C / C++ / MFC

about "windows belonging to different processes are mixed in a single window hierarchy"

19-Jun-11 23:49

Sometimes we need to know the retult of the message and using the return value or wparam or lparam of the message.

Take WM_GETTEXT as an example.
Only after the destination window processed this messasge and filled the lparam with it's text,can our program do something accordingly.

In such case we must use SendMessage.

Re: SendMessage

Sakhalean20-Jun-11 0:00

Sakhalean

20-Jun-11 0:00

s ok thank u

Re: SendMessage

Albert Holguin20-Jun-11 4:42

Albert Holguin

20-Jun-11 4:42

SendMessage() is a synchronous call, meaning it waits for the code and result of the operation (framework equivalent of making a blocking function call), whereas PostMessage() is asynchronous, meaning there's no waiting for result.

Where is either useful?
-SendMessage(): Your continuation of execution depends on the result of the operation and/or the CWnd's lie in the same thread (blocking calls are a non-issue).
-PostMessage(): Non-blocking is essential, such is the case for threaded programming.

doubi in vc++

Remya.pv19-Jun-11 18:24

Remya.pv

19-Jun-11 18:24

how to mdichildframe in pane of splitter aplication in vc++

Re: doubi in vc++

Richard MacCutchan19-Jun-11 21:49

Richard MacCutchan

19-Jun-11 21:49

Your question is not clear, please add some more detail about what you are trying to achieve.

The best things in life are not things.

Re: doubi in vc++

Chandrasekharan P19-Jun-11 21:55

Chandrasekharan P

19-Jun-11 21:55

Can you please re-phrase your query? Is not clear on what you are asking. make it a little elaborate.

Re: doubi in vc++

Mark Salsbery20-Jun-11 11:05

Mark Salsbery

20-Jun-11 11:05

Here's an example project (MFC)[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

xrg_soft@163.com19-Jun-11 17:40

Re: about "windows belonging to different processes are mixed in a single window hierarchy"

19-Jun-11 17:40

From MSDN page for WM_ACTIVATETOPLEVEL
http://msdn.microsoft.com/en-us/library/xkd95027(VS.80).aspx

I got the below description:
This message is similar in use to WM_ACTIVATEAPP, but works in situations where windows belonging to different processes are mixed in a single window hierarchy (common in OLE applications).

Does anybody know where is a example/demo/document available that illustrate "windows belonging to different processes are mixed in a single window hierarchy"?

I googled but found almost nothing.

Thanks!

Mark Salsbery19-Jun-11 18:11

Mark Salsbery

19-Jun-11 18:11

Since they mention OLE, you could start there perhaps...

Compound Documents[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: about "windows belonging to different processes are mixed in a single window hierarchy"

xrg_soft@163.com20-Jun-11 19:06

Re: register window message

20-Jun-11 19:06

Thanks!

I think I got the basic idea.
Just like embeded MS Word into your_app, the embeded MSWord view window is a chid window of your_app.exe but it's essentially relaies on a external process WinWord.exe

so0_lanhlung219-Jun-11 16:56

so0_lanhlung2

19-Jun-11 16:56

i registed my message on DlgMain WM_PK_MESSAGE by RegisterWindowMessage
and i have a DLL..have InjectDLL Function callback to a wndproc
i want my DLL get WM_PK_MESSAGE..
can you have some ideas for me Wink | ;)

tk so much

xrg_soft@163.com19-Jun-11 17:44

Re: register window message

19-Jun-11 17:44

Hi,

In each process you using the registered message, you should first call

WM_PK_MESSAGE = RegisterWindowMessage

and then you can use the WM_PK_MESSAGE.

softwaremonkey19-Jun-11 19:41

softwaremonkey

19-Jun-11 19:41

You also need to use the ON_REGISTERED_MESSAGE macro instead of the normal ON_MESSAGE e.g.

// In message map
BEGIN_MESSAGE_MAP(CMyWnd, CWnd)
  ON_REGISTERED_MESSAGE(m_nRegMsg, OnRegisteredMessage)
END_MESSAGE_MAP()

Moving Objects in small increments

Cyclone_S19-Jun-11 14:07

19-Jun-11 14:07

Hi,

I got a ball hitting a paddle and I want it's X velocity to increase/decrease depending on where it hits the paddle. The code below works with whole numbers but not for numbers like "0.67" or "2.45". I'm looking for a way to animate objects moving at smaller increments for better precision. Thanks.

int speed=Ball_List[b]->speed;
// Paddle center.
int paddle_center = Player->Location.X + Player->Width / 2;

// Ball center.
int ball_center = Ball_List[b]->gameBall->Location.X + Ball_List[b]->gameBall->Width / 2;

