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/* LICENSE BEGIN
This file is part of the SixtyFPS Project -- https://sixtyfps.io
Copyright (c) 2020 Olivier Goffart <olivier.goffart@sixtyfps.io>
Copyright (c) 2020 Simon Hausmann <simon.hausmann@sixtyfps.io>
SPDX-License-Identifier: GPL-3.0-only
This file is also available under commercial licensing terms.
Please contact info@sixtyfps.io for more information.
LICENSE END */
/*!
The backend is the abstraction for crates that need to do the actual drawing and event loop
*/
use std::path::Path;
use crate::graphics::{Image, Size};
use crate::window::ComponentWindow;
/// 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 backends
pub trait Backend: Send + Sync {
/// Instantiate a window for a component.
/// FIXME: should return a Box<dyn PlatformWindow>
fn create_window(&'static self) -> ComponentWindow;
/// 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);
/// This function can be used to register a custom TrueType font with SixtyFPS,
/// for use with the `font-family` property. The provided slice must be a valid TrueType
/// font.
fn register_font_from_memory(
&'static self,
data: &[u8],
) -> Result<(), Box<dyn std::error::Error>>;
/// This function can be used to register a custom TrueType font with SixtyFPS,
/// 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: &Path,
) -> Result<(), Box<dyn std::error::Error>>;
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) -> Size;
}
static PRIVATE_BACKEND_INSTANCE: once_cell::sync::OnceCell<Box<dyn Backend + 'static>> =
once_cell::sync::OnceCell::new();
pub fn instance() -> Option<&'static dyn Backend> {
use std::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 std::ops::Deref;
PRIVATE_BACKEND_INSTANCE.get_or_init(factory_fn).deref()
}