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GDI Problems

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#include <windows.h> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM); int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow ) { WNDCLASS WndClass; WndClass.style = 0; WndClass.cbClsExtra = 0; WndClass.cbWndExtra = 0; WndClass.lpfnWndProc = WndProc; WndClass.hInstance = hInstance; WndClass.hbrBackground = (HBRUSH) (COLOR_WINDOW+1); WndClass.hCursor = LoadCursor (NULL, IDC_ARROW); WndClass.hIcon = LoadIcon (NULL, IDI_APPLICATION); WndClass.lpszMenuName = 0; WndClass.lpszClassName = "WinProg"; RegisterClass(&WndClass); HWND hWindow; hWindow = CreateWindow("WinProg", "Window", WS_OVERLAPPEDWINDOW, 0,0,600,460,NULL,NULL, hInstance, NULL); ShowWindow (hWindow,nCmdShow); UpdateWindow (hWindow); MSG Message; while(GetMessage(&Message, NULL, 0, 0)) { DispatchMessage(&Message); } return (Message.wParam); } LRESULT CALLBACK WndProc (HWND hWnd, UINT uiMessage, WPARAM wParam, LPARAM lParam) { switch(uiMessage) { case WM_PAINT: HPEN hPen; HPEN hPenalt; HBRUSH hBrush; HBRUSH hBrushalt; hBrush = CreateSolidBrush (RGB(255,100,0)); hPen = CreatePen (PS_SOLID,2,RGB(0,255,255)); HDC hdc; PAINTSTRUCT ps; hdc = BeginPaint (hWnd, &ps); hBrushalt = SelectObject(hdc, hBrush); hPenalt = SelectObject (hdc, hPen); MoveToEx (hdc, 20,20, NULL); LineTo (hdc, 100, 100); Rectangle (hdc, 120, 20, 240, 140); RoundRect (hdc, 260, 20, 420, 140, 20, 20); RECT rect; SetRect (&rect, 20, 260, 240, 420); FrameRect (hdc, &rect, hBrush); SetRect (&rect, 260, 260, 420, 420); FillRect (hdc, &rect, hBrush); Ellipse (hdc, 440, 260, 480, 420); SelectObject (hdc, hBrushalt); SelectObject (hdc, hPenalt); DeleteObject (hPen); DeleteObject (hBrush); EndPaint (hWnd, &ps); return 0; case WM_DESTROY: PostQuitMessage(0); return 0; break; default: return DefWindowProc (hWnd, uiMessage, wParam, lParam); } }
hBrushalt = SelectObject(hdc, hBrush); hPenalt = SelectObject (hdc, hPen); thats the code and the error is 56 C:\Dev-Cpp\Nitty Gritty winapi\my very first window.cpp invalid conversion from `void*' to `HBRUSH__*' 57 C:\Dev-Cpp\Nitty Gritty winapi\my very first window.cpp invalid conversion from `void*' to `HPEN__*' im using windows xp and im using the Bloodshed dev c++ IDE..im not sure why im getting that error? can sombody try to explain to me whats going on and why it thinks he function is void..

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The Windows GDI API has the unfortunate habit of requiring casts to work properly at times. Just put in the right cast on the return of SelectObject() for your HPEN and HBRUSH.

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You have a couple of options, you can cast it:

hBrushalt = (HBRUSH) SelectObject(hdc, hBrush);
hPenalt = (HPEN) SelectObject (hdc, hPen);

Or you can #include <windowsx.h> and use:

hBrushalt = SelectBrush(hdc, hBrush);
hPenalt = SelectPen(hdc, hPen);

I recommend the latter option. This behavior is left over from back in the good old days when pretty much everybody programmed Windows in C and type checking was spotty at best.

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when i use either of those, i get like 100 undefined refrences to....

heres some examples

[Linker error] undefined reference to `CreateSolidBrush@4'

things like that? sorry to be a hassel lol

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Make sure you are linking the proper libraries. For Dev-C++, I believe you will have to add -lgdi32 to the linker settings.

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