// Find the location on the paddle that the ball hit
int paddle_location = ball_center - paddle_center;

// change angle according to distance from center of paddle.
double a=(90-paddle_location);
double angle = (Math::PI / 180) * a; // angle in radians.
Ball_List[b]->xVel = speed*Math::Cos(angle);
Ball_List[b]->yVel = -speed*Math::Sin(angle);

// Move the ball
Ball_List[b]->gameBall->Location = Point(Ball_List[b]->gameBall->Location.X + Ball_List[b]->xVel, Ball_List[b]->gameBall->Location.Y + Ball_List[b]->yVel);
[/code]

enhzflep19-Jun-11 15:03

19-Jun-11 15:03

Can you tell us what doesn't work when you use non-integers. And non-integers for what?

Cyclone_S19-Jun-11 16:03

19-Jun-11 16:03

I tried using doubles but for a value like 0.6 the ball doesn't move at all. The box control takes doubles but will round them down to the nearest integer. Is there a way to do this over the course of X number of frames?

I'm using non-integers for the box control's position. Right now there's only about 6 different directions the ball takes when hitting the paddle. I need finer control over the speed of the ball.

This problem happens with any sort of animation I try to do. What if I wanted smooth acceleration of a game object? This wouldn't be possible with the problem I'm encountering.

enhzflep19-Jun-11 16:23

19-Jun-11 16:23

Ah, okay gotcha.

Well, in that case you can use floats or doubles for the position and the velocity. It's just a matter of rounding the position to an int before using it to display the ball.

Or of course, you could keep an integer position of last impact, along with an integer number of frames since it occured and a double velocity, or position increment per frame. Each time you display, just show the ball at [impact.x + frames*velocity.x, impact.y + frames*velocity.y]

But the easier is to just keep the position and velocity as doubles, converting to an int when using for display purposes. (You might also have to add code that will check if the ball is within a threshold distance, since non-integers will mean your ball wont hit the walls or paddle 'exactly' - well not at the exact moment of a frame, anyway.

Cyclone_S19-Jun-11 16:49

19-Jun-11 16:49

I'm not sure I understand. Do you understand what I'm trying to do? after the ball hits the paddle it should move left/right depending on how far from the center it is. Just need finer precision on the angle(xvel) of the ball. Thanks.

I tried something like this. I took a number like 1.65 and did

1.65 - Math::Floor(1.65)

to get just the decimal part of the number 0.65.Then every frame I added 0.65 to 0.65 and checked if it was >= 1. If it was I added 1.0 to the left/right property of the box. I then repeated that.

The problem with it was I wasn't encounting for the speed of the ball. If the speed of the ball is 6 it moves 6 frames every timer tick. The code I was trying only moved 1 pixel at a time.

I'm just not sure on the math to incorporate the speed into it.

enhzflep19-Jun-11 18:24

19-Jun-11 18:24

Sorry about that. Um, I think I understand your intention.

It sounds to me much like a game of pong or similar. Lord knows what I've done with my old code. I can't be bothered even think about the physics right now, but I've thrown together some code that will throw a red dot into a parabolic arc.

In such a path, we'll have to both be able to have small increments of movement, and be able to vary them. You just have to assign the ball's velocity and position in an appropriate way for your application.

Enjoy. Smile | :)

#include <windows.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "CodeBlocksWindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR lpszArgument,
                     int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default colour as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "Click to release a ball",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           544,                 /* The programs width */
           375,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nCmdShow);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}

////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
float ballPosX, ballPosY, ballVelocityX, ballVelocityY;
const int myTimerId = 1;
const int intervalMs = 50;

VOID CALLBACK myTimerProc(HWND hwnd,        // handle to window for timer messages
    UINT message,     // WM_TIMER message
    UINT idTimer,     // timer identifier
    DWORD dwTime)     // current system time
{
	ballPosX += ballVelocityX;
	ballPosY += ballVelocityY;
	ballVelocityY -= 0.1;
	InvalidateRect(hwnd, NULL, true);
}

/*  This function is called by the Windows function DispatchMessage()  */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	PAINTSTRUCT ps;
	HDC hdc;

    switch (message)                  /* handle the messages */
    {
        case WM_DESTROY:
            KillTimer(hwnd, myTimerId);
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;

        case WM_PAINT:
            hdc = BeginPaint(hwnd, &ps);

            SetPixel(hdc, ballPosX, ballPosY, RGB(250,0,0));
            SetPixel(hdc, ballPosX, ballPosY+1, RGB(250,0,0));
            SetPixel(hdc, ballPosX+1, ballPosY, RGB(250,0,0));
            SetPixel(hdc, ballPosX+1, ballPosY+1, RGB(250,0,0));

