src/lib.rs

@@ -42,20 +42,24 @@ use im::Vector;
 pub type Canvas = Vector<CanvasElement>;
 
 #[derive(Clone, druid::Data)]
-pub struct History {
+pub struct VersionedCanvas {
+    // We internally guarantee that this vector
+    // is never empty
     versions: Vector<Canvas>,
     curr_version: usize,
 }
 
-impl History {
+impl VersionedCanvas {
-    pub fn new(canvas: Canvas) -> History {
+    pub fn new(canvas: Canvas) -> VersionedCanvas {
-        History {
+        VersionedCanvas {
             versions: im::vector![canvas],
             curr_version: 0,
         }
     }
 
+    // Get current canvas version
     pub fn get(&self) -> &Canvas {
+        let focus = self.versions.focus();
         self.versions.get(self.curr_version).unwrap()
     }
 
@@ -83,8 +87,7 @@ impl History {
         // This is a linear history,
         // so we first check if there are newer versions, if so
         // this means we are in the past, so a change in the past destroys the future
-        // and creates a new future. If we want to keep all ramifications, we should use a tree,
+        // and creates a new future.
-        // but honestly, this sounds like overkill.
         if self.has_newer_versions() {
             self.versions = self.versions.take(self.curr_version + 1);
         }
@@ -98,8 +101,7 @@ impl History {
         // This is a linear history,
         // so we first check if there are newer versions, if so
         // this means we are in the past, so a change in the past destroys the future
-        // and creates a new future. If we want to keep all ramifications, we should use a tree,
+        // and creates a new future.
-        // but honestly, this sounds like overkill.
         if self.has_newer_versions() {
             self.versions = self.versions.take(self.curr_version + 1);
         }

src/main.rs

@@ -19,13 +19,13 @@ use druid::kurbo::BezPath;
 use druid::widget::prelude::*;
 use druid::{AppLauncher, Color, Data, Event, LocalizedString, WindowDesc};
 
-use stiletto::{CanvasElement, History, Canvas};
+use stiletto::{CanvasElement, VersionedCanvas, Canvas};
 
 #[derive(Clone, Data)]
 struct CanvasData {
     current_element: Option<CanvasElement>,
     //elements: Vector<CanvasElement>,
-    history: History,
+    elements: VersionedCanvas,
 }
 
 impl CanvasData {
@@ -35,13 +35,13 @@ impl CanvasData {
 
     fn perform_undo(&mut self) {
         if !self.is_drawing() {
-            self.history.undo();
+            self.elements.undo();
         }
     }
 
     fn perform_redo(&mut self) {
         if !self.is_drawing() {
-            self.history.redo();
+            self.elements.redo();
         }
     }
 }
@@ -74,7 +74,7 @@ impl Widget<CanvasData> for CanvasWidget {
                 if data.is_drawing() {
                     if let Some(current_element) = data.current_element.take() {
 
-                        data.history.update(move |canvas: &Canvas| -> Canvas {
+                        data.elements.update(move |canvas: &Canvas| -> Canvas {
                             let mut new_canvas = canvas.clone();
                             new_canvas.push_back(current_element);
                             return new_canvas;
@@ -143,7 +143,7 @@ impl Widget<CanvasData> for CanvasWidget {
         // and we only want to clear this widget's area.
         ctx.fill(rect, &Color::WHITE);
 
-        for element in data.history.get().iter() {
+        for element in data.elements.get().iter() {
             element.draw(ctx);
         }
         if let Some(element) = &data.current_element {
@@ -177,7 +177,7 @@ pub fn main() {
         );
     let canvas_data = CanvasData {
         current_element: None,
-        history: History::new(vector![]),
+        elements: VersionedCanvas::new(vector![]),
     };
     AppLauncher::with_window(window)
         .use_simple_logger()