Use serde_bare and update format version

Closes #15

Cargo.toml

@@ -3,26 +3,30 @@ name = "stiletto"
 version = "0.1.0"
 authors = ["Enrico Lumetti <enrico.lumetti@gmail.com>"]
 edition = "2018"
+default-run = "stiletto"
 
 [dependencies]
 log = "0.4"
-druid = { version = "0.6.0", features = ["im", "svg"] }
+druid = { version = "0.7.0", features = ["im", "svg"] }
 im = { version = "*" }
 serde = { version = "1.0", features = ["derive"] }
-#serde_bare = "0.3.0"
+serde_bare = "0.3.0"
 serde_json = "1.0"
+clap = "3.0.0-beta.2"
 
-[patch.crates-io]
+[target.'cfg(target_os="linux")'.dependencies.gtk]
-druid = { git = "https://github.com/doppioandante/druid", branch = "v0.6.0_stiletto", features = ["im", "svg"] }
+version = "0.9.2"
-
-[dependencies.gtk]
-version = "0.8.1"
 features = ["v3_22"]
 
-[dependencies.gio]
+[target.'cfg(target_os="linux")'.dependencies.gio]
-version = "0.8.1"
+version = "0.9.1"
 features = ["v2_56"]
 
-[dependencies.gdk]
+[target.'cfg(target_os="linux")'.dependencies.gdk]
-version = "0.12.1"
+version = "0.13.2"
 features = ["v3_22"]
+
+[patch.crates-io]
+druid = { git = "https://github.com/doppioandante/druid", branch = "v0.7.0_stiletto", features = ["im", "svg"] }
+#druid = { path = "../druid/druid/", features = ["im", "svg"] }
+

src/bin/stlt_migrate.rs

@@ -0,0 +1,48 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  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 clap::{Arg, App};
+use stiletto::migration::open_stiletto_document;
+
+use std::fs::File;
+use std::path::PathBuf;
+
+fn main() {
+    let matches = App::new("Stiletto Migration CLI")
+        .version("0.1.0")
+        .author("Stiletto Authors")
+        .about("Migrate a stlt file to the latest version")
+        .arg(Arg::new("INPUT")
+            .about("Sets the input file to use")
+            .required(true)
+            .index(1))
+        .arg(Arg::new("OUTPUT")
+            .about("Sets the output file to use")
+            .required(true)
+            .index(2))
+        .get_matches();
+
+   let input_path = matches.value_of("INPUT").unwrap();
+   let output_path = matches.value_of("OUTPUT").unwrap();
+
+   let out_file = File::create(&output_path).expect("Cannot create output fle");
+
+   let result = open_stiletto_document(&PathBuf::from(&input_path));
+   if let Ok(document) = result {
+       let snapshot = document.migrate_to_latest();
+       snapshot.to_writer(out_file);
+   }
+}

src/canvas.rs

@@ -14,7 +14,9 @@
 //  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 im::Vector;
+use std::vec::Vec;
+
+use im::{vector, Vector};
 
 use serde::de::{Deserializer, SeqAccess, Visitor};
 use serde::ser::Serializer;
@@ -25,17 +27,76 @@ pub struct Path {
     pub kurbo_path: druid::kurbo::BezPath,
 }
 
-pub type Canvas = Vector<CanvasElement>;
+#[derive(Serialize, Deserialize)]
+#[serde(remote = "druid::Color")]
+enum ColorDef {
+    Rgba32(u32),
+}
+
+struct Interval {
+    start_pos: f64,
+    end_pos: f64,
+}
+
+impl Interval {
+    fn new(x1: f64, x2: f64) -> Interval {
+        Interval {
+            start_pos: x1.min(x2),
+            end_pos: x1.max(x2),
+        }
+    }
+
+    fn new_ordered(start: f64, end: f64) -> Interval {
+        Interval {
+            start_pos: start,
+            end_pos: end,
+        }
+    }
+
+    fn overlaps(&self, other: &Self) -> bool {
+        self.start_pos < other.end_pos && other.start_pos < self.end_pos
+    }
+}
+
+// O(1) complexity
+// TODO(francesco): Implement this in a way that is not so flamboyant
+// TODO(francesco): Implement intersection test for bezier curves
+fn segment_intersects_rect(segment: &druid::kurbo::PathSeg, rect: druid::Rect) -> bool {
+    match segment {
+        druid::kurbo::PathSeg::Line(line) => {
+            // A Segment intersects the rect
+            // if their projections on the x and y line both overlap
+            let line_x_proj = Interval::new(line.p0.x, line.p1.x);
+            let line_y_proj = Interval::new(line.p0.y, line.p1.y);
+
+            let rect_x_proj = Interval::new_ordered(rect.min_x(), rect.max_x());
+            let rect_y_proj = Interval::new_ordered(rect.min_y(), rect.max_y());
+
+            line_x_proj.overlaps(&rect_x_proj) && line_y_proj.overlaps(&rect_y_proj)
+        }
+
+        _ => {
+            unimplemented!();
+        }
+    }
+}
 
