gb-emu/gb-vst/src/ui.rs

use std::sync::{
    mpsc::{self, Receiver, Sender},
    Arc,
};

use baseview::{
    Event, EventStatus, Size, Window, WindowEvent, WindowHandler, WindowInfo, WindowOpenOptions,
};
use gb_emu_lib::{
    connect::{JoypadButtons, JoypadState, Renderer, HEIGHT, WIDTH},
    util::scale_buffer_in_place,
};
use keyboard_types::{Code, KeyState};
use nih_plug::prelude::*;
use pixels::{wgpu::PowerPreference, Pixels, SurfaceTexture};

use crate::{Frame, FrameReceiver, JoypadInfo, JoypadSender};

pub struct Emulator {
    frame_receiver: Arc<FrameReceiver>,
    joypad_sender: Arc<JoypadSender>,
}

impl Emulator {
    pub fn new(frame_receiver: Arc<FrameReceiver>, joypad_sender: Arc<JoypadSender>) -> Self {
        Self {
            frame_receiver,
            joypad_sender,
        }
    }
}

const EXTRA_SCALE: usize = 3;
const S_WIDTH: usize = WIDTH * EXTRA_SCALE;
const S_HEIGHT: usize = HEIGHT * EXTRA_SCALE;

impl Editor for Emulator {
    fn spawn(
        &self,
        parent: ParentWindowHandle,
        _context: Arc<dyn GuiContext>,
    ) -> Box<dyn std::any::Any + Send> {
        let fr_cloned = self.frame_receiver.clone();
        let js_cloned = self.joypad_sender.clone();

        let (size, scale) = if cfg!(target_os = "macos") {
            (
                Size::new(S_WIDTH as f64, S_HEIGHT as f64),
                baseview::WindowScalePolicy::SystemScaleFactor,
            )
        } else {
            (
                Size::new(WIDTH as f64, HEIGHT as f64),
                baseview::WindowScalePolicy::ScaleFactor(EXTRA_SCALE as f64),
            )
        };

        Window::open_parented(
            &parent,
            WindowOpenOptions {
                title: String::from("gb-emu"),
                size,
                scale,
                gl_config: None,
            },
            |w| EmulatorWindow::new(w, fr_cloned, js_cloned),
        );
        Box::new(Self::new(
            self.frame_receiver.clone(),
            self.joypad_sender.clone(),
        ))
    }

    fn size(&self) -> (u32, u32) {
        ((WIDTH * EXTRA_SCALE) as u32, (HEIGHT * EXTRA_SCALE) as u32)
    }

    fn set_scale_factor(&self, _factor: f32) -> bool {
        true
    }

    fn param_value_changed(&self, _id: &str, _normalized_value: f32) {}

    fn param_modulation_changed(&self, _id: &str, _modulation_offset: f32) {}

    fn param_values_changed(&self) {}
}

pub struct EmulatorWindow {
    pix: Pixels,
    scale: usize,
    scaled_buf: Frame,
    frame_receiver: Arc<FrameReceiver>,
    joypad_sender: Arc<JoypadSender>,
}

impl EmulatorWindow {
    fn new(
        window: &mut Window,
        frame_receiver: Arc<FrameReceiver>,
        joypad_sender: Arc<JoypadSender>,
    ) -> Self {
        let info = WindowInfo::from_logical_size(
            Size::new(WIDTH as f64, HEIGHT as f64),
            EXTRA_SCALE as f64,
        );

        let (pix, scale, scaled_buf) = init_pixbuf(info, window);

        Self {
            pix,
            scale,
            scaled_buf,
            frame_receiver,
            joypad_sender,
        }
    }
}

fn init_pixbuf(info: WindowInfo, window: &mut Window) -> (Pixels, usize, Frame) {
    let physical_size = info.physical_size();
    let scale = (physical_size.width as usize / WIDTH).min(physical_size.height as usize / HEIGHT);
    let scaled_buf = vec![[0, 0, 0, 0xFF]; WIDTH * scale * HEIGHT * scale];

