Win32 sample program of bitmap waving effect

main.c

// To compile (using VC):
// cl main.c /link gdi32.lib user32.lib kernel32.lib
#include <tchar.h>
#include <math.h>
#include <windows.h>

TCHAR *szWindowClass =_T("Window Class Name");

#define PI 3.14159265

typedef struct tag_DibStruct {
    HBITMAP hDib;
    HGDIOBJ hOldGdiObj;
    HDC hDc;
    int width;
    int height;
    void *buffer;
    size_t bufferSize;
} DIBSTRUCT;

DIBSTRUCT g_dib;

/* Load a bitmap file into g_dib. */
BOOL MyLoadBitmap(LPCTSTR szFileName) {
    HBITMAP hBmp = NULL;
    BITMAP bitmap;
    BITMAPINFO bmi;
    HDC hDesktopDc = NULL;
    HDC hTempDc = NULL;
    HGDIOBJ hOldObj = NULL;
    BOOL bResult = TRUE;

    /* Load a bitmap file and get a bitmap object. */
    hBmp = (HBITMAP)LoadImage(NULL, szFileName, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
    if (hBmp == NULL) {
        return (FALSE);
    }
    GetObject(hBmp, sizeof(bitmap), &bitmap);

    /* Get the desktop DC. */
    hDesktopDc = GetDC(GetDesktopWindow());

    /* Create a temporary DC for the loaded bitmap. */
    hTempDc = CreateCompatibleDC(hDesktopDc);
    hOldObj = SelectObject(hTempDc, hBmp);

    /* Create 32-bit DIB with the same size as the loaded bitmap. */
    memset(&g_dib, 0, sizeof(g_dib));
    g_dib.width = bitmap.bmWidth;
    g_dib.height = bitmap.bmHeight;
    memset(&bmi, 0, sizeof(bmi));
    bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmi.bmiHeader.biWidth = g_dib.width;
    bmi.bmiHeader.biHeight = - g_dib.height;
    bmi.bmiHeader.biPlanes = 1;
    bmi.bmiHeader.biBitCount = 32;
    bmi.bmiHeader.biCompression = BI_RGB;
    g_dib.hDib = CreateDIBSection(hDesktopDc, &bmi, DIB_RGB_COLORS, (void **)&g_dib.buffer, 0, 0);
    if (g_dib.buffer == NULL) {
        bResult = FALSE;
        goto Exit;
    }
    g_dib.bufferSize = g_dib.width * g_dib.height * 4;
    g_dib.hDc = CreateCompatibleDC(hDesktopDc);
    g_dib.hOldGdiObj = SelectObject(g_dib.hDc, g_dib.hDib);

    BitBlt(g_dib.hDc, 0, 0, g_dib.width, g_dib.height, hTempDc, 0, 0, SRCCOPY);

 Exit:
    SelectObject(hTempDc, hOldObj);
    DeleteDC(hTempDc);
    DeleteObject(hBmp);
    ReleaseDC(GetDesktopWindow(), hDesktopDc);
    return (bResult);
}

COLORREF *GetPixelPtr(void *src, int x, int y, int w) {
    return (((COLORREF *)src) + (w * y) + x);
}

void Wave() {
    void *tmpBuffer = NULL;
    int i, j, w, h, x, y, dx, dy;
    int cx, cy;

    cx = 30;
    cy = 30;

    tmpBuffer = malloc(g_dib.bufferSize);
    if (tmpBuffer == NULL) {
        return;
    }
    memcpy(tmpBuffer, g_dib.buffer, g_dib.bufferSize);

    w = g_dib.width;
    h = g_dib.height;

    for (j = 0; j < h; j++) {
        for (i = 0; i < w; i++) {
            dx = cx * cos((double)j / h * PI * 3);
            dy = cy * sin((double)i / w * PI * 3);
            x = i + dx;
            y = j + dy;
            if (x < 0) x += w;
            if (y < 0) y += h;
            if (x >= w) x -= w;
            if (y >= h) y -= h;
            
            *GetPixelPtr(g_dib.buffer, i, j, w) =
                *GetPixelPtr(tmpBuffer, x, y, w);
        }
    }
    free(tmpBuffer);
}

LRESULT CALLBACK MyWndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    HDC hWndDc = NULL;
    PAINTSTRUCT paint;
    switch (msg) {
    case WM_PAINT:
        hWndDc = BeginPaint(hWnd, &paint);
        BitBlt(hWndDc, 0, 0, g_dib.width, g_dib.height, g_dib.hDc, 0, 0, SRCCOPY);
        EndPaint(hWnd, &paint);
        break;
    case WM_DESTROY:
        SelectObject(g_dib.hDc, g_dib.hOldGdiObj);
        DeleteDC(g_dib.hDc);
        DeleteObject(g_dib.hDib);
        PostQuitMessage(0);
        break;
    default:
        return (DefWindowProc(hWnd, msg, wParam, lParam));
    }
    return (0L);
}

ATOM MyRegisterClass(HINSTANCE hInstance) {
    WNDCLASSEX wcex;
    memset(&wcex, 0, sizeof(wcex));

    wcex.cbSize = sizeof(wcex);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = (WNDPROC)MyWndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = szWindowClass;
    return (RegisterClassEx(&wcex));
}

int WINAPI _tWinMain(HINSTANCE hInstance, HINSTANCE hPreInst,
                     LPTSTR lpszCmdLine, int nCmdShow)
{
    HWND hWnd;
    MSG msg;

    if (!MyRegisterClass(hInstance)) {
        return FALSE;
    }

    MyLoadBitmap("test.bmp");
    Wave();

    hWnd = CreateWindow(szWindowClass, _T("Test"), WS_OVERLAPPEDWINDOW,
                        CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL,
                        hInstance, NULL);
    if (!hWnd) {
        return (FALSE);
    }
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);


    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return (msg.wParam);
}