C++ layered transparent window - main.h

// nur für Win 2000 und später kompilieren
#define WINVER 0x0500

#include <windows.h>
#include "main.h"

//using namespace std;

int WINAPI WinMain(HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nFunsterStil) {
    HWND hwnd;          // Main-Window handle
    MSG messages;           /* Here messages to the application are saved */
    WNDCLASSEX wincl;       /* Data structure for the windowclass */

    Init();

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;    /* This function is called by windows */
    wincl.style = CS_DBLCLKS;               /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;              /* No menu */
    wincl.cbClsExtra = 0;                   /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                   /* structure or the window instance */
    /* Use Windows's default color as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    hwnd = CreateWindowEx( // siehe http://msdn.microsoft.com/en-us/library/ms632680(v=vs.85).aspx
        0,
        szClassName,
        "Test...",                  // Titel
        WS_SYSMENU|WS_POPUP,        // Window-Long / Style
        50,                         // position x (default: CW_USEDEFAULT)
        200,                        // position y (default: CW_USEDEFAULT)
        WINDOW_WIDTH,               // Breite
        WINDOW_HEIGHT,              // Höhe
        HWND_DESKTOP,               // Kind vom Desktop
        NULL,                       // Kein Menü
        hThisInstance,              // Program Instance handler
        NULL
    );

    // Long des Fensters auf LAYER setzen, damit es transparent werden kann (WS_EX_TRANSPARENT macht das Fenster komplett transparent)
    SetWindowLong(hwnd, GWL_EXSTYLE, GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);

    // Alpha-Wert des Fensters setzen
    //SetLayeredWindowAttributes(hwnd, 0, (255 * 70) / 100, LWA_ALPHA);

    // Nur bestimmten Ausschnitt zeigen
    //SetWindowRgn(hwnd, CreateRectRgn(10,20,200,60), false);

    ShowWindow(hwnd, nFunsterStil); // Fenster sichtbar machen



    // Message-Loop (läuft solange wie GestMessage != 0 ist)
    while (GetMessage (&messages, NULL, 0, 0)) {
        TranslateMessage(&messages);     // virtual-key messagse to character messages
        DispatchMessage(&messages);     // Event behandeln
    }

    return messages.wParam;
}



void Init() {

    col = RGB(128,0,0);
    ColorRect.left = 10;
    ColorRect.top = 120;
    ColorRect.right = 290;
    ColorRect.bottom = 160;

}



LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{

    if (message == WM_PAINT) {
        PAINTSTRUCT ps;
        brush = CreateSolidBrush(col);
        HDC dc;
        dc = NULL;
        dc = BeginPaint(hwnd, &ps);
        SelectObject(dc, brush);
        FillRect(dc, &ColorRect, brush);
        EndPaint(hwnd, &ps);
    } else if (message == WM_DESTROY) {
        DeleteObject(brush);
        PostQuitMessage(0); // WM_QUIT zur message queue senden
    } else {
        return DefWindowProc(hwnd, message, wParam, lParam); // die message weitersenden damit evtl. andere Programme die message handeln können
    }

    return 0;
}