    (
        pixels::PixelsBuilder::new(
            physical_size.width,
            physical_size.height,
            SurfaceTexture::new(physical_size.width, physical_size.height, window),
        )
        .request_adapter_options(pixels::wgpu::RequestAdapterOptionsBase {
            power_preference: PowerPreference::HighPerformance,
            ..pixels::wgpu::RequestAdapterOptionsBase::default()
        })
        .build()
        .unwrap(),
        scale,
        scaled_buf,
    )
}

impl WindowHandler for EmulatorWindow {
    fn on_frame(&mut self, _window: &mut Window) {
        if let Some(ref mut receiver) = *self.frame_receiver.lock().expect("failed to lock mutex") {
            if let Some(ref buf) = receiver.try_iter().last() {
                if self.scale != 1 {
                    scale_buffer_in_place(buf, &mut self.scaled_buf, WIDTH, HEIGHT, self.scale);
                }
                for (pixel, source) in self
                    .pix
                    .frame_mut()
                    .chunks_exact_mut(4)
                    .zip(&self.scaled_buf)
                {
                    pixel.copy_from_slice(source);
                }
                self.pix.render().unwrap();
            }
        }
    }

    fn on_event(&mut self, window: &mut Window, event: baseview::Event) -> EventStatus {
        match event {
            Event::Window(WindowEvent::Resized(info)) => {
                (self.pix, self.scale, self.scaled_buf) = init_pixbuf(info, window);
                EventStatus::Captured
            }
            Event::Keyboard(event) => {
                let status = event.state == KeyState::Down;
                if let Some(button) = match event.code {
                    Code::Equal => Some(JoypadButtons::Start),
                    Code::Minus => Some(JoypadButtons::Select),
                    Code::Quote => Some(JoypadButtons::A),
                    Code::Semicolon => Some(JoypadButtons::B),
                    Code::KeyW | Code::ArrowUp => Some(JoypadButtons::Up),
                    Code::KeyA | Code::ArrowLeft => Some(JoypadButtons::Left),
                    Code::KeyS | Code::ArrowDown => Some(JoypadButtons::Down),
                    Code::KeyD | Code::ArrowRight => Some(JoypadButtons::Right),
                    _ => None,
                } {
                    if let Some(ref mut sender) =
                        *self.joypad_sender.lock().expect("failed to lock mutex")
                    {
                        sender.send((button, status)).unwrap();
                    }
                    EventStatus::Captured
                } else {
                    EventStatus::Ignored
                }
            }
            _ => EventStatus::Ignored,
        }
    }
}

pub struct EmulatorRenderer {
    tx: Sender<Frame>,
    joypad: JoypadState,
    keys: Receiver<JoypadInfo>,
}

impl EmulatorRenderer {
    pub(super) fn new() -> (Self, Receiver<Frame>, Sender<JoypadInfo>) {
        let (tx, rx) = mpsc::channel::<Frame>();
        let (keys_tx, keys) = mpsc::channel::<JoypadInfo>();
        (
            Self {
                tx,
                joypad: JoypadState::default(),
                keys,
            },
            rx,
            keys_tx,
        )
    }
}

impl Renderer<[u8; 4]> for EmulatorRenderer {
    fn prepare(&mut self, _width: usize, _height: usize) {}

    fn display(&mut self, buffer: &[[u8; 4]]) {
        let _ = self.tx.send(buffer.to_vec());
    }

    fn latest_joypad_state(&mut self) -> JoypadState {
        while let Ok((key, state)) = self.keys.try_recv() {
            match key {
                JoypadButtons::Down => self.joypad.down = state,
                JoypadButtons::Up => self.joypad.up = state,
                JoypadButtons::Left => self.joypad.left = state,
                JoypadButtons::Right => self.joypad.right = state,
                JoypadButtons::Start => self.joypad.start = state,
                JoypadButtons::Select => self.joypad.select = state,
                JoypadButtons::B => self.joypad.b = state,
                JoypadButtons::A => self.joypad.a = state,
            }
        }
        self.joypad
    }
}