C / C++ / MFC Discussion Boards

Member 169706311-Mar-04 0:25

11-Mar-04 0:25

I am getting an value like this

a+(b<<9)+(c<<17)=value

how can i recalculate a,b and c if i only have the value c is a fix value (512) and can also be obtained by
c= value>>17
how can i resolve a and b

Re: solve expression

Prakash Nadar11-Mar-04 0:38

Prakash Nadar

11-Mar-04 0:38

Mathematically not possible to solve a equation with 3 unknown and one equation.

You have to assume any three values and find the other.

MSN Messenger.
prakashnadar@msn.com

Re: solve expression

Robert A. T. Káldy11-Mar-04 0:56

Robert A. T. Káldy

11-Mar-04 0:56

<br />
a = value & 0x1FF;<br />
b = (value >> 9) & 0x1FF;<br />

where I assume, that a and b are from interval (0, 511)

Robert-Antonio

"CRAY is the only computer, which runs an endless loop in just 4 hours"

Re: solve expression

David Crow11-Mar-04 2:51

David Crow

11-Mar-04 2:51

perfect stranger wrote:
how can i recalculate a,b and c if i only have the value c is a fix value (512)...

If you already know the value of 'c', then there is no need to calculate its value. You are simply left with a problem of solving an equation with two unknowns. There are plenty of algebra/high school math sites that show how to do this.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Converting To Pixels

Pazzuzu10-Mar-04 23:43

Pazzuzu

10-Mar-04 23:43

Hi All,

Iam trying to Draw a Bitmap to screen using the DeviceContext function StretchBlt.

//These are my parameters in LogicalUnits
int xCord;
int yCord,
int bitmapwidth,bitmapheight

StretchBlt(xCord,ycord,bitmapwidth,bitmapheight,...
I want the first 4 parameters of the StretchBlt to be converted to deviceCo-ordinates(Pixels).How Could I do that.

I found the function "LPtoDp" in Msdn,But this function doesnt return me anything to pass the converted valuesto the stretchBlt function.

Help!
Thanks...

Re: Converting To Pixels

Robert A. T. Káldy11-Mar-04 0:08

Robert A. T. Káldy

11-Mar-04 0:08

POINT pt = {10, 20}; // in logical coords
LPtoDP(&pt, 1);
// pt now contains converted device coords

Robert-Antonio

"Science is a differerntial equation.
Religion is a boundary condition."

Re: Converting To Pixels

Pazzuzu11-Mar-04 1:28

Pazzuzu

11-Mar-04 1:28

Thanks..

Storing the visual representation in a document

mymauve2110-Mar-04 23:03

mymauve21

10-Mar-04 23:03

I am a novice in VC++ ( MFC) I need to build an application which allows me to store my visual represention craeted in the view and also retrieve it at alater point of time. Basically similar to opening, saving and closing a file as done in any windows application. I don't know which topic to look into and how to do the same.
Please can somebody guide me.....
Thanks for the same.

Storing the visual representation in a document

mymauve2110-Mar-04 23:02

mymauve21

10-Mar-04 23:02

Re: Storing the visual representation in a document

David Crow11-Mar-04 2:53

David Crow

11-Mar-04 2:53

Sounds like you need to read a chapter on serialization. Go through MSDN's Scribble tutorial.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Bitmap

Rassul Yunussov10-Mar-04 22:48

Rassul Yunussov

10-Mar-04 22:48

How To Copy the Desktop image to BMP file???
I'd appreshiate any help and especially for the clear WinAPI code without using any classes.

Re: Bitmap

Mike Dimmick11-Mar-04 1:01

Mike Dimmick

11-Mar-04 1:01

GetScreenDC, CreateCompatibleDC, CreateDIBSection, [edit] SelectObject the DIB into the compatible DC [/edit], BitBlt from the screen DC to your compatible DC, then work out how to fill in the BITMAPFILEHEADER and BITMAPINFOHEADER structures.

See Charles Petzold's Programming Windows, Fifth Edition for information on working with bitmaps.

Stability. What an interesting concept. -- Chris Maunder

Re: Bitmap

Rassul Yunussov11-Mar-04 22:20

Rassul Yunussov

11-Mar-04 22:20

I stell can't understand some moments.
I do this and get nothing, What am i doing wrong?:

char* data = new char[GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3];
BITMAPINFO BitmapInfo;
BITMAPFILEHEADER BFH;
memset(&BFH,0,sizeof(BITMAPFILEHEADER));
BFH.bfType = 'MB';
BFH.bfSize = sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3;
BFH.bfOffBits = sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER);
BITMAPINFOHEADER bitmapinfoheader;
bitmapinfoheader.biSize = sizeof(BITMAPINFOHEADER);
bitmapinfoheader.biWidth = GetSystemMetrics(SM_CXSCREEN);
bitmapinfoheader.biHeight = GetSystemMetrics(SM_CYSCREEN);
bitmapinfoheader.biPlanes = bitmapinfoheader.biBitCount = 24;
bitmapinfoheader.biCompression = 0;
bitmapinfoheader.biSizeImage = GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3;
bitmapinfoheader.biXPelsPerMeter = bitmapinfoheader.biYPelsPerMeter = bitmapinfoheader.biClrUsed =bitmapinfoheader.biClrImportant = 0;

