previews: run previews as notedeck apps

This allows ./preview to be a notedeck app runner. I am currently
using it for the ProfilePic app (which will because notedeck_viz)

Signed-off-by: William Casarin <jb55@jb55.com>

crates/notedeck/src/app.rs

@@ -1,5 +1,5 @@
 use crate::AppContext;
 
 pub trait App {
-    fn update(&mut self, ctx: &mut AppContext<'_>);
+    fn update(&mut self, ctx: &mut AppContext<'_>, ui: &mut egui::Ui);
 }

crates/notedeck/src/context.rs

@@ -15,5 +15,4 @@ pub struct AppContext<'a> {
     pub path: &'a DataPath,
     pub args: &'a Args,
     pub theme: &'a mut ThemeHandler,
-    pub egui: &'a egui::Context,
 }

crates/notedeck/src/storage/file_storage.rs

@@ -22,18 +22,12 @@ impl DataPath {
     pub fn default_base() -> Option<PathBuf> {
         dirs::data_local_dir().map(|pb| pb.join("notedeck"))
     }
-}
 
-pub enum DataPathType {
-    Log,
-    Setting,
-    Keys,
-    SelectedKey,
-    Db,
-    Cache,
-}
+    pub fn default_base_or_cwd() -> PathBuf {
+        use std::str::FromStr;
+        Self::default_base().unwrap_or_else(|| PathBuf::from_str(".").unwrap())
+    }
 
-impl DataPath {
     pub fn rel_path(&self, typ: DataPathType) -> PathBuf {
         match typ {
             DataPathType::Log => PathBuf::from("logs"),
@@ -50,6 +44,21 @@ impl DataPath {
     }
 }
 
+impl Default for DataPath {
+    fn default() -> Self {
+        Self::new(Self::default_base_or_cwd())
+    }
+}
+
+pub enum DataPathType {
+    Log,
+    Setting,
+    Keys,
+    SelectedKey,
+    Db,
+    Cache,
+}
+
 #[derive(Debug, PartialEq)]
 pub struct Directory {
     pub file_path: PathBuf,