slint/internal/core/backend.rs
Simon Hausmann 304e06f758 Begin rasterizing glyphs for glyph embedding
Enable with `SLINT_EMBED_GLYPHS=1` and select sizes like
`SLINT_FONT_SIZES=12,16`

This change just puts the data structures in place, rasterizes a fixed
subset, embeds that into the rust generated code and calls a backend
function for registering the font that is unimplemented.
2022-02-15 15:52:24 +01:00

107 lines
3.6 KiB
Rust

// Copyright © SixtyFPS GmbH <info@slint-ui.com>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-commercial
/*!
The backend is the abstraction for crates that need to do the actual drawing and event loop
*/
use alloc::boxed::Box;
use alloc::rc::Rc;
use alloc::string::String;
use crate::graphics::{Image, IntSize};
use crate::window::Window;
#[cfg(feature = "std")]
use once_cell::sync::OnceCell;
#[cfg(all(not(feature = "std"), feature = "unsafe_single_core"))]
use crate::unsafe_single_core::OnceCell;
#[derive(Copy, Clone)]
/// Behavior describing how the event loop should terminate.
pub enum EventLoopQuitBehavior {
/// Terminate the event loop when the last window was closed.
QuitOnLastWindowClosed,
/// Keep the event loop running until [`Backend::quit_event_loop()`] is called.
QuitOnlyExplicitly,
}
/// Interface implemented by back-ends
pub trait Backend: Send + Sync {
/// Instantiate a window for a component.
/// FIXME: should return a Box<dyn PlatformWindow>
fn create_window(&'static self) -> Rc<Window>;
/// Spins an event loop and renders the visible windows.
fn run_event_loop(&'static self, behavior: EventLoopQuitBehavior);
/// Exits the event loop.
fn quit_event_loop(&'static self);
#[cfg(feature = "std")] // FIXME: just because of the Error
/// This function can be used to register a custom TrueType font with Slint,
/// for use with the `font-family` property. The provided slice must be a valid TrueType
/// font.
fn register_font_from_memory(
&'static self,
data: &'static [u8],
) -> Result<(), Box<dyn std::error::Error>>;
#[cfg(feature = "std")]
/// This function can be used to register a custom TrueType font with Slint,
/// for use with the `font-family` property. The provided path must refer to a valid TrueType
/// font.
fn register_font_from_path(
&'static self,
path: &std::path::Path,
) -> Result<(), Box<dyn std::error::Error>>;
fn register_bitmap_font(&'static self, _font_data: &'static crate::graphics::BitmapFont) {
unimplemented!()
}
fn set_clipboard_text(&'static self, text: String);
fn clipboard_text(&'static self) -> Option<String>;
/// Send an user event to from another thread that should be run in the GUI event loop
fn post_event(&'static self, event: Box<dyn FnOnce() + Send>);
fn image_size(&'static self, image: &Image) -> IntSize;
fn duration_since_start(&'static self) -> core::time::Duration {
#[cfg(feature = "std")]
{
let the_beginning = *INITIAL_INSTANT.get_or_init(instant::Instant::now);
instant::Instant::now() - the_beginning
}
#[cfg(not(feature = "std"))]
core::time::Duration::ZERO
}
}
#[cfg(feature = "std")]
static INITIAL_INSTANT: once_cell::sync::OnceCell<instant::Instant> =
once_cell::sync::OnceCell::new();
#[cfg(feature = "std")]
impl std::convert::From<crate::animations::Instant> for instant::Instant {
fn from(our_instant: crate::animations::Instant) -> Self {
let the_beginning = *INITIAL_INSTANT.get_or_init(instant::Instant::now);
the_beginning + core::time::Duration::from_millis(our_instant.0)
}
}
static PRIVATE_BACKEND_INSTANCE: OnceCell<Box<dyn Backend + 'static>> = OnceCell::new();
pub fn instance() -> Option<&'static dyn Backend> {
use core::ops::Deref;
PRIVATE_BACKEND_INSTANCE.get().map(|backend_box| backend_box.deref())
}
pub fn instance_or_init(
factory_fn: impl FnOnce() -> Box<dyn Backend + 'static>,
) -> &'static dyn Backend {
use core::ops::Deref;
PRIVATE_BACKEND_INSTANCE.get_or_init(factory_fn).deref()
}