src/vram.rs

@@ -1,13 +1,13 @@
 use std::{
     collections::{hash_map::Entry, HashMap},
     hash::Hash,
-    sync::Mutex,
+    sync::{Arc, Mutex},
 };
 
 use egui::{
     epaint::ImageDelta,
     load::{LoadError, SizedTexture, TextureLoader, TexturePoll},
-    ColorImage, Context, TextureHandle, TextureOptions,
+    Color32, ColorImage, Context, TextureHandle, TextureOptions,
 };
 use serde::{Deserialize, Serialize};
 
@@ -27,21 +27,60 @@ impl<T: Serialize + for<'a> Deserialize<'a> + PartialEq + Eq + Hash> VramResourc
     }
 }
 
+pub enum VramImage {
+    Unchanged(Arc<ColorImage>),
+    Changed(ColorImage),
+}
+
+impl VramImage {
+    pub fn new(width: usize, height: usize) -> Self {
+        Self::Changed(ColorImage::new([width, height], Color32::BLACK))
+    }
+
+    pub fn write(&mut self, coords: (usize, usize), shade: u8) {
+        match self {
+            Self::Unchanged(image) => {
+                let value = image[coords];
+                if value.r() == shade {
+                    return;
+                };
+                let mut new_image = ColorImage::clone(image);
+                new_image[coords] = Color32::from_gray(shade);
+                *self = Self::Changed(new_image);
+            }
+            Self::Changed(image) => {
+                image[coords] = Color32::from_gray(shade);
+            }
+        }
+    }
+
+    pub fn take(&mut self) -> Option<Arc<ColorImage>> {
+        match self {
+            Self::Unchanged(_) => None,
+            Self::Changed(image) => {
+                let arced = Arc::new(std::mem::take(image));
+                *self = Self::Unchanged(arced.clone());
+                Some(arced)
+            }
+        }
+    }
+}
+
 pub trait VramImageLoader {
     type Resource: VramResource;
 
     fn id(&self) -> &str;
-    fn add(&self, resource: &Self::Resource) -> Option<ColorImage>;
+    fn add(&self, resource: &Self::Resource) -> Option<VramImage>;
     fn update<'a>(
         &'a self,
-        resources: impl Iterator<Item = &'a Self::Resource>,
+        resources: impl Iterator<Item = (&'a Self::Resource, &'a mut VramImage)>,
-    ) -> Vec<(&'a Self::Resource, ColorImage)>;
+    );
 }
 
 pub struct VramTextureLoader<T: VramImageLoader> {
     id: String,
     loader: Mutex<T>,
-    cache: Mutex<HashMap<T::Resource, TextureHandle>>,
+    cache: Mutex<HashMap<T::Resource, (TextureHandle, VramImage)>>,
 }
 
 impl<T: VramImageLoader> VramTextureLoader<T> {
@@ -76,26 +115,30 @@ impl<T: VramImageLoader> TextureLoader for VramTextureLoader<T> {
         }
         let loader = self.loader.lock().unwrap();
         let mut cache = self.cache.lock().unwrap();
-        for (resource, updated_image) in loader.update(cache.keys()) {
+        let resources = cache.iter_mut().map(|(k, v)| (k, &mut v.1));
-            if let Some(handle) = cache.get(resource) {
+        loader.update(resources);
-                let delta = ImageDelta::full(updated_image, TextureOptions::NEAREST);
+        for (handle, image) in cache.values_mut() {
+            if let Some(data) = image.take() {
+                let delta = ImageDelta::full(data, TextureOptions::NEAREST);
                 ctx.tex_manager().write().set(handle.id(), delta);
             }
         }
         match cache.entry(resource) {
             Entry::Occupied(entry) => {
-                let texture = SizedTexture::from_handle(entry.get());
+                let texture = SizedTexture::from_handle(&entry.get().0);
                 Ok(TexturePoll::Ready { texture })
             }
             Entry::Vacant(entry) => {
-                if let Some(image) = loader.add(entry.key()) {
+                let Some(mut image) = loader.add(entry.key()) else {
-                    let handle =
+                    return Err(LoadError::Loading("could not load texture".into()));
-                        entry.insert(ctx.load_texture(uri, image, TextureOptions::NEAREST));
+                };
-                    let texture = SizedTexture::from_handle(handle);
+                let Some(data) = image.take() else {
-                    Ok(TexturePoll::Ready { texture })
+                    return Err(LoadError::Loading("could not load texture".into()));
-                } else {
+                };
-                    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);
+                Ok(TexturePoll::Ready { texture })
             }
         }
     }
@@ -115,7 +158,7 @@ impl<T: VramImageLoader> TextureLoader for VramTextureLoader<T> {
             .lock()
             .unwrap()
             .values()
-            .map(|h| h.byte_size())
+            .map(|h| h.0.byte_size())
             .sum()
     }
 }