 #[derive(Debug, Clone, druid::Data, Serialize, Deserialize)]
 pub enum CanvasElement {
-    Freehand { path: Path, thickness: f64 },
+    Freehand {
+        path: Path,
+        thickness: f64,
+        #[serde(with = "ColorDef")]
+        stroke_color: druid::Color,
+    },
 }
 
 impl CanvasElement {
     pub fn bounding_box(&self) -> druid::Rect {
         match self {
-            CanvasElement::Freehand { path, thickness } => {
+            CanvasElement::Freehand {
+                path, thickness, ..
+            } => {
                 use druid::kurbo::Shape;
                 path.kurbo_path
                     .bounding_box()
@@ -43,29 +104,85 @@ impl CanvasElement {
             }
         }
     }
+
+    pub fn intersects_rect(&self, rect: druid::Rect) -> bool {
+        match self {
+            CanvasElement::Freehand { path, .. } => {
+                // TODO(enrico) this doesn't handle thickness
+                path.kurbo_path
+                    .segments()
+                    .any(|segment| segment_intersects_rect(&segment, rect))
+            }
+        }
+    }
+
     pub fn draw(&self, ctx: &mut druid::PaintCtx) {
         match self {
-            CanvasElement::Freehand { path, thickness } => {
+            CanvasElement::Freehand {
+                path,
+                thickness,
+                stroke_color,
+            } => {
                 use druid::RenderContext;
-                let stroke_color = druid::Color::rgb8(0, 128, 0);
+                ctx.stroke(&path.kurbo_path, &*stroke_color, *thickness);
-                ctx.stroke(&path.kurbo_path, &stroke_color, *thickness);
+            }
         }
     }
 }
 
-    pub fn get_path_mut(&mut self) -> Option<&mut Path> {
+#[derive(Clone, druid::Data)]
-        match self {
+pub struct Canvas {
-            CanvasElement::Freehand { path, .. } => Some(path),
+    elements: Vector<CanvasElement>,
+    content_size: druid::Size,
+}
+
+impl Canvas {
+    pub fn new() -> Self {
+        Canvas {
+            elements: vector![],
+            content_size: druid::Size::new(0.0, 0.0),
+        }
+    }
+
+    pub fn new_with_elements(elements: Vector<CanvasElement>) -> Self {
+        let mut cv = Canvas::new();
+        for e in elements {
+            cv.add_element(e);
+        }
+        cv
+    }
+
+    pub fn add_element(&mut self, element: CanvasElement) {
+        self.content_size = self
+            .content_size
+            .to_rect()
+            .union(element.bounding_box())
+            .size();
+        self.elements.push_back(element);
+    }
+
+    pub fn elements(&self) -> &Vector<CanvasElement> {
+        &self.elements
+    }
+
+    /// Find all CanvasElement that intersect with rect
+    pub fn find_intersections(&self, rect: druid::Rect) -> Vec<usize> {
+        let mut found_elements = Vec::<usize>::new();
+
+        for (i, elem) in self.elements.iter().enumerate() {
+            // Check if the element intersects the eraser rect
+            if elem.bounding_box().intersect(rect).area() > 0.0 {
+                if elem.intersects_rect(rect) {
+                    found_elements.push(i);
                 }
             }
         }
 
-impl<'de> Deserialize<'de> for Path {
+        found_elements
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    }
-    where
+
-        D: Deserializer<'de>,
+    pub fn content_size(&self) -> druid::Size {
-    {
+        self.content_size
-        deserializer.deserialize_seq(PathDeserializer)
     }
 }
 
@@ -80,13 +197,18 @@ impl Serialize for Path {
             PathEl::MoveTo(pt) => Some(Into::<(f64, f64)>::into(pt)),
             PathEl::LineTo(pt) => Some(Into::<(f64, f64)>::into(pt)),
             _ => None,
-        }))
+        }).collect::<Vec<(f64, f64)>>())
     }
 }
 
-struct PathDeserializer;
+impl<'de> Deserialize<'de> for Path {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct PathVisitor;
 
-impl<'de> Visitor<'de> for PathDeserializer {
+        impl<'de> Visitor<'de> for PathVisitor {
             type Value = Path;
 
             fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
@@ -113,3 +235,7 @@ impl<'de> Visitor<'de> for PathDeserializer {
                 Ok(Path { kurbo_path })
             }
         }
+
+        deserializer.deserialize_seq(PathVisitor)
+    }
+}

src/lib.rs

@@ -21,14 +21,28 @@ pub mod canvas;
 pub mod history;
 pub mod tool;
 pub mod widget;
+pub mod migration;
 
 pub mod commands {
     use druid::Selector;
 
     pub const UPDATE_TOOL: Selector = Selector::new("stiletto_update_tool");
+    pub const PUSH_ERASER: Selector<()> = Selector::new("push_eraser_context");
+    pub const POP_ERASER: Selector<()> = Selector::new("pop_eraser_context");
 }
 
+pub const STILETTO_FORMAT_MAJOR: u16 = 0;
+pub const STILETTO_FORMAT_MINOR: u16 = 2;
+
 #[derive(Serialize, Deserialize, Debug)]
 pub struct DocumentSnapshot {
+    pub format_version_major: u16,
+    pub format_version_minor: u16,
     pub canvas_elements: Vec<canvas::CanvasElement>,
 }
+
+impl DocumentSnapshot {
+    pub fn to_writer<W: std::io::Write>(&self, writer: W) -> Result<(), serde_bare::Error> {
+        serde_bare::to_writer(writer, &self)
+    }
+}

src/main.rs

@@ -14,53 +14,67 @@
 //  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 std::path::PathBuf;
+
 use log::{info, warn};
 
 use druid::commands;
 use druid::im::vector;
 use druid::widget::prelude::*;
 use druid::widget::{
-    Align, Button, CrossAxisAlignment, Flex, List, ListGrowDirection, SizedBox, WidgetExt,
+    Align, Button, Controller, CrossAxisAlignment, Flex, List, SizedBox, WidgetExt,
 };
 use druid::{
     AppDelegate, AppLauncher, Color, Command, Data, DelegateCtx, Env, FileDialogOptions, FileSpec,
-    Lens, LocalizedString, Target, WindowDesc,
+    Handled, Lens, Target, WindowDesc,
 };
 
 use im::Vector;
 
