Render images on background thread to keep UI responsive

Cargo.toml

@@ -35,7 +35,7 @@ rubato = "0.16"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 thread-priority = "1"
-tokio = { version = "1", features = ["io-util", "macros", "net", "rt", "sync"] }
+tokio = { version = "1", features = ["io-util", "macros", "net", "rt", "sync", "time"] }
 tracing = { version = "0.1", features = ["release_max_level_info"] }
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 wgpu = "23"

src/app.rs

@@ -20,6 +20,7 @@ use crate::{
     input::MappingProvider,
     memory::MemoryMonitor,
     persistence::Persistence,
+    vram::VramProcessor,
     window::{
         AboutWindow, AppWindow, BgMapWindow, CharacterDataWindow, GameWindow, GdbServerWindow,
         InputWindow,
@@ -45,6 +46,7 @@ pub struct Application {
     mappings: MappingProvider,
     controllers: ControllerManager,
     memory: MemoryMonitor,
+    vram: VramProcessor,
     persistence: Persistence,
     viewports: HashMap<ViewportId, Viewport>,
     focused: Option<ViewportId>,
@@ -63,6 +65,7 @@ impl Application {
         let mappings = MappingProvider::new(persistence.clone());
         let controllers = ControllerManager::new(client.clone(), &mappings);
         let memory = MemoryMonitor::new(client.clone());
+        let vram = VramProcessor::new();
         {
             let mappings = mappings.clone();
             let proxy = proxy.clone();
@@ -75,6 +78,7 @@ impl Application {
             proxy,
             mappings,
             memory,
+            vram,
             controllers,
             persistence,
             viewports: HashMap::new(),
@@ -205,11 +209,11 @@ impl ApplicationHandler<UserEvent> for Application {
                 self.open(event_loop, Box::new(about));
             }
             UserEvent::OpenCharacterData(sim_id) => {
-                let vram = CharacterDataWindow::new(sim_id, &mut self.memory);
+                let vram = CharacterDataWindow::new(sim_id, &mut self.memory, &mut self.vram);
                 self.open(event_loop, Box::new(vram));
             }
             UserEvent::OpenBgMap(sim_id) => {
-                let bgmap = BgMapWindow::new(sim_id, &mut self.memory);
+                let bgmap = BgMapWindow::new(sim_id, &mut self.memory, &mut self.vram);
                 self.open(event_loop, Box::new(bgmap));
             }
             UserEvent::OpenDebugger(sim_id) => {

src/vram.rs

@@ -1,29 +1,103 @@
 use std::{
-    collections::{hash_map::Entry, HashMap, HashSet},
-    hash::Hash,
-    sync::{Arc, Mutex},
+    collections::HashMap,
+    ops::Deref,
+    sync::{Arc, Mutex, Weak},
+    thread,
+    time::Duration,
 };
 
 use egui::{
     epaint::ImageDelta,
     load::{LoadError, SizedTexture, TextureLoader, TexturePoll},
-    Color32, ColorImage, Context, TextureHandle, TextureOptions,
+    Color32, ColorImage, TextureHandle, TextureOptions,
 };
-use serde::{Deserialize, Serialize};
+use tokio::{sync::mpsc, time::timeout};
 
-pub trait VramResource: Sized + Clone + PartialEq + Eq + Hash {
-    fn to_uri(&self) -> String;
-    fn from_uri(uri: &str) -> Option<Self>;
+pub struct VramProcessor {
+    sender: mpsc::UnboundedSender<Box<dyn VramRendererImpl>>,
 }
 
-impl<T: Serialize + for<'a> Deserialize<'a> + Clone + PartialEq + Eq + Hash> VramResource for T {
-    fn to_uri(&self) -> String {
-        format!("vram://{}", serde_json::to_string(self).unwrap())
+impl VramProcessor {
+    pub fn new() -> Self {
+        let (sender, receiver) = mpsc::unbounded_channel();
+        thread::spawn(move || {
+            tokio::runtime::Builder::new_current_thread()
+                .enable_all()
+                .build()
+                .unwrap()
+                .block_on(async move {
+                    let mut worker = VramProcessorWorker {
+                        receiver,
+                        renderers: vec![],
+                    };
+                    worker.run().await
+                })
+        });
+        Self { sender }
     }
 
