Trait kas::theme::Theme

pub trait Theme<Draw> {
    type Window: Window<Draw> + 'static;
    type DrawHandle: DrawHandle;
    fn new_window(&self, draw: &mut Draw, dpi_factor: f32) -> Self::Window;
    unsafe fn draw_handle(
        &self, 
        draw: &mut Draw, 
        theme_window: &mut Self::Window, 
        rect: Rect
    ) -> Self::DrawHandle;
    fn get_fonts<'a>(&self) -> Vec<Font<'a>>;
    fn light_direction(&self) -> (f32, f32);
    fn clear_colour(&self) -> Colour;
}

A theme provides widget sizing and drawing implementations.

The theme is generic over some Draw type.

Objects of this type are copied within each window's data structure. For large resources (e.g. fonts and icons) consider using external storage.

Associated Types

type Window: Window<Draw> + 'static

The associated Window implementation.

type DrawHandle: DrawHandle

The associated DrawHandle implementation.

Loading content...

Required methods

fn new_window(&self, draw: &mut Draw, dpi_factor: f32) -> Self::Window

Construct per-window storage

A reference to the draw backend is provided allowing configuration.

See also documentation on Window::set_dpi_factor.

unsafe fn draw_handle(
    &self,
    draw: &mut Draw,
    theme_window: &mut Self::Window,
    rect: Rect
) -> Self::DrawHandle

Construct a DrawHandle object

Drawing via this DrawHandle is restricted to the specified rect.

The theme_window is guaranteed to be one created by a call to Theme::new_window on self, and the draw reference is guaranteed to be identical to the one passed to Theme::new_window.

Note: this function is marked unsafe because the returned object requires a lifetime bound not exceeding that of all three pointers passed in. This ought to be expressible using generic associated types but currently is not: https://github.com/rust-lang/rust/issues/67089

fn get_fonts<'a>(&self) -> Vec<Font<'a>>

Get the list of available fonts

Currently, all fonts used must be specified up front by this method. (Dynamic addition of fonts may be enabled in the future.)

This is considered a "getter" rather than a "constructor" method since the Font type is cheap to copy, and each window requires its own copy. It may also be useful to retain a Font handle for access to its methods.

Corresponding FontIds may be created from the index into this list. The first font in the list will be the default font.

TODO: this part of the API is dependent on rusttype::Font. We should build an abstraction over this, or possibly just pass the font bytes (although this makes re-use of fonts between windows difficult).

fn light_direction(&self) -> (f32, f32)

Light source

This affects shadows on frames, etc. The light source has neutral colour and intensity such that the colour of flat surfaces is unaffected.

Return value: (a, b) where 0 ≤ a < pi/2 is the angle to the screen normal (i.e. a = 0 is straight at the screen) and b is the bearing (from UP, clockwise), both in radians.

Currently this is not updated after initial set-up.

fn clear_colour(&self) -> Colour

Background colour

Loading content...

Implementors

Loading content...