doukutsu-rs/src/framework/backend.rs

use imgui::DrawData;

use crate::common::{Color, Point, Rect};
use crate::framework::context::Context;
use crate::framework::error::GameResult;
use crate::framework::graphics::BlendMode;
use crate::Game;

pub trait Backend {
    fn create_event_loop(&self) -> GameResult<Box<dyn BackendEventLoop>>;
}

pub trait BackendEventLoop {
    fn run(&mut self, game: &mut Game, ctx: &mut Context);

    fn new_renderer(&self) -> GameResult<Box<dyn BackendRenderer>>;
}

pub trait BackendRenderer {
    fn clear(&mut self, color: Color);

    fn present(&mut self) -> GameResult;

    fn create_texture_mutable(&mut self, width: u16, height: u16) -> GameResult<Box<dyn BackendTexture>>;

    fn create_texture(&mut self, width: u16, height: u16, data: &[u8]) -> GameResult<Box<dyn BackendTexture>>;

    fn set_blend_mode(&mut self, blend: BlendMode) -> GameResult;

    fn set_render_target(&mut self, texture: Option<&Box<dyn BackendTexture>>) -> GameResult;

    fn draw_rect(&mut self, rect: Rect, color: Color) -> GameResult;

    fn draw_outline_rect(&mut self, rect: Rect, line_width: usize, color: Color) -> GameResult;

    fn imgui(&self) -> GameResult<&mut imgui::Context>;

    fn render_imgui(&mut self, draw_data: &DrawData) -> GameResult;

    fn prepare_frame(&self, ui: &imgui::Ui) -> GameResult;
}

pub trait BackendTexture {
    fn dimensions(&self) -> (u16, u16);

    fn add(&mut self, command: SpriteBatchCommand);

    fn clear(&mut self);

    fn draw(&mut self) -> GameResult;
}

pub fn init_backend() -> GameResult<Box<dyn Backend>> {
    #[cfg(feature = "backend_sdl")]
        {
            return crate::framework::backend_sdl2::SDL2Backend::new()
        }

    log::warn!("No backend compiled in, using null backend instead.");
    crate::framework::backend_null::NullBackend::new()
}

pub enum SpriteBatchCommand {
    DrawRect(Rect<f32>, Rect<f32>),
    DrawRectFlip(Rect<f32>, Rect<f32>, bool, bool),
    DrawRectTinted(Rect<f32>, Rect<f32>, Color),
}