win32_dvd_screensaver.cxx

#include <stdio.h>
#include <windows.h>
#include <vector>

RECT gUsableAreaCoords = {0};
RECT gCurrentPos = {0};
INT gVelocityX = 5;
INT gVelocityY = 5;

DWORD gLast = 0;

#define WINDOW_X 320
#define WINDOW_Y 200

POINT gLastMousePos = {0};

BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam) {
    std::vector<RECT>* windows = reinterpret_cast<std::vector<RECT>*>(lParam);
    RECT rc = {0};
    
    if (!GetWindowRect(hwnd, &rc)) {
        return TRUE;
    }
    
    if (!IsWindowVisible(hwnd) || IsZoomed(hwnd)) {
        return TRUE;
    }
    
    char string[128] = {0};
    GetWindowTextA(hwnd, string, 128);
    if (strlen(string) == 0 || !strcmp(string, "Start") || !strcmp(string, "Program Manager")) {
        return TRUE;
    }

    DWORD processId = 0;
    GetWindowThreadProcessId(hwnd, &processId);
    if (processId == GetCurrentProcessId()) {
        return TRUE;
    }

    windows->push_back(rc);
    return TRUE;
}

VOID CollisionCheck(VOID) {
    std::vector<RECT> windows;
    EnumWindows(EnumWindowsProc, reinterpret_cast<LPARAM>(&windows));

    // I wrote this late at night can be better
    for (int i = 0; i < windows.size(); i++) {
        if (gCurrentPos.left < windows[i].right && gCurrentPos.right > windows[i].left) {
            if (gCurrentPos.top < windows[i].bottom && gCurrentPos.bottom > windows[i].top) {
                if (gVelocityX > 0 && gCurrentPos.right > windows[i].left && gCurrentPos.left < windows[i].left) {
                    gVelocityX *= -1;
                } 
                else if (gVelocityX < 0 && gCurrentPos.left < windows[i].right && gCurrentPos.right > windows[i].right) {
                    gVelocityX *= -1;
                }

                if (gVelocityY > 0 && gCurrentPos.bottom > windows[i].top && gCurrentPos.top < windows[i].top) {
                    gVelocityY *= -1;
                } 
                else if (gVelocityY < 0 && gCurrentPos.top < windows[i].bottom && gCurrentPos.bottom > windows[i].bottom) {
                    gVelocityY *= -1;
                }
            }
        }
    }
    
    if (gCurrentPos.left < gUsableAreaCoords.left || gCurrentPos.right > gUsableAreaCoords.right) {
        gVelocityX *= -1;
    }
    if (gCurrentPos.top < gUsableAreaCoords.top || gCurrentPos.bottom > gUsableAreaCoords.bottom) {
        gVelocityY *= -1;
    }
}

LRESULT CALLBACK WindowProcessMessages(HWND hwnd, UINT msg, WPARAM param, LPARAM lparam) {
    DWORD now = GetTickCount();
    POINT currMousePos = {0};

    GetCursorPos(&currMousePos);
    if (currMousePos.x != gLastMousePos.x || currMousePos.y != gLastMousePos.y) { PostQuitMessage(0); }

    if ((now - gLast) > 10) {
        gLast = now;

        GetWindowRect(hwnd, &gCurrentPos);
        CollisionCheck();

        gCurrentPos.left += gVelocityX;
        gCurrentPos.top += gVelocityY;

        SetWindowPos(hwnd, 0, gCurrentPos.left, gCurrentPos.top, WINDOW_X, WINDOW_Y, SWP_NOZORDER | SWP_NOSIZE | SWP_NOACTIVATE);
    }

    RECT rc = {0};
    GetClientRect(hwnd, &rc);
    InvalidateRect(hwnd, &rc, TRUE);

    switch (msg) {
        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
        default:
            return DefWindowProc(hwnd, msg, param, lparam);
    }
}

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    gLast = GetTickCount();
    srand(gLast);
    GetCursorPos(&gLastMousePos);

    SystemParametersInfo(SPI_GETWORKAREA, 0, &gUsableAreaCoords, 0);

    WNDCLASS wc = {0};
    wc.hInstance = hInstance;
    wc.lpszClassName = L"Something";
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)COLOR_WINDOW;
    wc.lpfnWndProc = WindowProcessMessages;
    RegisterClass(&wc);

    int posX = rand() % (gUsableAreaCoords.right - WINDOW_X);
    int posY = rand() % (gUsableAreaCoords.bottom - WINDOW_Y);

    CreateWindowA("Something", "Fun", WS_SYSMENU | WS_VISIBLE, posX, posY, WINDOW_X, WINDOW_Y, NULL, NULL, NULL, NULL);

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

    return 0;
}

Hi, you are missing SS specific code for registering SS on Windows list of SS since it is available for Windows 95/2000/XP/7/8/10, so it will be available only as .EXE and not as actual SS with configurable parameters visible on a Desktop tab of SS properties.

Hi, you are missing SS specific code for registering SS on Windows list of SS since it is available for Windows 95/2000/XP/7/8/10, so it will be available only as .EXE and not as actual SS with configurable parameters visible on a Desktop tab of SS properties.

Interesting I'll take a look at this. Thanks!