-use stiletto::history::VersionedCanvas;
+use stiletto::tool::CanvasToolParams;
-use stiletto::tool::{CanvasToolCtx, CanvasToolParams};
+use stiletto::widget::tool_ctx::{CanvasToolCtx};
 use stiletto::widget::{build_simple_tool_widget, CanvasState, CanvasToolIconState, CanvasWidget};
 use stiletto::DocumentSnapshot;
 
 pub fn main() {
     let window = WindowDesc::new(build_ui)
         .window_size((1024.0, 1400.0))
-        .title(
+        .title(|data: &StilettoState, _env: &Env| {
-            LocalizedString::new("custom-widget-demo-window-title").with_placeholder("Stiletto"),
+            let doc_name = if let Some(path) = &data.current_file_path {
-        );
+                String::from(path.to_string_lossy())
+            } else {
+                String::from("New Document")
+            };
+            format!("Stiletto - {}", doc_name)
+        });
 
     let default_pen_params = CanvasToolParams::Pen {
         thickness: 2.0,
-        color: Color::rgb(0, 0, 0),
+        color: Color::rgb(0.0, 0.0, 0.0),
+    };
+    let default_pen_params_2 = CanvasToolParams::Pen {
+        thickness: 2.0,
+        color: Color::rgb(255.0, 0.0, 0.0),
     };
     let canvas_data = StilettoState {
-        canvas: CanvasState {
+        canvas: CanvasState::new(CanvasToolCtx::new(default_pen_params.clone())),
-            versioned_canvas: VersionedCanvas::new(vector![]),
-            tool_ctx: CanvasToolCtx::new(default_pen_params.clone()),
-        },
         tool_icons: vector![
             CanvasToolIconState {
                 tool_params: default_pen_params,
                 selected: true,
             },
+            CanvasToolIconState {
+                tool_params: default_pen_params_2,
+                selected: false,
+            },
             CanvasToolIconState {
                 tool_params: CanvasToolParams::Eraser,
                 selected: false,
-            }
+            },
         ],
         current_tool: 0,
+        eraser_tool_id: 2,
+        current_file_path: None,
     };
     AppLauncher::with_window(window)
         .use_simple_logger()
@@ -74,6 +88,22 @@ struct StilettoState {
     canvas: CanvasState,
     tool_icons: Vector<CanvasToolIconState>,
     current_tool: usize,
+    eraser_tool_id: usize,
+    #[data(same_fn = "PartialEq::eq")]
+    current_file_path: Option<PathBuf>,
+}
+
+impl StilettoState {
+    pub fn set_tool(&mut self, new_tool: usize) {
+        let old_tool = self.current_tool;
+        info!("Changing active tool to: tool #{}", new_tool);
+        self.tool_icons.get_mut(old_tool).unwrap().selected = false;
+        self.tool_icons.get_mut(new_tool).unwrap().selected = true;
+        self.current_tool = new_tool;
+        self.canvas.set_tool_ctx(CanvasToolCtx::new(
+            self.tool_icons.get(new_tool).unwrap().tool_params.clone(),
+        ));
+    }
 }
 
 fn build_ui() -> impl Widget<StilettoState> {
@@ -90,27 +120,37 @@ fn build_ui() -> impl Widget<StilettoState> {
     let save_dialog_options = FileDialogOptions::new()
         .allowed_types(vec![stlt])
         .default_type(stlt);
+    let save_dialog_options_clone = save_dialog_options.clone();
     let open_dialog_options = save_dialog_options.clone();
 
     let save_buttons = Flex::row()
         .cross_axis_alignment(CrossAxisAlignment::Center)
-        .with_child(Button::new("Open").on_click(move |ctx, _, _| {
+        .with_child(
-            ctx.submit_command(
+            Button::new("Save").on_click(move |ctx, data: &mut StilettoState, _| {
-                Command::new(
+                if data.current_file_path.is_some() {
-                    druid::commands::SHOW_OPEN_PANEL,
+                    ctx.submit_command(Command::new(commands::SAVE_FILE, (), Target::Auto));
-                    open_dialog_options.clone(),
+                } else {
-                ),
+                    ctx.submit_command(Command::new(
-                None,
+                        druid::commands::SHOW_SAVE_PANEL,
+                        save_dialog_options_clone.clone(),
+                        Target::Auto,
+                    ))
+                }
+            }),
         )
-        }))
+        .with_child(Button::new("Save As").on_click(move |ctx, _, _| {
-        .with_child(Button::new("Save").on_click(move |ctx, _, _| {
+            ctx.submit_command(Command::new(
-            ctx.submit_command(
-                Command::new(
                 druid::commands::SHOW_SAVE_PANEL,
                 save_dialog_options.clone(),
-                ),
+                Target::Auto,
-                None,
+            ))
-            )
+        }))
+        .with_child(Button::new("Open").on_click(move |ctx, _, _| {
+            ctx.submit_command(Command::new(
+                druid::commands::SHOW_OPEN_PANEL,
+                open_dialog_options.clone(),
+                Target::Auto,
+            ))
         }));
 