            EndPaint(hwnd, &ps);
            break;

        case WM_LBUTTONUP:
            ballPosX=0;
            ballPosY=0;
            ballVelocityX=3.2;
            ballVelocityY=8.1;

            KillTimer(hwnd, myTimerId);
            SetTimer(hwnd, myTimerId, intervalMs, myTimerProc);
            break;

        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

enhzflep19-Jun-11 21:35

19-Jun-11 21:35

I got bored. Here try if this if you like - it's two balls, a red one and a white one. If you hit the red one with the white one it will move in a direction away from the white one before being slowed to a halt by friction. Of course your collision handling stuff will be different(hopefully pixel-accurate, unlike mine) for the paddle and the ball, but it's the same concepts at work.

Rose | [Rose]

#include <math.h>
#include <windows.h>
#include <windowsx.h>
#include <wingdi.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

void handleCollisions();

/*  Make the class name into a global variable  */
char szClassName[ ] = "CodeBlocksWindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR lpszArgument,
                     int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor =LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default colour as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "Click to release a ball",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           544,                 /* The programs width */
           375,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nCmdShow);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}

////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
float ballPosX, ballPosY, ballVelocityX, ballVelocityY;
float curMouseX, lastMouseX, curMouseY, lastMouseY;
int clientWidth, clientHeight;

const int myTimerId = 1;
const int intervalMs = 50;
const int ballRadius = 10; // pixels
const int cursorRadius = 15; // pixels


void handleCollisions()
{
    float dx, dy, dist;

    // part 1 - check for collisions with the mouse cursor
    dx = ballPosX - curMouseX;
    dy = ballPosY - curMouseY;

    dist = sqrt( dx*dx + dy*dy);
    if (dist<ballRadius+cursorRadius)
    {
        ballVelocityX = 0.5 * dx;
        ballVelocityY = 0.5 * dy;
    }

    // part 2 - check for collisions with the walls
    if (ballPosX < ballRadius)
        ballVelocityX = abs(ballVelocityX);

    if (ballPosY < ballRadius)
        ballVelocityY = abs(ballVelocityY);

    if (ballPosX > clientWidth-ballRadius)
        ballVelocityX = -1 * abs(ballVelocityX);

    if (ballPosY > clientHeight-ballRadius)
        ballVelocityY = -1 * abs(ballVelocityY);
}

VOID CALLBACK myTimerProc(HWND hwnd,        // handle to window for timer messages
    UINT message,     // WM_TIMER message
    UINT idTimer,     // timer identifier
    DWORD dwTime)     // current system time
{
	ballPosX += ballVelocityX;
	ballPosY += ballVelocityY;
	ballVelocityX *= 0.9;
	ballVelocityY *= 0.9;

    handleCollisions();

	InvalidateRect(hwnd, NULL, true);
}

/*  This function is called by the Windows function DispatchMessage()  */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	PAINTSTRUCT ps;
	HDC hdc;
    RECT clientRect;

    HBRUSH newBr, oldBr;


    switch (message)                  /* handle the messages */
    {
        case WM_CREATE:
            ballPosX = 100;
            ballPosY = 100;
            SetTimer(hwnd, myTimerId, intervalMs, myTimerProc);
            GetClientRect(hwnd, &clientRect);
            clientWidth = clientRect.right;
            clientHeight = clientRect.bottom;
            return true;

        case WM_DESTROY:
            KillTimer(hwnd, myTimerId);
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;

        case WM_PAINT:
            hdc = BeginPaint(hwnd, &ps);

            //draw the red ball
            newBr = CreateSolidBrush(RGB(250,0,0));
            oldBr = (HBRUSH)SelectObject(hdc, newBr);
            Ellipse(hdc, ballPosX-ballRadius,ballPosY-ballRadius,ballPosX+ballRadius,ballPosY+ballRadius);
            SelectObject(hdc, oldBr);
            DeleteObject(newBr);

            // draw the white ball
            Ellipse(hdc, curMouseX-cursorRadius, curMouseY-cursorRadius, curMouseX+cursorRadius, curMouseY+cursorRadius);

            EndPaint(hwnd, &ps);
            break;

        case WM_MOUSEMOVE:
            lastMouseX = curMouseX;
            lastMouseY = curMouseY;
            curMouseX = GET_X_LPARAM(lParam);
            curMouseY = GET_Y_LPARAM(lParam);
            InvalidateRect(hwnd,NULL,true);
            break;

        case WM_LBUTTONUP:
            // shoot the red ball from the top left corner
            ballPosX=11;
            ballPosY=11;
            ballVelocityX=6.2;
            ballVelocityY=18.1;
            break;

        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}
}

Cyclone_S20-Jun-11 14:33