT);
	GetObject(hFont, sizeof(LOGFONT), &lf);

	lf.lfHeight = 0;
	cFont = CreateFontIndirect(&lf);
	SendMessage(target,WM_SETFONT,(WPARAM)cFont,MAKELPARAM(TRUE,0));
	SetWindowText(target,_T("C:\\Program Files\\অভিধান: ইংরেজী\\सरकारी &&"));
	break;

sorry for posting twice.

Regards,
Vishal

modified on Thursday, June 9, 2011 1:32 PM

Richard MacCutchan8-Jun-11 21:42

8-Jun-11 21:42

You need to convert the point height of your font into device units with the following formula:

lFont.lfHeight = MulDiv(nFontHeight, GetDeviceCaps(hDC, LOGPIXELSY), 72);// height of  font

See the MSDN page for CreateFont()[^] for more information.

The best things in life are not things.

vishalgpt8-Jun-11 22:16

8-Jun-11 22:16

i am using

-MulDiv(iPointSize,GetDeviceCaps(GetDC(target),LOGPIXELSY),72);

Where iPointSize is the size of font;

But, the results are not up-to mark. If i specify the

lFont.lfHeight = 14

then, the text in english font is ok but the text in hindi font seems like the lfHeight is 8.

But if i specify the

lFont.lfHeight = 0

Whether hindi or bengali or chinese every font is in same height and looks good, but their sizes are big.

I am using default MS Shell Dlg Font.

Regards,
Vishal

Richard MacCutchan9-Jun-11 4:07

9-Jun-11 4:07

Try the positive value returned by MulDiv() and/or one of the other fonts, if possible one that was designed for Hindi characters.

The best things in life are not things.

vishalgpt9-Jun-11 7:04

9-Jun-11 7:04

Yes sir, i had tried. Mangal gives positive result for hindi fonts.
And Trebuchet MS for others.

Sir, i have one small doubt. Do we have to distribute these fonts with application or these are system default fonts available on windows.

and (negative) -MulDiv() gives good result instead of (postive) MulDiv(). Is it OK. Please guide.

Regards,
Vishal

Richard MacCutchan9-Jun-11 7:23

9-Jun-11 7:23

vishalgpt wrote:
Please guide.

I'm afraid I don't have the answer to these questions, you will have to investigate the rest for yourself.

The best things in life are not things.

vishalgpt9-Jun-11 7:32

9-Jun-11 7:32

thanx.

Regards,
Vishal

Iain Clarke, Warrior Programmer

Iain Clarke, Warrior Programmer9-Jun-11 8:03

9-Jun-11 8:03

From memory, a negative lfHeight means "points" as opposed to pixels, but you'd have to check the definitions on msdn for LOGFONT.

Iain.

I am one of "those foreigners coming over here and stealing our jobs". Yay me!

vishalgpt10-Jun-11 17:28