Virtual Key Codes

Hi, here is my windows procedure:

LRESULT CALLBACK MessageProcedure(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)

{

static int X = 250;
static int Y = 250;
HINSTANCE hInstance;
hInstance = LoadLibrary (TEXT("Application01.exe"));

switch(message)

{
case WM_CREATE:

int MessageBoxID;
MessageBoxID = MessageBox(hWnd, TEXT(" Are ya ready kids?"), TEXT("Are ya ready kids?"),
MB_ICONQUESTION | MB_YESNO);

if (MessageBoxID == IDNO)
{
PostQuitMessage(0);
}

if (MessageBoxID == IDYES)
{
UpdateWindow(hWnd);
}

return FALSE;



case WM_PAINT:

HICON hIcon;
hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_ICON1));
HDC handleDeviceContext;
PAINTSTRUCT PaintSt;
handleDeviceContext = BeginPaint(hWnd, &PaintSt);
DrawIcon(handleDeviceContext, X, Y, hIcon);
EndPaint(hWnd, &PaintSt);
break;


case WM_KEYDOWN:

switch(wParam)

case VK_LEFT:
{
X -= 5;
InvalidateRect(hWnd, NULL, TRUE);
break;
}
case VK_RIGHT:
{
X += 5;
InvalidateRect(hWnd, NULL, TRUE);
break;
}

break;

case WM_DESTROY:
PostQuitMessage(0);
break;


}


return DefWindowProc (hWnd, message, wParam, lParam);

}



The X and Y variables are integers which are used here:

DrawIcon(handleDeviceContext, X, Y, hIcon);

So the X and Y are the location of the icon.

The problem I am having is that when i press the left arrow key, nothing happens, and when i press the right arrow key it DOES go right, but it also goes right when i press the up and down kep :S

Did you debug your code top be sure WM_KEYDOWN is processed for both VK_LEFT and VK_RIGHT?
Besides, why do you call DefWindowProc if you want to process this message in your own procedure? From MSDN:

Quote:

---

WM_KEYDOWN Message
...
Return Value

An application should return zero if it processes this message.

---

I call it to provide default processing for any window messages that my application does not process.

Quote:

---

Originally Posted by TpOreilly

I call it to provide default processing for any window messages that my application does not process.

---

But your application does process WM_KEYDOWN message when either VK_LEFT or VK_RIGHT code was supplied! :rolleyes:

I think i might be confused lol...

I havnt got "return DefWindowProc (hWnd, message, wParam, lParam);" in the case of the WM_KEYDOWN message, i have "DefWindwProc" right at the very end on the windows procedure.

It doesn't matter.
if you have processed this message you have to return 0. Period!

Quote:

---

Originally Posted by TpOreilly

Hi, here is my windows procedure:

---

Over 60 posts and you don't know how to use code tags?

Oh ok.

I have done what you said, but that results in my window not showing when i run the application. It doesnt show any errors either.

Quote:

---

Originally Posted by TpOreilly

I have done what you said, but that results in my window not showing when i run the application. It doesnt show any errors either.

---

What did you do? And how?

Returned 0.

Quote:

---

Originally Posted by TpOreilly

Returned 0.

---

:confused:
Where?

Start again :) As I am confused, could you correct my mistakes in my original code below and re-post it please :)

Code:

---

LRESULT CALLBACK MessageProcedure(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
        static int X = 250;
        static int Y = 250;
        HINSTANCE hInstance;
        hInstance = LoadLibrary (TEXT("Application01.exe"));

        switch(message)
        {
                case WM_CREATE:

                        int MessageBoxID;
                        MessageBoxID = MessageBox(hWnd, TEXT("        Are ya ready kids?"), TEXT("Are ya ready kids?"),
            MB_ICONQUESTION | MB_YESNO);

                        if (MessageBoxID == IDNO)
                        {
                                PostQuitMessage(0);
                        }

                        if (MessageBoxID == IDYES)
                        {
                                UpdateWindow(hWnd);
                        }

                        return FALSE;

                       

                case WM_PAINT:
                               