     let tool_buttons = Flex::row()
@@ -121,10 +161,10 @@ fn build_ui() -> impl Widget<StilettoState> {
                     .padding((8.0, 0.0))
                     .on_click(|ctx, tool_state, _| {
                         tool_state.selected = true;
-                        ctx.submit_command(stiletto::commands::UPDATE_TOOL, None);
+                        ctx.submit_notification(stiletto::commands::UPDATE_TOOL);
                     })
             })
-            .grow(ListGrowDirection::Right)
+            .horizontal()
             .lens(StilettoState::tool_icons),
             1.0,
         );
@@ -143,7 +183,57 @@ fn build_ui() -> impl Widget<StilettoState> {
         .cross_axis_alignment(CrossAxisAlignment::Center)
         .must_fill_main_axis(true)
         .with_child(SizedBox::new(Align::left(toolbar)).height(50.0))
-        .with_flex_child((CanvasWidget {}).lens(StilettoState::canvas), 1.0)
+        .with_flex_child((CanvasWidget).lens(StilettoState::canvas), 1.0)
+        .controller(ToolSwitcher::new())
+}
+
+struct ToolSwitcher {
+    saved_tool: usize,
+}
+
+impl ToolSwitcher {
+    pub fn new() -> Self {
+        ToolSwitcher { saved_tool: 0 }
+    }
+}
+
+impl<W: Widget<StilettoState>> Controller<StilettoState, W> for ToolSwitcher {
+    fn event(
+        &mut self,
+        child: &mut W,
+        ctx: &mut EventCtx,
+        event: &Event,
+        data: &mut StilettoState,
+        env: &Env,
+    ) {
+        match event {
+            Event::Notification(cmd) => {
+                let new_tool = if cmd.get(stiletto::commands::PUSH_ERASER).is_some() {
+                    ctx.set_handled();
+                    self.saved_tool = data.current_tool;
+                    Some(data.eraser_tool_id)
+                } else if cmd.get(stiletto::commands::POP_ERASER).is_some() {
+                    ctx.set_handled();
+                    Some(self.saved_tool)
+                } else if cmd.get(stiletto::commands::UPDATE_TOOL).is_some() {
+                    ctx.set_handled();
+                    let old_tool = data.current_tool;
+                    data.tool_icons
+                        .iter()
+                        .enumerate()
+                        .position(|(pos, x)| pos != old_tool && x.selected)
+                } else {
+                    None
+                };
+
+                if let Some(new_tool) = new_tool {
+                    data.set_tool(new_tool);
+                }
+            }
+            _ => {}
+        }
+        child.event(ctx, event, data, env);
+    }
 }
 
 struct Delegate;
@@ -156,53 +246,50 @@ impl AppDelegate<StilettoState> for Delegate {
         cmd: &Command,
         data: &mut StilettoState,
         _env: &Env,
-    ) -> bool {
+    ) -> Handled {
         use std::fs::File;
 
-        if let Some(Some(file_info)) = cmd.get(commands::SAVE_FILE) {
+        if cmd.get(commands::SAVE_FILE_AS).is_some() || cmd.get(commands::SAVE_FILE).is_some() {
-            let res_file = File::create(file_info.path());
+            let mut path_buf = cmd
+                .get(commands::SAVE_FILE_AS)
+                .map(|file_info| file_info.path().to_path_buf())
+                .or_else(|| data.current_file_path.as_ref().cloned())
+                .unwrap();
+            path_buf.set_extension("stlt");
+
+            let res_file = File::create(&path_buf);
             if let Ok(f) = res_file {
                 let write_res =
-                    serde_json::to_writer_pretty(f, &data.canvas.get_document_snapshot());
+                    data.canvas.get_document_snapshot().to_writer(f);
                 if write_res.is_err() {
                     warn!("Error while saving: {:?}", write_res.err());
                 } else {
-                    info!("Written to file: {}", file_info.path().display());
+                    info!("Written to file: {}", &path_buf.display());
+                    data.current_file_path = Some(path_buf);
                 }
             } else {
                 warn!("Cannot create file: {:?}", res_file.err());
             }
-            return true;
+            return Handled::Yes;
         }
         if let Some(file_info) = cmd.get(commands::OPEN_FILE) {
             if let Ok(f) = File::open(file_info.path()) {
-                let res_snapshot: Result<DocumentSnapshot, serde_json::Error> =
+                let res_snapshot: Result<DocumentSnapshot, serde_bare::Error> =
-                    serde_json::from_reader(f);
+                    serde_bare::from_reader(f);
                 if let Ok(document_snapshot) = res_snapshot {
                     data.canvas.set_from_snapshot(document_snapshot);
+                    data.current_file_path = Some(file_info.path().to_path_buf());
                     info!("Loaded file {}", file_info.path().display());
                 } else {
-                    warn!("didn't work: {:?}", res_snapshot.err());
+                    warn!(
+                        "Error while loading {}: {:?}",
+                        file_info.path().display(),
+                        res_snapshot.err()
+                    );
                 }
             }
-            return true;
+            return Handled::Yes;
         }
-        if cmd.get(stiletto::commands::UPDATE_TOOL).is_some() {
+        Handled::No
-            let old_tool = data.current_tool;
-            if let Some(new_tool) = data
-                .tool_icons
-                .iter()
-                .enumerate()
-                .position(|(pos, x)| pos != old_tool && x.selected)
-            {
-                info!("Changing active tool to: tool #{}", new_tool);
-                data.tool_icons.get_mut(old_tool).unwrap().selected = false;
-                data.current_tool = new_tool;
-                data.canvas.set_tool_ctx(CanvasToolCtx::new(
-                    data.tool_icons.get(new_tool).unwrap().tool_params.clone(),
-                ));
-            }
-        }
-        false
     }
 }