-    fn from_uri(uri: &str) -> Option<Self> {
-        let content = uri.strip_prefix("vram://")?;
-        serde_json::from_str(content).ok()
+    pub fn add<const N: usize, R: VramRenderer<N> + 'static>(
+        &self,
+        renderer: R,
+    ) -> ([VramImageHandle; N], VramParams<R::Params>) {
+        let handles = renderer.sizes().map(|[width, height]| {
+            let data = Arc::new(Mutex::new(None));
+            VramImageHandle {
+                size: [width as f32, height as f32],
+                data,
+            }
+        });
+        let images = renderer
+            .sizes()
+            .map(|[width, height]| VramImage::new(width, height));
+        let sink = Arc::new(Mutex::new(R::Params::default()));
+        let _ = self.sender.send(Box::new(VramRendererWrapper {
+            renderer,
+            params: Arc::downgrade(&sink),
+            images,
+            sinks: handles.clone().map(|i| i.data),
+        }));
+        let params = VramParams {
+            value: R::Params::default(),
+            sink,
+        };
+        (handles, params)
+    }
+}
+
+struct VramProcessorWorker {
+    receiver: mpsc::UnboundedReceiver<Box<dyn VramRendererImpl>>,
+    renderers: Vec<Box<dyn VramRendererImpl>>,
+}
+
+impl VramProcessorWorker {
+    async fn run(&mut self) {
+        loop {
+            if self.renderers.is_empty() {
+                // if we have nothing to do, block until we have something to do
+                if self.receiver.recv_many(&mut self.renderers, 64).await == 0 {
+                    // shutdown
+                    return;
+                }
+                while let Ok(renderer) = self.receiver.try_recv() {
+                    self.renderers.push(renderer);
+                }
+            }
+            self.renderers
+                .retain_mut(|renderer| renderer.try_update().is_ok());
+            // wait up to 10 ms for more renderers
+            if timeout(
+                Duration::from_millis(10),
+                self.receiver.recv_many(&mut self.renderers, 64),
+            )
+            .await
+            .is_ok()
+            {
+                while let Ok(renderer) = self.receiver.try_recv() {
+                    self.renderers.push(renderer);
+                }
+            }
+        }
     }
 }
 
@@ -67,55 +141,107 @@ impl VramImage {
     }
 }
 
-pub trait VramImageLoader {
-    type Resource: VramResource;
-
-    fn id(&self) -> &str;
-    fn add(&self, resource: &Self::Resource) -> Option<VramImage>;
-    fn update<'a>(
-        &'a self,
-        resources: impl Iterator<Item = (&'a Self::Resource, &'a mut VramImage)>,
-    );
+#[derive(Clone)]
+pub struct VramImageHandle {
+    size: [f32; 2],
+    data: Arc<Mutex<Option<Arc<ColorImage>>>>,
 }
 
-pub struct VramTextureLoader<T: VramImageLoader> {
-    id: String,
-    loader: Mutex<T>,
-    cache: Mutex<HashMap<T::Resource, (TextureHandle, VramImage)>>,
-    seen: Mutex<HashSet<T::Resource>>,
+impl VramImageHandle {
+    fn pull(&mut self) -> Option<Arc<ColorImage>> {
+        self.data.lock().unwrap().take()
+    }
 }
 