src/window/vram/bgmap.rs

@@ -1,8 +1,8 @@
 use std::sync::Arc;
 
 use egui::{
-    Align, CentralPanel, Checkbox, Color32, ColorImage, Context, Image, ScrollArea, Slider,
+    Align, CentralPanel, Checkbox, Color32, Context, Image, ScrollArea, Slider, TextEdit,
-    TextEdit, TextureOptions, Ui, ViewportBuilder, ViewportId,
+    TextureOptions, Ui, ViewportBuilder, ViewportId,
 };
 use egui_extras::{Column, Size, StripBuilder, TableBuilder};
 use serde::{Deserialize, Serialize};
@@ -10,7 +10,7 @@ use serde::{Deserialize, Serialize};
 use crate::{
     emulator::SimId,
     memory::{MemoryMonitor, MemoryView},
-    vram::{VramImageLoader, VramResource as _, VramTextureLoader},
+    vram::{VramImage, VramImageLoader, VramResource as _, VramTextureLoader},
     window::{utils::UiExt, AppWindow},
 };
 
@@ -242,7 +242,7 @@ impl BgMapLoader {
         }
     }
 
-    fn load_bgmap(&self, bgmap_index: usize, generic_palette: bool) -> Option<ColorImage> {
+    fn update_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();
@@ -265,7 +265,6 @@ impl BgMapLoader {
             ]
         };
 
-        let mut data = vec![0u8; 512 * 512];
         for (i, cell) in bgmaps
             .range::<u16>(bgmap_index * 4096, 4096)
             .iter()
@@ -275,21 +274,17 @@ impl BgMapLoader {
             let char = chardata.range::<u16>(char_index * 8, 8);
             let palette = &colors[palette_index];
 
-            let mut target_idx = (i % 64) * 8 + (i / 64) * 8 * 512;
             for row in 0..8 {
-                let dests = &mut data[target_idx..target_idx + 8];
+                let y = row + (i / 64) * 8;
-                let pixels = self.read_char_row(char, hflip, vflip, row);
+                for (col, pixel) in self.read_char_row(char, hflip, vflip, row).enumerate() {
-                for (dest, pixel) in dests.iter_mut().zip(pixels) {
+                    let x = col + (i % 64) * 8;
-                    *dest = palette[pixel as usize];
+                    image.write((x, y), palette[pixel as usize]);
                 }
-                target_idx += 512;
             }
         }
-
-        Some(ColorImage::from_gray([512, 512], &data))
     }
 
-    fn load_bgmap_cell(&self, index: usize, generic_palette: bool) -> Option<ColorImage> {
+    fn update_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();
@@ -297,7 +292,6 @@ impl BgMapLoader {
 
         let brts = brightness.range::<u8>(0, 8);
 
-        let mut data = vec![0u8; 8 * 8];
         let cell = bgmaps.read::<u16>(index);
 
         let (char_index, vflip, hflip, palette_index) = parse_cell(cell);
@@ -308,17 +302,11 @@ impl BgMapLoader {
             parse_palette(palettes.read(palette_index * 2), brts)
         };
 
-        let mut target_idx = 0;
         for row in 0..8 {
-            let dests = &mut data[target_idx..target_idx + 8];
+            for (col, pixel) in self.read_char_row(char, hflip, vflip, row).enumerate() {
-            let pixels = self.read_char_row(char, hflip, vflip, row);
+                image.write((col, row), palette[pixel as usize]);
-            for (dest, pixel) in dests.iter_mut().zip(pixels) {
-                *dest = palette[pixel as usize];
             }
-            target_idx += 8;
         }
-
-        Some(ColorImage::from_gray([8, 8], &data))
     }
 
     fn read_char_row(
@@ -343,24 +331,42 @@ impl VramImageLoader for BgMapLoader {
         concat!(module_path!(), "::BgMapLoader")
     }
 
-    fn add(&self, resource: &Self::Resource) -> Option<ColorImage> {
+    fn add(&self, resource: &Self::Resource) -> Option<VramImage> {
         match resource {
             BgMapResource::BgMap {
                 index,
                 generic_palette,
-            } => self.load_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,
-            } => self.load_bgmap_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>,
+        resources: impl Iterator<Item = (&'a Self::Resource, &'a mut VramImage)>,
-    ) -> Vec<(&'a Self::Resource, ColorImage)> {
+    ) {
-        let _ = resources;
+        for (resource, image) in resources {
-        vec![]
+            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),
+            }
+        }
     }
 }

src/window/vram/chardata.rs

@@ -1,8 +1,8 @@
 use std::{fmt::Display, sync::Arc};
 