src/migration.rs

@@ -0,0 +1,142 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  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 crate::{DocumentSnapshot, STILETTO_FORMAT_MAJOR, STILETTO_FORMAT_MINOR};
+
+use std::error::Error;
+use std::fmt;
+use std::fs::File;
+use std::io;
+use std::path::PathBuf;
+
+#[derive(Debug)]
+pub enum MigrationError {
+    SerdeJsonError(serde_json::Error),
+    SerdeBareError(serde_bare::Error),
+    IoError(io::Error),
+
+    UnexpectedVersion(u16, u16, u16, u16),
+}
+
+#[derive(Debug)]
+pub enum StilettoDocument {
+    DocumentSnapshot0_1(DocumentSnapshot),
+    DocumentSnapshot0_2(DocumentSnapshot),
+}
+
+impl StilettoDocument {
+    pub fn version(&self) -> (u16, u16) {
+        match &self {
+            StilettoDocument::DocumentSnapshot0_1(_) => (0, 1),
+            StilettoDocument::DocumentSnapshot0_2(_) => (0, 2),
+        }
+    }
+
+    pub fn migrate_to_next(self) -> StilettoDocument {
+        match self {
+            StilettoDocument::DocumentSnapshot0_1(snapshot) =>  StilettoDocument::DocumentSnapshot0_2(snapshot) ,
+            StilettoDocument::DocumentSnapshot0_2(_) => self,
+        }
+    }
+
+    pub fn migrate_to_latest(mut self) -> DocumentSnapshot {
+        while self.version() != (STILETTO_FORMAT_MAJOR, STILETTO_FORMAT_MINOR) {
+            self = self.migrate_to_next()
+        }
+
+        assert!(matches!(self, StilettoDocument::DocumentSnapshot0_2(_)));
+        match self {
+            StilettoDocument::DocumentSnapshot0_2(snapshot) => snapshot,
+            _ => panic!("Wrong Document Snapshot Version")
+        }
+    }
+}
+
+
+impl fmt::Display for MigrationError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self {
+            MigrationError::SerdeJsonError(e) => e.fmt(f),
+            MigrationError::SerdeBareError(e) => e.fmt(f),
+            MigrationError::IoError(e) => e.fmt(f),
+            MigrationError::UnexpectedVersion(major, minor, e_major, e_minor) => {
+                write!(
+                    f, "Unexpected version ({}, {}): was expecting ({}, {})",
+                    major, minor, e_major, e_minor
+                )
+            },
+        }
+    }
+}
+
+impl Error for MigrationError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            MigrationError::SerdeJsonError(e) => e.source(),
+            MigrationError::SerdeBareError(e) => e.source(),
+            MigrationError::IoError(e) => e.source(),
+            MigrationError::UnexpectedVersion(..) => None,
+        }
+    }
+}
+
+impl From<io::Error> for MigrationError {
+    fn from(error: io::Error) -> Self {
+        MigrationError::IoError(error)
+    }
+}
+
+impl From<serde_json::Error> for MigrationError {
+    fn from(error: serde_json::Error) -> Self {
+        MigrationError::SerdeJsonError(error)
+    }
+}
+
+impl From<serde_bare::Error> for MigrationError {
+    fn from(error: serde_bare::Error) -> Self {
+        MigrationError::SerdeBareError(error)
+    }
+}
+
+fn open_0_1(path: &PathBuf) -> Result<StilettoDocument, MigrationError> {
+    let f = File::open(path)?;
+    let document_snapshot: DocumentSnapshot = serde_json::from_reader(f)?;
+    if document_snapshot.format_version_major != 0 ||
+        document_snapshot.format_version_minor != 1 {
+        Err(MigrationError::UnexpectedVersion(
+            document_snapshot.format_version_major,
+            document_snapshot.format_version_minor,
+            0, 1
+        ))
+    } else {
+        Ok(StilettoDocument::DocumentSnapshot0_1(document_snapshot))
+    }
+}
+
+fn open_0_2(path: &PathBuf) -> Result<StilettoDocument, MigrationError> {
+    let f = File::open(path)?;
+    let document_snapshot: DocumentSnapshot = serde_bare::from_reader(f)?;
+    Ok(StilettoDocument::DocumentSnapshot0_2(document_snapshot))
+}
+
+pub fn open_stiletto_document(path: &PathBuf) -> Result<StilettoDocument, MigrationError> {
+    if let Ok(res) = open_0_1(path) {
+        return Ok(res);
+    }
+
+    open_0_2(path)
+}
+

src/tool.rs

@@ -14,12 +14,7 @@
 //  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 druid::kurbo::BezPath;
+use druid::{Color, Data};
-use druid::{Color, Data, Env, Event, EventCtx, PaintCtx};
-
-use crate::canvas;
-use crate::canvas::{Canvas, CanvasElement};
-use crate::history::VersionedCanvas;
 