-impl<T: VramImageLoader> VramTextureLoader<T> {
-    pub fn new(loader: T) -> Self {
+pub struct VramParams<T> {
+    value: T,
+    sink: Arc<Mutex<T>>,
+}
+
+impl<T> Deref for VramParams<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.value
+    }
+}
+
+impl<T: Clone + Eq> VramParams<T> {
+    pub fn write(&mut self, value: T) {
+        if self.value != value {
+            self.value = value.clone();
+            *self.sink.lock().unwrap() = value;
+        }
+    }
+}
+
+pub trait VramRenderer<const N: usize>: Send {
+    type Params: Clone + Default + Send;
+    fn sizes(&self) -> [[usize; 2]; N];
+    fn render(&mut self, params: &Self::Params, images: &mut [VramImage; N]);
+}
+
+struct VramRendererWrapper<const N: usize, R: VramRenderer<N>> {
+    renderer: R,
+    params: Weak<Mutex<R::Params>>,
+    images: [VramImage; N],
+    sinks: [Arc<Mutex<Option<Arc<ColorImage>>>>; N],
+}
+
+trait VramRendererImpl: Send {
+    fn try_update(&mut self) -> Result<(), ()>;
+}
+
+impl<const N: usize, R: VramRenderer<N> + Send> VramRendererImpl for VramRendererWrapper<N, R> {
+    fn try_update(&mut self) -> Result<(), ()> {
+        let params = match self.params.upgrade() {
+            Some(params) => params.lock().unwrap().clone(),
+            None => {
+                // the UI isn't using this anymore
+                return Err(());
+            }
+        };
+        self.renderer.render(&params, &mut self.images);
+
+        for (image, sink) in self.images.iter_mut().zip(&self.sinks) {
+            if let Some(update) = image.take() {
+                sink.lock().unwrap().replace(update);
+            }
+        }
+        Ok(())
+    }
+}
+
+pub struct VramTextureLoader {
+    cache: Mutex<HashMap<String, (VramImageHandle, Option<TextureHandle>)>>,
+}
+
+impl VramTextureLoader {
+    pub fn new(renderers: impl IntoIterator<Item = (String, VramImageHandle)>) -> Self {
+        let mut cache = HashMap::new();
+        for (key, image) in renderers {
+            cache.insert(key, (image, None));
+        }
         Self {
-            id: loader.id().to_string(),
-            loader: Mutex::new(loader),
-            cache: Mutex::new(HashMap::new()),
-            seen: Mutex::new(HashSet::new()),
+            cache: Mutex::new(cache),
+        }
     }
 }
 
-    pub fn begin_pass(&self) {
-        let mut cache = self.cache.lock().unwrap();
-        let mut seen = self.seen.lock().unwrap();
-        cache.retain(|res, _| seen.contains(res));
-        seen.clear();
-    }
-}
-
-impl<T: VramImageLoader> TextureLoader for VramTextureLoader<T> {
+impl TextureLoader for VramTextureLoader {
     fn id(&self) -> &str {
-        &self.id
+        concat!(module_path!(), "VramTextureLoader")
     }
 
     fn load(
         &self,
-        ctx: &Context,
+        ctx: &egui::Context,
         uri: &str,
         texture_options: TextureOptions,
         _size_hint: egui::SizeHint,
     ) -> Result<TexturePoll, LoadError> {
-        let Some(resource) = T::Resource::from_uri(uri) else {
+        let mut cache = self.cache.lock().unwrap();
+        let Some((image, maybe_handle)) = cache.get_mut(uri) else {
             return Err(LoadError::NotSupported);
         };
         if texture_options != TextureOptions::NEAREST {
@@ -123,54 +249,45 @@ impl<T: VramImageLoader> TextureLoader for VramTextureLoader<T> {
                 "Only TextureOptions::NEAREST are supported".into(),
             ));
         }
-        let mut cache = self.cache.lock().unwrap();
-        let mut seen = self.seen.lock().unwrap();
-        seen.insert(resource.clone());
-        let loader = self.loader.lock().unwrap();
-        let resources = cache.iter_mut().map(|(k, v)| (k, &mut v.1));
-        loader.update(resources);
-        for (handle, image) in cache.values_mut() {
-            if let Some(data) = image.take() {
-                let delta = ImageDelta::full(data, TextureOptions::NEAREST);
+        match (image.pull(), maybe_handle.as_ref()) {
+            (Some(update), Some(handle)) => {
+                let delta = ImageDelta::full(update, texture_options);
                 ctx.tex_manager().write().set(handle.id(), delta);
-            }
-        }
-        match cache.entry(resource) {
-            Entry::Occupied(entry) => {
-                let texture = SizedTexture::from_handle(&entry.get().0);
+                let texture = SizedTexture::new(handle, image.size);
                 Ok(TexturePoll::Ready { texture })
             }
-            Entry::Vacant(entry) => {
-                let Some(mut image) = loader.add(entry.key()) else {
-                    return Err(LoadError::Loading("could not load texture".into()));
-                };
-                let Some(data) = image.take() else {
-                    return Err(LoadError::Loading("could not load texture".into()));
-                };
-                let handle = ctx.load_texture(uri, data, TextureOptions::NEAREST);
-                let (handle, _) = entry.insert((handle, image));
-                let texture = SizedTexture::from_handle(handle);
+            (Some(update), None) => {
+                let handle = ctx.load_texture(uri, update, texture_options);
+                let texture = SizedTexture::new(&handle, image.size);
+                maybe_handle.replace(handle);
                 Ok(TexturePoll::Ready { texture })
             }
+            (None, Some(handle)) => {
+                let texture = SizedTexture::new(handle, image.size);
+                Ok(TexturePoll::Ready { texture })
+            }
+            (None, None) => {
+                let size = image.size.into();
+                Ok(TexturePoll::Pending { size: Some(size) })
+            }
         }
     }
 
