Win32: full-screen and hiding taskbar

Solution 1:

Edit 2. There is even a better way for doing fullscreen, the chromium way, source taken from here:

http://src.chromium.org/viewvc/chrome/trunk/src/ui/views/win/fullscreen_handler.cc?revision=HEAD&view=markup

void FullscreenHandler::SetFullscreenImpl(bool fullscreen, bool for_metro) {
  ScopedFullscreenVisibility visibility(hwnd_);

  // Save current window state if not already fullscreen.
  if (!fullscreen_) {
    // Save current window information.  We force the window into restored mode
    // before going fullscreen because Windows doesn't seem to hide the
    // taskbar if the window is in the maximized state.
    saved_window_info_.maximized = !!::IsZoomed(hwnd_);
    if (saved_window_info_.maximized)
      ::SendMessage(hwnd_, WM_SYSCOMMAND, SC_RESTORE, 0);
    saved_window_info_.style = GetWindowLong(hwnd_, GWL_STYLE);
    saved_window_info_.ex_style = GetWindowLong(hwnd_, GWL_EXSTYLE);
    GetWindowRect(hwnd_, &saved_window_info_.window_rect);
  }

  fullscreen_ = fullscreen;

  if (fullscreen_) {
    // Set new window style and size.
    SetWindowLong(hwnd_, GWL_STYLE,
                  saved_window_info_.style & ~(WS_CAPTION | WS_THICKFRAME));
    SetWindowLong(hwnd_, GWL_EXSTYLE,
                  saved_window_info_.ex_style & ~(WS_EX_DLGMODALFRAME |
                  WS_EX_WINDOWEDGE | WS_EX_CLIENTEDGE | WS_EX_STATICEDGE));

    // On expand, if we're given a window_rect, grow to it, otherwise do
    // not resize.
    if (!for_metro) {
      MONITORINFO monitor_info;
      monitor_info.cbSize = sizeof(monitor_info);
      GetMonitorInfo(MonitorFromWindow(hwnd_, MONITOR_DEFAULTTONEAREST),
                     &monitor_info);
      gfx::Rect window_rect(monitor_info.rcMonitor);
      SetWindowPos(hwnd_, NULL, window_rect.x(), window_rect.y(),
                   window_rect.width(), window_rect.height(),
                   SWP_NOZORDER | SWP_NOACTIVATE | SWP_FRAMECHANGED);
    }
  } else {
    // Reset original window style and size.  The multiple window size/moves
    // here are ugly, but if SetWindowPos() doesn't redraw, the taskbar won't be
    // repainted.  Better-looking methods welcome.
    SetWindowLong(hwnd_, GWL_STYLE, saved_window_info_.style);
    SetWindowLong(hwnd_, GWL_EXSTYLE, saved_window_info_.ex_style);

    if (!for_metro) {
      // On restore, resize to the previous saved rect size.
      gfx::Rect new_rect(saved_window_info_.window_rect);
      SetWindowPos(hwnd_, NULL, new_rect.x(), new_rect.y(),
                   new_rect.width(), new_rect.height(),
                   SWP_NOZORDER | SWP_NOACTIVATE | SWP_FRAMECHANGED);
    }
    if (saved_window_info_.maximized)
      ::SendMessage(hwnd_, WM_SYSCOMMAND, SC_MAXIMIZE, 0);
  }
}

Edit. It is probably better to create a fullscreen window as BrendanMcK pointed it out in a comment to this answer, see this link: http://blogs.msdn.com/b/oldnewthing/archive/2005/05/05/414910.aspx ("How do I cover the taskbar with a fullscreen window?")

The new code using the link above would be:

HWND CreateFullscreenWindow(HWND hwnd)
{
 HMONITOR hmon = MonitorFromWindow(hwnd,
                                   MONITOR_DEFAULTTONEAREST);
 MONITORINFO mi = { sizeof(mi) };
 if (!GetMonitorInfo(hmon, &mi)) return NULL;
 return CreateWindow(TEXT("static"),
       TEXT("something interesting might go here"),
       WS_POPUP | WS_VISIBLE,
       mi.rcMonitor.left,
       mi.rcMonitor.top,
       mi.rcMonitor.right - mi.rcMonitor.left,
       mi.rcMonitor.bottom - mi.rcMonitor.top,
       hwnd, NULL, g_hinst, 0);
}

Old answer below - do not use it, stays only for the record on how NOT to do this.

You have to hide taskbar and menubar to see fullscreen immediately.

Here is the code (uses WTL), call SetFullScreen(true) to go into full screen mode:

template <class T, bool t_bHasSip = true>
class CFullScreenFrame
{
public:
    bool m_fullscreen;
    LONG m_windowstyles;
    WINDOWPLACEMENT m_windowplacement;

    CFullScreenFrame() 
        :
        m_fullscreen(false),
        m_windowstyles(0)
    { }

    void SetFullScreen(bool fullscreen)
    {
        ShowTaskBar(!fullscreen);

        T* pT = static_cast<T*>(this);

        if (fullscreen) {
            if (!m_fullscreen) {
                m_windowstyles = pT->GetWindowLongW(GWL_STYLE);
                pT->GetWindowPlacement(&m_windowplacement);
            }

        }

        // SM_CXSCREEN gives primary monitor, for multiple monitors use SM_CXVIRTUALSCREEN.
        RECT fullrect = { 0 };              
        SetRect(&fullrect, 0, 0, GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN));