 #[derive(Clone, Data)]
 pub enum CanvasToolParams {
@@ -33,98 +28,3 @@ pub enum CanvasToolType {
     Eraser,
 }
 
-#[derive(Clone, Data)]
-pub enum CanvasToolState {
-    Idle,
-    DrawingFreehand { current_path: CanvasElement },
-}
-
-#[derive(Clone, Data)]
-pub struct CanvasToolCtx {
-    initial_params: CanvasToolParams,
-    state: CanvasToolState,
-}
-
-impl CanvasToolParams {
-    pub fn tool_type(&self) -> CanvasToolType {
-        match self {
-            CanvasToolParams::Pen { .. } => CanvasToolType::Pen,
-            CanvasToolParams::Eraser => CanvasToolType::Eraser,
-        }
-    }
-}
-
-impl CanvasToolCtx {
-    pub fn new(params: CanvasToolParams) -> Self {
-        CanvasToolCtx {
-            initial_params: params,
-            state: CanvasToolState::Idle,
-        }
-    }
-
-    pub fn handle_event(
-        &mut self,
-        ctx: &EventCtx,
-        event: &Event,
-        mut vcanvas: &mut VersionedCanvas,
-        env: &Env,
-    ) {
-        match self.initial_params.tool_type() {
-            CanvasToolType::Pen => self.handle_pen_event(&ctx, &event, &mut vcanvas, &env),
-            _ => {}
-        }
-    }
-
-    pub fn handle_pen_event(
-        &mut self,
-        _ctx: &EventCtx,
-        event: &Event,
-        vcanvas: &mut VersionedCanvas,
-        _env: &Env,
-    ) {
-        match (&mut self.state, event) {
-            (CanvasToolState::Idle, Event::MouseDown(mouse_event)) => {
-                let mut kurbo_path = BezPath::new();
-                kurbo_path.move_to((mouse_event.pos.x, mouse_event.pos.y));
-                self.state = CanvasToolState::DrawingFreehand {
-                    current_path: CanvasElement::Freehand {
-                        path: canvas::Path { kurbo_path },
-                        thickness: 2.0,
-                    },
-                };
-            }
-            (
-                CanvasToolState::DrawingFreehand {
-                    ref mut current_path,
-                },
-                Event::MouseMove(mouse_event),
-            ) => {
-                current_path
-                    .get_path_mut()
-                    .unwrap()
-                    .kurbo_path
-                    .line_to((mouse_event.pos.x, mouse_event.pos.y));
-            }
-            (CanvasToolState::DrawingFreehand { .. }, Event::MouseUp(_)) => {
-                vcanvas.update(move |canvas: &mut Canvas| {
-                    let current_state = std::mem::replace(&mut self.state, CanvasToolState::Idle);
-                    if let CanvasToolState::DrawingFreehand { current_path } = current_state {
-                        canvas.push_back(current_path);
-                    }
-                });
-            }
-            _ => {}
-        }
-    }
-
-    pub fn needs_repaint(&self) -> bool {
-        true
-    }
-
-    pub fn paint(&self, ctx: &mut PaintCtx, _env: &Env) {
-        match &self.state {
-            CanvasToolState::DrawingFreehand { current_path } => current_path.draw(ctx),
-            _ => {}
-        }
-    }
-}

src/widget/canvas.rs

@@ -16,20 +16,29 @@
 
 use im::Vector;
 
+use super::tool_ctx::{CanvasToolCtx};
+use crate::canvas::Canvas;
 use crate::history::VersionedCanvas;
-use crate::tool::CanvasToolCtx;
 use crate::DocumentSnapshot;
 
 use druid::widget::prelude::*;
-use druid::{Color, Data, Env, Event};
+use druid::{Color, Data, Env, Event, PointerType};
 
 #[derive(Clone, Data)]
 pub struct CanvasState {
-    pub versioned_canvas: VersionedCanvas,
+    versioned_canvas: VersionedCanvas,
-    pub tool_ctx: CanvasToolCtx,
+    tool_ctx: CanvasToolCtx,
+    temporary_erasing: bool,
 }
 
 impl CanvasState {
+    pub fn new(tool_ctx: CanvasToolCtx) -> Self {
+        CanvasState {
+            versioned_canvas: VersionedCanvas::new(Canvas::new()),
+            tool_ctx: tool_ctx,
+            temporary_erasing: true,
+        }
+    }
     pub fn perform_undo(&mut self) {
         //if !self.is_drawing() {
         self.versioned_canvas.undo();
@@ -44,25 +53,75 @@ impl CanvasState {
 
     pub fn get_document_snapshot(&self) -> DocumentSnapshot {
         DocumentSnapshot {
-            canvas_elements: self.versioned_canvas.get().iter().cloned().collect(),
+            format_version_major: 0,
+            format_version_minor: 1,
+            canvas_elements: self
+                .versioned_canvas
+                .get()
+                .elements()
+                .iter()
+                .cloned()
+                .collect(),
         }
     }
 
     pub fn set_from_snapshot(&mut self, snapshot: DocumentSnapshot) {
-        self.versioned_canvas = VersionedCanvas::new(Vector::from(snapshot.canvas_elements));
+        self.versioned_canvas = VersionedCanvas::new(Canvas::new_with_elements(Vector::from(
+            snapshot.canvas_elements,
+        )));
     }
 