     fn forget(&self, uri: &str) {
-        if let Some(resource) = T::Resource::from_uri(uri) {
-            self.cache.lock().unwrap().remove(&resource);
-        }
+        let _ = uri;
     }
 
-    fn forget_all(&self) {
-        self.cache.lock().unwrap().clear();
-    }
+    fn forget_all(&self) {}
 
     fn byte_size(&self) -> usize {
         self.cache
             .lock()
             .unwrap()
             .values()
-            .map(|h| h.0.byte_size())
+            .map(|(image, _)| {
+                let [width, height] = image.size;
+                width as usize * height as usize * 4
+            })
             .sum()
     }
 }

src/window/vram/bgmap.rs

@@ -5,12 +5,11 @@ use egui::{
     TextureOptions, Ui, ViewportBuilder, ViewportId,
 };
 use egui_extras::{Column, Size, StripBuilder, TableBuilder};
-use serde::{Deserialize, Serialize};
 
 use crate::{
     emulator::SimId,
     memory::{MemoryMonitor, MemoryView},
-    vram::{VramImage, VramImageLoader, VramResource as _, VramTextureLoader},
+    vram::{VramImage, VramParams, VramProcessor, VramRenderer, VramTextureLoader},
     window::{utils::UiExt, AppWindow},
 };
 
@@ -18,26 +17,32 @@ use super::utils::{parse_palette, CharacterGrid, GENERIC_PALETTE};
 
 pub struct BgMapWindow {
     sim_id: SimId,
-    loader: Arc<VramTextureLoader<BgMapLoader>>,
+    loader: Arc<VramTextureLoader>,
     bgmaps: MemoryView,
     cell_index: usize,
     cell_index_str: String,
+    generic_palette: bool,
+    params: VramParams<BgMapParams>,
     scale: f32,
     show_grid: bool,
-    generic_palette: bool,
 }
 
 impl BgMapWindow {
-    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
+    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor, vram: &mut VramProcessor) -> Self {
+        let renderer = BgMapRenderer::new(sim_id, memory);
+        let ([cell, bgmap], params) = vram.add(renderer);
+        let loader =
+            VramTextureLoader::new([("vram://cell".into(), cell), ("vram://bgmap".into(), bgmap)]);
         Self {
             sim_id,
-            loader: Arc::new(VramTextureLoader::new(BgMapLoader::new(sim_id, memory))),
+            loader: Arc::new(loader),
             bgmaps: memory.view(sim_id, 0x00020000, 0x1d800),
             cell_index: 0,
             cell_index_str: "0".into(),
+            generic_palette: false,
+            params,
             scale: 1.0,
             show_grid: false,
-            generic_palette: false,
         }
     }
 
