Make 'VersionedCanvas' into a generic 'Versioned<T>' data structure

src/history.rs

@@ -14,27 +14,26 @@
 //  You should have received a copy of the GNU Affero General Public License
 //  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-use super::canvas::Canvas;
 use im::Vector;
 
 #[derive(Clone, druid::Data)]
-pub struct VersionedCanvas {
+pub struct Versioned<T: druid::Data + Clone> {
     // We internally guarantee that this vector
     // is never empty
-    versions: Vector<Canvas>,
+    versions: Vector<T>,
     curr_version: usize,
 }
 
-impl VersionedCanvas {
+impl<T: druid::Data + Clone> Versioned<T> {
-    pub fn new(canvas: Canvas) -> VersionedCanvas {
+    pub fn new(first_version: T) -> Versioned<T> {
-        VersionedCanvas {
+        Versioned {
-            versions: im::vector![canvas],
+            versions: im::vector![first_version],
             curr_version: 0,
         }
     }
 
-    // Get current canvas version
+    // Get current version
-    pub fn get(&self) -> &Canvas {
+    pub fn get(&self) -> &T {
         self.versions.get(self.curr_version).unwrap()
     }
 
@@ -58,10 +57,10 @@ impl VersionedCanvas {
         }
     }
 
-    pub fn update(&mut self, update_fn: impl FnOnce(&mut Canvas)) {
+    pub fn update(&mut self, update_fn: impl FnOnce(&mut T)) {
-        // Make a new copy of the current canvas version,
+        // Make a new copy of the current version,
         // so that we can safely modify it without losing
-        // the previous canvas version
+        // the previous version
         let mut new_version = self.get().clone();
         update_fn(&mut new_version);
 
@@ -77,8 +76,8 @@ impl VersionedCanvas {
     }
 
     // Do inplace update, which will be irreversible
-    pub fn irreversible_update(&mut self, update_fn: impl FnOnce(&mut Canvas)) {
+    pub fn irreversible_update(&mut self, update_fn: impl FnOnce(&mut T)) {
-        // Do the update directly on the current canvas version
+        // Do the update directly on the current version
         update_fn(self.versions.back_mut().unwrap());
 
         // This is a linear history,

src/lib.rs

@@ -36,3 +36,5 @@ pub struct DocumentSnapshot {
     pub format_version_minor: u16,
     pub canvas_elements: Vec<canvas::CanvasElement>,
 }
+
+pub type VersionedCanvas = history::Versioned<canvas::Canvas>;

src/widget/canvas.rs

@@ -18,8 +18,7 @@ use im::Vector;
 
 use super::tool_ctx::{CanvasToolCtx};
 use crate::canvas::Canvas;
-use crate::history::VersionedCanvas;
+use crate::{DocumentSnapshot, VersionedCanvas};
-use crate::DocumentSnapshot;
 
 use druid::widget::prelude::*;
 use druid::{Color, Data, Env, Event, PointerType};

src/widget/tool_ctx.rs

@@ -16,7 +16,7 @@
 
 use crate::tool::{CanvasToolParams, CanvasToolType};
 use crate::canvas::{Canvas, CanvasElement};
-use crate::history::VersionedCanvas;
+use crate::VersionedCanvas;
 
 use druid::kurbo::BezPath;
 use druid::{Color, Data, Env, Event, EventCtx, MouseButton, MouseEvent, PaintCtx, RenderContext};