        WINDOWPLACEMENT newplacement = m_windowplacement;
        newplacement.showCmd = SW_SHOWNORMAL;
        newplacement.rcNormalPosition = fullrect;

        if (fullscreen) {
            pT->SetWindowPlacement(&newplacement);
            pT->SetWindowLongW(GWL_STYLE,  WS_VISIBLE);
            pT->UpdateWindow();
        } else {
            if (m_fullscreen) {
                pT->SetWindowPlacement(&m_windowplacement);
                pT->SetWindowLongW(GWL_STYLE, m_windowstyles);
                pT->UpdateWindow();
            }
        }

        m_fullscreen = fullscreen;
    }

    void ShowTaskBar(bool show)
    {
        HWND taskbar = FindWindow(_T("Shell_TrayWnd"), NULL);
        HWND start = FindWindow(_T("Button"), NULL);

        if (taskbar != NULL) {
            ShowWindow(taskbar, show ? SW_SHOW : SW_HIDE);
            UpdateWindow(taskbar);
        }
        if (start != NULL) { 
            // Vista
            ShowWindow(start, show ? SW_SHOW : SW_HIDE);
            UpdateWindow(start);
        }       
    }
};

You also have to add some code to WM_CLOSE message:

case WM_CLOSE:
    ShowTaskBar(true);

There is one caveat with this solution, if your application crashes or is killed through task manager, then user losses taskbar on his system permanently! (unless he runs your application again, goes into fullscreen and exits, then he will see the taskbar again).

Earlier in my answer I pointed to "atlwince.h" but that function worked only on Windows CE, the one I pasted above works fine with XP, Vista and 7.

Solution 2:

Yup, HWND_TOPMOST does it for me. Here is a section of code that makes full-screen work well (and quick) for me:

bool enterFullscreen(HWND hwnd, int fullscreenWidth, int fullscreenHeight, int colourBits, int refreshRate) {
    DEVMODE fullscreenSettings;
    bool isChangeSuccessful;
    RECT windowBoundary;

    EnumDisplaySettings(NULL, 0, &fullscreenSettings);
    fullscreenSettings.dmPelsWidth        = fullscreenWidth;
    fullscreenSettings.dmPelsHeight       = fullscreenHeight;
    fullscreenSettings.dmBitsPerPel       = colourBits;
    fullscreenSettings.dmDisplayFrequency = refreshRate;
    fullscreenSettings.dmFields           = DM_PELSWIDTH |
                                            DM_PELSHEIGHT |
                                            DM_BITSPERPEL |
                                            DM_DISPLAYFREQUENCY;

    SetWindowLongPtr(hwnd, GWL_EXSTYLE, WS_EX_APPWINDOW | WS_EX_TOPMOST);
    SetWindowLongPtr(hwnd, GWL_STYLE, WS_POPUP | WS_VISIBLE);
    SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, fullscreenWidth, fullscreenHeight, SWP_SHOWWINDOW);
    isChangeSuccessful = ChangeDisplaySettings(&fullscreenSettings, CDS_FULLSCREEN) == DISP_CHANGE_SUCCESSFUL;
    ShowWindow(hwnd, SW_MAXIMIZE);

    return isChangeSuccessful;
}

Note that this will change the resolution if you tell it the wrong settings. This is what I usually want, but if you don't like that, you can find out your resolution by using (where mainWindow is returned from something like CreateWindow() or CreateWindowEx()):

windowHDC = GetDC(mainWindow);
fullscreenWidth  = GetDeviceCaps(windowHDC, DESKTOPHORZRES);
fullscreenHeight = GetDeviceCaps(windowHDC, DESKTOPVERTRES);
colourBits       = GetDeviceCaps(windowHDC, BITSPIXEL);
refreshRate      = GetDeviceCaps(windowHDC, VREFRESH);

When you want to get out of full-screen you do something like this:

bool exitFullscreen(HWND hwnd, int windowX, int windowY, int windowedWidth, int windowedHeight, int windowedPaddingX, int windowedPaddingY) {
    bool isChangeSuccessful;

    SetWindowLongPtr(hwnd, GWL_EXSTYLE, WS_EX_LEFT);
    SetWindowLongPtr(hwnd, GWL_STYLE, WS_OVERLAPPEDWINDOW | WS_VISIBLE);
    isChangeSuccessful = ChangeDisplaySettings(NULL, CDS_RESET) == DISP_CHANGE_SUCCESSFUL;
    SetWindowPos(hwnd, HWND_NOTOPMOST, windowX, windowY, windowedWidth + windowedPaddingX, windowedHeight + windowedPaddingY, SWP_SHOWWINDOW);
    ShowWindow(hwnd, SW_RESTORE);

    return isChangeSuccessful;
}

I set my code to change between full-screen and windowed mode using a hotkey, and I keep the windowed mode variables as global, so that when changing to windowed mode, it stays put.

This code also has the advantage of running in the equivalent of "exclusive mode" (I'm using XP, and haven't tried it on the newer versions of windows), which means it'll be much, much faster. Let me know if I've made any mistakes from condensing the code (from my much bigger code).

Solution 3:

Raymond Chen describes the "correct" way to do this at his blog:

https://devblogs.microsoft.com/oldnewthing/20100412-00/?p=14353

Fiddling with the task bar window explicitly is not recommended behaviour.