PR/Proposal: Add setFullScreen support to DesktopWindow

[manol-o]

Hi,

I needed cross-platform full-screen support for DesktopWindow and asked perplexity to implement it for Windows, Mac, and Linux. Here are the diffs if you'd like to include them.
I tested the linux version and it works, the MacOS and Win variant is untested.

1. Header Interface

Add to DesktopWindow struct:

void setFullScreen (bool);

2. Linux Pimpl (#if CHOC_LINUX)

void setFullScreen (bool b) {
    if (b) gtk_window_fullscreen (GTK_WINDOW (window));
    else   gtk_window_unfullscreen (GTK_WINDOW (window));
}

3. macOS Pimpl (#if CHOC_APPLE)

Add constant to Pimpl statics:

static constexpr long NSWindowStyleMaskFullScreen = (1 << 14);

Add method:

void setFullScreen (bool shouldBeFullScreen) {
    CHOC_AUTORELEASE_BEGIN
    auto style = objc::call<unsigned long> (window, "styleMask");
    if (((style & NSWindowStyleMaskFullScreen) != 0) != shouldBeFullScreen)
        objc::call<void> (window, "toggleFullScreen:", (id) nullptr);
    CHOC_AUTORELEASE_END
}

4. Windows Pimpl (#if CHOC_WINDOWS)

Add members to Pimpl:

bool isFullScreen = false;
WINDOWPLACEMENT savedWindowPlacement = {};
LONG savedStyle = 0;

Add method:

void setFullScreen (bool shouldBeFullScreen) {
    if (shouldBeFullScreen == isFullScreen) return;
    isFullScreen = shouldBeFullScreen;

    if (isFullScreen) {
        savedStyle = GetWindowLong (hwnd, GWL_STYLE);
        savedWindowPlacement.length = sizeof (WINDOWPLACEMENT);
        GetWindowPlacement (hwnd, &savedWindowPlacement);
        MONITORINFO mi = { sizeof(mi) };
        if (GetMonitorInfo (MonitorFromWindow (hwnd, MONITOR_DEFAULTTOPRIMARY), &mi)) {
            SetWindowLong (hwnd, GWL_STYLE, savedStyle & ~(WS_CAPTION | WS_THICKFRAME));
            SetWindowPos (hwnd, HWND_TOP, mi.rcMonitor.left, mi.rcMonitor.top,
                          mi.rcMonitor.right - mi.rcMonitor.left, mi.rcMonitor.bottom - mi.rcMonitor.top,
                          SWP_NOOWNERZORDER | SWP_FRAMECHANGED);
        }
    } else {
        SetWindowLong (hwnd, GWL_STYLE, savedStyle);
        SetWindowPlacement (hwnd, &savedWindowPlacement);
        SetWindowPos (hwnd, nullptr, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_NOOWNERZORDER | SWP_FRAMECHANGED);
    }
}

5. Implementation Footer

inline void DesktopWindow::setFullScreen (bool b) { pimpl->setFullScreen (b); }