 use egui::{
-    Align, CentralPanel, Color32, ColorImage, ComboBox, Context, Image, ScrollArea, Slider,
+    Align, CentralPanel, Color32, ComboBox, Context, Image, ScrollArea, Slider, TextEdit,
-    TextEdit, TextureOptions, Ui, Vec2, ViewportBuilder, ViewportId,
+    TextureOptions, Ui, Vec2, ViewportBuilder, ViewportId,
 };
 use egui_extras::{Column, Size, StripBuilder, TableBuilder};
 use serde::{Deserialize, Serialize};
@@ -10,7 +10,7 @@ use serde::{Deserialize, Serialize};
 use crate::{
     emulator::SimId,
     memory::{MemoryMonitor, MemoryView},
-    vram::{VramImageLoader, VramResource as _, VramTextureLoader},
+    vram::{VramImage, VramImageLoader, VramResource as _, VramTextureLoader},
     window::{utils::UiExt as _, AppWindow},
 };
 
@@ -294,38 +294,34 @@ impl CharDataLoader {
         }
     }
 
-    fn load_character(&self, palette: VramPalette, index: usize) -> Option<ColorImage> {
+    fn update_character(&self, image: &mut VramImage, palette: VramPalette, index: usize) {
         if index >= 2048 {
-            return None;
+            return;
         }
         let palette = self.load_palette(palette);
         let chardata = self.chardata.borrow();
         let character = chardata.range::<u16>(index * 8, 8);
-        let mut buffer = Vec::with_capacity(8 * 8);
+        for (row, pixels) in character.iter().enumerate() {
-        for row in character {
+            for col in 0..8 {
-            for offset in (0..16).step_by(2) {
+                let char = (pixels >> (col * 2)) & 0x03;
-                let char = (row >> offset) & 0x3;
+                image.write((col, row), palette[char as usize]);
-                buffer.push(palette[char as usize]);
             }
         }
-        Some(ColorImage::from_gray([8, 8], &buffer))
     }
 
-    fn load_character_data(&self, palette: VramPalette) -> Option<ColorImage> {
+    fn update_character_data(&self, image: &mut VramImage, palette: VramPalette) {
         let palette = self.load_palette(palette);
         let chardata = self.chardata.borrow();
-        let mut buffer = vec![0; 8 * 8 * 2048];
+        for (row, pixels) in chardata.range::<u16>(0, 8 * 2048).iter().enumerate() {
-        for (i, row) in chardata.range::<u16>(0, 8 * 2048).iter().enumerate() {
+            let char_index = row / 8;
-            let bytes =
+            let row_index = row % 8;
-                [0, 2, 4, 6, 8, 10, 12, 14].map(|off| palette[(*row as usize >> off) & 0x3]);
-            let char_index = i / 8;
-            let row_index = i % 8;
             let x = (char_index % 16) * 8;
             let y = (char_index / 16) * 8 + row_index;
-            let write_index = (y * 16 * 8) + x;
+            for col in 0..8 {
-            buffer[write_index..write_index + 8].copy_from_slice(&bytes);
+                let char = (pixels >> (col * 2)) & 0x03;
+                image.write((x + col, y), palette[char as usize]);
+            }
         }
-        Some(ColorImage::from_gray([8 * 16, 8 * 128], &buffer))
     }
 
     fn load_palette(&self, palette: VramPalette) -> [u8; 4] {
@@ -346,18 +342,34 @@ impl VramImageLoader for CharDataLoader {
         concat!(module_path!(), "::CharDataLoader")
     }
 
-    fn add(&self, resource: &Self::Resource) -> Option<ColorImage> {
+    fn add(&self, resource: &Self::Resource) -> Option<VramImage> {
         match resource {
-            CharDataResource::Character { palette, index } => self.load_character(*palette, *index),
+            CharDataResource::Character { palette, index } => {
-            CharDataResource::CharacterData { palette } => self.load_character_data(*palette),
+                let mut image = VramImage::new(8, 8);
+                self.update_character(&mut image, *palette, *index);
+                Some(image)
+            }
+            CharDataResource::CharacterData { palette } => {
+                let mut image = VramImage::new(8 * 16, 8 * 128);
+                self.update_character_data(&mut image, *palette);
+                Some(image)
+            }
         }
     }
 
     fn update<'a>(
         &'a self,
-        resources: impl Iterator<Item = &'a Self::Resource>,
+        resources: impl Iterator<Item = (&'a Self::Resource, &'a mut VramImage)>,
-    ) -> Vec<(&'a Self::Resource, ColorImage)> {
+    ) {
-        let _ = resources;
+        for (resource, image) in resources {
-        vec![]
+            match resource {
+                CharDataResource::Character { palette, index } => {
+                    self.update_character(image, *palette, *index)
+                }
+                CharDataResource::CharacterData { palette } => {
+                    self.update_character_data(image, *palette)
+                }
+            }
+        }
     }
 }