Thread: Changing color of pen

Hi, I have got a problem with changing color of the pen...
Can someone analyse what is wrong in the source

Compiler sais that problem is on line which is highlighted...
Crosses initialization of 'struct HPEN__ * hBluePen'

Dev-c++

Code:

#include <windows.h>
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
                   PSTR szCmdLine, int iCmdShow)
{
    TCHAR szAppName[] = TEXT("Default window");           // Header
    HWND hWnd;
    MSG msg;
    WNDCLASSEX wc;
    
    wc.cbSize = sizeof(wc);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);            // Ico
    wc.hIconSm = NULL;                                     // Ico_sm
    wc.hCursor = (HCURSOR)LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+0);           // Background
    wc.lpszMenuName = "WMENU";
    wc.lpszClassName = szAppName;
    
    RegisterClassEx(&wc);
    
    hWnd = CreateWindowEx(0,szAppName,
                        szAppName,
                        WS_OVERLAPPEDWINDOW,
                        CW_USEDEFAULT,                    // Margin from left
                        CW_USEDEFAULT,                    // Margin from top
                        CW_USEDEFAULT,                    // Widht
                        CW_USEDEFAULT,                    // Height
                        NULL,
                        NULL,
                        hInstance,NULL);
    ShowWindow(hWnd, iCmdShow);
    UpdateWindow(hWnd);
    
    while(GetMessage(&msg, NULL, 0, 0))
    {
          TranslateMessage(&msg);
          DispatchMessage(&msg);
    }
    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HDC              hDC;
PAINTSTRUCT      ps;
 HPEN hPen = CreatePen(PS_SOLID, 1, RGB(0,0,255));
         switch(message)
         {
          case WM_PAINT:
            HPEN hBluePen = SelectObject(hDC, hBluePen);
            hDC = BeginPaint(hWnd, &ps);
            TextOut(hDC, 50, 50, TEXT("ahoj"), 5);
            EndPaint(hWnd, &ps);
            return 0;
          case WM_DESTROY:
          PostQuitMessage(0);
          return 0;
        }
        return DefWindowProc(hWnd, message, wParam, lParam);
}

Thx for help

Originally Posted by Salem

Declaring variables inside switch statements is the cause.

Try this code which uses braces to make the variable be declared in a smaller scope.

Code:

          case WM_PAINT: {
            HPEN hBluePen = SelectObject(hDC, hBluePen);
            hDC = BeginPaint(hWnd, &ps);
            TextOut(hDC, 50, 50, TEXT("ahoj"), 5);
            EndPaint(hWnd, &ps);
            return 0;
          }

The normal way of a switch is break, not return

I tried your code but it reports new error: "ANSI C++ forbids implicit conversion from 'void*' in initialization"

The problem was that you used hBluePen instead of hPen. That's all.

To Salem:
Declaring variables in switch statements is possible if you put braces around it, which is just what he already did.