Window transparency

[Weasy666]

Description

Version / OS

• azul version: 741e3e9

• Operating system: Windows 10 1809

• rust toolchain:

  • nightly-x86_64-pc-windows-msvc (default)
  • rustc 1.32.0-nightly (6b9b97bd9 2018-11-15)

Steps to Reproduce

Create a new azul app and replace the code in main.rs with the following:

extern crate azul;
use azul::prelude::*;


fn main() {
    let mut app_data = AppData {};

    let app = App::new(app_data, AppConfig::default());

    let mut create = WindowCreateOptions::<AppData>::default();
    create.state.is_transparent = true;
    create.background = ColorF { r: 1.0, g: 1.0, b: 1.0, a: 0.0 };
    let window = Window::new(create, Css::native()).unwrap();
    app.run(window).unwrap();
}

pub struct AppData {}
impl Layout for AppData {
    fn layout(&self, _: WindowInfo<Self>) -> Dom<Self> {
        Dom::new(NodeType::Div)
    }
}

Expected Behavior

Window background should correctly render the background color given in WindowCreateOptions.

Actual Behavior

Colors are rendered like seen in the following examples: ColorF { r: 1.0, g: 1.0, b: 1.0, a: 0.0 }

ColorF { r: 0.5, g: 0.5, b: 0.5, a: 0.0 }

ColorF { r: 0.0, g: 0.0, b: 0.0, a: 0.0 }

Additional Information

[fschutt]

Ok, I think I know where the issue is: The RendererOptions always has a clear color, if I disable this line:

https://github.com/maps4print/azul/blob/ca9f8a2785478ee38c51cf141092b0cdfa0f8057/src/window.rs#L786

I get a transparent window:

[Weasy666]

Hm...i looked a bit at the code and i'm still wondering why it didn't work with ColorF { r: 0.0, g: 0.0, b: 0.0, a: 0.0 } as the background in WindowCreateOptions. As i see it, WindowCreateOptions is handed over as a parameter in the Windows::new() function and inside the new-function you use its backround variable as the clear_color parameter for get_renderer_opts. So shouldn't it produce the same result with ColorF { r: 0.0, g: 0.0, b: 0.0, a: 0.0 } as WindowCreateOptions.background, as it does with the hard coded clear_color value of ColorF { r: 0.0, g: 0.0, b: 0.0, a: 0.0 }? 😕

[MrMinimal]

I tried this code because I want to create a fullscreen transparent overlay but the code does not compile anymore. The fields background and state.is_transparent don't exist anymore.

@fschutt Is there a way of achieving transparency on the current master branch?

[fschutt]

No, it's because of how window transparency works. This requires changes in winit - right now winit only allows a window to be 100% transparent or 100% opaque, it doesn't allow parts of the window to be opaque.

[MrMinimal]

Thanks for the quick input, given the screenshots in this issue I thought transparency was currently possible. So you're saying as soon as winit allows it, azul will support it as well? Any links for tracking progress in that regard?