@@ -88,11 +93,7 @@ impl BgMapWindow {
                         });
                     });
                 });
-            let resource = BgMapResource::Cell {
-                index: self.cell_index,
-                generic_palette: self.generic_palette,
-            };
-            let image = Image::new(resource.to_uri())
+            let image = Image::new("vram://cell")
                 .maintain_aspect_ratio(true)
                 .tint(Color32::RED)
                 .texture_options(TextureOptions::NEAREST);
@@ -154,14 +155,14 @@ impl BgMapWindow {
                 });
             });
         });
+        self.params.write(BgMapParams {
+            cell_index: self.cell_index,
+            generic_palette: self.generic_palette,
+        });
     }
 
     fn show_bgmap(&mut self, ui: &mut Ui) {
-        let resource = BgMapResource::BgMap {
-            index: self.cell_index / 4096,
-            generic_palette: self.generic_palette,
-        };
-        let grid = CharacterGrid::new(resource.to_uri())
+        let grid = CharacterGrid::new("vram://bgmap")
             .with_scale(self.scale)
             .with_grid(self.show_grid)
             .with_selected(self.cell_index % 4096);
@@ -192,7 +193,6 @@ impl AppWindow for BgMapWindow {
     }
 
     fn show(&mut self, ctx: &Context) {
-        self.loader.begin_pass();
         CentralPanel::default().show(ctx, |ui| {
             ui.horizontal_top(|ui| {
                 StripBuilder::new(ui)
@@ -219,20 +219,20 @@ fn parse_cell(cell: u16) -> (usize, bool, bool, usize) {
     (char_index, vflip, hflip, palette_index)
 }
 
-#[derive(Serialize, Deserialize, Clone, PartialEq, Eq, Hash)]
-enum BgMapResource {
-    BgMap { index: usize, generic_palette: bool },
-    Cell { index: usize, generic_palette: bool },
+#[derive(Default, Clone, PartialEq, Eq)]
+struct BgMapParams {
+    cell_index: usize,
+    generic_palette: bool,
 }
 
-struct BgMapLoader {
+struct BgMapRenderer {
     chardata: MemoryView,
     bgmaps: MemoryView,
     brightness: MemoryView,
     palettes: MemoryView,
 }
 
-impl BgMapLoader {
+impl BgMapRenderer {
     pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
         Self {
             chardata: memory.view(sim_id, 0x00078000, 0x8000),
@@ -242,7 +242,7 @@ impl BgMapLoader {
         }
     }
 
-    fn update_bgmap(&self, image: &mut VramImage, bgmap_index: usize, generic_palette: bool) {
+    fn render_bgmap(&self, image: &mut VramImage, bgmap_index: usize, generic_palette: bool) {
         let chardata = self.chardata.borrow();
         let bgmaps = self.bgmaps.borrow();
         let brightness = self.brightness.borrow();
@@ -284,7 +284,7 @@ impl BgMapLoader {
         }
     }
 
-    fn update_bgmap_cell(&self, image: &mut VramImage, index: usize, generic_palette: bool) {
+    fn render_bgmap_cell(&self, image: &mut VramImage, index: usize, generic_palette: bool) {
         let chardata = self.chardata.borrow();
         let bgmaps = self.bgmaps.borrow();
         let brightness = self.brightness.borrow();
@@ -324,49 +324,19 @@ impl BgMapLoader {
     }
 }
 
-impl VramImageLoader for BgMapLoader {
-    type Resource = BgMapResource;
+impl VramRenderer<2> for BgMapRenderer {
+    type Params = BgMapParams;
 
-    fn id(&self) -> &str {
-        concat!(module_path!(), "::BgMapLoader")
+    fn sizes(&self) -> [[usize; 2]; 2] {
+        [[8, 8], [8 * 64, 8 * 64]]
     }
 
