Transparent Window

[nyovaya]

Should transparency be allowed for bordered windows?
no
Platforms support:

• Windows [TODO]
• OSX [TODO]
• Linux(X11/Wayland)
• Redox

How should it be enabled?
A: Set a flag in struct WindowOptions.

[nyovaya]

@FloVanGH Does Redox support window transparency?

[nyovaya]

@emoon We might let this open as its not implemented on Windows and OSX

[emoon]

Do you plan to implement support for Windows and macOS also?

[nyovaya]

@emoon I will definitely try to implement it on windows but not on osx because I dont have a device to test on it.

[nyovaya]

I will link to some working implementation for alpha transparency on OSX as well as the Windows one:
godotengine/godot@ddae098#diff-65f347288a42e15c028ce4f494698fa1R2137-R2142

[emoon]

Alright. That code uses OpenGL on macOS which is deprecated. I use Metal on macOS which is the supported API but I guess it should be possible to do the same thing.

[rupansh]

@nifker
Manually using winapi isn't working either

    let wind = Window::new("", w as usize, h as usize, WindowOptions {
        title: false,
        borderless: true,
        ..WindowOptions::default()
    }).unwrap();
    match wind.raw_window_handle() {
        RawWindowHandle::Windows(wnd) => {
            let hwnd = wnd.hwnd as HWND;
            unsafe { SetWindowLongA(hwnd, GWL_EXSTYLE, (WS_EX_LAYERED | WS_EX_TRANSPARENT) as i32) };
            unsafe { SetLayeredWindowAttributes(hwnd, 0, 255, LWA_ALPHA)};
            let mut margs = MARGINS {
                cxLeftWidth: -1,
                cxRightWidth: -1,
                cyTopHeight: -1,
                cyBottomHeight: -1,
            };
            unsafe { DwmExtendFrameIntoClientArea(hwnd, &mut margs) };
            unsafe { UpdateWindow(hwnd) };
            unsafe { SetWindowPos(hwnd, HWND_TOPMOST, l, t, w as i32, h as i32, SWP_SHOWWINDOW) };
        }
        _ => {}
    }

However the same code works fine with sfml window and Style::NONE

    let mut set = ContextSettings::default();
    set.antialiasing_level = 4;
    let wind = RenderWindow::new((w, h), "", Style::NONE, &set);
    let hwnd = wind.system_handle() as HWND;
    unsafe { SetWindowLongA(hwnd, GWL_EXSTYLE, (WS_EX_LAYERED | WS_EX_TRANSPARENT) as i32) };
    unsafe { SetLayeredWindowAttributes(hwnd, 0, 255, LWA_ALPHA)};
    let mut margs = MARGINS {
        cxLeftWidth: -1,
        cxRightWidth: -1,
        cyTopHeight: -1,
        cyBottomHeight: -1,
    };
    unsafe { DwmExtendFrameIntoClientArea(hwnd, &mut margs) };
    unsafe { UpdateWindow(hwnd) };
    unsafe { SetWindowPos(hwnd, HWND_TOPMOST, l, t, w as i32, h as i32, SWP_SHOWWINDOW) };

EDIT: If i force flags to be like this, it works fine.
https://github.com/rupansh/rust_minifb/commit/70dd9b1ff424ea32f8e679d60ad84e5c4c093ec7#diff-592c2d0944cb99fd96ad100fb80c1956R545