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gretty

FillRgn() Wont Work?

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Hello I have a simple win32 Pong game I am making. But when I try to fill a rectangular region with a white HBRUSH it doesn't work. For some reason the region doesnt get filled? Here is my app; the problem occurs in line 112 in the "WndProc" function:
#include <windows.h>
#include <stdio.h>

static HINSTANCE gInstance;
struct PLAYER {
    
    HRGN rgn;
    int x;
    int y;
    int width;
    int height;    
};
PLAYER player;
bool redrawPlayer = true;

// Functions List //
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);


int WINAPI WinMain(HINSTANCE gInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;

    //Step 1: Registering the Window Class
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = gInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+3);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = "My Class";
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    // if registration of main class fails
    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    // Step 2: Creating the Window
    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        "My Class",
        "Pong",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,500,500,
        NULL, NULL, gInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    // Step 3: The Message Loop
    while(GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
    return Msg.wParam;
}

// Step 4: the Window Procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CREATE:
        {
            player.x = 10;
            player.y = 200;
            player.width = 50;
            player.height = 100;
            player.rgn = CreateRectRgn(player.x,player.y,player.x+player.width,player.y+player.height);
        }     
        break;
        case WM_KEYDOWN:
        {
             switch(LOWORD(wParam)) {
                
                case 65:
                     MessageBox(hwnd,"a pressed","",MB_OK);
                     redrawPlayer = true;
                     InvalidateRect(hwnd,NULL,true); 
                break;
                default:
                break;                    
             }
        }
        break;
        case WM_PAINT:
        {
            HDC hdc;
            PAINTSTRUCT ps;
            
            hdc = BeginPaint(hwnd,&ps);
            
            if (redrawPlayer) {
                FillRgn(hdc,player.rgn,(HBRUSH)RGB(255,255,255));  // this function isn't working
                //Rectangle(hdc,player.x,player.y,player.x+player.width,player.y+player.height);
                redrawPlayer = false;             
            }
            
            EndPaint(hwnd,&ps); 
        }     
        break;
        case WM_CLOSE:
            DestroyWindow(hwnd);
        break;
        case WM_DESTROY:
            PostQuitMessage(0);
        break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}


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Hi,

You can't just cast the RGB values to an HBRUSH like you are doing. Remember to check return codes. FillRgn was returning an error. Do this instead:


HBRUSH b = CreateSolidBrush(RGB(255, 255, 255));
FillRgn(hdc, player.rgn, b);
DeleteObject(b);



Of course, you probably don't want to create the brush at every WM_PAINT, so create it at the start of the game. You can also use GetStockObject to get the WHITE_BRUSH brush.

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