     pub fn set_tool_ctx(&mut self, ctx: CanvasToolCtx) {
         self.tool_ctx = ctx;
     }
+
+    pub fn get_tool_ctx(&self) -> &CanvasToolCtx {
+        &self.tool_ctx
+    }
+
+    pub fn get_tool_ctx_mut(&mut self) -> &mut CanvasToolCtx {
+        &mut self.tool_ctx
+    }
+
+    pub fn handle_event(&mut self, mut ctx: &mut EventCtx, event: &Event, env: &Env) {
+        self.tool_ctx
+            .handle_event(ctx, event, &mut self.versioned_canvas, env);
+    }
 }
 
 pub struct CanvasWidget;
 
 impl Widget<CanvasState> for CanvasWidget {
     fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut CanvasState, env: &Env) {
-        data.tool_ctx
+        ctx.request_focus();
-            .handle_event(ctx, event, &mut data.versioned_canvas, env);
+        let mut toggle_eraser_event = false;
+        let mut enable_temporary_erasing = false;
+        match event {
+            Event::MouseDown(mouse_event) => {
+                toggle_eraser_event = true;
+                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+            }
+            Event::MouseMove(mouse_event) => {
+                toggle_eraser_event = true;
+                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+            }
+            Event::MouseUp(mouse_event) => {
+                toggle_eraser_event = true;
+                enable_temporary_erasing = mouse_event.pointer_type == PointerType::Eraser;
+            }
+            _ => {}
+        }
+        // TODO: the first eraser toggle is not handled
+        if toggle_eraser_event && data.temporary_erasing != enable_temporary_erasing {
+            if enable_temporary_erasing {
+                ctx.submit_notification(crate::commands::PUSH_ERASER);
+            } else {
+                ctx.submit_notification(crate::commands::POP_ERASER);
+            }
+            data.temporary_erasing = enable_temporary_erasing;
+        } else {
+            data.handle_event(ctx, event, env);
+        }
     }
 
     fn lifecycle(
@@ -117,11 +176,9 @@ impl Widget<CanvasState> for CanvasWidget {
         // (ctx.size() returns the size of the layout rect we're painting in)
         let size = ctx.size();
         let rect = size.to_rect();
-        // Note: ctx also has a `clear` method, but that clears the whole context,
-        // and we only want to clear this widget's area.
-        ctx.fill(rect, &Color::WHITE);
 
-        for element in data.versioned_canvas.get().iter() {
+        ctx.fill(rect, &Color::WHITE);
+        for element in data.versioned_canvas.get().elements().iter() {
             element.draw(ctx);
         }
         if data.tool_ctx.needs_repaint() {

src/widget/mod.rs

@@ -1,5 +1,6 @@
 pub mod canvas;
 pub mod tool_icon;
+pub mod tool_ctx;
 
 pub use canvas::*;
 pub use tool_icon::*;