HDC hDC = ::GetDC(NULL);
HDC hCompatibleDC = ::CreateCompatibleDC(hDC);
HBITMAP hBitmap =::CreateDIBSection(hCompatibleDC,&BitmapInfo,DIB_RGB_COLORS,(void**)data,NULL,NULL);
BitBlt(hDC,0,0,GetSystemMetrics(SM_CXSCREEN),GetSystemMetrics(SM_CYSCREEN),hCompatibleDC,0,0,SRCCOPY);
CFile file;
file.Open("New.bmp",CFile::modeWrite|CFile::modeCreate);
file.Write(&BFH,sizeof(BITMAPFILEHEADER));
file.Write(&bitmapinfoheader,sizeof(BITMAPINFOHEADER));
RGBQUAD rgb;
file.Write(&rgb,sizeof(RGBQUAD));
file.Write(data,GetSystemMetrics(SM_CXSCREEN)*GetSystemMetrics(SM_CYSCREEN)*3);
file.Close();

Re: Bitmap

Mike Dimmick12-Mar-04 8:36

Mike Dimmick

12-Mar-04 8:36

Firstly I'd pull out every use of GetSystemMetrics(SM_CXSCREEN) and GSM(SM_CYSCREEN) and store them in variables instead - this will make the code clearer.

The value of a two-character literal is undefined. Set BFH.bfType to 0x4D42.

The documentation for BITMAPINFOHEADER indicates that biPlanes should be set to 1. I think you can get away with setting biClrUsed to zero; if you do this, you should not write any RGBQUAD structures after the BITMAPINFOHEADER.

biCompression should be set to BI_RGB. You should probably set biXPelsPerMeter and biYPelsPerMeter: you can either compute them from GetDeviceCaps( hDC, LOGPIXELSX ) or simply write in the appropriate value for 96dpi: 3780.

A line of a DIB is always an exact multiple of 4 bytes long. If the number of bytes per pixel multiplied by the number of pixels per line is not a multiple of 4, you must round up to the next multiple. This also affects your original block allocation.

I seem to remember that there are also some odd alignment requirements for a BMP file, but I can't remember them off-hand.

If other programs render your bitmap upside down, you may need to set biHeight to a negative value (e.g. -480 for a 480-pixel high image).

If none of this helps, step through the code and see which line fails, and what the Windows error value is.

Stability. What an interesting concept. -- Chris Maunder

Draw a great circle of a sphere in c++

Tal S.10-Mar-04 22:40

Tal S.

10-Mar-04 22:40

Hi,

I want to draw the great circle of a sphere (radius R, center (0,0,0) ), between 2 given points: P1(x1, y1, z1), P2(x2, y2, z2).

Do you have any general algorithm for that?

Do you know where can I get more information about this subject?

Thank you.

Re: Draw a great circle of a sphere in c++

Robert A. T. Káldy11-Mar-04 1:18

Robert A. T. Káldy

11-Mar-04 1:18

All information you can find in any book about analytic geometry. Math is fun Smile | :)

Robert-Antonio

"Czech Railways discovered, that in case of disaster the most damaged wagons
were the first and the last. So they decided to create trains without them."

Re: Draw a great circle of a sphere in c++

Tal S.14-Mar-04 20:07

Tal S.

14-Mar-04 20:07

Can you recomand for a book?

Thanks,

Reli. Cool | :cool:

File IO

vikramlinux10-Mar-04 22:14

vikramlinux

10-Mar-04 22:14

HI ALL,
I have already created directory.I want to monior this directory, for any chages, like file copying , removing. Which method I should use?

VikramS

Re: File IO

Antti Keskinen10-Mar-04 22:30

Antti Keskinen

10-Mar-04 22:30

For an "easy" approach, try implementing a FileSystemWatcher object from the .Net Framework. This object has capabilities to watch for all events you specified.

Without the .Net Framework, I remember that there was a discussion over this matter earlier on the forums. You could try searching.

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

Re: File IO

Brian D10-Mar-04 22:37

Brian D

10-Mar-04 22:37

This should help you:
http://www.codeproject.com/file/directorychangewatcher.asp[^]

Regards
BD

"You know "that look" women get when they want sex? Me neither."

--Steve Martin

Re: File IO

David Crow11-Mar-04 2:55

David Crow

11-Mar-04 2:55

In addition to Brian D's suggestion, also check out FindFirstChangeNotification().

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Named Pipes Vs Sockets

vikramlinux10-Mar-04 22:04

vikramlinux

10-Mar-04 22:04

Hi ALL,
I want to communicate between 2 different machines , for data transfer.Which is the best method using pipes or Sockets? Hmmm | :|

VikramS

Re: Named Pipes Vs Sockets

Antti Keskinen10-Mar-04 22:26

Antti Keskinen

10-Mar-04 22:26

As far as I know, named pipes are memory sections that allow processes running on the same computer to exchange data between each other. A socket, on the other hand, represents a connection to an external computer.

Because you are running two different machines, I would see the sockets as the only reasonable option.

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

Re: Named Pipes Vs Sockets

Steve S11-Mar-04 0:32

Steve S

11-Mar-04 0:32

Nope. Named pipes support communication with other computers too, although it depends on the OS version. I don't think W9x allows you to create a named pipe, so if you have 9x/ME as a taget, you must run with sockets.

Steve S

Re: Named Pipes Vs Sockets

GuimaSun11-Mar-04 0:40

GuimaSun

11-Mar-04 0:40

Hi, basically sockets is a portable mechanism to comunicate between process and machines boundaries over any platform, if you are programming pipes on windows it will work just on windows based networks (not for internet) and finally pipes programming are easier then sockets programming.

GuimaSun
www.nexsun.com.br

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