feat: add kraft paper tiled background texture for comfortable reading

src/app.rs

@@ -8,6 +8,7 @@ pub struct App {
     pub state: AppState,
     settings: Settings,
     settings_dir: std::path::PathBuf,
+    kraft_texture: Option<egui::TextureHandle>,
 }
 
 pub struct AppState {
@@ -51,6 +52,7 @@ impl App {
         let settings_dir = persistence::settings_dir();
         let settings = persistence::load_settings(&settings_dir).unwrap_or_default();
         cc.egui_ctx.set_style(theme::create_style(&settings.theme));
+        let kraft_texture = Some(crate::texture::generate_kraft_paper(&cc.egui_ctx));
         Self {
             state: AppState {
                 book: None,
@@ -62,6 +64,7 @@ impl App {
             },
             settings,
             settings_dir,
+            kraft_texture,
         }
     }
 
@@ -189,6 +192,8 @@ impl eframe::App for App {
                 &mut self.settings.font_size,
                 &self.settings.theme,
                 &file_path,
+                self.kraft_texture.as_ref(),
+                self.settings.use_kraft_bg,
             );
 
             if action.go_back {
@@ -198,6 +203,10 @@ impl eframe::App for App {
                 self.state.current_page = 0;
             }
 
+            if action.toggle_kraft_bg {
+                self.settings.use_kraft_bg = !self.settings.use_kraft_bg;
+            }
+
             if action.toggle_theme {
                 self.settings.theme = match self.settings.theme {
                     theme::Theme::Light => theme::Theme::Dark,