src/widget/tool_ctx.rs

@@ -0,0 +1,179 @@
+//  Stiletto
+//  Copyright (C) 2020 Stiletto Authors
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU Affero General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU Affero General Public License for more details.
+//
+//  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 crate::tool::{CanvasToolParams, CanvasToolType};
+use crate::canvas::{Canvas, CanvasElement};
+use crate::history::VersionedCanvas;
+
+use druid::kurbo::BezPath;
+use druid::{Data, Env, Event, EventCtx, MouseButton, MouseEvent, PaintCtx};
+
+#[derive(Clone, Data)]
+pub enum CanvasToolState {
+    Idle,
+    DrawingFreehand {
+        pen_params: CanvasToolParams,
+        current_path: CanvasElement,
+    },
+    Erasing,
+}
+
+#[derive(Clone, Data)]
+pub struct CanvasToolCtx {
+    initial_params: CanvasToolParams,
+    state: CanvasToolState,
+}
+
+impl CanvasToolParams {
+    pub fn tool_type(&self) -> CanvasToolType {
+        match self {
+            CanvasToolParams::Pen { .. } => CanvasToolType::Pen,
+            CanvasToolParams::Eraser => CanvasToolType::Eraser,
+        }
+    }
+}
+
+fn pressed(mouse_event: &MouseEvent) -> bool {
+    mouse_event.buttons.contains(MouseButton::Left)
+        || mouse_event.button == MouseButton::Left
+}
+
+impl CanvasToolCtx {
+    pub fn new(params: CanvasToolParams) -> Self {
+        CanvasToolCtx {
+            initial_params: params,
+            state: CanvasToolState::Idle,
+        }
+    }
+
+    pub fn handle_event(
+        &mut self,
+        ctx: &EventCtx,
+        event: &Event,
+        mut vcanvas: &mut VersionedCanvas,
+        env: &Env,
+    ) {
+        match self.initial_params.tool_type() {
+            CanvasToolType::Pen => self.handle_pen_event(&ctx, &event, &mut vcanvas, &env),
+            CanvasToolType::Eraser => self.handle_erase_event(&ctx, &event, &mut vcanvas, &env),
+        }
+    }
+
+    pub fn handle_erase_event(
+        &mut self,
+        _ctx: &EventCtx,
+        event: &Event,
+        vcanvas: &mut VersionedCanvas,
+        _env: &Env,
+    ) {
+        match (&mut self.state, event) {
+            (CanvasToolState::Idle, Event::MouseDown(mouse_event)) if pressed(mouse_event) => {
+                self.state = CanvasToolState::Erasing;
+            }
+            (CanvasToolState::Erasing, Event::MouseMove(mouse_event)) if pressed(mouse_event) => {
+                let eraser_rect = druid::Rect::from_center_size(mouse_event.pos, (5.0, 5.0));
+                let old_elements = vcanvas.get().elements();
+                let mut new_elements = old_elements.clone();
+                new_elements.retain(|elem| {
+                    // Check if the element intersects the eraser rect
+                    if elem.bounding_box().intersect(eraser_rect).area() > 0.0 {
+                        if elem.intersects_rect(eraser_rect) {
+                            return false;
+                        }
+                    }
+                    return true;
+                });
+                if new_elements.len() != old_elements.len() {
+                    vcanvas.update(|canvas: &mut Canvas| {
+                        *canvas = Canvas::new_with_elements(new_elements);
+                    });
+                }
+            }
+            (CanvasToolState::Erasing, Event::MouseUp(mouse_event)) if pressed(mouse_event) => {
+                self.state = CanvasToolState::Idle;
+            }
+            _ => {}
+        }
+    }
+
+    pub fn handle_pen_event(
+        &mut self,
+        _ctx: &EventCtx,
+        event: &Event,
+        vcanvas: &mut VersionedCanvas,
+        _env: &Env,
+    ) {
+        match (&mut self.state, event) {
+            (CanvasToolState::Idle, Event::MouseDown(mouse_event)) if pressed(mouse_event) => {
+                let mut kurbo_path = BezPath::new();
+                kurbo_path.move_to((mouse_event.pos.x, mouse_event.pos.y));
+                if let CanvasToolParams::Pen { thickness, color } = &self.initial_params {
+                    self.state = CanvasToolState::DrawingFreehand {
+                        pen_params: self.initial_params.clone(),
+                        current_path: CanvasElement::Freehand {
+                            path: crate::canvas::Path { kurbo_path },
+                            thickness: *thickness,
+                            stroke_color: color.clone(),
+                        },
+                    };
+                }
+            }
+            (
+                CanvasToolState::DrawingFreehand {
+                    ref mut current_path,
+                    ..
+                },
+                Event::MouseMove(mouse_event),
+            ) => if pressed(mouse_event) {
+                if let CanvasElement::Freehand { ref mut path, .. } = current_path {
+                    path.kurbo_path
+                        .line_to((mouse_event.pos.x, mouse_event.pos.y));
+                }
+            }
+            (CanvasToolState::DrawingFreehand { .. }, Event::MouseUp(mouse_event)) if pressed(mouse_event) => {
+                vcanvas.update(move |canvas: &mut Canvas| {
+                    let current_state = std::mem::replace(&mut self.state, CanvasToolState::Idle);
+                    if let CanvasToolState::DrawingFreehand { current_path, .. } = current_state {
+                        if let CanvasElement::Freehand {
+                            mut path,
+                            mut thickness,
+                            stroke_color,
+                        } = current_path
+                        {
+                            canvas.add_element(CanvasElement::Freehand {
+                                path,
+                                thickness,
+                                stroke_color,
+                            });
+                        }
+                    }
+                });
+            }
+            _ => {}
+        }
+    }
+
+    pub fn needs_repaint(&self) -> bool {
+        true
+    }
+
+    pub fn paint(&self, ctx: &mut PaintCtx, _env: &Env) {
+        match &self.state {
+            CanvasToolState::DrawingFreehand { current_path, .. } => current_path.draw(ctx),
+            _ => {}
+        }
+    }
+}

src/widget/tool_icon.rs

@@ -17,7 +17,7 @@
 use druid::widget::{Container, SizedBox, Svg, SvgData, ViewSwitcher, WidgetExt};
 use druid::{Color, Data, UnitPoint};
 
-use crate::tool::{CanvasToolParams, CanvasToolType};
+use crate::tool::CanvasToolParams;
 
 #[derive(Clone, Data)]
 pub struct CanvasToolIconState {
@@ -26,10 +26,6 @@ pub struct CanvasToolIconState {
 }
 
 impl CanvasToolIconState {
-    fn tool_type(&self) -> CanvasToolType {
-        self.tool_params.tool_type()
-    }
-
     fn svg_data(&self) -> SvgData {
         match self.tool_params {
             CanvasToolParams::Pen { .. } => include_str!("../../icons/pen.svg")
@@ -46,9 +42,9 @@ pub fn build_simple_tool_widget(
     width: f64,
     height: f64,
     padding: f64,
-) -> ViewSwitcher<CanvasToolIconState, (CanvasToolType, bool)> {
+) -> ViewSwitcher<CanvasToolIconState, CanvasToolIconState> {
-    ViewSwitcher::<CanvasToolIconState, (CanvasToolType, bool)>::new(
+    ViewSwitcher::<CanvasToolIconState, CanvasToolIconState>::new(
-        |tool_state, _| (tool_state.tool_type(), tool_state.selected),
+        |tool_state, _| tool_state.clone(),
         move |_, tool_state, _| {
             Box::new(
                 Container::new(
@@ -62,7 +58,7 @@ pub fn build_simple_tool_widget(
                 )
                 .border(
                     if tool_state.selected {
-                        Color::rgb(10, 10, 10)
+                        Color::rgb(10.0, 10.0, 10.0)
                     } else {
                         Color::BLACK
                     },