                                HICON hIcon;
                                hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_ICON1));
                                HDC handleDeviceContext;
                                PAINTSTRUCT PaintSt;
                                handleDeviceContext = BeginPaint(hWnd, &PaintSt);
                                DrawIcon(handleDeviceContext, X, Y, hIcon);
                                EndPaint(hWnd, &PaintSt);
                                break;
                       

                case WM_KEYDOWN:

                        switch(wParam)
                       
                                case VK_LEFT:
                        {
                                        X -= 5;
                                        InvalidateRect(hWnd, NULL, TRUE);
                                        break;
                        }
                                case VK_RIGHT:
                        {
                                        X += 5;
                                        InvalidateRect(hWnd, NULL, TRUE);
                                        break;
                        }

                                       



                case WM_DESTROY:
            PostQuitMessage(0);
                        break;
               

               
        }


                        return DefWindowProc (hWnd, message, wParam, lParam);
       
}

---

Quote:

---

Originally Posted by TpOreilly

Start again :) As I am confused, could you correct my mistakes in my original code below and re-post it please :)

Code:

---

LRESULT CALLBACK MessageProcedure(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
        static int X = 250;
        static int Y = 250;
        HINSTANCE hInstance;
        hInstance = LoadLibrary (TEXT("Application01.exe"));

        switch(message)
        {
                ....
                case WM_KEYDOWN:
                        switch(wParam)
                                case VK_LEFT:
                        {
                                        X -= 5;
                                        InvalidateRect(hWnd, NULL, TRUE);
                                        break;
                        }
                                case VK_RIGHT:
                        {
                                        X += 5;
                                        InvalidateRect(hWnd, NULL, TRUE);
                                        break;
                        }

                case WM_DESTROY:
            PostQuitMessage(0);
                        break;
        }
                        return DefWindowProc (hWnd, message, wParam, lParam);
}

---

---

Does it compile? :confused:
Note also that your case WM_KEYDOWN does not have break, so after each WM_KEYDOWN this code would call PostQuitMessage(0) and app would exit. So I wonder how it could "work" at all! :confused:

I have added the

Code:

---

break;

---

.

Before I added that it did actually compile :P

Also, i still have the same problem.

Quote:

---

Originally Posted by TpOreilly

I have added the

Code:

---

break;

---

.

Before I added that it did actually compile :P

Also, i still have the same problem.

---

Because if you have processed WM_KEYDOWN message you have to return 0, what you don't do! :cool:

Ok then... Where are you telling me to put "return 0;"???

Right after your processing code for VK_LEFT/VK_RIGHT of WM_KEYDOWN message.

Thanks :)

The left and right arrow key is now working as it should, although when i press a key such as 'S' or any other key which I have not defined code for makes my icon move right.

Show your actual code.

Code:

---

case WM_KEYDOWN:

                        switch(wParam)
                       
                                case VK_LEFT:
                        {
                                        X -= 5;
                                        InvalidateRect(hWnd, NULL, TRUE);
                                        return 0;

                                       
                                       
                        }
                                case VK_RIGHT:
                        {
                                        X += 5;
                                        InvalidateRect(hWnd, NULL, TRUE);
                                        return 0;
                                       
                                       
                        }

                        break;

---

Try:

Code:

---

case WM_KEYDOWN:
{
  switch(wParam) {
    case VK_LEFT:
        X -= 5;
        InvalidateRect(hWnd, NULL, TRUE);
        break;
    case VK_RIGHT:
        X += 5;
        InvalidateRect(hWnd, NULL, TRUE);
        break;
  }
}
return(0);
break;

---

Besides, the line, hInstance = LoadLibrary (TEXT("Application01.exe"));, is run every time a message arrives, which might occur several dozen of times per seconds. That line might take a lot of time and resources. I would advise you to load that library only in WM_CREATE, and declare hInstance as a static variable.

Actually, GetModuleHandle(NULL) would be enough, as long as it is about getting main .exe instance handle.

Quote:

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Originally Posted by Igor Vartanov

Actually, GetModuleHandle(NULL) would be enough, as long as it is about getting main .exe instance handle.

---

If it is, the instance handle is passed into WinMain(), and is typically saved in a global variable.

I'm almost sure it is, as nobody loads external .exe to the process. :)