-    fn add(&self, resource: &Self::Resource) -> Option<VramImage> {
-        match resource {
-            BgMapResource::BgMap {
-                index,
-                generic_palette,
-            } => {
-                let mut image = VramImage::new(64 * 8, 64 * 8);
-                self.update_bgmap(&mut image, *index, *generic_palette);
-                Some(image)
-            }
-            BgMapResource::Cell {
-                index,
-                generic_palette,
-            } => {
-                let mut image = VramImage::new(8, 8);
-                self.update_bgmap_cell(&mut image, *index, *generic_palette);
-                Some(image)
-            }
-        }
-    }
-
-    fn update<'a>(
-        &'a self,
-        resources: impl Iterator<Item = (&'a Self::Resource, &'a mut VramImage)>,
-    ) {
-        for (resource, image) in resources {
-            match resource {
-                BgMapResource::BgMap {
-                    index,
-                    generic_palette,
-                } => self.update_bgmap(image, *index, *generic_palette),
-                BgMapResource::Cell {
-                    index,
-                    generic_palette,
-                } => self.update_bgmap_cell(image, *index, *generic_palette),
-            }
-        }
+    fn render(&mut self, params: &Self::Params, images: &mut [VramImage; 2]) {
+        self.render_bgmap_cell(&mut images[0], params.cell_index, params.generic_palette);
+        self.render_bgmap(
+            &mut images[1],
+            params.cell_index / 4096,
+            params.generic_palette,
+        );
     }
 }

src/window/vram/chardata.rs

@@ -10,14 +10,15 @@ use serde::{Deserialize, Serialize};
 use crate::{
     emulator::SimId,
     memory::{MemoryMonitor, MemoryView},
-    vram::{VramImage, VramImageLoader, VramResource as _, VramTextureLoader},
+    vram::{VramImage, VramParams, VramProcessor, VramRenderer, VramTextureLoader},
     window::{utils::UiExt as _, AppWindow},
 };
 
 use super::utils::{self, CharacterGrid};
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
 pub enum VramPalette {
+    #[default]
     Generic,
     Bg0,
     Bg1,
@@ -77,26 +78,34 @@ impl Display for VramPalette {
 
 pub struct CharacterDataWindow {
     sim_id: SimId,
-    loader: Arc<VramTextureLoader<CharDataLoader>>,
+    loader: Arc<VramTextureLoader>,
     brightness: MemoryView,
     palettes: MemoryView,
     palette: VramPalette,
     index: usize,
     index_str: String,
+    params: VramParams<CharDataParams>,
     scale: f32,
     show_grid: bool,
 }
 
 impl CharacterDataWindow {
-    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
+    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor, vram: &mut VramProcessor) -> Self {
+        let renderer = CharDataRenderer::new(sim_id, memory);
+        let ([char, chardata], params) = vram.add(renderer);
+        let loader = VramTextureLoader::new([
+            ("vram://char".into(), char),
+            ("vram://chardata".into(), chardata),
+        ]);
         Self {
             sim_id,
-            loader: Arc::new(VramTextureLoader::new(CharDataLoader::new(sim_id, memory))),
+            loader: Arc::new(loader),
             brightness: memory.view(sim_id, 0x0005f824, 8),
             palettes: memory.view(sim_id, 0x0005f860, 16),
-            palette: VramPalette::Generic,
-            index: 0,
-            index_str: "0".into(),
+            palette: params.palette,
+            index: params.index,
+            index_str: params.index.to_string(),
+            params,
             scale: 4.0,
             show_grid: true,
         }
@@ -150,11 +159,7 @@ impl CharacterDataWindow {
                         });
                     });
                 });
-            let resource = CharDataResource::Character {
-                palette: self.palette,
-                index: self.index,
-            };
-            let image = Image::new(resource.to_uri())
+            let image = Image::new("vram://char")
                 .maintain_aspect_ratio(true)
                 .tint(Color32::RED)
                 .texture_options(TextureOptions::NEAREST);
@@ -207,6 +212,11 @@ impl CharacterDataWindow {
                 ui.checkbox(&mut self.show_grid, "Show grid");
             });
         });
+
+        self.params.write(CharDataParams {
+            palette: self.palette,
+            index: self.index,
+        });
     }
 
