Question

How to use the SetPixel function to draw a diagonal line using the Win32 API in C++

Answer 1

#include <windows.h>

// Window procedure
LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
        case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);

            // Draw a diagonal line using SetPixel
            for (int i = 0; i < 300; i++) {
                SetPixel(hdc, 50 + i, 50 + i, RGB(255, 0, 0)); // red pixel
            }

            EndPaint(hWnd, &ps);
        }
        return 0;

        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }

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

// WinMain – program entry point
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR, int nCmdShow)
{
    const wchar_t CLASS_NAME[] = L"SetPixelDemo";

    WNDCLASS wc = {};
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;

    wc.lpszClassName = CLASS_NAME;
    RegisterClass(&wc);

    HWND hWnd = CreateWindowEx(
        0,
        CLASS_NAME,
        L"SetPixel Example",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        640, 480,
        NULL,
        NULL,
        hInstance,
        NULL
    );

    ShowWindow(hWnd, nCmdShow);

    // Message loop
    MSG msg = {};
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}




/*
run



*/

 

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