     fn load_palette_colors(&self) -> [u8; 4] {
@@ -220,10 +230,7 @@ impl CharacterDataWindow {
     }
 
     fn show_chardata(&mut self, ui: &mut Ui) {
-        let resource = CharDataResource::CharacterData {
-            palette: self.palette,
-        };
-        let grid = CharacterGrid::new(resource.to_uri())
+        let grid = CharacterGrid::new("vram://chardata")
             .with_scale(self.scale)
             .with_grid(self.show_grid)
             .with_selected(self.index);
@@ -254,7 +261,6 @@ impl AppWindow for CharacterDataWindow {
     }
 
     fn show(&mut self, ctx: &Context) {
-        self.loader.begin_pass();
         CentralPanel::default().show(ctx, |ui| {
             ui.horizontal_top(|ui| {
                 StripBuilder::new(ui)
@@ -279,6 +285,82 @@ enum CharDataResource {
     CharacterData { palette: VramPalette },
 }
 
+#[derive(Clone, Default, PartialEq, Eq)]
+struct CharDataParams {
+    palette: VramPalette,
+    index: usize,
+}
+
+struct CharDataRenderer {
+    chardata: MemoryView,
+    brightness: MemoryView,
+    palettes: MemoryView,
+}
+
+impl VramRenderer<2> for CharDataRenderer {
+    type Params = CharDataParams;
+
+    fn sizes(&self) -> [[usize; 2]; 2] {
+        [[8, 8], [16 * 8, 128 * 8]]
+    }
+
+    fn render(&mut self, params: &Self::Params, image: &mut [VramImage; 2]) {
+        self.render_character(&mut image[0], params.palette, params.index);
+        self.render_character_data(&mut image[1], params.palette);
+    }
+}
+
+impl CharDataRenderer {
+    pub fn new(sim_id: SimId, memory: &mut MemoryMonitor) -> Self {
+        Self {
+            chardata: memory.view(sim_id, 0x00078000, 0x8000),
+            brightness: memory.view(sim_id, 0x0005f824, 8),
+            palettes: memory.view(sim_id, 0x0005f860, 16),
+        }
+    }
+
+    fn render_character(&self, image: &mut VramImage, palette: VramPalette, index: usize) {
+        if index >= 2048 {
+            return;
+        }
+        let palette = self.load_palette(palette);
+        let chardata = self.chardata.borrow();
+        let character = chardata.range::<u16>(index * 8, 8);
+        for (row, pixels) in character.iter().enumerate() {
+            for col in 0..8 {
+                let char = (pixels >> (col * 2)) & 0x03;
+                image.write((col, row), palette[char as usize]);
+            }
+        }
+    }
+
+    fn render_character_data(&self, image: &mut VramImage, palette: VramPalette) {
+        let palette = self.load_palette(palette);
+        let chardata = self.chardata.borrow();
+        for (row, pixels) in chardata.range::<u16>(0, 8 * 2048).iter().enumerate() {
+            let char_index = row / 8;
+            let row_index = row % 8;
+            let x = (char_index % 16) * 8;
+            let y = (char_index / 16) * 8 + row_index;
+            for col in 0..8 {
+                let char = (pixels >> (col * 2)) & 0x03;
+                image.write((x + col, y), palette[char as usize]);
+            }
+        }
+    }
+
+    fn load_palette(&self, palette: VramPalette) -> [u8; 4] {
+        let Some(offset) = palette.offset() else {
+            return utils::GENERIC_PALETTE;
+        };
+        let palette = self.palettes.borrow().read(offset);
+        let brightnesses = self.brightness.borrow();
+        let brts = brightnesses.range(0, 8);
+        utils::parse_palette(palette, brts)
+    }
+}
+
+/*
 struct CharDataLoader {
     chardata: MemoryView,
     brightness: MemoryView,
@@ -373,3 +455,4 @@ impl VramImageLoader for CharDataLoader {
         }
     }
 }
+ */